A USGS analytical method using gas chromatography/mass selective detector (GC/MSD) was modified and used to identify the source of pesticides and to calculate the pesticide load in river water during storm seasons. The method was validated to cover 12 organophosphate pesticides and 5 pyrithroids. The limits of quantitation for these target compounds are 10–500 ppt using a GC/MSD selected ion monitoring (SIM) method.
This document describes a validated analytical method for identifying the source of pesticides and calculating pesticide loads in river water during storm seasons. The method was modified from a USGS analytical method using gas chromatography/mass selective detector (GC/MSD) to cover 12 organophosphate pesticides and 5 pyrithroids, with limits of quantitation between 10-500 ppt.
| Target Compounds | 12 organophosphate pesticides and 5 pyrithroids |
|---|---|
| Limits of Quantitation | 10-500 ppt |
| Column | 30 m x 0.25 mm x 0.25 um HP-5MS |
| Inlet Temperature | 230 °C |
| Injection Volume | 2 uL (splitless) |
| Oven Ramp | 70(2)/25/ 150(0)/3/200(0)/8/280(12) |
| SIM Mode | Max. sensitivity Auto Tune |
| Dwell Time | 50 ms |
The limits of quantitation for these target compounds are 10-500 ppt.
The method covers 12 organophosphate pesticides and 5 pyrithroids.
Typical recoveries for the compounds are 80%-90%, though EPTC shows the worst recovery in the 40%-60% range.