Abstract
A method based on flow injection-isotope dilution-cold vapor-inductively coupled plasma mass spectrometry (FI-ID- CV-ICP/MS) has been applied to determine trace level of mercury in fly ash. 200 Hg isotopic spike was added to 0.25 g of BCR176R fly ash and then decomposed by microwave digestion procedure with acid mixture A (8 mL HNO3 +2m L HCl + 2 mL HF) and acid mixture B (8 mL HNO3 +2m L HClO4 + 2 mL HF) for applying IDMS. Mercury cold vapor was gener- ated by using reductant solution of 0.2% (w/w) NaBH4 and 0.05% (w/w) NaOH. The measurements of n( 200 Hg)/n( 202 Hg) isotope ratio was made using a quadrupole ICP/MS system. The accuracy in this method was verified by the analysis of certified reference material (CRM) of fly ash (BCR 176R). The indicative value of Hg in BCR 176R fly ash was 1.60 ± 0.23 mg/kg (k = 2). The deter- mined values of Hg in BCR 176R fly ash by the method of FI-CV-ID-ICP/MS described in this paper were 1.60 ± 0.24 mg/kg (k = 3.18) and the analysis results were in well agreement with the indicative value within the range of uncertainty.
Highlights
Mercury (Hg) is a major concern among hazardous heavy metals because of its high volatility and high toxicity
Hg usually occurs in very low contents, so that highly sensitive analytical methods are needed for the determination of the element.[1]
An ID-CV-inductively coupled plasma mass spectrometry (ICP/MS) method coupled with flow injection (FI) has been applied to determine the content of Hg in BCR 176 fly ash certified reference material (CRM)
Summary
Mercury (Hg) is a major concern among hazardous heavy metals because of its high volatility and high toxicity. An ID-CV-ICP/MS method coupled with flow injection (FI) has been applied to determine the content of Hg in BCR 176 fly ash CRM. For mercury cold vapor generation, the solutions of 0.05% (w/w) NaOH and 0.2% (w/w) NaBH4 with3 % (w/w) HCl solution were used as reductant. Two different acid mixtures (acid mixture-A: 8 mL HNO3 + 2 mL HCl + 2 mL HF, acid mixture-B: 8 mL HNO3 + 2 mL HClO4 + 2 mL HF) were compared for fly acid sample digestion. The mineral acid mixtureB (HNO3 + HClO4 + HF) was used according to the method that has been used for decomposition of NIST 1633a coal fly ash.[12] To investigate the validity of the method described in this paper, Mercury in BCR CRM 176R fly CRM was analyzed and compared with the indicative value. The sample was decomposed at 120 oC for 5 min, 80 oC for 3 min, 180 oC for 10 min, 220 oC for 35 min, step by step
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