PAH Induction upon Pyrolysis of Hydroxyl-Terminated Polybutadiene-Based Solid Rocket Fuels

During the manufacture of pharmaceuticals, <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=45&amp;search=1%2C+4-Dioxane">1, 4-Dioxane</a> is used as a cleansing agent. It is also a byproduct of plastic manufacturing. The most likely exposure to 1, 4-Dioxane is at an industrial site. However, if any 1, 4-Dioxane is released into the environment during manufacturing there is a potential for it to migrate into ground water. The fact that 1, 4-Dioxane is so miscible in water makes degradation of the chemical challenging. Ethanol, on the other hand, has been a popular gasoline additive. Since it burns more quickly and completely than gasoline, emissions from car exhaust are decreased. The downside of this is underground storage tank leakage and fuel spills cause ground water and drinking water to be contaminated with both the fuel and the ethanol additive. Since ethanol is also very miscible in water, the detection of ethanol contamination in water can be difficult.&nbsp;There have been several innovations that help overcome the obstacles of detecting 1, 4-Dioxane and Ethanol. The first one is the SIM mode of the mass spectrometer. This mode allows better detection of hard to extract compounds. Furthermore, mass spectrometers are now equipped to run SIM/Scan, this not only helps detect more difficult compounds, but also enables the detection of an extensive list of <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=45&amp;search=USEPA+Method+8260">USEPA Method 8260</a> compounds without having to run the samples twice. Advancements in purge and trap sampling have also facilitated better detection of these compounds. Most effective in this has been the ability to heat the samples. However, there are drawbacks to better detection. The most problematic of these is the tendency of 1, 4-Dioxane and Ethanol to “stick” to the glass ware. This susceptibility has caused many headaches in environmental labs.&nbsp;This application note will investigate seven variations of <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=45&amp;search=purge+and+trap">purge and trap</a> sampling. The data will then be evaluated in order to recommend the optimum purge and trap sampling parameters for your lab.<h4>Experimental:&nbsp;</h4>The sampling system used for this study was the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2160">EST Analytical Evolution concentrator</a> affixed with a Vocarb 3000 trap. The <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2159">Centurion WS autosampler</a> equipped with the syringe option was employed as the autosampler. The separation and analysis were performed by an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=7890A+Gas+Chromatograph">Agilent 7890A Gas Chromatograph (GC)</a> and <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=5975C+Mass+Spectrometer">5975C inert XL Mass Spectrometer (MS).</a> The GC was configured with a <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=7&amp;search=Rxi-624+Sil+MS">Restek Rxi-624 Sil MS</a> 30m x 0.25mm x 1.4µm column. The purge and trap and GC/MS parameters used for this study are listed below.<h5>Purge and Trap Parameters</h5><ul><li>Concentrator: EST Encon Evolution</li><li>Trap type: Vocarb 3000</li><li>Valve oven temperature: 150 °C</li><li>Transfer line temperature: 150 °C</li><li>Trap temperature: 35 °C</li><li>Moisture Reduction Trap (MoRT) temperature: 39 °C</li><li>Purge time: 11 min</li><li>Purge flow: 40 mL/min</li><li>Dry purge: Ambient temperature, 40 mL/min, 1.0 min</li><li>Desorb pressure: 5 psi (with control ON)</li><li>Desorb time: 0.5 min</li><li>Desorb preheat delay: 10 sec</li><li>Desorb temperature: 250 °C</li><li>MoRT bake temperature: 210 °C</li><li>Bake temperature: 260 °C</li><li>Sparge vessel bake temperature: 40 °C for 3 min, ramp to 100–110 °C, hold</li><li>Bake time: 6 min</li><li>Bake flow: 85 mL/min</li></ul><h5>Auto-Sampler (EST Centurion WS):</h5><ul><li>Sample type: Water</li><li>Sample volume: 5 or 10 mL</li><li>Internal standard volume: 5 µL</li></ul><h5>GC/MS Parameters</h5><ul><li>System: Agilent 7890A GC / 5975C inert XL MS</li><li>Inlet: Split mode, 220 °C, 40:1 split ratio, 12.153 psi head pressure</li><li>Column: Restek Rxi-624Sil MS, 30 m × 0.25 mm × 1.4 µm</li><li>Oven program: 45 °C (1 min) → ramp 15 °C/min → 220 °C, hold 1.33 min (total run ~14 min)</li><li>Column flow rate: 1 mL/min helium</li><li>Total flow: 44 mL/min</li><li>Source temperature: 230 °C</li><li>Quadrupole temperature: 150 °C</li><li>Transfer line temperature: 180 °C</li><li>Scan range: m/z 35–300, 5.2 scans/sec</li><li>SIM ions:<ul><li>45, 46 (0.7–3.49 min)</li><li>58, 88 (3.5–14 min)</li></ul></li><li>Solvent delay: 0.7 min</li></ul>For each parameter iteration, see the text below, a calibration curve was established with a linear range of 0.5 to 200ppb using standards from Restek. After each of the prescribed curves was determined; Method Detection Limits (MDLs), precision and accuracy and carryover studies were performed. A series of seven low level standards were run in order to establish MDLs per 40CFR Part 136, Appendix B. Next, seven replicate samples of the 50ppb standard were run in order to establish the precision and the accuracy of the experimental parameters. Finally, a series of four 50ppb standards were run with each standard followed by three blanks. The amount of carryover was then analyzed in the first blank. The data from each parameter variation was compiled and compared in order to determine the optimum conditions for this analysis. An average of the results for each analysis condition is listed in Table 1.