Application Of Dispersive Liquid-liquid Microextraction Coupled With Inductively Coupled Plasma-mass Spectrometry In The Separation And Preconcentration Of Trace Metal Elements

With the developing of modern industry, heavy metals such as cadmium, nickel, copper, cobalt and zinc are inevitably released into the environment as a result of human activities and rapid industrialization. Moreover, food and water are the main sources of exposure to Cd, Ni, Cu, Co and Zn for the general population; these heavy metals could enter food chain gradually accumulate in living organisms even at a very low concentration levels and finally cause damage to human health. Therefore, the determination of heavy metal ions at trace levels in real samples including food and environmental water is a very important task for the public health safety.The objective of this work aims to develop new methods for analysis of trace metal elements and engineered nanomaterials in real samples by the combination of dispersive liquid-liquid microextraction with inductively coupled plasma-mass spectrometry. Herein, in this paper, dispersive liquid-liquid microextraction combined with dispersive micro-solid phase extraction for separation, enrichment and analysis of trace heavy metals in complex matrices by ICP-MS was established for the first time. The details were as follows:(1)A rapid and innovative two-step microextraction technique, combining dispersive liquid-liquid microextraction and dispersive micro-solid phase extraction, was developed for the preconcentration and extraction of cadmium, nickel and copper in food and environmental water samples, prior to analyzed by inductively coupled plasma-mass spectrometry(ICP-MS). In the proposed approach, DDTC was used as chelating agent and carbon tetrachloride was selected as extraction solvent. Several parameters that influencing the extraction efficiency, such as the kind and volume of the extraction solvent, p H of sample solution, concentration of the chelating agent, amount of Fe3O4 magnetic nanoparticles, salt effect, sonication time and matrix effect were optimized in details. The method was successfully applied to the determination of Cd, Ni and Cu ions in food and environmental water samples with satisfactory results.(2)A simple and powerful microextraction technique was used for the detection of the nano-Zn O trace amounts in environmental water samples using the ultrasound-assisted dispersive liquid-liquid microextraction (USA-DLLME), followed by the inductively coupled plasma-mass spectrometry(ICP-MS). Several parameters that affect the extraction efficiency, such as the volume of the extraction solvent, p H of sample solution, salt effect, extraction time and extraction temperature were investigated and optimized. The proposed method was successfully applied to the extraction and determination of nano-Zn O in nature water samples.(3)The method based on ultrasound-assisted dispersive liquid-liquid microextraction(USA-DLLME) preconcentration and inductively coupled plasma-mass spectrometry(ICP-MS) detection was successfully proposed for the determination of trace Cd, Co and Zn in environmental water samples. In the proposed approach, APDC and toluene were selected as the chelating agent and extraction solvent. Several parameters that affect the extraction efficiency, such as the volume of the extraction solvent, p H of sample solution, concentration of the chelating agent, salt effect, and sonication time were investigated and optimized. The method was successfully applied to determination of Cd, Co and Zn in tap, river and lake water samples.