[FI-KR non-separated method coupled with FAAS for the determination of Fe(II) and Fe(III) in water].

An FI-KR non-separated method coupled with FAAS for the determination of Fe(II) and Fe(III) was developed. With 60 s of sampling at a flow rate of 6.0 mL x min(-1), EF of 41 for Fe(III) and 9 for Fe(II) were obtained. The precision (RSD, n = 11) for Fe(III) and Fe(II) was 2.3% and 3.1% at the 0.04 mg x L(-1) level respectively. When 0.1 per thousand phi TEA was used as masking reagent, the recovery rate for Fe(III) and Fe(II) was from 97% to 101% and from 96% to 100% respectively.

[Two steps elution method FI on-line adsorption and preconcentration coupled with FAAS for the determination of trace zinc].

A flow injection two steps elution method on-line sorption and preconcentration system coupled to flame atomic absorption spectrometry (FAAS) was developed for the determination of trace Zn in water samples. The conventional elution procedure was divided into two steps: elution procedure and detection procedure. During the elution procedure, the eluent was pumped into KR by the suction of the peristaltic pump and through PTFE tube instead of peristaltic pump tube. By the new method, the dispersion of the analyte was decreased notably, and high absorbance peak value was achieved. Because the eluent was not through the peristaltic pump tube, the peristaltic pump tube was protected from being eroded. Emptying procedure was added in order to insure the veracity and repeatability of the experiment of every time. With 60 s (sample throughput of 37 x h(-1)) of sampling at a flow rate of 6.0 mL x min(-1), an enhancement factor (EF) of 28 (higher than 9 achieved by conventional elution method) and a detection limit (3sigma) of 0.35 x L(-1) were obtained. The precision (RSD, n=11) was 2.1% at the 20 microg x L(-1) level. When 0.1% phi triethannolamine was used as masking reagent, the recovery rate was from 98.7% to 99.6%.

[A flow injection on-line unequal flow complexation preconcentration procedure coupled with flame atomic absorption spectrometry for determination of lead in tap water].

A simple, environmentally friendly, cost-effective, and sensitive method was developed for the determination of trace lead in tap water by flow injection (FI) on-line unequal flow complexation preconcentration procedure coupled with flame atomic absorption spectrometry (FAAS). Compared with conventional preconcentration method, the unequal flow complexation preconcentration procedure, increased the flow rate of sample while decreased the flow rate of complexing agent. The new method decreased the dilution effect of sample caused by the chelating agent, increased the sorption preconcentration effect, and increased the enhancement factor. The decrease in the flow rate of chelating agent will not result in a deficient complex formation because the concentration of APDC is much higher than that of the sample's. Compared with other sorption preconcentration methods, such as, multiplexed sorption preconcentration procedure, the unequal flow complexation preconcentration procedure need not to prolong the preconcentration time, but received even better results. Taking lead as a model element, ammonium pyrrolidine dithiocarbamate (APDC) as the chelating agent, and ethanol as the eluent, the proposed FI on-line KR unequal flow complexation preconcentration procedure was coupled with FAAS for the determination of trace lead in tap water. With a sample loading flow rate of 10. 4 mL x min(-1) and preconcentration time of 60 s, the enhancement factor increased from 30 (conventional equal flow complexation preconcentration procedure) to 59 (unequal flow complexation preconcentration procedure), the detection limit (3sigma) of 5.6 microg x g L(-1) was obtained at a sampling frequency of 40 samples x h(-1). The relative standard deviations (n = 11) were found to be 2.1% at the level of 0.5 mg x L(-1). The recovery ranged from 98.5% to 102%. The proposed method has been successfully applied to the determination of lead in tap water samples.

[Flame atomic absorption spectrometric determination of copper and lead in beer after preconcentration using a rapid coprecipitation technique with 8-oxyquinoline].

A method was proposed for the determination of trace copper and lead in beer with flame atomic absorption spectrometry after preconcentration of copper and lead by rapid coprecipitation technique with 8-oxyquinoline-Mg(II) using manganese as an internal standard at pH 9. The standard addition recovery of lead is between 97.6%-103.0%. The detection limit is 6.28 x 10(-3) microg x mL(-1) for copper and 2.26 x 10(-2) microg x mL(-1) for lead 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.

[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.

[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.

[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.

[Combined bio-process for treatment of municipal wastewater containing Cu2+].

A combined bioprocess consisting of biosorption section with P. putida 5-x cell as biosorbent followed by a SBR is developed to treat Cu2+ containing municipal wastewater. The optimal preparing technique of P. putida 5-x cell as biosorbent is studied. Under the optimal condition, adsorption capacity of the P. putida 5-x cell to Cu2+ reached 87.3 mg x g(-1). The performance of the combined bioprocess for treating Cu2+ containing wastewater is assessed. The experimental results indicate that after treatment by the biosorption section, the Cu2+ concentration in wastewater reduced to the level that did not inhibit COD removal efficiency of subsequent SBR activated sludge process, although it still affectes the COD adsorption capacity of activated sludge. In terms of COD removal, the biosorption section is efficient for reducing Cu2+ concentration to provide biodegradable wastewater for subsequent SBR activated sludge process.