In this study, calibration characteristics of odorous amine compounds were investigated by gas chromatography (GC)-nitrogen phosphorous detector (NPD). To this end, three different amine compounds (methyl amine (MTA), dimethyl amine (DMA), and trimethyl amine (TMA)) were analyzed in a series of calibration experiments. As the first step, the liquid phase standards of these amines were calibrated at 5 concentration levels with the fixed standard volume (FSV) method. The results showed that response factors of three amines were in the order of TMA ＞ DMA ＞ MTA with their correlation coefficients (r) above 0.97. The results of FSV calibration also indicated that the analytical sensitivity of amines increased with reducing injection volume due to the decrease in matrix effect. However, when these compounds were calibrated by the fixed standard concentration (FSC) method, the results were not stable under most circumstances. In addition, the reliability of internal calibration approach was also tested using pyridine, nitrobenzene, and nicotine. When pyridine was used as internal standard of these amines, analytical reproducibility of amines was improved greatly compared to external calibration results (e.g., an improvement of 75% for DMA).

Pesticides were extracted from samples with 70% acetone and methylene chloride in order, and then cleaned up via open-column chromatography apparatus packed with florisil, and finally analyzed simultaneously the organophosphorus pesticides using GC/NPD. Ultra-2 and Ultra-1 fused silica capillary columns were used to separate and identify the products. Recovery of most analytes from soybean sample, taken from pesticide residues well, was greater than(80%) for all except(6) analytes. This method can simultaneously determine multiple pesticides with a high degree of accuracy and precision.