PREPARATION OF PLASMA SAMPLES FOR AMINO-ACID ANALYSIS BY EQUILIBRIUM DIALYSIS

A claim that losses of free amino acids in plasma can occur on deproteinisation with sulphosalicylic acid has been confirmed in studies with synthetic amino acid mixtures. The use of equilibrium dialysis is proposed as a simple, quick, and effective means of preparing protein-free extracts of plasma amino acids from plasma. Dialysis against citrate buffer ensures that the amino acid-containing extract is in a form suitable for direct application to an amino acid analyser. Apart from tryptophan, the amino acid concentrations of the dialysate appear stable at 0° for up to 10 weeks. © 1978.