A Green Method for the Determination of Cadmium in Natural Waters Based on Multi-Fibre Supported Liquid Membranes

Overview

This paper from the University of Cadiz describes a hollow-fibre liquid-phase microextraction (HF-LPME) method for Cd(II) preconcentration in natural waters prior to determination by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS-GFAAS). The organic liquid membrane is Cyanex 272 (bis-(2,4,4-trimethylpentyl)phosphinic acid) dissolved in dihexylether, immobilised in polypropylene hollow fibres. Four fibres are used simultaneously per sample, improving throughput and reproducibility. Under optimised conditions the method achieves an enrichment factor of 292 (reduced to 130 with extraction time cut to 2 hours for practical work), a detection limit of 0.13 ng/L Cd, and a linear range up to 3 µg/L. The method was applied to mineral, tap, and seawater samples. This is a water-analysis method; no food matrix data are reported.

Key numbers

• LOD: 0.13 ng/L (0.00013 µg/L) Cd in water
• Linear range: up to 3 µg/L Cd
• Enrichment factor: 292 (full extraction), 130 (2-hour practical)
• Reproducibility: 3.3% RSD
• Optimal conditions: fibre length 6 cm, Cyanex 272 1.06 M, 0.04 M HNO3, 600 rpm, 4.26 h extraction; practical: 2 h

Methods (brief)

HF-LPME with Cyanex 272 in dihexylether liquid membrane in polypropylene hollow fibres. Four fibres per sample run simultaneously. Detection by HR-CS-GFAAS. Univariate pre-optimisation followed by multivariate central composite design. Applied to mineral water, tap water, and seawater (not food matrices).

Implications

Certification: Not applicable to food HMT&C threshold setting; water analysis only. LOD of 0.13 ng/L is far below any food-relevant threshold. Courses: Useful reference for trace-level cadmium analytical capability and green chemistry approaches to heavy metal extraction. App: Not applicable.

Wiki pages updated on ingest

• cadmium-detection-methods

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