HPLC gradients are a fantastic means of analyzing a sample for which the analytes exhibit a wide range of retentive strengths along the stationary-phase of your preferred column. Gradients are not always accommodating towards buffers when attempting to maintain a specific pH. If the buffer is limited to your aqueous mobile-phase while the organic mobile-phase remains strictly an organic solvent, then the gradient is prone to solubility limitations and inconsistent buffering strength as the ratio of organic solvent increases during the gradient. This may be overcome by applying an even distribution of the buffer towards both the “weak” and “strong” mobile-phases of your method, for which we will review some approaches and examples.How about spiking both the “weak” and “strong” mobile-phases with an acidic or basic additive, such as the formic acid (HCO2H) at 0.1% (v/v)?The spike in both mobile-phases will ideally maintain a consistent level of the additive in the overall mobile-phase as the ratio of “weak” and “strong” mobile-phases alters during the gradient. The shortcomings of such a spike are that the additive may be prone to volatilization from the mobile-phase mixture, while also inducing inconsistent strengths of protonation or deprotonation towards analytes. Perhaps some of us can admit to having been less than precise in our preparation of (v/v) spikes at one time or another. Alternatively, a proper buffer with the corresponding salt for a specific additive will precisely maintain the consistent pH at which it is prepared without the risk of the additive volatilizing.Ammonium formate (NH4HCO2) and ammonium acetate (NH4CH3CO2) buffers are the most amenable towards gradients, as these salts are soluble in methanol, while the corresponding aqueous buffers may be mixed with high ratios of acetonitrile. The necessary buffering strength typically ranges only 5 – 10 mM in each mobile-phase, but compare this with an isocratic method of 60:40 “20 mM buffer”/acetonitrile, for which the buffer concentration relative to the overall mobile-phase is only 12 mM. Figure 1 features an analysis of Mycotoxins on a <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/1514">Kinetex™ Biphenyl</a> with 5 mM ammonium acetate buffers comprising both the aqueous and methanol mobile-phases, and for which the ammonium acetate was dissolved directly in the methanol.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_The_effects_of_gradient_on_buffer_capacity_3_788ba526cf.jpg" alt="Phenomenex: The effects of gradient on buffer capacity: Figure 1 - Mycotoxin Analysis on Kinetex Biphenyl (App ID 21951)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_The_effects_of_gradient_on_buffer_capacity_3_788ba526cf.jpg 245w," sizes="100vw" width="904" height="475">Acetonitrile will need to be mixed with an aqueous buffer of common buffering reagents to maintain the solubility of the buffering salt. Figure 2 features the HILIC-mode analysis of underivatized amino acids on a <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/1542">Biozen™ Glycan</a>, for which a stock buffer of 100 mM ammonium formate buffer (pH 3.1) was spiked into either water or acetonitrile in a 9:1 ratio of solvent/buffer. The resulting mobile phases each featured overall buffer concentrations of 10 mM ammonium formate, allowing the gradient to maintain a consistent overall buffering strength.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_The_effects_of_gradient_on_buffer_capacity_2_bb25c9ae6a.jpg" alt="Phenomenex: The effects of gradient on buffer capacity: Figure 2 - Underivatized Amino Acids on bioZen Glycan (Tech Note 1264)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_The_effects_of_gradient_on_buffer_capacity_2_bb25c9ae6a.jpg 245w," sizes="100vw" width="987" height="486">Ammonium fluoride (NH4F) is often included in small amounts (0.1 – 0.2 mM) in the overall mobile-phase to generate highly sensitive fluoride adducts [M+F]- during ESI-negative mode LC/MS, or to encourage the generation of either [M+H]+ or [M+NH4]+ ions in ESI-positive mode. Figure 3 demonstrates the use of a third solvent line by which a 1 mM NH4F buffer is constantly delivered at a ratio of 10% of the overall mobile-phase, corresponding to 0.1 mM in the overall mobile-phase throughout the gradient. Ternary and quaternary pumps facilitate this method, but an initial isocratic hold is recommended at the beginning of the method to accommodate the transferability of the method among instruments. Ternary and quaternary gradients are subject to dwell volumes that are specific to each instrument, and can be a concern even when one of the solvent lines is maintained at a constant percentage of the overall gradient.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_The_effects_of_gradient_on_buffer_capacity_dd2c7475e7.jpg" alt="Phenomenex: The effects of gradient on buffer capacity: Figure 3 - Microcystins on Luna Omega Polar C18 (App ID 23568)." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_The_effects_of_gradient_on_buffer_capacity_dd2c7475e7.jpg 245w," sizes="100vw" width="1071" height="550">Be mindful of solubility considerations when attempting to incorporate either ammonium bicarbonate buffers or phosphate buffers into a gradient, particularly when working with phosphate buffers. These buffers run the risk of precipitation when blended with high percentages of organic solvents, and a solubility study is recommended. Lastly, be sure to include your intended mobile-phase buffer as a portion of your sample diluent to align the pH of your mobile phase, which will benefit the peak shape and reproducibility. Using a gradient where the mobile phase has a consistent buffering strength and pH value will ultimately improve the reproducibility of the LC method.

