Headspace liquid-phase microextraction using ionic liquid as extractant for the preconcentration of dichlorodiphenyltrichloroethane and its metabolites at trace levels in water samples.

A novel technique, high temperature headspace liquid-phase microextraction (HS-LPME) with room temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6]) as extractant, was developed for the analysis of dichlorodiphenyltrichloroethane (p,p'-DDT and o,p'-DDT) and its metabolites including 4,4'-dichlorodiphenyldichloroethylene (p,p'-DDE) and 4,4'-dichlorodiphenyldichloroethane (p,p'-DDD) in water samples by high performance liquid chromatography with ultraviolet detection. The parameters such as salt content, sample pH and temperature, stirring rate, extraction time, microdrop volume, and sample volume, were found to have significant influence on the HS-LPME. The conditions optimized for extraction of target compounds were as follows: 35% NaCl (w/v), neutral pH condition, 70 degrees C, 800 rpm, 30 min, 10 microL [C4MIM][PF6], and 25 mL sample solutions.

[Highly sensitive fluorescent reaction of acridine red with chromium (VI) and its application].

A simple and highly sensitive fluorimetric method for the determination of Cr(VI) was developed in the present paper. The method is based on the fluorescence enhancement of acridine red with Cr(VI) in the sulfuric acid medium. The effects of some experimental conditions on the determination of Cr(VI) were investigated in detail.

[Speciation analysis of selenium by flow-injection catalytic spectrophotometry].

A new flow-injection catalytic spectrophotometric method was proposed for the determination of Se(IV) based on its catalytic effect on the reduction reaction of azure I by Na2S in pH 7.0 citric-acid sodium-hydrogen-phosphate buffer solution. Some different schematic diagrams of FIA were compared.