摘要：Electron capture detector-gas chromatography was investigated for determination of ultra-micro amount of chromium which was converted to a chromium chelate [tris-(1, 1, 1-trifluoro-2, 4-pentanedionato) chromium (III), Cr (TFA)3] by reacting with 1, 1, 1-trifluoro-2, 4-pentanedione (TFA). A mixture of 10 ml of a sample solution containing less 100 ppb of Cr (III), 5 ml of TFA-benzene solution, and 2 ml of acetate buffer of pH 4.6 was sealed in a glass ampule, and submitted to two times of heating-mixing operation (heating at 100°for 3 min and mixing vigorously for 1 min), and cooled to room temperature. Then the ampule was broken to separate the benzene fraction from the aqueous layer, and the benzene fraction was washed with 5 ml of 0.5 N NaOH and twice with 5 ml each of water. The benzene fraction was submitted to gas chromatography. In the gas chromatography, a calibration curve showed a linear relationship between the weight of Cr (TFA)3 peak in the gas chromatogram and amount of Cr up to 80 ng/10 ml. The proposed method was found to be effective for determination of Cr (III), but it needed reduction with hydroquinone in order to measure Cr (VI). To determine Cr content in a deposit sample, the sample was divided into two fractions, soluble and insoluble fractions. From the results obtained by this method, Cr (VI) was found scarce in both fractions. Therefore, Cr in the deposit sample might be mainly present in the state of Cr (III).
