Choline in Infant Formula and Adult Nutritionals by Ion Chromatography and Suppressed Conductivity: First Action 2012.20

Abstract

Single-laboratory validation (SLV) data from a method for the determination of choline in infant formula and adult nutritionals by ion chromatography (IC) and suppressed conductivity were generated and presented to the Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) Expert Review Panel (ERP) at the AOAC Annual Meeting held in Las Vegas, NV, during September 30 to October 3, 2012. The ERP reviewed the data and concluded that the data met the standard method performance requirements (SMPRs) established and approved the method as AOAC Official First Action. At the ERP's request, a second, full SLV was performed on 17 SPIFAN matrixes that included fortified and placebo products. Prior to IC analysis, microwave-assisted acid hydrolysis was used to digest and release bound choline from powder and ready-to-feed (RTF) infant formula and adult nutritional samples. Following hydrolysis, separation of choline from common cations was achieved on a Thermo Scientific Dionex IonPac CS19 column followed by suppressed conductivity detection. Total choline was measured and reported as the choline ion in mg/100 g reconstituted material or RTF as-is. The system was calibrated over the analytical range specified in the SMPR (2-250 mg/100 g). Recoveries of spiked samples at 50 and 100% of the fortified choline amounts ranged from 93.1 to 100.7% with RSDs < or = 6.7% for product containing < 2 mg/100 g and < or = 4.1% for product containing 2-100 mg/100 g. Accuracy for the National Institute of Standards and Technology Standard Reference Material 1849a was determined over a 6-day interval and found to be 10.2 +/- 0.2 mg/100 g calculated as the reconstituted powder with an RSD of 1.8%. The LOD was determined to be 0.009, and the LOQ 0.012 mg/100 g, well below the SMPR requirements of 0.7 and 2 mg/100 g, respectively. Repeatability RSDs over the range of the assay (2-200 mg/100 g) ranged from 1.0 to 5.93%

Determination of betaine, l‐carnitine, and choline in human urine using a self‐packed column and column‐switching ion chromatography with nonsuppressed conductivity detection

“…Various methods have been reported for the determination of betaine, l‐ carnitine, and choline either alone or in various combinations in complex matrix. Previous reported methods such as GC , conventional HPLC , and IC were proposed for the determination of these target compounds either separately or simultaneously. The limitation of GC analysis is the need of conversion of betaine, l‐ carnitine, and choline into volatile derivatives .…”

“…In comparison, IC is a powerful analytical technique for the separation of cations, anions, and polar and hydrophilic compounds, such as sugars, amino acids, peptides, and proteins. Accordingly, IC with conductivity detection has been evaluated for the separation and determination . Here, we describe an IC method for simultaneous and rapid determination of betaine, carnitine, and choline in the human urine.…”

Simple determination of betaine, l‐carnitine and choline in human urine using self‐packed column and column‐switching ion chromatography with nonsuppressed conductivity detection

“…Analytical techniques such as gas chromatographic (GC) (Zeisel & Dacosta, ), conventional high‐performance liquid chromatography (HPLC) (Seim & Staedtler, ; Vernez et al, ; Zhao, Xiong, & Curtis, ) and ion chromatography (IC) (Oates et al, ; Suo, Li, Zhang, & Su, ; Zhang & Zhu, ) have been proposed for the determination of betaine, carnitine and choline either alone or in various combinations. The limitation of GC analysis is the need to conversion of betaine, l ‐carnitine and choline into volatile derivatives (Lewin, Peshin, & &, Sklarz, B., ).…”

“…Another option is IC with conductivity detection, which is known as a powerful analytical technique for the separation of cations, anions and polar and hydrophilic compounds. The applicability of IC coupled with suppressed conductivity has been reported for the determination of choline in infant formula and adult nutritionals (Oates et al, ). However, the suppressed IC method is not applicable for the determination of zwitterionic compounds such as l ‐carnitine.…”