[Determination of trace lead and iron in nickel chloride and manganese sulfate by flame atomic absorption spectrometry after coprecipitation with yttrium phosphate].

Using yttrium phosphate as the coprecipitation collector for the separation and preconcentration of trace lead and iron in nickel chloride and manganese sulfate, flame atomic absorption spectrometric (FAAS) determination was described in the present paper. Coprecipitation parameters including the pH of the solution, and the amounts of YCl3 and H3 PO4 were discussed. It was found that lead and iron in nickel chloride could be coprecipitated quantitatively in the range of pH 3.0-4.0, and so could be lead in manganese sulfate. The detection limits (3sigma) of lead and iron in 20 mL solution were 1.63 x 10(-2) mg x L(-1) and 4.58 x 10(-2) mg x L(-1) respectively. In NiCl2 solution the standard addition recoveries for lead and iron were 100.91% and 99.73% respectively, and in MnSO4 solution the standard addition recoveries were 99.45% and 98.98% respectively. The method has eliminated the interference of matrix, and the result is satisfied.

[Determination of trace copper and cadmium in water by flame atomic absorption spectrometry coupled with flow injection on-line preconcentration using air segmentation].

The flow injection on-line preconcentration with a knotted reactor (KR) system for the determination of copper and cadmium in water by flame atomic absorption spectrometry (FAAS) was described in the present paper. The precipitation preconcentration of trace copper and cadmium was achieved by on-line merging of the sample and ammonia solutions. The resultant precipitates were on-line collected by a knotted reactor (KR) without filtration, and then the authors used a process of air segmentation. A solution of 1 mol x L(-1) HNO3 was employed to dissolve the collected precipitates and to deliver the analyte into the FAAS system for on-line detection. With a sample loading flow rate of 4.4 mL x min(-1) and a preconcentration time of 90 s, the enhancement factor was 34 (for Cu) and 36 (for Cd) as compared with the conventional FAAS method. The detection limits (3sigma) are found to be 1.9 and 0.3 microg x L(-1) for copper and cadmium respectively. The precision (RSD, n = 11) was found to be 2.3% at the level of 30.0 microg x L(-1) of Cu (II), and 2.6% at the level of 20.0 microg x L(-1) of Cd (II). The proposed method has been successfully applied to the determination of Cu (II) and Cd (II) in water samples.

[Application of internal standardization to rapid coprecipitation technique using APDC-Cu(II) for FAAS determination of lead in salt].

A method was proposed for the determination of trace lead in salt with flame atomic absorption spectrometry after preconcentration of lead by rapid coprecipitation technique with APDC-Cu(II) using nickel as an internal standard at pH 2.5. The standard addition recovery of lead is between 92%-101%. The detection limit is 3.27 x 10(-3) microg x mL(-1) when the sample volume is 100 mL. The effect of matrix can be overcome by the method, and the results are satisfying. The method proposed here is rapid and has good reproducibility.