Determination of glucosamine in dietary supplement samples by capillary electrophoresis using capacitively coupled contactless conductivity detector (CE-C4D)

The quantification of glucosamine in dietary supplements was investigated by using capillary with capacitively coupled contactless conductivity detection (CE-C4D). Optimal conditions included electrophoresis buffer solution 10 mM Tris/Ace; pH = 5,0; sample injection height 25 cm; sample injection time 30 s; separation voltage 20 kV. The limit of detection (LOD) and the limit of quantification (LOQ) of glucosamine were 8.00 ppm and 26.67 ppm, respectively. Calibration curve was constructed over the range from 20 to 1000 ppm giving a good linear correlation coefficient (R2 = 0.9993). The relative standard deviation (RSD) ranged from 1.28% to 2.33% (n = 3) and the recovery efficiency ranged from 95.2 to 102.3% which indicated good precision and trueness of our method. The method was applied to determine glucosamine in 4 dietary supplement samples randomly collected at the local markets. The CE-C4D results were compared with those obtained by reference HPLC-FLD method, showing good agreement between the two methods (relative error < 15%).