<h5>Purge and Trap Sampling Test Parameters</h5><ul><li>Baseline: 5 mL traditional sparger, room temp purge, 110 °C sparge bake</li><li>Iteration A: 5 mL traditional sparger, 40 °C purge, 110 °C sparge bake</li><li>Iteration B: 5 mL traditional sparger, 60 °C purge, 110 °C sparge bake</li><li>Iteration C: 5 mL traditional sparger, 40 °C purge, no sparge bake</li><li>Iteration D: 40 mL vial, 10 mL purge volume, 40 °C purge, no sparge bake</li><li>Iteration E: 5 mL fritless bulbless sparger, 40 °C purge, 110 °C sparge bake</li><li>Iteration F: 5 mL fritless bulbless sparger, 40 °C purge, no sparge bake (Iteration E used the patented Water/Soil prep mode)</li></ul><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Table_4_Averaged_Results_Summary_306dcbfde6.jpg" alt="EST Analytical: Table 1 Averaged Results Summary" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Table_4_Averaged_Results_Summary_306dcbfde6.jpg 245w," sizes="100vw" width="1493" height="351">The primary compounds of interest for the study were Ethanol and 1, 4-Dioxane. For this reason, the data for these compounds was compiled separately in order to better distinguish the benefits or detriment of each purge and trap parameter set. The experimental results of the precision and percent recovery studies are displayed in Tables 2 and 3.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Table_5_Ethanol_and_1_4_Dioxane_Precision_at_50ppb_3a195e1acb.jpg" alt="EST Analytical: Table 2 Ethanol and 1, 4-Dioxane Precision at 50ppb" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Table_5_Ethanol_and_1_4_Dioxane_Precision_at_50ppb_3a195e1acb.jpg 245w," sizes="100vw" width="1316" height="236"><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Table_6_Ethanol_and_1_4_Dioxane_Percent_Recovery_at_50ppb_cb12616f47.jpg" alt="EST Analytical: Table 3 Ethanol and 1, 4-Dioxane Percent Recovery at 50ppb" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Table_6_Ethanol_and_1_4_Dioxane_Percent_Recovery_at_50ppb_cb12616f47.jpg 245w," sizes="100vw" width="1318" height="234">For the carryover studies, Ethanol and 1, 4-Dioxane were examined along with the carryover of 1, 2, 4- Trichlorobenzene, Naphthalene and 1, 2, 3-Trichlorobenzene. The reason the heavier compounds were included in this study was a concern that changing the sampling parameters may help the Ethanol and 1, 4-Dioxane carryover, but harm the carryover of the heavier compounds of interest. Table 4 shows a listing of the carryover results, in parts per billion, while Figure 1 displays the percent carryover of the different purge and trap experimental parameters for just the Ethanol and 1, 4-Dioxane.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Table_7_Carryover_in_First_Blank_after_a_50ppb_Standard_7d2bc81626.jpg" alt="EST Analytical: Table 4 Carryover in First Blank after a 50ppb Standard" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Table_7_Carryover_in_First_Blank_after_a_50ppb_Standard_7d2bc81626.jpg 245w," sizes="100vw" width="1332" height="426"><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Figure_1_Ethanol_and_1_4_Dioxane_Percent_Carryover_after_a_50ppb_Standard_Graphic_f57c981913.jpg" alt="EST Analytical: Figure 1 Ethanol and 1, 4-Dioxane Percent Carryover after a 50ppb Standard Graphic" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Figure_1_Ethanol_and_1_4_Dioxane_Percent_Carryover_after_a_50ppb_Standard_Graphic_f57c981913.jpg 245w," sizes="100vw" width="1358" height="787">After all the studies were completed, two purge and trap parameter variations showed the best precision, percent recovery, and carryover while meeting the USEPA Method 8260 linearity and response factor requirements. An abbreviated listing of the results for these two iterations are shown in Table 5.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Table_8_Results_of_the_Water_Extraction_and_the_Fritless_Bulbless_Sparge_Vessel_With_Sparge_Bake_Studies_9b71ec4951.jpg" alt="EST Analytical: Table 5 Results of the Water Extraction and the Fritless - Bulbless Sparge Vessel With Sparge Bake Studies" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Table_8_Results_of_the_Water_Extraction_and_the_Fritless_Bulbless_Sparge_Vessel_With_Sparge_Bake_Studies_9b71ec4951.jpg 161w," sizes="100vw" width="1256" height="1221"><h4>Conclusions:&nbsp;</h4>All seven purge and trap parameter iterations passed the USEPA Method 8260 requirements for linearity and method detection limits. The problem with some of the experimental parameters was found in the carryover and precision and accuracy studies. The carryover using the traditional sparge vessel showed a large amount of carryover for the Ethanol and 1, 4-Dioxane. Since the carryover was so high, the precision and accuracy data suffered. The Fritless/Bulbless sparge vessel, on the other hand, displayed much lower carryover for the Ethanol and 1, 4-Dioxane especially when the patented sparge bake was not used. However, the 1, 2, 4-Trichlorobenzene, Naphthalene and 1, 2, 3-Trichlorobenzene carryover after the 50ppb standard was above the lower limit of the curve.&nbsp;Thus, the sparge bake would be recommended in order to limit the carryover of the heavier compounds. The optimum purge and trap parameters proved to be the patented water extraction technique. This technique provided linearity and method detection limits that met the USEPA Method 8260 requirements, while providing excellent precision and accuracy data. During water extraction, the sample is transferred to an empty 40ml vial and then purged in the soil station of the Centurion. The “fresh” vial provides a clean sparge vessel for every sample thus limiting carryover for both the Ethanol and 1, 4-Dioxane and for the heavy compounds. This lack of carryover aided in providing optimum precision and accuracy and carryover results and would be the recommended method for examining these troublesome compounds.

