Determination of calcium and zinc in gluconates oral solution and blood samples by liquid cathode glow discharge-atomic emission spectrometry

A novel flowing liquid cathode glow discharge (LCGD) was developed as an excitation source of the atomic emission spectrometry (AES) for the determination of Ca and Zn in digested calcium and zinc gluconates oral solution and blood samples, in which the glow discharge is produced between the electrolyte (as cathode) overflowing from a quartz capillary and the needle-like Pt anode. The electron temperature and electron density of LCGD were calculated at different discharge voltages. The discharge stability and parameters affecting the LCGD were investigated in detail. In addition, the measured results of real samples using LCGD-AES were verified by ICP-AES. The results showed that the optimized analytical conditions are pH = 1 HNO3 as supporting electrolyte, 4.5 mL min(-1) solution flow rate. The power consumption of LCGD is 43.5-66.0 W. The R-2 and the RSD ranged from 630 to 680 V are 0.9942-0.9995 and 0.49%-2.43%, respectively. The limits of detections (LODs) for Zn and Ca are 0.014-0.033 and 0.011-0.097 mg L-1, respectively, which are in good agreement with the closed-type electrolyte cathode atmospheric glow discharge (ELCAD). The obtained results of Ca and Zn in real samples by LCGD-AES are basically consistent with the ICP-AES and reference value. The results suggested that LCGD-AES can provide an alternative analytical method for the detection of metal elements in biological and medical samples.