| Autor: |
de Wuilloud, Jorgelina C. A., Wuilloud, Rodolfo G., Sadi, Baki B. M., Caruso, Joseph A. |
| Zdroj: |
Analyst; 2003, Vol. 128 Issue: 5 p453-458, 6p |
| Abstrakt: |
A preconcentration and determination method for humic and fulvic acids at trace levels in natural water samples was developed. Cloud point extraction was successfully employed for the preconcentration of humic acid HA and fulvic acid FA prior to the determination by using a flow injection FI system coupled to a spectrophotometric UV-Vis detector. The quantitative extraction of HA and FA within the pH range 1–12 was obtained by neutralization of the anionic charge on the humic substances with a cationic surfactant, hexadecyltrimethylammonium bromide CTAB. This generated a hydrophobic species that was subsequently incorporated solubilized into the micelles of a non-ionic surfactant polyethylene glycol, tert-octylphenyl ether Triton X-114. The FI method for HA and FA determination was developed by injection of 100 µl of the extracted surfactant-rich phase using an HPLC pump with spectrophotometric detection at 350 nm. A 50 ml sample solution preconcentration allowed an enrichment factor of 167. The limit of detection LOD obtained under the optimal conditions was 5 µg l−1. The precision for ten replicate determinations at 0.2 mg l−1HA was 3.1 relative standard deviation RSD, calculated from the peak heights. The calibration using the preconcentration system for HA and FA was linear with a correlation coefficient r2 of 0.9997 at levels near the detection limits up to at least 1 mg l−1. The method was successfully applied to the determination of HA and FA in natural water samples river water. |
| Databáze: |
Supplemental Index |
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