Optimization of 1,4-Dioxane and Ethanol Detection Using USEPA Method 8260

<a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=45&amp;search=USEPA+Method+524.2">USEPA Method 524.2</a> calls for purge and trap sampling coupled with a Gas Chromatograph (GC) and Mass Spectrometer (MS) for separation and analysis. It has an extensive list of compounds and requires lower detection limits due to its use in drinking water testing. A 20% relative standard deviation for compound response factors is required across the calibration curve while the calibration check standard analytes have to be within 30% of the expected concentration. Currently, this method calls for a 5mL or 25mL purge volume and a four minute desorb time. These method requirements can pose a challenge for the analyst due to the amount of moisture that is created.&nbsp;The negative effects of the increased water vapor include instability of the chromatography, band eluting and poor peak shape to name a few. A side effect of this instability is sample re-runs and lost laboratory productivity. In addition, a common practice for mitigating moisture is increasing the GC inlet split rate. This poses yet another difficulty as the increased split rate can result in reduced sensitivity. EST Analytical’s eight port valve in the Evolution purge and trap concentrator aids in limiting the water exposure because the water management of the system is not part of the desorb pathway. This feature also enables laboratories to use a smaller split ratio at the GC inlet thus increasing sensitivity.<h4>Experimental:&nbsp;</h4>The sampling system used for this study was the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2160">EST Analytical Evolution purge and trap concentrator</a> and the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2159">Centurion WS autosampler</a>. The concentrator was affixed with a Vocarb 3000 trap and connected to an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=7890A">Agilent 7890A GC</a> and <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=5975C">5975C inert XL MS</a>. The GC was configured with a <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=7&amp;search=Restek+Rxi-624+Sil+MS">Restek Rxi-624 Sil MS</a> 30m x 0.25mm x 1.4µm column. The purge and trap and GC/MS parameters used for this study are listed below.<h5>Purge and Trap Parameters</h5><ul><li>Concentrator: EST Evolution</li><li>Trap type: Vocarb 3000</li><li>Valve oven temperature: 130 °C</li><li>Transfer line temperature: 130 °C</li><li>Trap temperature: 35 °C</li><li>Moisture Reduction Trap (MoRT) temperature: 39 °C</li><li>Purge time: 11 min</li><li>Purge flow: 40 mL/min</li><li>Dry purge Temp.: Ambient</li><li>Dry Purge Flow: 40mL/min</li><li>Dry Purge Time: 1.0 min &nbsp;</li><li>Desorb pressure Control: ON</li><li>Desorb Pressure: 5psi</li><li>Desorb time: 4 min</li><li>Desorb preheat delay: 15 sec</li><li>Desorb temperature: 250 °C</li><li>MoRT bake temperature: 210 °C</li><li>Bake temperature: 260 °C</li><li>Sparge vessel bake temperature: 110 °C</li><li>Bake time: 6 min</li><li>Bake flow: 70 mL/min</li></ul><h5>Auto-Sampler (EST Centurion WS):</h5><ul><li>Sample type: Water</li><li>Water volume: 25 mL</li><li>Internal standard volume: 5 µL</li></ul><h5>GC/MS Parameters</h5><ul><li>System: Agilent 7890A GC / 5975C inert XL MS</li><li>Inlet: Split mode, 220 °C, 40:1 split ratio, 12.153 psi head pressure</li><li>Column: Restek Rxi-624Sil MS, 30 m × 0.25 mm × 1.4 µm</li><li>Oven program: 45 °C (1 min) → ramp 15 °C/min → 220 °C, hold 1.33 min (total run ~14 min)</li><li>Column flow rate: 1 mL/min helium</li><li>Total flow: 44 mL/min</li><li>Source temperature: 230 °C</li><li>Quadrupole temperature: 150 °C</li><li>Transfer line temperature: 180 °C</li><li>Scan range: m/z 35–300, 5.2 scans/sec</li><li>Solvent delay: 0.7 min</li></ul>A calibration curve was established with a linear range of 0.25 to 40µg/L using the USEPA Method 524.2 standards from Restek. After the curve was determined, method detection limits were ascertained by running a series of seven replicate 0.25 µg/L standards and calculated using the procedure outlined in 40 CFR Part 136 Appendix B. Finally, seven 20 µg/L standards were examined in order to verify the precision and accuracy of the analysis. The results of this study are displayed in Tables 1 and 2 while Figure 1 presents a 20 µg/L standard GC/MS chromatogram.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Table_3_Compound_Linearity_and_Response_Factor_Table_f63b77844f.jpg" alt="EST Analytical: Table 1 - Compound Linearity and Response Factor Table" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Table_3_Compound_Linearity_and_Response_Factor_Table_f63b77844f.jpg 153w," sizes="100vw" width="1104" height="1126"><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Table_4_MDL_and_Precision_and_Percent_Recovery_Table_27572600f0.jpg" alt="EST Analytical: Table 2 - MDL and Precision and Percent Recovery Table" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Table_4_MDL_and_Precision_and_Percent_Recovery_Table_27572600f0.jpg 186w," sizes="100vw" width="1358" height="1143"><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Figure_1_20mg_L_Standard_Chromatogram_7ff795984b.jpg" alt="EST Analytical: Figure 1 - 20 µg/L Standard Chromatogram" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Figure_1_20mg_L_Standard_Chromatogram_7ff795984b.jpg 245w," sizes="100vw" width="1431" height="789"><h4>Conclusions:&nbsp;</h4>This study demonstrated the effectiveness of the Evolution/Centurion purge and trap sampling system. The results passed all of the USEPA Method 524.2 criteria for both linearity and detection limits. Since the Evolution bypasses the water management trap during the four minute desorb process, the amount of water effecting the experiments was limited. Furthermore, the forty to one split ratio at the GC inlet provided excellent detection limits as the system was more sensitive to the low level standard requirements of the method. The lower split rate has an added benefit of reducing laboratory helium consumption when setting it against other system’s higher split ratios. Finally, the precision and percent recovery results showed the reliability of the system in producing accurate experimental findings.

