Direct determination the content of carbohydrates in honey by underivatized capillary zone electrophoresis

A new method was established to determine the content of carbohydrates in honey, and the detection mechanism was expounded. An elastic quartz capillary tube ( effective length/total length = 52/62 cm) was used with a running buffer of130 mmol/L Na OH + 30 mmol/L Na2HPO4 ( p H = 12.8) at 20 ℃, the separation voltage was raised linearly within 1 min from0 k V to + 16 k V, the detection wavelength was 270 nm. The pressure of injection was 20 psi, the contents were calculated by internal standard method.The contents of fructose, glucose, sucrose and maltose in honey samples were 42.8%, 36.1%, 4.67%and 2.16%, respectively.The detection mechanism may be photochemical reaction of carbohydrates in the alkali solution and detection was carried out in non-equilibrium state.The linear ranges of fructose and glucose were 0.04⁰.8 mg/m L, sucrose and maltose were 0.005⁰.1 mg/m L.The detection limits ( at S/N of 3) of fructose, glucose, sucrose and maltose were 9, 9, 18 and18 μg/m L which were significantly lower than that of high performance liquid chromatography-refractive index detector ( HPLC-RID) .The recoveries of fructose, glucose, sucrose and maltose were 99.4%, 97.9%, 97.1% and 102.7%, respectively. This method is accurate and simple which can be used for determining the contents of carbohydrates in honey.