This document describes a method for quantifying pesticides in the parts-per-trillion range using retention time locking and GC/MS application. By using a selected ion monitoring method and large volume injection capability, the target compound quantitation limit can be lowered to the low parts-per-billion (pg/µL) range. Additionally, an automated 567-compound retention time locking pesticide mass spectral library can screen an acquired sample's data file for all 567 compounds in seconds. The library can also be used for rapid screening of samples acquired in selected ion monitoring method. Using the compound library information, a selected ion monitoring method for 80 target compounds was created in less than 2 hours without running any analyses.
The document details an analytical approach to lower mass spectrometer detection limits from sub-ppm to low parts-per-billion or parts-per-trillion levels. This is achieved by combining selected ion monitoring (SIM) mode, large volume injections (LVI), and higher electron multiplier voltage with a specialized retention time locking (RTL) pesticide library.
The text provides specific system configurations for the Agilent 6890 GC and 5973 MSD, including column specifications and software versions. It outlines experimental procedures using an 80-pesticide mixture and explains how to construct SIM methods from the RTL database to improve signal-to-noise ratios and simplify data analysis.
The typical pesticide quantitation limit for a mass spectrometer in the Scan mode is in the sub-ppm range.
Target compounds at parts-per-trillion can be quantified by adding large volume injection capability to a retention time locked gas chromatography/mass spectrometry method.
G1701BA version B.00.00 MSD ChemStation software or higher is required.