Method of stabilizing blood for the determination of methemoglobin.

Methemoglobin (MetHb) is a significant clinical problem for some poisonings. Its measurement is a problem as both formation and reduction of MetHb can occur even after sampling with time. The objective of this study was to discover a method to stabilize the blood samples for the determination of MetHb. First, hemolysates were prepared by diluting the MetHb blood samples with phosphate buffers under different pH values. The samples were stored at 4-8 °C and a day-to-day variability in the amount of MetHb was determined using the method described by Evelyn and Malloy. The results show that there is a significantchange in the amount of MetHbstored in both KH2PO4/Na2HPO4 and KH2PO4/Na2HPO4 .2H2O buffer solutions at pH of 6.7 and 6.9. Buffer solution containing phosphate composition of KH2PO4/Na2HPO4 ·2H2O (pH=7.0) gives relatively stable values for MetHb during the storage and the amount of MetHb samples in the buffer solution retain constant up to 9 days. Therefore, stabilized MetHb blood samples can be prepared using KH2PO4/Na2HPO4 ·2H2O buffer solution (pH=7) with non-ionic detergent and the samples can be stored for several days at 4-8 °C.