Glass capillary column gas chromatography of phenol-alkylamines after flas-heater derivatization using a double injection technique

Abstract

Glass capillary column gas chromatography has been used for quantitative and qualitative analyses of some phenolalkylamines. The compounds are converted into the corresponding N-trifluoroacetyl-O-trimethylsilyl derivatives using a double injection technique. The phenolalkylamines are first flash-heater trimethylsilylated with N-methyl-N-(trimethylsilyl)trifluoroacetamide injected together with the sample, followed by N-acylation with N-methyl-bis(trifluoroacetamide0 in a second injection. The N-acylation occurs on-column. The identity of the derivatives was confirmed by gas chromatography—mass spectrometry. The phenolalkylamines were also analysed using on-column derivatization combined with a packed column and a double injection technique. Several parameters were studied for both methods in order to get optimal response with good reproductivity. The injection technique proved to be the most important parameter in this study and had to be carefully controlled. For the quantitative analyses, the linearity, reproducibility and lower detection limit were controlled. A concentration range of 5–50 μg/ml was investigated using the capillary column and 25–100 μg/ml for the packed column. The main advantages of this derivatization method are its speed and simplicity, which result in a substantial saving of time.