We proposed a simple and effective method, by coupling ionic liquid-based aqueous two-phase systems (IL-ATPSs) with high performance liquid chromatography (HPLC), for the analysis of determining tartrazine and sunset yellow in food samples. Under the optimized conditions, IL-ATPSs generated an extraction efficiency of 99% for both analytes, which could then be directly analyzed by HPLC without further treatment. Calibration plots were linear in the range of 0.01–50.0 μg/mL for both Ta and SY. The limits of detection were 5.2 ng/mL for Ta and 6.9 ng/mL for SY. This method proves successful for the separation/analysis of tartrazine and sunset yellow in soft drink sample, candy sample, and instant powder drink and leads to consistent results as obtained from the Chinese national standard method.

A rapid and simple method was optimized and validated for the separation and quantification of paraquat, a frequently used herbicide and a leading cause of fatal poisoning worldwide, at trace levels with UV-Vis spectrophotometry in plasma and urine samples by direct magnetic solid-phase extraction. Fe₃O₄@SiO₂nanoparticles (NPs) were used as the magnetic solid-phase extraction agents and the paraquat absorbed on NPs was eluted using NaOH and ascorbic acid. Upon optimization, paraquat could be extracted and concentrated from various samples by 35-fold. The linear range, limit of detection (LOD), correlation coefficient (R), and relative standard deviation (RSD) could reach 15.0–400.0 μg/L, 12.2 μg/L, 0.9987, and 0.65% (n=5,c= 40.0 μg/L), respectively. The Fe₃O₄@SiO₂NPs could be reused up to five times. The method was successfully applied to the determination of paraquat in urine and plasma at different hemoperfusion numbers in a local hospital for the patient of paraquat poisoning. The experiment result could not only enable immediate medical intervention but also benefit patients’ survival.

Aqueous two-phase system (ATPS) consisting of a hydrophilic ionic liquid 1-butyl-3-methylimidazolium bromide and K₂HPO₄, which is a novel, simple, fast, non-toxic and effective sample pretreatment technique coupled with UV-Vis spectrophotometry, was developed for the simultaneous separation, enrichment and rapid determination of amaranth and brilliant blue. Under the optimal conditions, the extraction efficiency for both analytes was nearly 100% in a one-step extraction. Linear calibration curves were obtained in the range of 25–2400 μg/L for amaranth and 4.5–1300 μg/L for brilliant blue. The limits of detection were 10 and 1.3 ng/mL for amaranth and brilliant blue, respectively. The method was applied to the simultaneous determination of amaranth and brilliant blue in beverages and candy samples. Compared with the results obtained by Chinese national standard method, there was no significant difference after being evaluated by t-test when the confidence level was 95%.

A simple method for the determination of paraquat in environment samples was developed. 1‑Ethyl-3-methylimidazolium ethyl sulfate and anhydrous potassium hydrogen phosphate were used to form aqueous two-phase system. The system was applied to the extraction of paraquat and its determination by HPLC. To achieve optimum extraction performance, several experimental parameters, including the type and the amount of salt, the amount of ionic liquid, extraction time, were investigated and optimized. Under the optimal experimental conditions, good linearity was observed in the range of 10–5 × 10³ ng/mL. The limit of detection was 8 ng/mL along with enrichment factor of 18. The phase behavior of aqueous two-phase system and extraction mechanism were investigated by UV-Vis spectroscopy. The present method was successfully applied to the determination of paraquat in environment samples, and the recovery was in the range of 92.3–95.1%. The results showed that the present method is rapid, feasible and environmentally friendly.