Short Communication

Determination of L-carnitine in infant powdered milk samples after derivatization

Jung Min Park1, Jong Ho Koh2, Jin Man Kim1,*
Author Information & Copyright
1Konkuk University, Seoul 05029, Korea.
2Korea Polytechnic University, Korea, ChongNam 32940, Korea.
*Corresponding Author: Jin Man Kim, Konkuk University, Seoul 05029, Korea. Phone: +82-2-450-3688. E-mail: jinmkim@konkuk.ac.kr.

© Copyright 2021 Korean Society for Food Science of Animal Resources. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: Mar 12, 2021 ; Revised: Apr 21, 2021 ; Accepted: Apr 24, 2021

Published Online: Apr 27, 2021

Abstract

Herein, a novel HPLC–FLD (High performance liquid chromatorgraphy-fluorescence detectors) analytical method is developed for rapidly measuring an L-carnitine ester derivative in infant powdered milk. In this study, solid-phase extraction cartridges filled with derivatized methanol and distilled water were used to effectively separate L-carnitine. Protein precipitation pretreatment was carried out to remove the protein and recover the analyte extract with a high recovery (97.16–106.56%), following which carnitine in the formula was derivatized to its ester form. Precolumn derivation with 1-aminoanthracene (1AA) was carried out in a phosphate buffer using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) as the catalyst. Method validation was performed following the AOAC guidelines. The calibration curves were linear in the L-carnitine concentration range of 0.1–2.5 mg/L. The lower limit of quantitation and limit of detection of L-carnitine were 0.076 and 0.024 mg/L, respectively. The intra- and interday precision and recovery results were within the allowable limits. The results showed that our method helped reduce the sample preparation time. It also afforded higher resolution and better reproducibility than those obtained by traditional methods. Our method is suitable for detecting the quantity of L-carnitine in infant powdered milk containing a large amount of protein or starch.

Keywords: L-carnitine; infant formula; HPLC; derivatization; analytical method