Determination of Chloride in Infant Formula and Adult/Pediatric Nutritional Formula by Potentiometric Titration: Single-Laboratory Validation, First Action 2015.07

• Published in: Journal of AOAC International 2016-01, Vol.99 (1), p.198-203
• Main Authors: Bolong, Wu, Fengxia, Zhang, Xiaoning, Ma, Fengjuan, Zhou, Brunelle, Sharon L
• Format: Article
• Language: English
• Subjects: Adult; Chlorides; Chlorides - analysis; Food Analysis; Food testing; Food, Formulated - analysis; Humans; Identification and classification; Infant; Infant Formula - chemistry; Infant formulas; Laboratories; Methods; Nutritive Value; Potentiometry; Testing
• ISSN: 1060-3271; 1944-7922
• DOI: 10.5740/jaoacint.15-0143

A potentiometric method for determination of chloride was validated against AOAC Standard Method Performance Requirement (SMPR(®)) 2014.015. Ten AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) matrixes, including National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 1849a, were tested in duplicate on 6 independent days. The repeatability (RSDr) ranged from 0.43 to 1.34%, and the intermediate reproducibility (RSDiR) ranged from 0.80 to 3.04%. All results for NIST SRM 1849a were within the range of the certified concentration (701 ± 17 mg/100 g). Recovery was demonstrated with two overspike levels, 50 and 100%, in the 10 SPIFAN matrixes. Samples were tested in duplicate on 3 different days, and all results were within the SMPR requirement of 95 to 105%. The LOQs of the method for powdered products and ready-to-feed or reconstituted products were 20 mg/100 g and 2.2 mg/100 mL, respectively. A wide analytical range from the LOQ to 99.5% chlorine content can be reached with an appropriate dilution factor, but in practice, the upper analytical value observed in routine matrix testing was approximately 1080 mg/100 g in skim milk powder. This is a rapid, simple, and reliable chlorine-testing method applicable to infant formula, adult nutritionals, and ingredients used in these dairy-based products, such as skim milk powder, desalted whey powder, whey protein powder, and whole milk powder.