Title : Quantification of target compounds in environmental waters by the combination of MEPS and PTV-GC-MS/MS, optimized through experimental design-PCA approaches: A case study with benzothiazoles, benzotriazoles and benzenesulfonamides
This study proposes a new method for the fast quantification of benzothiazoles (BTs), benzotriazoles (BTRs), and benzenesulfonamides (BSAs) in tap water, river water, and wastewater. The presented approach is based on the use of microextraction by packed sorbent (MEPS) combined with programmed temperature vaporization-gas chromatography-triple quadrupole mass spectrometry (PTV-GC-QqQ-MS) operating in tandem mass spectrometry. After the evaluation of different sorbent/solvent pairs, the variables influencing both PTV technique and MEPS procedure were simultaneously optimized by “Experimental design”. Indeed, since some of the variables affecting PTV can be related to factors influencing MEPS extraction, comprehensive designs were used for evaluating at the same time all factors involved pointing out any synergistic effects between variables. Instead of the traditionally used Derringer’s desirability function to convert a multi-response problem into a single-response one, we choose to apply the principal component analysis (PCA) to use the score on the first PC as a “comprehensive” response of the results of the experimental designs. Furthermore, this optimization strategy offered to the analyst response surfaces which, in compliance with the principles of Green Sample Preparation (GSP)  allow an informed choice of experimental conditions according to the required analytical performance.
Very good linearities were achieved in the tested calibration ranges for all analytes achieving determination coefficient values >0.99. Intra-day and inter-day accuracies and RSD values tested at three concentrations were in the range of 79% to 132%, and from 1 to 18%, respectively. The LODs obtained can be considered good, ranging between 0.005 to 0.85 µg/L. The Analytical Eco-Scale, Green Analytical Procedure Index (GAPI), and Analytical Greenness metric for sample Preparation (AGREEprep) approaches were applied to evaluate the “green” character of the procedure. The satisfactory results achieved from the testing with real water samples demonstrate its applicability for monitoring campaigns and exposome studies.
Audience Take Away:
- A new method for benzothiazoles, benzotriazoles, and benzenesulfonamides quantitation in waters is presented, using commercially available equipment.
- The “Experimental design” was used to achieve the simultaneous optimization of MEPS extraction and PTV technique and to provide an in-depth understanding of the whole analytical system.
- The “green” character of the procedure described in this study was evaluated by the use of greenness metrics.
- The new high throughput protocol is reliable, fast, and automatable. It can potentially be used for monitoring purposes of the target compounds in environmental waters.