title: A rapid and accurate method for determining protein content in dairy products based on asynchronous-injection alternating merging zone flow-injection spectrophotometry.
abstract: An accurate and rapid method and a system to determine protein content using asynchronous-injection alternating merging zone flow-injection spectrophotometry based on reaction between coomassie brilliant blue G250 (CBBG) and protein was established. Main merit of our approach is that it can avoid interferences of other nitric-compounds in samples, such as melamine and urea. Optimized conditions are as follows: Concentrations of CBBG, polyvinyl alcohol (PVA), NaCl and HCl are 150 mg/l, 30 mg/l, 0.1 mol/l and 1.0% (v/v), respectively; volumes of the sample and reagent are 150 μl and 30 μl, respectively; length of a reaction coil is 200 cm; total flow rate is 2.65 ml/min. The linear range of the method is 0.5-15 mg/l (BSA), its detection limit is 0.05 mg/l, relative standard deviation is less than 1.87% (n=11), and analytical speed is 60 samples per hour.
authors.affiliation: School of Chemical Engineering, Sichuan University, Chengdu 610065, China.
authors.forename: Qin-Qin
authors.initials: QQ
authors.lastname: Liang
authors.forename: Yong-Sheng
authors.initials: YS
authors.lastname: Li
mesh_terms: D000818:Animals; D002417:Cattle; D003611:Dairy Products / Q000032:analysis*; D017022:Flow Injection Analysis / Q000379:methods*; D008894:Milk Proteins / Q000032:analysis*; D013053:Spectrophotometry / Q000295:instrumentation / Q000379:methods*
chemical_list: D008894:Milk Proteins
keywords: Asynchronous-injection merging zone; Coomassie brilliant blue; Dairy products; Flow-injection analysis; Protein determination; Spectrophotometry