Use of W-Ir permanent modifier for direct determination of cadmium in urine by electrothermal atomic absorption spectrometry

Objective:To study W-Ir as permanent chemical modifier in the direct determination of cadmium in urine by electrothermal atomic absorption spectrometry(ETAAS).Methods:250 μg W+200 μg Ir coating on the integrated platform of a transversely heated graphite atomizer(THGA)was used in the tests.Pyrolysis temperature curves and atomic temperature curves of urine with different dilution times were observed.The analytical performances were estimated and comparisons with the conventional modifier NH4H2PO4+Mg(NO3)2 were performed.Results:The background signal was low and the sensitivity was high.The lower atomic temperature was in favor of prolonging the lifetime of graphite platform when compared with NH4H2PO4+Mg(NO3)2 conventional modifiers.Under the optimized conditions,the RSD(n=5) was 0.3%～2.7%,the recoveries 92.0%～108.0%,the detect limit for urine 0.025 μg/L and the characteristic mass(mo) 1.5 pg.Conclusion:This method is accurate,simple and sensitive.