Analytical evaluation of the Tosoh HLC-723 G7 automated HPLC analyzer for hemoglobin A2 and F determination

Objectives: The analytical performance of a new automated HPLC system (Tosoh HLV-723 G7) for Hb A2 and Hb F quantification in blood was studied. Design and methods: Hb A2 and Hb F measurements were studied for imprecision, linearity, carry-over, interferences and sample concentration effect. Method comparison study was performed with the Bio-Rad Variant II HPLC system. Hb F results were also compared with those obtained by the alkaline denaturation test. The detection of some common Hb variants was also studied. Results: Hb A2 within-run and between-run CVs were found between 0.8–2.2% and 2.9–7.2%, respectively, while CVs for Hb F were up to 10.0% in normal and between 1.9–5.3% at more clinically relevant Hb F concentrations (>1.5%). Comparison study with Bio-Rad Variant II for Hb A2 determination showed good correlation but highlighted calibration differences. The following results were obtained in two different laboratories: y = 1.163x − 0.52, r = 0.9918, n = 144 (Lab A); y = 1.060x − 0.40, r = 0.9920, n = 93 (Lab B). With regard to the determination of Hb F, the measurements performed by the tested method was found to correlate well with the alkaline denaturation test (y = 1.0138x − 0.36, r = 0.9842, n = 20) and with the Variant II HPLC system (y = 0.812x + 0.52, r = 0.9835, n = 110). An excellent linearity (r = 0.999) was found for both Hb A2 and Hb F in the range 0.8–19%. Hb S, Hb C and Hb D can be presumptively identified by the assigned retention time windows. Conclusion: The new analyzer Tosoh HLV-723 G7 was found to be a reliable method for Hb A2 and Hb F quantification and for the presumptive identification of some common Hb variants.