Pesticides target compound analysis

Target compound analysis using high mass resolution, for example, for PCDD/ PCDFs, pesticides, POPs or pharmaceutical residues are typically performed by monitoring the compound-specific accurate mass ions at the expected retention time for each analyte. High resolution GC-MS target compound applications benefit from a unique technical feature referred to as the lock-mass technique for performing MID analyses. The lock mass technique provides ease of use, combined with a maximum quantitative precision and certainty in analyte confirmation. 

GC-MS/MS Target Compound Analysis of Pesticide Residues in Difficult Matrices... 

The ECD is used in analysis of chlorinated pesticides (EPA Method 8081), herbicides (EPA Method 8151), and PCBs (EPA Method 8082). These analyses are prone to interferences from naturally occurring and manmade non-target compounds, such as the following ... 

Matrix solid-phase dispersion (MSPD) is an SPE variant where samples are ground and mixed with a support. In the initial application, samples were placed in a disposable column previously packed with Florisil, which trapped the fat from the sample and allowed the compounds of interest to be eluted. This has successfully been applied to the determination of lipophilic pesticides from both fatty and non-fatty matrixes. Recently, an orthogonal technique, dispersive solid-phase extraction, for the isolation and analysis of a variety of pesticides on numerous food matrixes has been introduced. The technique is called QuEChERS, which stands for quick, easy, cheap, effective, rugged, and safe. The technique offers advantages in time and solvent usage since it uses approximately 10 ml of solvent per sample when compared to the potentially hundreds of milliliters of solvent used for more standard extraction and isolation protocols. It uses a combination of MgS04 and primary secondary amine (PSA) sorbent not only to remove water and non-target compounds, but also isolate the compounds of interest. 

In recent years, GC-ion-trap detection (ITD) systems that can perform tandem MS (MS-MS) on a routine basis have become commercially available [86]. Because ITD provides good sensitivity as well as increased selectivity in the MS-MS mode, an on line SPE-GC ITD system was optimized for the trace-level determination of polar and apolar pesticides [53]. The Autoloop interface (see section 3.2.3) was operated at an injection temperature of 90X, which permitted the determination of thermolabile pesticides such as carbofuran and carbaryl. With sample volumes of 10 to 30 ml and a copolymer SPE cartridge, linear calibration curves were obtained for several pesticides over the range of 0.1 to 500 ng/L. Fully satisfactory tandem mass spectra were obtained at levels as low as 0.1 ng/L level in tap and river water. The system was used to analyze water from European and Asian rivers, and the determination of microcontaminants at 8 to 16 ng/L levels did not cause any problems (Fig. 11). Relevant analytical data are presented in Table 7. One conclusion may be that, for this target-compound type of analysis, a sample volume of 1 ml or less will be sufficient to comply with governmental directives. 

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