Development of miniaturized solid phase microextraction of copper in serum using a micropipette tip in-syringe system combined with micro sampling flame atomic absorption spectrometry

A new miniaturized solid phase microextraction (SPmE) method, using a micropipette tip, packed with carbon cloth, mounted on a syringe, was developed for preconcentration and determination of trace levels of copper in serum samples of male adolescents having hepatitis C. For comparative purposes healthy boys of the same age group (12-15 years), socioeconomic status and residential areas were also selected. The sample solution was treated with a complexing reagent 8-hydroxyquinoline (oxine), drawn into the syringe fitted with an ACC filled micropipette tip and dispensed manually for 2-10 drawing/discharging cycles. The analytes retained on ACC in a micropipette tip-syringe system were eluted with different volumes (50-200 mL) of 2 mol L-1 HNO3 in ethanol by 1-5 drawing/dispensing cycles. The influence of different analytical parameters (amount of ACC, oxine concentration, sample volume, pH, drawing and dispensing cycles, type and volume of eluent) was investigated to optimize the developed method. The developed method showed a linear response for standards of Cu, over the concentration range of 5-75 mg L-1 with correlation coefficients (R-2) >= 0.997. Under the optimized experimental variables, the enhancement factors and limits of detection (LODs) were obtained to be 56 and 0.36 mu g L-1, respectively, with a relative standard deviation of <= 5%. The validity and accuracy of the developed method were checked using the matrix matched certified reference material of human serum (Sero-M10181). The method was successfully applied for the preconcentration and determination of trace levels of Cu2+ in serum samples of adolescent male HCV patients and healthy controls of the same age group.