Analysis of Pesticides Using Low-Pressure GC-MS with Nitrogen Carrier Gas
1.Introduction
1.1. low-pressure GC-MS (LPGC-MS)
Vam Deemter equation shows that the separation performance of chromatography depends on the diffusion coefficient of the substance in the mobile phase. It is also established that the diffusion coefficient of a substance in a gas is inversely proportional to the pressure. The low-pressure GC-MS (LPGC-MS) method is a technique that applies this principle and improves the analysis speed by maintaining the column pressure at a vacuum using the vacuum system of the MS. LPGC-MS uses a short analytical column with an inner diameter of 0.53mm to 0.32mm, with a restrictor connected to the GC inlet side (→Figure 1). Reducing the length of the column would normally reduce the separation performance, but in LPGC-MS, we can minimise this effect by improving the separation performance through reducing the internal pressure.