| Summary: | 碩士 === 國立臺灣師範大學 === 化學系 === 96 === Successful application of the Hadamard transform (HT) technique to gas chromatography/mass spectrometry (GC/MS). Novel sample injection devices were developed to achieve multiple sample injections in GC instrument by using an electromagnetic valve to control the air pressure. The injection devices permitted successive injections precisely, resulting in clearly modulated chromatograms encoded by Hadamard matrices. After inverse Hadamard transformation of the encoded chromatogram, the signal-to-noise (S/N) ratios of the signals were substantially improved compared with those expected from theoretical values. The S/N ratios were enhanced ~10-fold in HT-GC/MS, using the matrices of 511 and 1023, respectively. This experiment considered the factors of the injection pressure, injection frequency and the temperature of oven that were affect the efficiency of Hadamard transformation. Two well known, abused drugs, 3,4-Methylenedioxy-N-methylamphetamine (3,4-MDMA) and N,N-dimethyltryptamine (DMT), were employed as model samples. The HT-GC/MS was successfully applied to the determination of drugs in the urine sample of a suspect.
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