A novel automatic flow-batch extraction induced by emulsion breaking platform for on-line copper determination in edible oil samples by atomic absorption spectrometry.

ABSTRACT

A novel automatic flow-batch platform coupled with atomic spectrometry for on-line acidic extraction induced by emulsion breaking with heating (FB-EIEBH) for metal determination in edible oils (corn, sunflower and olive oil), was developed for the first time. The proposed system was demonstrated for copper determination in conjunction with flame atomic absorption spectrometry. The extraction of metal is accomplished after the oil emulsification with an aqueous solution consisted of Triton X-114 and nitric acid, in an on-line programmed manner. All the main parameters affecting the extraction procedure, such as oil dilution, type and concentration of surfactant and nitric acid as well as temperature and time for the emulsion breaking and phase separation, have been investigated and optimized. A mixture of oil/xylene at 102 proportion was found to be appropriate to use in the flow manifold. Optimum conditions were verified employing 8.0 mL of oil sample, 990 µL of extractant solution containing 10.0% m/v Triton X-114 and 10.0% v/v HNO3. Emulsion breaking and phases separation were completed at temperature 90 °C, and time 300 s. The detection and quantification limit for copper determination was found to be 5.8 µg L-1 and 19.3 µg L-1, employing aqueous standards, which are proved to produce similar performance characteristics with oil-based standards. Recovery tests were executed by appropriate additions of oil-based standard solution of copper and the recoveries ranged between 94.2 and 102.4%.