The effects of gradient on buffer capacity

When looking at data generated from HPLC analysis, it is natural to focus on retention time, peak asymmetry and efficiency. These parameters will allow the user to identify and quantify analytes: the more precise this information is the greater the confidence in peak identity and analyte concentration.Capacity factor is often an overlooked parameter of separations, but when utilized correctly can guide the user to produce more robust methodology. The capacity factor serves to normalize the retention time of an analyte to the dimensions of the analytical column, and is defined as:<h5 style="text-align:center;">K’ = tr - t0/t0</h5>Where tr is the retention time of the analyte, and t0 the elution time of an unretained compound.The importance of capacity factor can best be illustrated by an example: &nbsp;<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_How_can_capacity_factors_drive_method_robustness_2_f6553ef593.jpg" alt="Phenomenex: How can capacity factors drive method robustness? 1. Oxalic acid, 2. Tartaric acid, 3. Glycolic acid, 4. Formic acid, 5. Pyruvic acid, 6. Malonic acid, 7. Acetic acid, 8. Maleic acid, 9. Citric acid." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_How_can_capacity_factors_drive_method_robustness_2_f6553ef593.jpg 245w," sizes="100vw" width="547" height="345">Here we have a separation of organic acids, run on a C18 column which is stable to 100% aqueous conditions. The mobile phase is 20 mM potassium phosphate buffer at pH 2.9, with a flow rate of 0.7 ml/min. At first glance oxalic acid is retained at almost 4 minutes, but upon looking at this a little more closely the t0 for this column is approximately 3.7 minutes. When this is considered it is clear that oxalic acid, a very polar diacid, is barely retained by the column at all.<h5 style="text-align:center;">K’ = 3.9 - 3.7/3.7 = 0.054</h5>This indicates that oxalic acid spends almost no time associating with the stationary phase during its transit through the column. In such cases analyte retention will be greatly influenced by small, unintentional changes in parameters including:<ul><li>Mobile phase composition</li><li>Mobile phase pH</li><li>Sample diluent strength</li><li>Temperature</li></ul>Such a method is therefore unlikely to be robust, with oxalic acid retention varying from run to run, column to column and from one batch of mobile phase to another.This leads to the recommendation, whenever methods are being developed, that capacity factors should lie in the range of 2 - 10. We have seen the potential for problems with capacity factors of less than 2, but why stop at a capacity factor of 10?During an isocratic run, peak width increases with increasing retention time due to diffusion. Whilst the use of smaller particle columns and optimal flow rates will help to reduce this diffusion, it cannot be eliminated. Additionally, high capacity factors ultimately result in long run times, which are generally undesirable in a productive laboratory environment.&nbsp;<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_How_can_capacity_factors_drive_method_robustness_22b7c55c44.jpg" alt="Phenomenex: How can capacity factors drive method robustness? 1. Hydrocortisone, 2. Corticosterone, 3. 11-a-Hydroxyprogesterone, 4. Cortisone acetate, 5. 11-Ketoprogesterone." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_How_can_capacity_factors_drive_method_robustness_22b7c55c44.jpg 245w," sizes="100vw" width="685" height="339">Here we have an example of steroids run on a 150 x 4.6 mm column at 1 ml/min. 11-etoprogesterone elutes at around 17.5 minutes, with a capacity factor of approximately 10.6. Peak broadening is evident in this isocratic run, indicating that the latest eluting peak is being retained on column for an excessive period of time.Understanding the guideline (capacity factors of between 2 and 10) is helpful, but leaves us with the question, how can they be adjusted?The capacity factor is inversely related to the elutropic strength of the mobile-phase. A higher elutropic strength will lower the capacity factor, and vice versa. When low capacity factors cannot be increased by reducing the elutropic strength of the mobile phase then it may be necessary to switch to a stationary phase that can offer greater retention of the analytes, for example by using a more polar stationary phase for polar analytes.

