title: Determination of total iron in water and foods by dispersive liquid-liquid microextraction coupled with microvolume UV-vis spectrophotometry.
abstract: A novel microvolume UV-vis spectrophotometry method was proposed for the rapid determination of total iron coupling with an efficient pretreatment method known as dispersive liquid-liquid microextraction (DLLME). The basis of the method is a quantitative colorimetric reaction between ferrous iron and 2-(5-bromo-2-pyridylazo)-5-(diethyl amino) phenol (5-Br-PADAP) after the reduction of Fe(III) to Fe(II) by using ascorbic acid as reducing agent. Parameters related to the efficiency of microextraction, such as pH, complexant concentration, the volume ratio of disperser solvent and extraction solvent were discussed and optimized in detail. Under the optimized conditions, the absorbance was in proportion to iron concentration in the range of 5-400μgL(-1) with a correlation coefficient (R) of 0.9993. The limit of detection (LOD) and limit of quantitation (LOQ) were 1.5μgL(-1) and 5.2μgL(-1), respectively. The relative standard deviation (RSD) for samples were 1.37- 4.42% (n=3). Good recoveries of iron were obtained in the range of 95.4-103.2% in food samples, 96.9-103.6% in water samples and 98.8-102.3% in Certified Reference Material. The proposed method was rapid, reliable and high-selective for the determination of total iron in food and water samples.
authors.affiliation: Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China. Electronic address: pengbo.nwnu@hotmail.com.
authors.forename: Bo
authors.initials: B
authors.lastname: Peng
authors.affiliation: Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China.
authors.forename: Yingping
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China.
authors.forename: Zhuantao
authors.initials: Z
authors.lastname: Gao
authors.affiliation: Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Bioelectrochemistry & Environmental Analysis of Gansu Province, Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China.
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Gansu Entry-Exit Inspection and Quarantine Bureau, Lanzhou 730020, China.
authors.forename: Shengguo
authors.initials: S
authors.lastname: Zhao
mesh_terms: D005504:Food Analysis / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000032:analysis*; D057230:Limit of Detection; D059627:Liquid Phase Microextraction / Q000379:methods*; D012997:Solvents; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D014867:Water / Q000032:analysis*
chemical_list: D012997:Solvents; D014867:Water; D007501:Iron
keywords: 5-Br-PADAP; Dispersive liquid–liquid microextraction; Iron; UV–vis spectrophotometry