USEPA 524.2 Method Validation Using the Evolution Purge and Trap Concentrator and the Centurion WS Autosampler

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 15th September 2025? Check out new documents from the field of the gas phase, especially GC and GC/MS techniques!<blockquote>👉 <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library">SEARCH THE LARGEST REPOSITORY OF DOCUMENTS ABOUT GCMS AND RELATED TECHNIQUES</a></blockquote><blockquote>👉 Need info about different analytical techniques? Peek into <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library">LabRulezLCMS</a> or <a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/library">LabRulezICPMS</a> libraries.</blockquote>This week we bring you posters by Agilent Technologies / ASMS, Shimadzu / ASMS and application note by EST Analytical!<h3>1. Agilent Technologies / ASMS: Beyond Aligners: Unmasking Hidden Extractables and Leachables in Orthodontic Devices</h3><ul><li>Poster</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/ps_7250_extractables_leachables_asms_2025_tp_318_en_ucsf_3e88cfbf5c.pdf">Full PDF for download</a></li></ul>Increasingly popular in orthodontics, clear aligners promised to users’ improved comfort, compliance and flexibility. It also came with prolonged intraoral exposure. The literature on the potential for leaching components of the polymer used to manufacture the invisible aligners is sparse. Despite the benefits, user submitted cases in the FDA retrospective analysis report several adverse effect ranging from swelling, hives, itchiness and even difficulty breathing1 . Previous works examined the potential of leaching in retainers but used conditions far from the in-vivo setting2 . We used samples closest to user conditions and harnessed the power of Gas Chromatography High Resolution Mass Spectrometry (GC-HRMS) and the power of curated and annotated libraries to find candidate compounds that could be at the origin of the reported adverse effects. We also used multivariate statistics to establish relationships between the compounds and metadata.<h4>Experimental</h4><h5>Sample Analysis&nbsp;</h5>Samples were analyzed using the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?manufacturerItems=1&amp;search=7250">Agilent 7250 accurate mass GC-qTOF</a> equipped with the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?manufacturerItems=1&amp;search=8890+GC">8890 GC</a> and a DB-5MS UI column (30m x 0.25 x 0.25). The inlet temperature was 280°C and the transfer line temperature was 325°C. The oven program was as follows: 50°C for 1 min, ramp at 25°C to 170°C, hold for 1 min; then ramp at 15°C to 300°C, hold for 10 min; then ramp at 20 °C to 325°C and hold for 5 min. The solvent delay was 4 min. The data were acquired in electron ionization (EI) mode using mass range 45 to 1000 m/z. The source temperature was 230°C, and the emission current was 5 µA. A mix of alkanes was run along with the samples and blanks and an Extractables and Leachables (E&amp;L) standard mixture was run as a quality check.&nbsp;<h5>Data Analysis&nbsp;</h5>Retention indices were used in consolidating library matches in both the Agilent HRMS E&amp;L library and the NIST23 library. Data analysis was conducted on Unknown Analysis software from Agilent that performs compound annotation based on library matching and retention index. All compounds were individually reviewed based on ExactMass, retention index delta and library match factor (Figure 2). Canonical Correlation Analysis was performed using the FactoMineR package in R.<h4>Conclusions</h4>The aligners used in the current study were approved in the late 90s when E&amp;Ls methods were not as prominent or sensitive as they are today. This study stands out with:&nbsp;<ul><li>The first report of numerous E&amp;L compounds with known potential adverse effects in a population of clear aligner users&nbsp;</li><li>Providing an insight of the relationships between E&amp;Ls and user’s metadata such as age, DWT and TSS&nbsp;</li><li>Providing the necessary libraries to find parent compounds and their potential metabolites</li></ul><h3>2. EST Analytical: Optimization of 1,4-Dioxane and Ethanol Detection Using USEPA Method 8260</h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/Purge_and_Trap_1_4_Dioxane_and_Ethanol_by_8260_App_Note_b669c79f53.pdf">Full PDF for download</a></li></ul>During the manufacture of pharmaceuticals, 1, 4-Dioxane is used as a cleansing agent. It is also a byproduct of plastic manufacturing. The most likely exposure to 1, 4-Dioxane is at an industrial site. However, if any 1, 4-Dioxane is released into the environment during manufacturing there is a potential for it to migrate into ground water. The fact that 1, 4-Dioxane is so miscible in water makes degradation of the chemical challenging. Ethanol, on the other hand, has been a popular gasoline additive. Since it burns more quickly and completely than gasoline, emissions from car exhaust are decreased. The downside of this is underground storage tank leakage and fuel spills cause ground water and drinking water to be contaminated with both the fuel and the ethanol additive. Since ethanol is also very miscible in water, the detection of ethanol contamination in water can be difficult.&nbsp;There have been several innovations that help overcome the obstacles of detecting 1, 4-Dioxane and Ethanol. The first one is the SIM mode of the mass spectrometer. This mode allows better detection of hard to extract compounds. Furthermore, mass spectrometers are now equipped to run SIM/Scan, this not only helps detect more difficult compounds, but also enables the detection of an extensive list of USEPA Method 8260 compounds without having to run the samples twice. Advancements in purge and trap sampling have also facilitated better detection of these compounds. Most effective in this has been the ability to heat the samples. However, there are drawbacks to better detection. The most problematic of these is the tendency of 1, 4-Dioxane and Ethanol to “stick” to the glass ware. This susceptibility has caused many headaches in environmental labs.&nbsp;This application note will investigate seven variations of purge and trap sampling. The data will then be evaluated in order to recommend the optimum purge and trap sampling parameters for your lab.<h4>Experimental</h4>The sampling system used for this study was the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2160">EST Analytical Evolution concentrator</a> affixed with a Vocarb 3000 trap. The <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2159">Centurion WS autosampler</a> equipped with the syringe option was employed as the autosampler. The separation and analysis were performed by an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?manufacturerItems=1&amp;search=7890A">Agilent 7890A Gas Chromatograph (GC)</a> and <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?manufacturerItems=1&amp;search=5975C">5975C inert XL Mass Spectrometer (MS)</a>. The GC was configured with a <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?manufacturerItems=9&amp;search=Rxi-624+Sil+MS">Restek Rxi-624 Sil MS</a> 30m x 0.25mm x 1.4µm column. The purge and trap parameters used for this study are listed in Tables 1 and 2 while Table 3 shows the GC/MS parameters.