How can capacity factors drive method robustness?

In this technical tip, we will address the common issue of peak tailing encountered when working with basic analytes and “type A” silicas and offer two strategies to overcome it.<h4>Introduction:</h4>Early reversed phase columns were based on “type A” silicas, these materials had substantial metal contamination, causing the silanol groups on the surface of the silica to have greater and more variable activity. Manufacturers endcapped the materials as far as possible after bonding with C18 reagents, in an attempt to reduce the number of sites where ion exchange could take place. However basic compounds would generally tail badly. Let’s explore how we can overcome this limitation.<h4>Strategies for peak shape improvement:</h4><ul><li>Working at low pH can help neutralise the silanol groups on the silica surface, preventing ion exchange from taking place. A 10-20 mM phosphate buffer, pH 2.5 is ideal for this purpose, although care must be taken if using acetonitrile as the organic solvent, to avoid precipitating the phosphate buffer when running a gradient.</li><li>Adding a competing base (or silanol suppressor) to the mobile phase. Mobile phase additives like TEA (triethylamine) at 5 mM concentration would typically be used. The idea here is that the competing base associates with the anionic silanol groups, reducing their availability to interact with analytes. This approach, whilst successful, generally leads to short column lifetime as silanol suppressors also tend to cause more rapid column stationary phase and endcapping hydrolysis, which in turn exposes more silica allowing for more tailing to occur.</li></ul>These strategies will help diminish the tailing effect but may not completely remove it as demonstrated in the below example chromatograms (Figure A and B).<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Phenomenex_Overcoming_Peak_Tailing_of_Basic_Analytes_in_Silica_Type_A_Stationary_Phases_in_RP_4c1effe7d3.jpg" alt="Phenomenex: Overcoming Peak Tailing of Basic Analytes in Silica Type A Stationary Phases in RP: A) Mobile Phase: 20 mM potassium phosphate buffer pH= 2.5 : Methanol (70:30) Flow rate: 1 mL/min Detection: UV-Vis @254 nm; B) Mobile Phase: 20 mM potassium phosphate buffer pH= 3 with 400uL/L Triethylamine : Acetonitrile (63:37) Flow rate: 1 mL/min Detection: UV-Vis @230 nm." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Phenomenex_Overcoming_Peak_Tailing_of_Basic_Analytes_in_Silica_Type_A_Stationary_Phases_in_RP_4c1effe7d3.jpg 245w," sizes="100vw" width="939" height="332">Figure A shows the moderate effect of using an acidic pH to mitigate tailing for benzylamine, while Figure B shows the resulting chromatography after adding triethylamine as a modifier.<blockquote>We recommend the use of type B (ultra-pure) silica in the development of new separations. <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products?category=341&amp;manufacturerItems=50&amp;search=omega">Luna™ Omega</a> fully porous and <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products?category=339&amp;manufacturerItems=50&amp;search=Kinetex">Kinetex™ Core-Shell</a> columns provide excellent peak shape for challenging compounds.</blockquote>

Overcoming Peak Tailing of Basic Analytes in Silica Type A Stationary Phases in RP

