Introduction: the measurement of plasma haemoglobin is utilized in the evaluation of various haemolytic phenomenons, especially at the time of sampling. Besides, the methods used to titrate plasmatic haemoglobin, an analysis which is of great interest to cardiac surgery, must be very accurate, because plasmatic levels are much lower than those found in whole blood.
Background: the purpose of this work is to present a new technique for direct determination of plasmatic haemoglobin.
Material and methods: this method was studied and adapted on a multiparametric analyzer Konelab 30 (Thermo Electron Corporation). The correlation was assessed with a Sigma Diagnostics spectrophotometric method, using the 3,3',5,5'-tetramethylbenzidine (TMB), a non carcinogenic reagent. The reaction of haemoglobin with TMB was studied with a SECOMAM S500P UV-Visible spectrometer.
Results and discussion: the method demonstrates linearity, precision, and sensitivity suitable for clinical use and not affected by the presence of bilirubin, nor triglycerides. The method was precise (CV < 1,00%), accurate (CE < 5,00%) and showed excellent recovery of haemolysis (R > 0,95). The CV for the automated assay was less than 1%. Reference ranges were studied and lithium heparinate seems to be the best anticoagulant to use so as to minimize haemolysis.
Conclusion: the studied technique is practical, specific, accurate, fast, reliable and inexpensive, and was adopted in emergency as in daily routine in our laboratory for plasmatic haemoglobin determination in various situations.