An alternative derivatization method for the analysis of amino acids in cerebrospinal fluid by gas chromatography-mass spectrometry.

The determination of the concentrations of l-amino acids in cerebrospinal fluid (CSF) has been used to gain biochemical insight into central nervous system disorders. This paper describes a microwave-assisted derivatization (MAD) method using N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA) as a derivatizing agent for determining the concentrations of l-amino acids in human CSF by gas chromatography with mass spectrometry (GC/MS). The experimental design used to optimize the conditions showed that the optimal derivatization time was 3min with a microwave power of 210W. The method showed good performance for the validation parameters. The sensitivity was very good, with limits of detection (LODs) ranging from 0.01μmolL(-1) to 4.24μmolL(-1) and limits of quantification (LOQs) ranging from 0.02 to 7.07μmolL(-1). The precision, measured using the relative standard deviation (RSD), ranged from 4.12 to 15.59% for intra-day analyses and from 6.36 to 18.71% for inter-day analyses. The coefficients of determination (R(2)) were above 0.990 for all amino acids. The optimized and validated method was applied to the determination of amino acid concentrations in human CSF.