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Abstract
The quantification of lead in water samples is presented at the sub-ppb level through preconcentration with cloud point extraction (using Triton x-100 and eriochrome black T) and atomic absorption spectrometry with electrothermal atomization. In order to study the influence of several variables, experimental design analyses were carried out. Linearity was observed between 0.15 to 1.20 ng mL−1 (r = 0.98), with a detection limit of 0.04 ng mL−1 and a quantification limit of 0.15 ng mL−1. A mean recovery of 90 ± 9% (n = 6, P = 0.05) was found; at the precision was 9% expressed as the coefficient of variation. Anions and cations that were studied did not affect the recovery of lead. Water samples of different sources were analyzed directly as well as by the standard addition method; no statistical differences were found between the two procedures. Finally, the present methodology was compared with liquid–liquid extraction of the lead-ditizone complex, using green analytical indicators proposed for this purpose.
Acknowledgments
The authors acknowledge the financial support provided by the SEP in Mexico ((PROMEP/1035/10/5489) for the achievement of this work.
Notes
a Pearson values (P) lower than 0.05 showed significant differences at a 95% confidence level.
a Pearson values (P) lower than 0.05 showed significant differences at a 95% confidence level.
a Pearson values (P) lower than 0.05 showed significant differences at a 95% confidence level.
a Standard deviation of the blank, 2.6 × 10−3.
b Coefficient of variation under repeatability conditions.
c Expressed as the mean recovery ± confidence limits (α = 0.05).
Note. All concentrations in ng mL−1.
a Standard error according to Bruce and Gill Citation1999.
a E Factor: includes volume of sample.