A simple spectrophotometric method for the quantification of residual haemoglobin in platelet concentrates

BACKGROUND AND OBJECTIVES: High levels of residual haemoglobin (Hb 0.1 g/l) are known to decrease the efficiency of pathogen-inactivation systems. We evaluated three separate methods to quantify Hb in platelet concentrates (PC). MATERIALS AND METHODS: Nine PC prepared in platelet additive solution (PASIII) (median platelet yield of 283 x 10(9)/unit, range 46-353) were spiked to known Hb concentrations with whole blood and the samples were measured by using each of three methods: the 3,3',5,5'-tetramethylbenzidine (TMB) oxidation method (Sigma Diagnostics, 527-A); the Harboe spectrophotometric method; and the HemoCue plasma low-Hb photometer (PLHP). RESULTS: The TMB and Harboe methods showed linear results compared to expected Hb (r2 > or = 0.981, P < 0.001) over the range tested (0.09-0.28 g/l) when the samples were haemolysed. The TMB method underestimated by an average of 6%, at and around 0.1 g/l Hb, compared to a 4% overestimation by the Harboe method and a threefold overestimation by the PLHP. The Harboe intra-assay coefficient of variation was < or = 1.85% across all concentrations, which contrasted with 30% at and around 0.1 g/l for the TMB method. CONCLUSIONS: The Harboe spectrophotometric method is convenient, safe, accurate and reproducible, and outperforms the TMB and PLHP methods for quantification of residual Hb in PC.