<h4>Conclusions</h4>All seven purge and trap parameter iterations passed the USEPA Method 8260 requirements for linearity and method detection limits. The problem with some of the experimental parameters was found in the carryover and precision and accuracy studies. The carryover using the traditional sparge vessel showed a large amount of carryover for the Ethanol and 1, 4-Dioxane. Since the carryover was so high, the precision and accuracy data suffered. The Fritless/Bulbless sparge vessel, on the other hand, displayed much lower carryover for the Ethanol and 1, 4-Dioxane especially when the patented sparge bake was not used. However, the 1, 2, 4-Trichlorobenzene, Naphthalene and 1, 2, 3-Trichlorobenzene carryover after the 50ppb standard was above the lower limit of the curve. Thus, the sparge bake would be recommended in order to limit the carryover of the heavier compounds. The optimum purge and trap parameters proved to be the patented water extraction technique. This technique provided linearity and method detection limits that met the USEPA Method 8260 requirements, while providing excellent precision and accuracy data. During water extraction, the sample is transferred to an empty 40ml vial and then purged in the soil station of the Centurion. The “fresh” vial provides a clean sparge vessel for every sample thus limiting carryover for both the Ethanol and 1, 4-Dioxane and for the heavy compounds. This lack of carryover aided in providing optimum precision and accuracy and carryover results and would be the recommended method for examining these troublesome compounds.<h3>3. Shimadzu / ASMS: Quantitation of Acetaldehyde, Ethylene Oxide, 2-Chloroethanol, Ethylene Glycol, 1,4-Dioxane &amp; Diethylene Glycol in PEG 3350 by using dynamic headspace GC-MS/MS</h3><ul><li>Poster</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/ASMS_2025_TP_301_ad1ab4ac3e.pdf">Full PDF for download</a></li></ul>Polyethylene glycol 3350 (PEG 3350) is used to treat occasional constipation and it is in a class of medications called osmotic laxatives. PEG 3350 is an addition polymer of ethylene oxide and water with formula H(OCH2CH2)n OH, in which n represents the average number of oxyethylene groups. The average molecular weight of PEG 3350 is 3015–3685 g/mol (Da). Acetaldehyde, Ethylene Oxide (EtO), 2-Chloroethanol (2-CE), Ethylene Glycol (EG), 1,4- Dioxane and Diethylene Glycol (DEG) are the probable impurities of PEG 3350. All these above impurities are highly toxic &amp; hazardous substances.&nbsp;As per the USP monograph, different chromatography techniques and sample preparation methods are used to quantify above mentioned impurities. This study reports a single sensitive and reliable analytical method for quantitation of all above impurities by using dynamic headspace (Trap) coupled with GC-MS/MS system. Limit of impurities and detail method of analysis are shown in table 1.This study reports highly sensitive single method for the simultaneous quantification of multiple probable impurities of PEG 3350 by using dynamic headspace (Trap) coupled with triple quadrupole gas chromatography (GC-MS/MS) system.&nbsp;<h4>Materials and methods&nbsp;</h4>For this study, individual impurity reference standards were procured from Sigma Aldrich, whereas PEG 3350 powder sample was procured from local medical store. 10% of PEG 3350 powder sample solution (as such sample solution) and respective levels of matrixmatched calibration standard solutions were prepared in acetonitrile. Standard addition method was used to quantify impurities in the PEG 3350 sample. This method was part validated with respect to (w.r.t) precision, linearity/accuracy and sample analysis. <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?manufacturerItems=3&amp;search=GCMS-TQ8050+NX">GCMS-TQ8050 NX</a> equipped with headspace sampler <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?manufacturerItems=3&amp;search=HS-20+NX">HS-20 NX </a>(Trap) (Figure 1), manufactured by Shimadzu Corporation Japan, was used to quantify impurities in the PEG 3350 sample<h4>Conclusion</h4><ul><li>Trace level quantification of Acetaldehyde, EtO, 2-CE, 1,4-Dioxane, EG and DEG in PEG 3350 sample was successfully performed by using Shimadzu GCMS-TQ8050 NX with HS-20 NX (Trap) dynamic headspace sampler.</li><li>Dynamic headspace mode outperforms the current regulatory limits, delivering multifold times more sensitivity compared to other injection techniques.</li><li>Shimadzu GCMS-TQ8050 NX features a new highly efficient detector and superior noise reduction technology that enhance sensitivity and enables quantitation of impurities even at trace levels.</li></ul>

News from LabRulezGCMS Library - Week 38, 2025

Our Library never stops expanding. What are the most recent contributions to LabRulezGCMS Library in the week of 22nd September 2025? Check out new documents from the field of the gas phase, especially GC and GC/MS techniques!<blockquote>👉 <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library">SEARCH THE LARGEST REPOSITORY OF DOCUMENTS ABOUT GCMS AND RELATED TECHNIQUES</a></blockquote><blockquote>👉 Need info about different analytical techniques? Peek into <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library">LabRulezLCMS</a> or <a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/library">LabRulezICPMS</a> libraries.</blockquote>This week we bring you application notes by Agilent Technologies, EST Analytical, Shimadzu and Thermo Fisher Scientific!<h3>1. Agilent Technologies: A Chemometric Approach for Ambient Air Monitoring Using Thermal Desorption GC/MS</h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/an_voc_8890_chemometric_ambient_air_monitoring_5994_8451en_agilent_fef7d171bb.pdf">Full PDF for download</a></li></ul>Monitoring VOCs is crucial for assessing air quality in industrial and urban settings. These compounds, which include propene, hexachlorobutadiene, and naphthalene, vary in volatility and encompass both polar and nonpolar chemicals. Recognizing the importance of standardized monitoring, the Bureau of Indian Standards (BIS) has developed specific methodologies for these compounds under the IS 5182 series.&nbsp;IS 5182-27 focuses on the measurement of vapor-phase organic chemicals such as vinyl chloride and nC22 hydrocarbons in air and gaseous emissions. This method employs diffusive (passive) sampling onto sorbent tubes or cartridges, followed by TD (see Figure 1) and capillary GC analysis. The passive sampling approach offers advantages in terms of ease of deployment and cost-effectiveness, making it suitable for widespread monitoring applications.To reveal relevant patterns and sources of variation in these large environmental datasets according to the IS-5182 guidance, this application note proposes chemometric analysis using the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=6&amp;search=TD100-xr">Markes TD100-xr automated thermal desorber</a> (Figure 2) and the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=8890+gc">Agilent 8890 GC system</a> with <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=5977c">5977C GC/MSD</a> (Figure 3). Chemometrics is a discipline that uses mathematics, statistics, and formal logic to design or select optimal experimental procedures. Chemometric techniques commonly used for clustering are the hierarchical agglomerative cluster analysis and PCA with factor analysis.