title: A sensitive colorimetric method for the determination of nitrite in water supplies, meat and dairy products using ionic liquid-modified methyl red as a colour reagent.
abstract: This paper describes a colorimetric approach to determine trace amounts of nitrite in water supplies, meat and dairy products using 1-butyl-3-methylimidazolium-modified methyl red ([BMIM]MR) as a colour reagent. The technique capitalises on the catalytic effect of nitrite on the oxidative degradation of [BMIM]MR by potassium bromate in acidic media. The absorbances were proportional to nitrite concentrations in the range of 8.70×10(-2) to 4.17 μM with a detection limit of 1.64×10(-2) μM. Compared with the method using methyl red as a colour reagent, 60 times improvement of sensitivity was obtained. Activation energy and the apparent rate constant for the catalytic reaction are 61.11 kJ mol(-1) and 1.18×10(4) s(-1), respectively. The proposed method was successfully applied for the analysis of nitrite in Yellow River water, chicken, and milk with recoveries ranging from 96% to 105%.
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China; College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China.
authors.forename: Haijuan
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China; College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China. Electronic address: qishd@lzu.edu.cn.
authors.forename: Shengda
authors.initials: S
authors.lastname: Qi
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China; College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China.
authors.forename: Yalei
authors.initials: Y
authors.lastname: Dong
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China; College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China.
authors.forename: Xiaojiao
authors.initials: X
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China; College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China.
authors.forename: Yinyin
authors.initials: Y
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China; College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China.
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China; College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, China; Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, Lanzhou 730000, China. Electronic address: chenxg@lzu.edu.cn.
authors.forename: Xingguo
authors.initials: X
authors.lastname: Chen
mesh_terms: D001391:Azo Compounds / Q000032:analysis / Q000737:chemistry; D003611:Dairy Products / Q000032:analysis*; D052578:Ionic Liquids / Q000737:chemistry*; D008461:Meat Products / Q000032:analysis*; D009573:Nitrites / Q000032:analysis*; D014881:Water Supply
chemical_list: D001391:Azo Compounds; D052578:Ionic Liquids; D009573:Nitrites; C008492:methyl red
keywords: Chicken; Colorimetric method; Ionic liquid-modified methyl red; Milk; Nitrite; Yellow River water