Optimization and Validation of a Rapid Method to Determine Citrate and Inorganic Phosphate in Milk by Capillary Electrophoresis

• Published in: Journal of dairy science 2003-01, Vol.86 (1), p.86-95
• Main Authors: Izco, J.M., Tormo, M., Harris, A., Tong, P.S., Jimenez-Flores, R.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; capillary electrophoresis; citric acid; Citric Acid - analysis; Dairy Products - analysis; Dairy Products - standards; Electrophoresis, Capillary; Food industries; Food Technology; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; milk; Milk - chemistry; Milk and cheese industries. Ice creams; phosphate; Phosphates - analysis; Reproducibility of Results; Sensitivity and Specificity; Time Factors
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(03)73587-5

Quantification of phosphate and citrate compounds is very important because their distribution between soluble and colloidal phases of milk and their interactions with milk proteins influence the stability and some functional properties of dairy products. The aim of this work was to optimize and validate a capillary electrophoresis method for the rapid determination of these compounds in milk. Various parameters affecting analysis have been optimized, including type, composition, and pH of the electrolyte, and sample extraction. Ethanol, acetonitrile, sulfuric acid, water at 50°C or at room temperature were tested as sample buffers (SB). Water at room temperature yielded the best overall results and was chosen for further validation. The extraction time was checked and could be shortened to less than 1min. Also, sample preparation was simplified to pipet 12μl of milk into 1ml of water containing 20ppm of tartaric acid as an internal standard. The linearity of the method was excellent (R2>0.999) with CV values of response factors