GC/MS actual detection spectrum analysis

GC/MS has two ion acquisition modes, full scan (SCAN) and selective ion scan (SIM)

Figure 2-44 Total ion current chromatogram of 52 pesticides mixed standard

The grouping of the selected ion scan mode is carried out according to the following principles: each pesticide selects a quantitative ion (target ion), and selects 2 to 3 reference ions according to the number of compounds in each group

Table 2-14 Selected ion scanning mode The main fragment ions and pollutant sources that must be avoided by the selected ions

The following shows a qualitative and quantitative example of chlorpyrifos by a GC/MS gas- mass spectrometer .

Figure 2-45 Standard GC/MS processing spectrum of poisonous cicada

Figure 2-46 Qualitative and quantitative detection results of chlorpyrifos in the sample (each ion peaks accurately and the ratio meets the requirements)

Single-stage mass spectrometry is more prone to false positive results

Figure 2-47 Positive detection results of permethrin in lotus root samples

Figure 2-48 False-positive identification map of gongfu pyrethroid in spinach (large deviation of the ratio of m/z208 ion)

Figure 2-49 Screenshot of pp'-DDT false positive identification in cucumber (m/z165, 237 ion ratio deviation is large)

Related links: Analysis of the actual detection spectrum of liquid chromatography