Quantification of pyrethroids in environmental samples using NCI-GC-MS with stable isotope analogue standards

Stable isotope internal standards are useful in correcting for matrix effects and instrumental variability when environmental samples such as wastewaters and biosolids are analyzed by mass spectral methods. This paper reports the use of deuterium-labeled analogues of eight pyrethroid insecticides to improve accuracy for the analysis of environmental samples by negative chemical ionization gas chromatography with mass spectrometric detection (NCI-GC-MS). Data for the analysis of effluent water from wastewater treatment facilities are presented which demonstrate that the method is rugged and capable of achieving limits of quantification (LOQs) as low as 0.5 ng/L (ppt), with individual recoveries within the range of 81-94% for those compounds with minimal control background concentrations. In addition, an alternate use of the deuterium-labeled standards is proposed for the determination of method recoveries at low levels that would normally have been precluded due to background pyrethroid levels present in environmental samples being used for control fortifications.