An unknown peak was observed in spinach extract during routine analysis of 7 pyrethroid insecticides by gas chromatography with electron capture detection (GC-ECD) using a DB-1 column (20 m x 0.25 mm id, 0.1 μm film thickness). It eluted later than the 7 pyrethroids, and it was also found in other agricultural crops. The intensity of the unknown peak was related to the green color of the sample: It was absent in white vegetables such as radish root or onion. Data from GC/direct deposi- tion/Fourier-transform infrared spectroscopy (FTIR) suggested it might be phylloquinone (vitamin K1). The identity was confirmed also by using electron impact capillary GC/mass spectrometry (MS). Although phylloquinone has no halogens, it showed very high sensitivity by ECD (63Ni), responding to 10 pg.
A capillary GC-MS method has been developed for analysis of guazatine.On a short capillary column (DB-5, 0. 25 mm-5 x 5 m, df =0. 1 m), a symmetrical peak of trifluoroacetate of bis(trifluoromethyl)pyrimidine derived from guazatine was recorded. Its El mass spectrum showed the base peak at m/z 244 and the molecular ion peak at m/z 795. By the SIM method with these two ions, calibration curves were fairly linear in the range of 40-750 pg. The minimum detectable quantity was determined to be 40 pg.
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