Rapid Trace Analysis of Synthetic Pyrethroids in Stormwater Using online preconcentration followed by Liquid Chromatography-Tandem Mass Spectrometry
Synthetic pyrethroids (SPs) are a class of pesticides for which there is an emerging concern, particularly in urban areas. Because certain SPs are written into NPDES permits, this requires a laboratory that is capable of performing this analysis while meeting certain data quality objectives. This also may require that laboratories provide reporting limits that are at or below concentrations for which SPs are toxic to sensitive aquatic fauna. Toxicity studies of SPs have produced a wide range of toxic concentrations and, in a few cases, these toxicity levels require the ability to detect SPs at a level that commercial laboratories may find difficult to acheive. Currently, most analytical methods for SPs used by laboratories involve either a solid phase extraction (SPE) or continuous liquid-liquid extraction (CLLE) followed by gas chromatography-mass spectrometry (GC-MS). Currently, the most sensitive GC-MS technique uses electron capture chemical ionization (ECNI) commonly referred to as negative chemical ionization (NCI). Because GC techniques require a heated injection port during analysis, the ability to detect SPs at lower levels introduces additional challenges. Specifically that some SPs like Tralomethrin absorb or breakdown at such low concentrations and high temperatures.
With these challenges in mind, a method was developed to increase sample throughput, sensitivity, selectivity, and robustness. This method requires one 40mL VOA vial which provides enough volume to analyze the sample and a matrix spike/duplicate (MS/MSD). The benefits of this are reduced shipping costs, increased sample throughput, and reducing the labor required to extract 1 liter of sample. Reporting limits, method detection limit study data, and matrix spike data are presented for this method and are compared with data quality produced by a continuous liquid-liquid extraction followed by the same LC-MS-MS analysis.