Fully automated pesticide analyzer

Figure 4. First fully automated pesticide analyzer...

The major difficulty in analyzing OPPs in fatty samples has to do with the wide polarity range for both pesticides and lipids present in the matrix. Normal-phase HPLC is an adequate technique for cleaning up this type of sample using silica gel and modifiers with different polarity. In fact, an automated sample-cleanup system based on normal-phase HPLC using a silica gel column has been reported efficiently to clean up and fractionate chlorpyriphos, chlorpyriphos methyl, and their metabolites in molluscs. The system presents several advantages The procedure is fully automated, from the injection of the extract to the collection of fractions, which are injected directly into the GC system, and a diode array detector (DAD) allows online monitoring of the elution of lipids (68). 

Liquid chromatographic systems for environmental pesticide analysis have been extensively reviewed in a previous paper. Nowadays, LC is the technique of choice for analyzing those pesticides which, being thermolabile, are not amenable to direct GC analysis, such as phenylurea and SUHs. LC methods of analysis also have the important advantage over GC methods in that online pre- and postcolumn reaction systems are compatible with LC instrumentation. Furthermore, the LC apparatus can easily be coupled online with the enrichment step using SPE on precolumns, thereby making the analysis fully automated. 

Recently a fully automated and flexible on-line LC-GC system has been described [68]. The system is based on standard LC and capillary GC instrumentation. The on-line LC-GC system was evaluated for the determination of pesticides in orange oil. The essential oil was fractionated by normal phase LC, resulting in a separation according to polarity. The fraction containing pesticides was tran.sferred and analyzed by capillary GC-... 

GC are therefore expected in the direction of fully automated sample preparation and sample introduction systems. Some instrumentation nowadays is already tailor-made for a given application. More can be expected in the future and development may result in specific instruments, such as a pesticide analyzer, a PCB analyzer, or a sugar analyzer. 

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