PW13 Sediment Chemistry
Exhibit Hall
8:00 AM - Wednesday, 12 November 2003
(PW204) Evaluation of an Atmospheric Pressure Ionization Mass Spectrometry (API-LC/MS) method for the determination of triazine-based herbicides in complex environmental matrices.
Arroyo, L1, Wu, J1, Gardinali, P1, 2, 1 Florida International University, Chemistry Department, Miami, Florida, USA2 Southeast Environmental Research Center, SERC, Miami, Florida, USA
ABSTRACT- A comprehensive evaluation of twelve organonitrogen herbicides, including the novel antifouling agent IRGAROL 1051, and two metabolites in complex environmental matrices is presented. Two different quantification approaches are compared in terms of analytical instrumentation, sensitivity, precision and selectivity. Although GC/MS has being successfully used to perform the analysis of triazine-based herbicides in water samples its performance with dirty matrices like sediments with high organic matter content is often limited by the presence of large amounts of co-extractants that should be removed by extensive cleanup procedures. In the present investigation, the isolation and fractionation of the triazines was conducted with Accelerated Solvent Extraction (ASE) using water/methanol mixtures followed by Solid Phase Extraction (SPE) with polymeric cartridges. The final extracts were then injected in a GC/MS system and also in a LC/MS system in order establish the potential advantages of each method. The overall recoveries values ranged from 85-98% and the linearity range was tested between 0.05 ng/ul and 3.5 ng/ul. Coefficient correlation values were better than 0.99. Although the limits of detection for both techniques were very similar (below 35ng/g), the LC/MS method has the added advantage of allowing the measurement of some metabolites like deisopropyl atrazine and desethyl atrazine. The screening of these pesticides was performed for 35 different sampling sites collected along the most important ecosystems involved in the CERP as part of the ongoing assessment of contaminants in South Florida Ecosystems.
Key words: mass spectrometry, Sediments, ASE, triazines