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Improved amino acid quantification in environmental samples: charge-matched recovery standards and reduced analysis time

1992; Elsevier BV; Volume: 37; Issue: 3-4 Linguagem: Inglês

10.1016/0304-4203(92)90079-p

1872-7581

Gregory L. Cowie, John I. Hedges,

Mass Spectrometry Techniques and Applications

We describe an improved technique for hydrolytic extraction of amino acids from environmental samples and reverse-phase liquid chromatographic separation of their o-phthaldialdehyde derivatives. Modifications to existing procedures are employed to reduce sample hydrolysis and preparation times. Quantification is improved relative to existing methods by addition of a variety of non-protein amino acids before hydrolysis. They are used as charge-matched recovery standards which help to compensate for differential losses of acidic, neutral and basic amino acids during extraction and analysis. Two experiments demonstrate that selective amino acid losses can be important in the analysis of environmental samples and may have considerable effect on final hydrolysate composition. The results also indicate that the selected recovery standards accurately mimic the behaviour of their corresponding charge classes of protein amino acids. Use of multiple recovery standards is likely also to be of value in dissolved amino acid analyses, particularly in cases such as pore waters where the solution contacts mineral surfaces and associated organic materials.