Use of different anticoagulants for HPLC separation and quantification of the free amino acid content of plasma

Amino acid analysis in plasma samples is a very important and difficult task and could represent a useful tool for preventing the occurrence of some diseases (diabetes, cancer, HIV disease). Even though amino acid analysis has been thoroughly investigated, there are still some steps which are not so clear in this analytical procedure, e.g. the coagulation process of the blood to afford plasma and serum. Various anticoagulants are used in clinical chemistry: in this paper we have investigated three commonly used anticoagulants, heparin, EDTA, and sodium citrate. The blood samples have been divided into three portions and each portion treated with a different anticoagulant. The entire analytical procedure (from blood collection to the coagulation all the way to HPLC analysis) has been extensively investigated; the chromatograms and the amino acid recoveries are reported, and the three anticoagulants compared. Finally, the best anticoagulant has been used to analyze glycemic curves of healthy patients: the behavior of essential amino acids in the different blood samples withdrawn has been studied.