<h4>Conclusion&nbsp;</h4>This application note highlights the comparison of different air sampling strategies and shows their effect on qualitative and quantitative analysis of VOCs. Active (pumped) sampling helped with faster analysis, which is required for controlled and sensitive real-time monitoring of ambient air. Chromatograms of air sampled at various locations showed the presence of VOCs such as benzene, toluene, ethyl benzene, and xylenes. Many common and unique compounds were found at each location. The intensity of these compounds showed variations at different locations. Fewer compounds with lower intensities were observed in air samples from a residential area, whereas more compounds with higher intensities were observed in air samples from a traffic area.&nbsp;Passive sampling was a comparatively cost‑effective and long-term approach and provided consistent replicate results. The chromatographic overlays of different sampling times indicated an increasing trend in peak intensities with respect to time. There was a considerable rise in peak intensities for the 1-week sampling period, as compared to 24-hour sampling. There was a slight rise in peak intensities for the 2-week sampling period, as compared to 1-week sampling. The PCA plot suggested the peak distribution obtained in each dataset. One-week sampling results showed consistent replicate results. Use of the chemometrics software Agilent Mass Profiler Professional added value by providing data visualization for interpretation.<h3>2. EST Analytical: USEPA 524.2 Method Validation Using the Evolution Purge and Trap Concentrator and the Centurion WS Autosampler</h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/Purge_and_Trap_524_2_Application_Note_2d327854f2.pdf">Full PDF for download</a></li></ul>USEPA Method 524.2 calls for purge and trap sampling coupled with a Gas Chromatograph (GC) and Mass Spectrometer (MS) for separation and analysis. It has an extensive list of compounds and requires lower detection limits due to its use in drinking water testing. A 20% relative standard deviation for compound response factors is required across the calibration curve while the calibration check standard analytes have to be within 30% of the expected concentration.&nbsp;Currently, this method calls for a 5mL or 25mL purge volume and a four minute desorb time. These method requirements can pose a challenge for the analyst due to the amount of moisture that is created. The negative effects of the increased water vapor include instability of the chromatography, band eluting and poor peak shape to name a few. A side effect of this instability is sample re-runs and lost laboratory productivity. In addition, a common practice for mitigating moisture is increasing the GC inlet split rate. This poses yet another difficulty as the increased split rate can result in reduced sensitivity. EST Analytical’s eight port valve in the Evolution purge and trap concentrator aids in limiting the water exposure because the water management of the system is not part of the desorb pathway. This feature also enables laboratories to use a smaller split ratio at the GC inlet thus increasing sensitivity.<h4>Experimental</h4>The sampling system used for this study was the<a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2160"> EST Analytical Evolution purge and trap concentrator </a>and the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2159">Centurion WS autosampler</a>. The concentrator was affixed with a Vocarb 3000 trap and connected to an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?manufacturerItems=1&amp;search=7890A">Agilent 7890A GC</a> and <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?manufacturerItems=1&amp;search=5975C">5975C inert XL MS</a>. The GC was configured with a <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?manufacturerItems=9&amp;search=Rxi-624+Sil+MS">Restek Rxi-624 Sil</a> MS 30m x 0.25mm x 1.4µm column. Sampling parameters are listed in Table 1 while Table 2 enumerates the GC/MS parameters.<h4>Conclusions</h4>This study demonstrated the effectiveness of the Evolution/Centurion purge and trap sampling system. The results passed all of the USEPA Method 524.2 criteria for both linearity and detection limits. Since the Evolution bypasses the water management trap during the four minute desorb process, the amount of water effecting the experiments was limited. Furthermore, the forty to one split ratio at the GC inlet provided excellent detection limits as the system was more sensitive to the low level standard requirements of the method. The lower split rate has an added benefit of reducing laboratory helium consumption when setting it against other system’s higher split ratios. Finally, the precision and percent recovery results showed the reliability of the system in producing accurate experimental findings.<h3>3. Shimadzu: Dual-Column Analysis of Blood AlcoholContent (BAC) Using Nitrogen Carrier Gas with <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=Brevis+GC-2050">Brevis GC-2050</a></h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/an_01_00899_en_af0d9bafe7.pdf">Full PDF for download</a></li></ul>Analysis of blood alcohol content (BAC) and other volatile organic compounds (VOCs) is essential for law enforcement agencies to determine alcohol intoxication and its role in traffic accidents, assaults, and injuries, as well as to identify the causes of certain criminal behaviors, poisonings, and so on.&nbsp;Typically, this analysis is performed by a gas chromatograph (GC) that is combined with a headspace sampler (HS) and a flame ionization detector (FID). Since accurate results are essential with BAC analysis, 2 columns can be used with different separation characteristics so that cross-checking can be performed. By using an integrated HS-GC system equipped with 2 FIDs connecting to a dual-column configuration, crosschecking can be performed in a single analysis. In this system, the columns are directly connected to the transfer line using a 2-hole ferrule, which minimizes sample losses due to adsorption.&nbsp;In addition to the high-end <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=Nexis+GC-2030">Nexis GC-2030</a>, Shimadzu also offers the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=Brevis+GC-2050">Brevis GC-2050</a> as a compact gas chromatography solution, and in this Application News, it is used with an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=1&amp;search=HS-20+NX+headspace+sampler">HS-20 NX headspace sampler </a>(Fig. 1) to perform BAC analysis. Hydrogen was used as the carrier gas in a similar experiment in Application News 01-00570, but in this experiment, nitrogen was used because it is a cheaper alternative carrier gas. Nitrogen generally has an adverse effect on separation, so this experiment also investigated the conditions for separation for 10 types of blood VOCs.