Analysis of amino acids in blood samples is an important tool for the diagnosis of neonatal amino acid metabolism disorders. In the work, a novel, rapid and sensitive method was developed for the determination of amino acids in neonatal blood samples, which was based on microwave-assisted silylation followed by gas chromatography/mass spectrometry (GC/MS). The amino acids were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) under microwave irradiation. The controlled reaction was carried out employing BSTFA under conventional heating at 1208C for 30 min. Experimental results show that microwave irradiation can accelerate the derivatization reaction of amino acids with BSFTA, and much shorten analysis time. The method validations (linear range, detection limit, precision and recovery) were studied. Finally, the method was tested by determination of amino acids in neonatal blood by the measurement of their trimethylsilyl derivatives by GC/MS in electron impact (EI) mode. Two biomarkers of L-phenylalanine and L-tyrosine in phenylketonuria (PKU)-positive blood and control blood were quantitatively analyzed by the proposed method. The results demonstrated that microwave-assisted silylation followed by GC/ MS is a rapid, simple and sensitive method for amino acid analysis and is also a potential tool for fast screening of neonatal aminoacidurias. Copyright # 2005 John Wiley & Sons, Ltd.When there is a deficiency of enzymes associated with an amino acid metabolic pathway, an amino acid metabolic disorder occurs in the human body and this leads to abnormal accumulation of amino acids and their precursors in the body. As a result, amino acid concentrations change in blood and urine. If this problem is the result of a genetic defect, an amino acid error occurs in newborns. Such inborn errors can cause major intellectual disturbances, but, if a neonatal diagnosis is made, appropriate treatment can be initiated. Neonatal screening for such metabolic disorders can be performed by the measurement of the appropriate amino acids. For example, phenylketonuria (PKU) is a fairly common metabolic disorder caused by a deficiency of phenylalanine hydroxylase. 1 The enzyme defect leads to a specific pattern of plasma amino acids with increased phenylalanine (Phe). 2 Newborn screening for PKU relies on the detection of Phe in the blood from filter paper. In 1963, Guthrie and Susi developed a simple and semi-quantitative method of bacterial inhibition assay (BIA) for the analysis of amino acids, and applied it to neonatal screening for metabolic disorders. 3 Sequentially, high-performance liquid chromatography (HPLC), ion-exchange chromatography, capillary electrophoresis, fluorometry and micellar electrokinetic chromatography were developed for the analysis of amino acids in neonatal blood samples. [4][5][6][7][8] Recently, a high-throughput technique of tandem mass spectrometry (MS/MS) was developed for determination of amino acids in blood samples that has been used for neonatal screening. [9][10][11][12][13][14] D...
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