Determination of silver by chemical vapor generation with in situ trapping flame atomic absorption spectrometry

摘要

The hyphenation of chemical vapor generation with an integrated atom trap system for flame atomic absorption spectrometry (CVG-IAT-FAAS) was evaluated for determination of silver in real samples (coal fly ash, sediment, and nickel alloy). The volatile species of silver were formed by reaction with sodium tetrahydroborate(III) in the presence of nitric acid. A new CVG-IAT-FAAS design (versus a water-cooled single silica tube, double-slotted quartz tube) significantly improved the sensitivity and detection limits compared with conventional flame atomic absorption spectrometry (FAAS) for determination of silver. The concentration limit of detection was 0.7ngmL ~1 for Ag. The overall efficiency of the vapor generation process was estimated to be ca. 12%. For a 2min in situ preconcentration time, sensitivity was enhanced 143-fold for Ag using the vapor generation atom trapping technique, compared to conventional FAAS. Sensitivity can be further improved by increasing the collection time. The precision of measurement at 10ngmL ~1 of Ag was 10% RSD. The accuracy of this method was validated by analyses of NRC GBW 07302 (Stream Sediment), BCS CRM No. 346 (Nickel Alloy), NIST SRM 2710 (Montana Soil), NRCC LUTS-1 (Lobster Hepatopancreas), and NIST SRM 1643e (Trace Element in Water) certified reference materials. The measured Ag contents in these five reference materials were in satisfactory agreement with the certified values (spanning the range of 0.066-35g g ~1).