<h4>Separation of 10 Blood VOCs&nbsp;</h4>A solution of 10 VOCs spiked with blood (0.1 mg/mL) was analyzed to determine the separation of methanol, acetaldehyde, ethanol, isopropyl alcohol, acetonitrile, acetone, tert-butanol, 1-propanol, methyl ethyl ketone, and ethyl acetate. The resulting chromatogram is shown in Fig. 6. All peaks were detected within 6.0 minutes in the BAC PLUS1 column and within 3.5 minutes in the BAC PLUS2 column, indicating good separation. The elution sequence of the 10 blood VOCs differed significantly between the columns, which enhanced the system’s qualitative capability. Table 4 shows the retention time of each compound and the repeatability (n=5) of the peak area ratio for the tert-butanol internal standard.<h4>Conclusion&nbsp;</h4>This experiment involved dual-column analysis of blood alcohol content (BAC) by the compact Brevis GC-2050 and the HS-20 NX. Dual-column configuration enables cross-checking in a single analysis. In addition, nitrogen was used as the carrier gas instead of helium. While hydrogen enables high-speed analysis, it also requires careful handling, so from the perspective of safety, installation of various optional tools such as hydrogen sensor and stop valve have been recommended. Nitrogen gas is relatively inexpensive and easy to handle, and this experiment demonstrated that it also provides reliable results while maintaining good separation.<h3>4. Thermo Fisher Scientific: Routine analysis of 7N high purity gallium phosphide by Glow Discharge Mass Spectrometry</h3><ul><li>Application note</li><li><a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/labrulez-bucket-strapi-h3hsga3/an_003578_ioms_gd_ms_element_gd_plus_gallium_an003578_em_en_1666255eb4.pdf">Full PDF for download</a></li></ul>Gallium phosphide (GaP) is a semiconductor material used in electronic and optoelectronic devices, including light-emitting Diodes (LEDs), solar cells as well as high-frequency and high-power electronics1-5. GaP wafers offer several advances over traditional silicon wafers, including high efficiency, high-speed operation, and highpower handling capabilities4-5.&nbsp;This application note describes the direct analysis of impurities in high purity gallium phosphide with sub-ppb detection limits using the Thermo Scientific <a target="_blank" rel="noopener noreferrer" href="https://icpms.labrulez.com/products/1690">Element GD PLUS GD Mass Spectrometer</a>.&nbsp;<h4>Experiment&nbsp;</h4>The flat samples are analyzed directly, with no digestion required. Instrumental conditions for the analysis with the Element GD PLUS GD-MS are shown in Table 1. Potential sample surface contaminations were removed by short presputtering within the instrument.&nbsp;<h4>Method development&nbsp;</h4>The developed method ensures a reliable separation of interferences from the analyte ions. The interferences PO, POH and GaGa could potentially lead to falsely high Ti, Ba and Ce results. The formation of these interferences is low in the fast-flow source of the Element GD PLUS GD-MS: 69Ga69Ga/69Ga ≈ 1 ppm and ( 31P16O1 H + 31P17O)/31P ≈ 10 ppm. They can easily be resolved at Medium Mass Resolution (R = M / Δm = 4000). This is visualized in the mass scans shown in Figures 1 and 2 with much wider mass windows than later being used for quantification. Therefore, the Medium Mass Resolution of the Element GD PLUS GD-MS enables interference free measurements of Ti, Ba and Ce in GaP matrix.<h4>Conclusions&nbsp;</h4>Trace contaminations in 7N high purity gallium phosphide can be determined reliably and routinely with the Element GD PLUS GD-MS without prior digestion.&nbsp;While most analytes like Ti, Ba and La are resolved from interferences in medium mass resolution (R = 4000), high mass resolution (R = 10000) is required for Ag because of the GaAr interference. Sub-ppb detection limits, even for elements like Sb and Ge, are achieved by neglectable formation of triatomic interferences and reduced abundance sensitivity. That is enabled by the fast-flow source design and the reverse Nier-Johnson geometry.Semiquantitative quantification of element concentrations can be performed without standard reference materials using the standard RSF factor approach. The high sensitivity of the instrument, the reliable separation of interferences in medium and high mass resolution, the outstanding peak stability, the low formation of interferences and the low abundance sensitivity enable limits of detection of 0.05 to 1 ppb for most elements.&nbsp;The sum of all impurities in the GaP sample was below 50 ppb, implying that a purity of 7N GaP can be assessed with the instrument.

News from LabRulezGCMS Library - Week 39, 2025

<h4>Abstract&nbsp;</h4>Before the advent of orange juice from concentrate, people would fresh squeeze oranges for their juice. Concentrate helped make orange juice easier to make and increased its popularity. Following concentrate, manufacturers used flash pasteurization and created ready to drink orange juice and again sales increased. Due to disease in the orange groves and the possibility of the crops getting destroyed by frost, the production of orange juice has gotten more expensive. The increase in production costs creates competition within the orange juice industry to create an orange juice that the public will enjoy and increase their consumption. This application will look at the flavor compound abundances of three different brands of orange juice using purge and trap concentration.&nbsp;<h4>Introduction</h4>Pasteurization is the first step in the creation of commercial orange juice. This is required in order to kill any harmful bacteria in the juice before it is sold. After the juice is pasteurized, it can be sold. However, since different orange varieties are in season at different times, most juice is squeezed and stored. The storage times vary and with storage there can be other issues. One of these issues is oxidation. Thus, many companies remove the oxygen from the juice before they store it. Between pasteurization and oxygen removal, the juice will lose some of its flavor. This is where juice manufacturers can differentiate themselves.&nbsp;Flavor compounds and amounts can make a substantial difference in the overall taste, acidity and odor of the juice. So, to create a juice that the public wants to buy, it is essential that the analysis of the flavor compounds and the percentage of these flavors be accounted for. Purge and trap is an excellent technique for the extraction of volatile flavor compounds within a liquid matrix. This is an exhaustive technique and generates reproducible results. This application will compare the reproducibility and ratios of flavor compounds in orange juice using the EST Analytical Evolution purge and trap concentrator.