Detectability of and interference by major and minor hemoglobin variants using a new-generation ion-exchange HPLC...

High-performance liquid chromatography (HPLC) is commonly used to measure hemoglobin A_1c (HbA_1c) levels and detect hemoglobin variants (Hb-Vars). HLC-723GR01 (GR01) is a new-generation automated ion-exchange HPLC system with two switchable analysis modes, namely short (30 s/test) and long modes (50 s/test). We evaluated the general performance of both analysis modes of GR01 for quantifying HbA_1c and detecting Hb-Vars.

We evaluated the instrument's precision based on CLSI protocol EP-05-A3. A comparison of the two analysis modes of GR01 against the standard mode of HLC-723G11 was performed on 100 whole blood samples. The GR01 long mode was compared with affinity HPLC (AF-HPLC) for detecting common Hb-Vars (HbE, HbD, HbS, and HbC, >20 samples). To examine the detection capability for minor Hb-Vars, we analyzed 26 Hb-Vars using multiple analyzers, including both analysis modes of GR01.

Both modes of GR01 had within-laboratory coefficients of variation of ≤1.0 % from four samples with HbA_1c concentrations of 32-86 mmol/mol. Good correlation was observed between GR01 and HLC-723G11. The results for HbA_1c detection in the presence of the major variants revealed a strong correlation between the long mode of GR01 and AF-HPLC (r = 0.986-0.998), and the difference biases ranged 0.1-1.9 mmol/mol. In the long mode, only one variant had a difference bias exceeding 14 % [10 % (%NGSP)].

The two analysis modes of GR01 were fast and had high accuracy and reproducibility, indicating their utility for routine clinical use in measuring HbA_1c samples with Hb-Vars.