Abstract:Cadmium is among the most toxic metals in the aquatic environment. It particularly affects shellfish because the latter can accumulate large amounts of cadmium from the water. To reduce the potential risk on the health of public consumers, it is necessary to measure and monitor the level of cadmium in shellfish. Conventional analysis methods are usually time-consuming due to the prolonged sample digestion and pretreatments. A direct solid sampling technology without digestion treatment has been applied in the fast determination of cadmium concentration in agricultural produces such as grains and vegetables. Here, we tried to employ this method in the rapid measurement of cadmium concentration in shellfish. Solid sampling (SS) device was coupled with atomic fluorescence spectrometry (AFS), and the SS-AFS instrument was assembled with a tungsten coil trap (TCT) and porous carbon ETV. Meanwhile, electrothermal vaporization atomic fluorescence spectrometry (ETV-AFS) with a tungsten coil trap was optimized, and SS-ETV-AFS was established as a novel direct sampling method of detecting cadmium in shellfish. The results showed that a tungsten coil could work as a cadmium trap and eliminate most of the matrix interferences. Samples were homogenized and diluted with different acids, and 1% HNO3 was determined to be the optimal acid reagent. Under the optimized conditions, the fitting with both the standard addition method and the standard curve method showed good linearity with regression coefficient (R2) larger than 0.995. The relative standard deviation (RSD) of the standard addition method and the standard curve method were 6.5%–7.7% and 3.3%–8.6% respectively; the spiked recoveries of them were 96.4%–105.5% and 98.1%–110.6%; the limit of detection (LOD) were 0.6 pg and 3 pg. Moreover, the time elapsed (including sample pretreatments) was within 5 min. The standard addition method generated data with similar accuracy to those measured with graphite furnace atomic absorption spectrophotometry (GFAAS) or certified reference materials (CRMs) (P﹥0.05) . Therefore, the standard addition method could be suitable to the field analysis and monitoring of cadmium in shellfish.
