title: Significant sensitivity improvement of alternating current driven-liquid discharge by using formic acid medium for optical determination of elements.
abstract: A method has been developed to improve the performance of alternating-current electrolyte atmospheric liquid discharge (ac-EALD) optical emission spectrometry for the determination of elements. Significant enhancement of emission intensity was achieved by adding organic substance into the nitric acid electrolyte solutions. Under the optimized conditions, 3% (v/v) formic acid in nitric acid (pH 1.0) produced 13 times enhancement for Ag and 7% (v/v) formic acid resulted in 17 times enhancement for Cd. The emission of Pb was even enhanced 78 times in the presence of 3% formic acid. In addition, the signal stability was also improved compared with that in the absence of organic substances. Repeatability was 0.8% for 0.1 mg L(-1) Ag, 0.7% for 0.2 mg L(-1) Cd and 2.6% for 1 mg L(-1) Pb standard solutions (n=5). The limits of detection of Ag, Cd and Pb were 1, 17 and 45 μg L(-1), respectively. The accuracy of the method was demonstrated by determination of elements in simulated natural water samples (GBW(E)080402 and GBW(E)080399).
authors.affiliation: State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Xiao
authors.forename: Zhenli
authors.initials: Z
authors.lastname: Zhu
authors.forename: Hongtao
authors.initials: H
authors.lastname: Zheng
authors.forename: Haiyang
authors.initials: H
authors.lastname: He
authors.forename: Chunying
authors.initials: C
authors.lastname: Huang
authors.forename: Shenghong
authors.initials: S
authors.lastname: Hu
mesh_terms: D002104:Cadmium / Q000032:analysis*; D005561:Formates / Q000737:chemistry*; D005618:Fresh Water / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007854:Lead / Q000032:analysis*; D057230:Limit of Detection; D017942:Nitric Acid; D015203:Reproducibility of Results; D012834:Silver / Q000032:analysis*; D013054:Spectrophotometry, Atomic / Q000379:methods; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D005561:Formates; D014874:Water Pollutants, Chemical; D002104:Cadmium; C030544:formic acid; D007854:Lead; D012834:Silver; D017942:Nitric Acid