An HPAE-PAD method for determination of saccharides in atmospheric aerosol samples

Significance of the topic

Atmospheric saccharides, including anhydro sugars, monosaccharides, disaccharides and sugar alcohols, are key constituents of water-soluble organic carbon in aerosols. They serve as tracers for biomass burning and biogenic detritus, enabling source apportionment of aerosol particles. High-resolution analysis of these compounds is critical for understanding air quality, climate impacts and human health effects.

Study objectives and overview

This study aims to develop and validate a single-column high-performance anion-exchange chromatography with pulsed amperometric detection (HPAE-PAD) method for simultaneous quantification of 14 saccharides in atmospheric aerosol samples. The method focuses on simplifying analysis by using one Dionex CarboPac MA1 column, optimizing gradient conditions to resolve anhydro sugars, mono- and disaccharides, and sugar alcohols.

Methodology

A 4×250 mm CarboPac MA1 analytical column with a 4×50 mm guard column was employed at 30 °C. Eluents comprised deionized water (A) and 1 M sodium hydroxide (B) delivered at 0.4 mL/min. A 55 min gradient increased NaOH from 200 mM to 700 mM over 34 min, then to 800 mM, before returning to initial conditions. Samples were collected via passive diffusion onto glass fiber filters, extracted in water by sonication, and filtered. Calibration standards ranged from 0.024 to 50 mg/L. Method variants with altered initial NaOH concentrations (60 mM or 400 mM) improved separation of sorbitol, arabitol and galactitol.

Used Instrumentation

• Thermo Scientific Dionex ICS-5000 RFIC system with SP or DP pumps
• Dionex CarboPac MA1 analytical and guard columns
• Dionex Electrochemical Detector with gold on PTFE disposable electrode
• AS-AP autosampler with cooling tray
• 25 µL sample loop, 0.2 µm nylon filters and GF/A filter paper

Main results and discussion

The optimized method resolved 11 saccharides with resolution values above 1.6 in a 55 min run. Precision was excellent, with retention time RSDs below 0.07% and peak area RSDs below 4.5%. Calibration showed linearity (r2 ≥0.998) over three orders of magnitude. Spike recovery in aerosol matrix ranged from 82% to 122%, demonstrating accuracy. Method modifications allowed separation of three additional sugar alcohols, extending analyte coverage to 14.

Benefits and practical applications

• Single-column approach reduces analysis time and complexity
• High sensitivity and broad dynamic range facilitate trace-level quantification
• Specificity of PAD minimizes matrix interferences
• Applicable to routine monitoring of aerosol tracers for air quality and climate studies

Future trends and potential applications

Advances may include coupling HPAE-PAD with high-resolution mass spectrometry for comprehensive molecular characterization, development of faster gradients and miniaturized systems for field deployment, and integration with data analytics for source apportionment models. Expansion to emerging saccharide markers and other polar organics could further enhance aerosol research.

Conclusion

A robust HPAE-PAD method using a single CarboPac MA1 column has been established for the accurate, precise and efficient quantification of key saccharides in atmospheric aerosols. The approach streamlines analysis, offers high resolving power across 14 analytes, and meets performance criteria for environmental monitoring.

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