Optimization of an ultrasound-assisted derivatization for GC/MS analysis of oxygenated organic species in atmospheric aerosol

Abstract

A novel ultrasound-assisted derivatization followed by GC/MS analysis was developed for the quantification of oxygenated organic species in ambient aerosol. Derivatization parameters mostly influencing the analytical response were investigated, i.e., solvent type, reagent concentration, and reaction duration. Response surface methodology was used to design experiments and a quadratic model was utilized to predict the variables and establish the optimal conditions. The study was performed on standard solutions of 30 compounds representing the major classes of oxygenated compounds typically found in ambient aerosol, i.e., low molecular weight carboxylic acids, sugars, and phenols. In comparison with conventional methods, the optimized procedure uses mild reaction temperature (room temperature instead of 70 °C), reduces the amount of silyl reagent (24 vs. 40 μL), and shortens derivatization times (45 vs. 70 min), participating in the current trend of analytical chemistry towards clean, green methods that reduce costs and decrease pollution. Once optimized, the ultrasound procedure was validated by assessing for repeatability, linearity, detection limits, and derivative stability. For all oxygenated organic species, the proposed method showed a good reproducibility-as the relative standard deviations (RSDs%, n = 5) of intra-day analysis were ≤7% - a good linearity with the correlation coefficients of calibration curves R ≥ 99.8, and low detection limits, ranging from 0.34 to 6.50 ng μL; thus it is suitable for its applicability in air quality monitoring. Finally, this method was successfully applied to determine 30 oxygenated organic species in three ambient PM samples collected at an urban site in Northern Italy in three different seasons. Graphical abstract Ultrasound-assisted derivatization is a green alternative method for GC/MS analysis of oxygenated organic species in atmospheric aerosol towards reduction of energy and reactive consumption.

GC–MS analysis of organic acids in rat urine: A protocol of direct ultrasound‐assisted derivatization

“…In particular, the use of US in sample preparation should be promoted (Castro & Delgado‐Povedano, ), and the reaction process can be shortened with US (Fiamegos, Nanos, & Stalikas, ). Pietrogrande et al optimized mild conditions with US‐assisted derivatization at room temperature for 45 min (Pietrogrande et al, ). Prata et al found that the derivatization time can be reduced with US for detecting THCOOH in urine samples (Prata et al, ).…”

“…The total ratio of OA derivatives was higher at 40 min than at 20, 30, or 50 min. Pietrogrande et al have reported that the derivatization time for oxygenated organic species in atmospheric aerosol can be shortened from 70 min, as required by the conventional heating method, to 45 min with US assistance (Pietrogrande et al, ). In agreement with those findings, our results indicated the duration time could be shortened with US, and 40 min was chosen as the optimal condition for derivatization.…”

Gas chromatography/mass spectrometry analysis of organic acid profiles in human serum: A protocol of direct ultrasound‐assisted derivatization

“…Ultrasonic cavitation through solvent can increase the reaction temperature and pressure and promote interactions between a substrate and the derivatization reagent, thereby enhancing the chemical reaction. Pietrogrande et al 20 used ultrasound‐assisted derivatization to shorten the derivatization time of oxyorganics in atmospheric aerosols (45 vs. 70min).…”

Standard-Free Quantification of Dicarboxylic Acids: Case Studies with Salt-Rich Effluents and Serum

“…DCAs can be found as degradation markers of modern painting oils, , biodegradable plastics, and biomass burning . Also, dicarboxylic acids were known to be important components in the process of secondary organic aerosols formation ,− and pristine atmosphere …”