Of Fireworks and Tourism: GC×GC-HRMS Analysis of Summer Impacts on Lake Michigan Water Quality

Significance of the Topic

Firework displays and summer tourism events can temporarily alter water chemistry in recreational areas. Understanding these short-term impacts helps environmental scientists and regulators monitor pollutant influxes and protect water quality.

Objectives and Study Overview

This work evaluates chemical changes in Lake Michigan water before and after Fourth of July fireworks at Silver Beach. It also examines the influence of increased beachgoer activity on personal care product residues via non-targeted GC×GC-HRTOFMS analysis.

Methodology

• Sample Collection: 60 mL water taken at Silver Beach and Tiscornia Beach on July 2 (pre-fireworks) and one hour after fireworks on July 4. Samples acidified to pH 2 and frozen until analysis.
• SPME Arrow Extraction: 1.5 mm DVB/CarbonWR/PDMS fiber, conditioned at 270 °C for 1 min; stirring at 1200 rpm; extraction at 30 °C for 30 min; thermal desorption at 250 °C for 2 min.
• GC×GC-HRTOFMS Analysis: LECO Quad Jet Thermal modulator; primary column Rxi-5ms (30 m×0.25 mm×0.25 μm), secondary Rxi-17SilMS (1.5 m×0.25 mm×0.25 μm); helium at 1.4 mL/min; oven program 40 °C (2 min) to 300 °C (10 °C/min, hold 5 min); modulation period 5 s; MS range 40–520 m/z at 200 spectra/s.

Used Instrumentation

• SPME Arrow with DVB/CarbonWR/PDMS fiber
• LECO Pegasus HRT+ TOF-MS with EFPI source
• LECO GC×GC system with Quad Jet Thermal modulator
• Primary column: Rxi-5ms; Secondary column: Rxi-17SilMS
• Carrier gas: Helium; Data rate: 200 spectra/s

Main Results and Discussion

No direct pyrotechnic residues were detected, but many personal care compounds showed marked increases post-fireworks. Key observations include:

• Homosalate (sunscreen): 40× increase
• Octocrylene (sunscreen): 15× increase
• Diethyltoluamide (insect repellent): 5× increase
• Benzoic acid (insect bite treatment): 4× increase
• Diisopropyl adipate (skin softener): 10× increase
• Newly observed fragrances: δ-nonalactone, γ-dodecalactone, vanillin
• Additional emerging compounds: N-n-butylphthalimide, 2-ethylhexyl salicylate, oxybenzone

Enhanced two-dimensional separation resolved coeluting peaks, and mass accuracies below 2 ppm enabled confident identifications via library matching and IGS grading.

Practical Benefits and Applications

• Tenfold sorption capacity gain with SPME Arrow for trace volatiles
• Superior GC×GC resolution to separate complex mixtures
• High-resolution mass accuracy for definitive compound confirmation
• Applicable workflow for routine environmental monitoring and water quality assessments

Future Trends and Applications

• Wider adoption of SPME Arrow in field sampling and in situ analysis
• Coupling with real-time sensors for continuous water monitoring
• Machine learning algorithms to enhance non-target screening
• Expansion to sediments, biota, and other environmental matrices

Conclusion

The integrated SPME Arrow and GC×GC-HRTOFMS approach effectively characterized personal care product loading from summer tourism. While firework-specific chemicals were not observed, the method demonstrated exceptional sensitivity and specificity for environmental contaminants, offering valuable insights for QA/QC and ecological studies.

References

• Kelly CN, Richards TS, Binkley JE, Fell LM; LECO Corporation. Of Fireworks and Tourism: GC×GC-HRMS Analysis of Summer Impacts on Lake Michigan Water Quality.