Determination Of Lead In Water Samples Research Articles

Sequential injection solvent dispersive micro solid phase extraction (SI-SD-μSPE) platform coupled with atomic absorption spectrometry for lead determination in water samples

A novel automatic versatile sequential injection solvent dispersive micro solid phase extraction platform coupled with flame atomic absorption spectrometry is developed for the first time. The analytical procedure is based on chemical dispersion of benzophenone and ternary component systems. The full dispersion of sorbent into the aqueous phase, in the shape of micro particles, is achieved by on-line mixing of the two flows; a small flow of methanol containing the sorbent in a low concentration and a higher one of the aqueous sample solution. The resulted cloudy mixture is consisted of sorbent's fine particles, which are dispersed into the whole aqueous phase. Via this continuous process, metal chelating complexes are retained onto the sorbent particles. An integrated, easy and fast reusable syringe filter was studied for the on-line collection and dissolution of the sorbent. The potentials of this novel schema were demonstrated for trace Pb(II) determination in water samples. All the critical parameters affecting the performance of the proposed method were optimized. For a sample consumption of 11.0 mL, the working range was 5.28–400.0 μg L−1, while the enhancement factor, the detection limit and the relative standard deviation were 120, 1.59 μg L-1 and 2.4% (at 50.0 μg L−1) respectively. The developed method was evaluated by analyzing certified reference materials and applied to the analysis of environmental water samples.

Fabrication of Nano Flower‐shaped Platinum on Glassy Carbon Electrode as a Sensitive Sensor for Lead Electrochemical Analysis

AbstractPlatinum nanoflowers modified glassy carbon electrodes (PtNFs/GCE) was fabricated simply for lead determination in water samples. The modified electrodes were prepared by electrodeposition in hexachloroplatinic acid solution at constant potential. The influence of deposition time and potential on surface morphology, chemical composition, electrochemical properties of electrode were investigated. At −0.2 V of potential and 150 s of deposition duration, platinum developed as nanoflower shape and scattered densely all over the glassy carbon surface, producing the largest electrochemically active surface areas. The highest differential pulse stripping voltammetry (DPSV) signal of lead was obtained by using the prepared electrode. Under optimized experimental condition of electrolyte, accumulation potential and time, the peak current was found to be linear proportion to lead concentration in range of 1 to 100 μg L−1 (slope=0.371) with a limit of detection of 0.398 μg L−1. The method has good repeatability and reproducibility with relative standard deviations of 1.47 % and 4.83 %, respectively. The modified PtNFs/GCE also demonstrated an excellent long‐term stability with only 9 % decrease in Pb peak current over 30 days. Moreover, the performance of the modified PtNFs/GCE in determination of Pb(II) in two industrial wastewaters was good agreement with data obtained by a graphite furnace atomic absorption spectrometry (GFAAS) method.

Automatic sequential injection liquid–liquid micro-extraction system for on-line flame atomic absorption spectrometric determination of trace metal in water samples

An automatic sequential injection (SI) liquid–liquid micro-extraction system incorporating a dual-conical micro-gravitational phase separator is proposed as versatile approach for on-line metal preconcentration and/or separation. Coupled to flame atomic absorption spectrometry (FAAS) the potentials of this novel schema are demonstrated for lead determination in water samples at the μg l −1 level. The non-charged lead complex with ammonium pyrrolidine dithiocarbamate (APDC) was extracted on-line into 300 μl isobutyl methyl ketone (IBMK) through the extraction coil. The organic phase containing the extracted metal complex is collected in the upper cavity of the phase separator and then forwarded to the nebulizer. All the critical parameters were optimized and offered good performance characteristics and high preconcentration ratios. A sample consumption of 10.5 ml enabled the determination of Pb(II) in the range of 3.0–250.0 μg l −1 with an enhancement factor of 120 and a sampling frequency of 25 h −1. The detection limit and the precision were 1.4 μg l −1 and 2.9% (at 50.0 μg l −1 concentration level), respectively. The proposed method was evaluated by analyzing certified reference material and was applied successfully to the analysis of natural water samples.

Factorial design in the optimization of preconcentration procedure for lead determination by FAAS

The present paper proposes a preconcentration procedure for lead determination using flame atomic absorption spectrometry (FAAS). It is based on lead(II) ions extraction as brilliant cresyl blue (BCB) complex and its sorption onto Diaion HP-2MG, a methacrylic ester copolymer. The optimization step was carried out using factorial design and the variables studied were pH, shaking time and reagent concentration. In the established experimental conditions, lead can be determinate with a limit of detection of 3.7 μg L −1 lead ( N = 20) and a relative standard deviation of 7% for a lead concentration of 100 μg L −1. The accuracy was confirmed by analysis of a certified reference material, the stream sediment furnished by National Research Centre for Certified Reference Materials (NRCCRM), China (GBW 07310). Effect of other ions in the procedure proposed was also studied. The method was applied for lead determination in real samples of water, tea, soil and dust. Tests of addition/recovery in the experiments for lead determination in water samples revealed that the proposed procedure could be applied satisfactorily for analysis of these samples.