The goal of the study is to investigate the presence of pharmaceuticals, personal care products, and industrial chemicals in treated wastewater discharged from expedition cruise ships operating in polar regions. As cruise traffic increases in these sensitive environments, there is a growing concern over the release of contaminants of emerging concern.By analyzing samples from three ships using LC-HRMS and data-dependent acquisition, the study identified over 160 compounds, including multiple antibiotics and cardiovascular drugs. The findings highlight the potential for cruise ship effluent to contribute to environmental contamination and the spread of antibiotic resistance, emphasizing the need for further research and regulatory attention.<blockquote><h4>The original article</h4><h4><a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/full/10.1021/acs.estlett.5c00209">Occurrence of Pharmaceuticals and Other Anthropogenic Compounds in the Wastewater Effluent of Arctic Expedition Cruise Ships</a></h4>Veronica van der Schyff*, Marek Stiborek, Zdeněk Šimek, Branislav Vrana, Verena Meraldi, Andrew Luke King, Lisa MelymukEnviron. Sci. Technol. Lett. 2025, 12, 5, 648–654<a target="_blank" rel="noopener noreferrer" href="https://doi.org/10.1021/acs.estlett.5c00209">https://doi.org/10.1021/acs.estlett.5c00209</a><h6>licensed under <a target="_blank" rel="noopener noreferrer" href="https://creativecommons.org/licenses/by/4.0/">CC-BY 4.0</a></h6></blockquote>Selected sections from the article follow. Formats and hyperlinks were adapted from the original.Cruise ships discharge wastewater generated from onboard activities. Many ships have advanced wastewater treatment systems (WWTS) onboard. Passenger ships produce graywater (drainage from dishwashers, galley sinks, showers, laundry, baths, and washbasins) and blackwater (from toilets, sanitary areas, and areas with animals). The volume of graywater discharged by cruise ships in 2023 was estimated to be 14 billion L, a 40% increase from 2014 to 2023, largely driven by the growing number of cruise ships. <a href="javascript:void(0);">(11)</a>According to the International Convention for the Prevention of Pollution from Ships (MARPOL) Annex IV, <a href="javascript:void(0);">(12)</a> treated blackwater may be discharged more than 3 nautical miles (NM) from the nearest land. Untreated blackwater may be discharged more than 12 NM from land, as the high seas are considered to be capable of assimilating blackwater through natural bacterial action. <a href="javascript:void(0);">(12)</a> Similarly, the Polar Code states that untreated blackwater should be discharged more than 12 NM from land, fast ice, or ice shelf, and treated wastewater &gt;3 NM. <a href="javascript:void(0);">(13)</a> There are currently no global regulations on the emission of graywater. <a href="javascript:void(0);">(14)</a> Depending on the onboard WWTS, gray- and blackwater can be discharged separately or together. The Baltic Sea is currently the only “special area” under MARPOL Annex IV. There, the discharge of untreated blackwater is strictly prohibited by passenger ships, and where possible, ships are expected to discharge blackwater at ports with reception facilities. <a href="javascript:void(0);">(15)</a>Conventional terrestrial-based WWTS do not eliminate all chemical compounds, and treated effluent contains a complex mix of organic and inorganic micropollutants that are then released into the environment. <a href="javascript:void(0);">(16−18)</a> This limitation likely extends to ship-based WWTS, particularly given their faster processing times and space constraints compared to terrestrial systems. As with the general population, cruise passengers and crew take medication and excrete metabolites into wastewater, with a potential impact on marine environments. <a href="javascript:void(0);">(19)</a> A particular concern is the release of antibiotics, which can promote the development of antibiotic-resistant microbes. <a href="javascript:void(0);">(4,5)</a> In addition, ship wastewater may contain other compounds like surfactants, personal care products, plasticizers, and flame retardants, which are often persistent, bioaccumulative, and toxic to biota. <a href="javascript:void(0);">(4)</a> Ocean currents can transport these contaminants from their point of release to remote areas, potentially affecting sensitive regions and ecosystems. Arctic regions are especially vulnerable to pollution since the efficiency of the naturally occurring bacterial decay of organic contaminants in seawater is slowed by low temperatures. Other environmental factors such as sea ice and fluctuating ultraviolet light exposure due to large seasonal variation also impact pollutant accumulation patterns in the Arctic. <a href="javascript:void(0);">(20,21)</a>With the number and passenger capacity of cruises increasing, it is unclear whether dilution remains sufficient to mitigate the impact of contaminants released from wastewater, particularly in regions with a high density of cruise ships. Pharmaceuticals and other chemicals have been detected in seawater in remote Arctic regions. <a href="javascript:void(0);">(20,22)</a> While substandard WWTS in remote Arctic regions are considered the main source of contaminants, <a href="javascript:void(0);">(23)</a> other studies <a href="javascript:void(0);">(24,25)</a> suggest that the effects of ship effluent should also be studied as a source of pollution.Limited attention has been paid to wastewater effluent discharges of cruise ships. To the best of our knowledge, only two studies have quantified synthetic compounds in treated wastewater, <a href="javascript:void(0);">(4,26)</a> and no chemical screening has been conducted on treated wastewater intended for offshore discharge from cruise ships while in operation. This study aims to identify organic contaminants associated with wastewater discharge from cruise ships as a first step to better evaluate the impact of contaminant emissions from cruise ships on sensitive marine environments.