Direct injection of human serum and pharmaceutical formulations for glucosamine determination by CE-C4D method

A simple CE-C4D method has been developed for the determination of glucosamine by direct injection of human serum and pharmaceutical samples. Glucosamine was electrokinetically injected and analysed in its protonated form using 20 mM MES/His (pH 6) as background electrolyte in order to separate it from the matrix and to provide a better response to the C4D detector. Separation of glucosamine in human serum and pharmaceutical samples was performed in 3 min without the need for protein precipitation or matrix removal. Good precision in terms of %RSD for the migration time and peak area were less than 1.91% (n = 10). The conductivity signal was linear with glucosamine concentration in the range 0.10–2.50 mg/mL, with a detection limit of 0.03 mg/mL. Recoveries of glucosamine in serum and pharmaceutical samples were 86.5–104.78%. The method was successfully applied for the determination of the glucosamine content in pharmaceutical formulations and validated with high performance liquid chromatography (HPLC). Good agreements were observed between the developed method, label values and the HPLC method. Glucosamine could be detected in spiked serum sample by direct injection. This was not possible by HPLC due to co-eluting interferences.