&nbsp;<h4>Experimental</h4>The <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2160">EST Analytical Evolution purge and trap concentrator </a>was set up with a Vocarb™ 3000 trap while the <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/products/2159">Centurion WS autosampler</a> was set to run in soil mode. The sampling system was configured to an <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=7890A">Agilent 7890A Gas Chromatograph (GC)</a> and <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=10&amp;search=5975C">5975C inert XL Mass Spectrometer (MS) </a>for separation and analysis. As the compounds of interest for this analysis were volatile, a <a target="_blank" rel="noopener noreferrer" href="https://gcms.labrulez.com/library?mainauthorItems=7&amp;search=Restek+Rxi-624+Sil+MS">Restek Rxi® 624 Sil MS</a> 30m X 0.25mm X 1.4µm column was affixed in the GC. Sampling and analysis parameters were optimized and are listed below.<h5>Purge and Trap Parameters</h5><ul><li>Concentrator: EST Encon Evolution</li><li>Trap type: Vocarb 3000</li><li>Valve oven temperature: 150 °C</li><li>Transfer line temperature: 150 °C</li><li>Trap temperature: 35 °C</li><li>Moisture Reduction Trap (MoRT) temperature: 39 °C</li><li>Purge time: 11 min</li><li>Purge flow: 40 mL/min</li><li>Dry purge Temp.: Ambient</li><li>Dry Purge Flow: 40mL/min</li><li>Dry Purge Time: 1.0 min &nbsp;</li><li>Desorb pressure Control: ON</li><li>Desorb Pressure: 6psi</li><li>Desorb time: 0.5 min</li><li>Desorb preheat delay: 5 sec</li><li>Desorb temperature: 260 °C</li><li>MoRT bake temperature: 210 °C</li><li>Bake temperature: 270 °C</li><li>Sparge vessel bake temperature: 120 °C</li><li>Bake time: 8 min</li><li>Bake flow: 85 mL/min</li></ul><h5>Auto-Sampler (EST Centurion WS):</h5><ul><li>Sample type: Soil</li><li>Sample Fill Mode: Syringe</li><li>Water Heater Temp.: 85°C</li><li>Sample Preheat Time: 0.5min</li><li>Sample Preheat Temp.: 40°C</li><li>Soil Valve Temp.: 85°C</li><li>Soil Transfer Line Temp.: 150°C</li><li>Minimizer Time: 2 min</li></ul><h5>GC/MS Parameters</h5><ul><li>System: Agilent 7890/5975C</li><li>Inlet: Split mode, 220 °C, 40:1 split ratio, 12.153 psi head pressure</li><li>Liner: Restek Split liner, 1mm x 6.3 x 78.5</li><li>Column: Restek Rxi-624Sil MS, 30 m × 0.25 mm × 1.4 µm</li><li>Oven program: 45 °C (1 min) → ramp 15 °C/min → 300 °C, hold 5.00 min (total run ~23 min)</li><li>Column flow rate: 1 mL/min helium</li><li>Total flow: 44 mL/min</li><li>Source temperature: 230 °C</li><li>Quadrupole temperature: 150 °C</li><li>Transfer line temperature: 180 °C</li><li>Scan range: m/z 30–350, 4.4 scans/sec</li><li>Solvent delay: 0.7 min</li></ul>Three&nbsp;different&nbsp;orange&nbsp;juice&nbsp;brands&nbsp;were&nbsp;purchased&nbsp;at&nbsp;the&nbsp;local&nbsp;market.&nbsp;&nbsp;Ten&nbsp;milliliters&nbsp;of&nbsp;each&nbsp;orange&nbsp;juice&nbsp;was&nbsp;measured&nbsp;and&nbsp;placed&nbsp;in&nbsp;a&nbsp;40ml&nbsp;vial.&nbsp;&nbsp;Each&nbsp;vial&nbsp;was&nbsp;then&nbsp;deposited&nbsp;in&nbsp;the&nbsp;Centurion&nbsp;WS&nbsp;autosampler&nbsp;to&nbsp;be&nbsp;purged&nbsp;in&nbsp;soil&nbsp;mode&nbsp;and&nbsp;concentrated&nbsp;on&nbsp;a&nbsp;Vocarb&nbsp;3000&nbsp;trap&nbsp;in&nbsp;the&nbsp;Evolution&nbsp;concentrator.&nbsp;Finally,&nbsp;the&nbsp;samples&nbsp;were&nbsp;in&nbsp;run&nbsp;in&nbsp;triplicate&nbsp;in&nbsp;order&nbsp;to&nbsp;ensure&nbsp;the&nbsp;reproducibility&nbsp;of&nbsp;the&nbsp;results.&nbsp;&nbsp;Agilent&nbsp;MassHunter&nbsp;Qualitative&nbsp;Analysis&nbsp;software&nbsp;was&nbsp;used&nbsp;for&nbsp;the&nbsp;determination&nbsp;of&nbsp;the&nbsp;flavor&nbsp;compounds&nbsp;in&nbsp;the&nbsp;juice&nbsp;samples.&nbsp;&nbsp;Table&nbsp;1&nbsp;displays&nbsp;the&nbsp;reproducibility&nbsp;of&nbsp;the&nbsp;sampling&nbsp;process&nbsp;whereas&nbsp;Table&nbsp;2&nbsp;lists&nbsp;a&nbsp;comparison&nbsp;of&nbsp;the&nbsp;flavor&nbsp;compound&nbsp;abundances.&nbsp;&nbsp;<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Table_1_Reproducibility_of_the_Results_fa8fd6f4be.jpg" alt="EST Analytical: Table 1 Reproducibility of the Results" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Table_1_Reproducibility_of_the_Results_fa8fd6f4be.jpg 245w," sizes="100vw" width="1199" height="754"><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Table_2_Flavor_Compound_Abundance_Summary_d16be388f3.jpg" alt="EST Analytical: Table 2 Flavor Compound Abundance Summary" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Table_2_Flavor_Compound_Abundance_Summary_d16be388f3.jpg 244w," sizes="100vw" width="1197" height="767">Figure&nbsp;1&nbsp;is&nbsp;a&nbsp;bar&nbsp;graph&nbsp;comparison&nbsp;of&nbsp;the&nbsp;compounds&nbsp;in&nbsp;the&nbsp;three&nbsp;juice&nbsp;brands&nbsp;while&nbsp;Figures&nbsp;2,&nbsp;3&nbsp;and&nbsp;4&nbsp;are&nbsp;the&nbsp;respective&nbsp;chromatograms&nbsp;of&nbsp;the&nbsp;juice&nbsp;samples.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Figure_1_Bar_Graph_Compound_Abundance_Comparison_f2fd098cdf.jpg" alt="EST Analytical: Figure 1 Bar Graph Compound Abundance Comparison" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Figure_1_Bar_Graph_Compound_Abundance_Comparison_f2fd098cdf.jpg 221w," sizes="100vw" width="1342" height="950"><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Figure_2_Brand_A_Chromatogram_0d5f5f8daa.jpg" alt="EST Analytical: Figure 2 Brand A Chromatogram" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Figure_2_Brand_A_Chromatogram_0d5f5f8daa.jpg 245w," sizes="100vw" width="1399" height="871"><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Figure_3_Brand_B_Chromatogram_eefc215bd1.jpg" alt="EST Analytical: Figure 3 Brand B Chromatogram" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Figure_3_Brand_B_Chromatogram_eefc215bd1.jpg 245w," sizes="100vw" width="1390" height="887"><img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/EST_Analytical_Figure_4_Brand_C_Chromatogram_07adab6c82.jpg" alt="EST Analytical: Figure 4 Brand C Chromatogram" srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_EST_Analytical_Figure_4_Brand_C_Chromatogram_07adab6c82.jpg 245w," sizes="100vw" width="1399" height="871"><h4>Conclusions</h4>Using the EST Analytical Evolution purge and trap concentrator coupled to the Centurion WS autosampler to evaluate flavor compounds in orange juice samples proved to be a reliable sampling technique. The results were reproducible and the chromatography was excellent. The three different orange juice brands had very similar chromatograms; however upon further analysis many subtle differences in the abundances of the flavor compounds could be discerned. Traditionally, headspace and solid phase micro extraction sampling are used for this type of analysis. However, the purge and trap sampling technique used for this examination offered an excellent alternative for the determination of the volatile components in a juice matrix.

Flavor Compound Abundances in Orange Juice Comparison Using Purge and Trap

Synthesis and Identification of 3-Oxazolines in Cocoa

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