<h4>Methods and Materials</h4><h5>LC-HRMS Analyses and Data Processing</h5>In brief, high-resolution mass spectrometry was used for qualitative analyses of the wastewater extracts. Two aliquots per ship were analyzed. Chromatographic separation was performed using an Agilent <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library?manufacturerItems=1&amp;search=1290+Infinity+LC">1290 Infinity LC </a>System (Agilent Technologies, Santa Clara, CA) equipped with a <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/products/1514">Kinetex Core–Shell Biphenyl column</a> (150 mm × 2.1 mm, particle size of 1.7 μm) and a precolumn (Phenomenex, Torrance, CA). Mass spectrometry detection was performed by using an Agilent <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library?manufacturerItems=1&amp;search=6550+Q-TOF+iFunnel">6550 Q-TOF iFunnel</a> System operating in positive and negative electrospray ionization (ESI) modes. Iterative data-dependent acquisition (DDA) of MS/MS spectra was applied, with a maximum of four precursor ions fragmented per cycle at collision energies of 10, 20, and 40 eV. A detailed description of the analytical method is presented in the <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/suppl/10.1021/acs.estlett.5c00209/suppl_file/ez5c00209_si_001.pdf">Supporting Information</a>.Combined full-scan and MS/MS raw data files were processed with Agilent <a target="_blank" rel="noopener noreferrer" href="https://lcms.labrulez.com/library?manufacturerItems=1&amp;search=MassHunter+Qualitative+Analysis+Software">MassHunter Qualitative Analysis Software</a> 10.0 (Agilent Technologies). Data processing included peak picking, molecular formula assignment, isotope pattern scoring, and identification of the found features based on compliance with the predicted molecular formula and MS/MS spectra present in mass spectrum libraries. A full list of databases used and quality assurance is included in the <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/full/10.1021/acs.estlett.5c00209#notes1">Supporting Information</a>. All compounds reported here were identified at confidence level 1 or 2 according to the Schymanski identification confidence levels (SL1, confirmed a with reference standard, or SL2, probable structure; library match or diagnostic evidence) in high-resolution mass spectrometric analysis. <a href="javascript:void(0);">(28)</a><h4>Results and Discussion</h4>Wastewater samples from the older ships built in the 2000s (ships 1 and 2) had &gt;11 000 found features, while the newest ship, ship 3, built 2020, had 7571 (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/suppl/10.1021/acs.estlett.5c00209/suppl_file/ez5c00209_si_001.pdf">Table S1</a>). From these features, a total of 168 compounds were confirmed at SL1 or the chemical structure was proposed at SL2 in treated wastewater across all three ships: 86, 99, and 78 compounds from ships 1–3, respectively (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/full/10.1021/acs.estlett.5c00209#fig1">Figure 1</a> and <a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/suppl/10.1021/acs.estlett.5c00209/suppl_file/ez5c00209_si_001.pdf">Tables S2–S4</a>). Twenty-seven compounds were identified at SL1 or SL2 across all ships (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/full/10.1021/acs.estlett.5c00209#tbl1">Table 1</a>), with pharmaceuticals and industrial chemicals (10 each) constituting the majority, followed by five food/natural compounds, one pesticide, and one UV blocker. Eight of the 27 compounds common to all ships were identified at SL1 based on external standards (EnviMix, Helmholtz-Centre for Environmental Research <a href="javascript:void(0);">(29)</a>), and 19 identified at SL2.<img src="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/Environ_Sci_Technol_Lett_2025_12_5_648_654_Figure_1_A_Number_of_compounds_identified_at_SL_1_or_SL_2_in_three_expedition_ships_8915e4f530.jpg" alt="Environ. Sci. Technol. Lett. 2025, 12, 5, 648–654: Figure 1. (A) Number of compounds identified at SL1 or SL2, in three expedition ships showing overlap in the compounds found in wastewater among the three ships and (B–D) distribution and number of confirmed or probable compounds according to use category in wastewater effluent from three expedition ships." srcset="https://storage.googleapis.com/labrulez-bucket-strapi-h3hsga3/thumbnail_Environ_Sci_Technol_Lett_2025_12_5_648_654_Figure_1_A_Number_of_compounds_identified_at_SL_1_or_SL_2_in_three_expedition_ships_8915e4f530.jpg 245w," sizes="100vw" width="1624" height="917">For all ships, pharmaceuticals, primarily cardiovascular medication, dominated in terms of the number of compounds identified at SL1 or SL2 (43–59%), followed by industrial chemicals (21–31%) and natural/food compounds (12–17%) (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/full/10.1021/acs.estlett.5c00209#fig1">Figure 1</a>).Industrial chemicals such as surfactants, lubricants, and cleaning products can originate from onboard operations, or from being incorporated into onboard products, like in the case of flame retardants and plasticizers, with release to dust and transfer to wastewater during cleaning or laundering. <a href="javascript:void(0);">(36)</a> Many natural compounds can originate from food preparation and consumption, including some with potential environmental impacts, such as caffeine and aromatic amines, the latter being mutagenic. <a href="javascript:void(0);">(37)</a>The compound group of the highest concern consists of pharmaceuticals due to their potential biological activity at low concentrations. <a href="javascript:void(0);">(38)</a> The pharmaceuticals were primarily cardiovascular medications, with the sartan group (losartan, irbesartan, candesartan, and telmisartan) identified at SL1 or SL2 (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/full/10.1021/acs.estlett.5c00209#tbl1">Table 1</a>) in all three ship wastewater profiles. Other cardiovascular medications, flecainide, and bisoprolol, were also identified in wastewater from all three ships (<a target="_blank" rel="noopener noreferrer" href="https://pubs.acs.org/doi/full/10.1021/acs.estlett.5c00209#tbl1">Table 1</a>). <a href="javascript:void(0);">(25)</a> Since the aforementioned medications are persistent and known for incomplete removal, even in typical WWTS, it stands to reason that they should be prominent in wastewater from ships too. <a href="javascript:void(0);">(39,40)</a>There is a significant gap in our understanding of the types of compounds present in ship wastewater discharges. This issue is becoming increasingly urgent as the cruise industry expands, especially in sensitive polar regions, and as sustainable development and tourism become more important priorities. Identification and quantification of pharmaceuticals and industrial compounds can support better environmental risk assessment. Water in shipping lanes and cruising routes should be studied to evaluate the effectiveness of dilution and degradability in marine water, particularly in areas where ships are permitted to discharge wastewater. If needed, sensitive regions should be denoted (in addition to the 3 and 12 NM limits) where wastewater discharges should be avoided. Special emphasis should be placed on compounds consistently identified across multiple vessels, including SSRIs, antibiotics, and other substances that could pose environmental concerns at increased concentrations. Moreover, the mixture effects of the various chemicals found in wastewater should be thoroughly examined, as the combined presence of different pharmaceuticals and industrial chemicals may result in additive or synergistic effects that can intensify their harmful impact on marine ecosystems. <a href="javascript:void(0);">(55,56)</a> Current regulations and treatment standards of graywater may need reevaluation as we gain an understanding of the impact of trace organic contaminants on marine systems.

