GC-MS/MS 200+ Multiresidue Pesticide Screening Workflow—Comparison of Conventional 30 m Column and LPGC Kit

Sample throughput is one of the most important productivity goals for most testing labs. While there are several ways to increase the speed of GC analysis, the low-pressure gas chromatography (LPGC) technology is unique in using a shorter, wide-bore column rather than a shorter, narrow-bore column. Low-pressure GC-MS (LPGC-MS) is a technique that uses the MS vacuum system along with a specially designed column setup to lower pressure inside the entire column, thereby significantly speeding up analysis. By using a 0.53 mm ID analytical column that is inserted directly into the MS and is connected to a narrow-bore guard column acting as a flow restrictor on the GC inlet side, low pressure can be maintained throughout the 0.53 mm ID analytical column. Using LPGC-MS, some efficiency is traded for speed; however, because a mass spectrometer is used, most coeluting components can be deconvoluted by the MS detector. The analytical column’s wider ID and thicker film also provide higher capacity, robustness, and inertness. To demonstrate the technique, spinach was spiked with over 200 pesticides at two levels,100 ppb and 10 ppb. Spinach samples were prepared using a QuEChERS procedure followed by analyses comparing the conventional 30 m x 0.25 mm x 0.25 μm column to the LPGC-MS column set. Using this technique, a conventional GC pesticides analysis is three to four times faster delivering a significant increase in throughput and lab productivity.