Abstract
A sensitive and reliable method for determination of trace levels of Cu and Zn in microdialysis samples using flow injection combined with direct injection nebulization and inductively coupled plasma mass spectrometry (FI-DIN-ICP-MS) has been developed and optimized. Under the optimized conditions, the method can be successfully applied to the determination of Cu and Zn down to the several ng/mL levels in biological fluid samples; but as the analyte concentrations further decreasing to the levels of <5ng/mL, the data appear to be randomly distributed caused most probably by serious fluctuation of blank. This blank problem has been solved simply by replacing the stainless steel syringe with a homemade PEEK syringe system, and consequently result in pronounced improvement of detection limit by a factor 7 and 25 respectively for Cu and Zn compared to the previous ones. The effects of spectral and nonspectral interferences for the determination of Cu and Zn in the microdialysis sample were also investigat -d and discussed. The analytical reliability has been confirmed by the good agreement of data obtained both with DIN-ICP-MS system and with graphite furnace atomic absorption spectrometry (GFAAS). The hyphenation of HPLC with ICP-MS using DIN as an interface has been established for speciation of arsenic in urine samples. The speciation of As in urine was conducted by a self-packed microbore anion-exchange column (1.0mm i.d.) followed by DIN-ICP-MS determination. Parameters affecting the separation such as pH and concentrations of mobile phase were studied. Under the optimized conditions, the four As species can be completely separated within 10min.. The characteristics of both microbore column and analytical column in terms of separation time, peak broadening and detection limit were also discussed in detail. The effects of spectral and nonspectral interference for the determination of As species in urine samples with this analytical system were also investigated, and the results indicated that the determination can be completely freed from interferences with the prior column separation step. The validity of the method developed was confirmed by the analysis of urine standard reference matei-al (NIST SRM 2670).