Occurrence of Pharmaceuticals and Other Anthropogenic Compounds in the Wastewater Effluent of Arctic Expedition Cruise Ships

One of the most common causes of short column lifetime is column contamination, often resulting in high back pressure and a so called “plugged” inlet frit.This technical tip aims to explain what is happening, and also how column contamination can be avoided.&nbsp;In the manufacture of particulate based HPLC and UHPLC columns, frits are used to prevent extraneous material entering the column, and to prevent the HPLC packing material from leaving the column. These frits are discs of porous metal, generally 0.5, 1.0 or 2.0 μm in porosity. If samples contain undissolved material, it will be filtered out of the mobile phase solvent stream, sitting on the outside of the inlet frit. As this process continues, the amount of the frit available for mobile phase to pass through becomes smaller, restricting the flow of mobile phase which in turn increases the back pressure. Eventually it becomes impossible to push solvent through the frit and the HPLC pump shuts down.This process can be averted by the filtration of samples prior to injection onto the HPLC system. It is generally advised to use 0.45 μm porosity syringe filters for samples that will be run on 5 μm columns, 0.2 μm filters for 3 μm columns and smaller. Care should be taken as ideally the sample diluent should match the mobile phase. If it does not, you may find that some sample components are soluble in the sample diluent allowing them to pass through the syringe filter. When they are injected into the mobile phase they may precipitate causing frit blockage. This can be avoided by either dissolving the sample in mobile phase, or alternatively installing an inlet frit, or a guard cartridge as a sacrificial device to prevent the inlet of the column becoming fouled.Alternatively, we have this <a target="_blank" rel="noopener noreferrer" href="https://www.phenomenex.com/tools/security-guard-selection#bybrand">web tool</a> which will guide you through guard cartridge selection.&nbsp;

Column contamination – what is happening, and how it can be avoided

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Column contamination – what is happening, and how it can be avoided

Overcoming Peak Tailing of Basic Analytes in Silica Type A Stationary Phases in RP

Occurrence of Pharmaceuticals and Other Anthropogenic Compounds in the Wastewater Effluent of Arctic Expedition Cruise Ships

How can capacity factors drive method robustness?

The effects of gradient on buffer capacity

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