# Development of a New Purity Certified Reference Material of Gamma Linolenic Acid Methyl Ester

## TL;DR

This paper describes the development of a new certified reference material for gamma-linolenic acid methyl ester to improve accuracy in food and pharmaceutical testing.

## Contribution

The first purity certified reference material of gamma-linolenic acid methyl ester was developed following international standards.

## Key findings

- The CRM was prepared using preparative HPLC and molecular distillation from evening primrose oil.
- The certified purity value is 98.9% ± 0.4% with stability of 12 months at -18°C.
- The CRM is homogeneous and suitable for quality control in food and pharmaceutical industries.

## Abstract

In the study, a new purity certified reference material (CRM) of gamma‐linolenic acid methyl ester (GLA‐ME), designated as (GBW (E) 091214), was first developed in accordance with ISO Guides 17034 and 35. The research involved comprehensive investigations into the preparation, structure determination, characterization, homogeneity testing, stability testing, and uncertainty evaluation of the GLA‐ME purity CRM. It was prepared by the preparative high‐performance liquid chromatography (Pre HPLC) and molecular distillation (MD) method using evening primrose oil (EPO) as a raw material. The identity of GLA‐ME was confirmed using high‐resolution mass spectrometry (HRMS), nuclear magnetic resonance (NMR), and infrared spectrophotometry (IR). The purity of GLA‐ME was accurately determined by the mass balance (MB) and further validated via quantitative nuclear magnetic resonance (qNMR). The homogeneity, long‐term stability, short‐term stability, and uncertainty were systematically studied using the MB. The uncertainty was evaluated by combining the contributions from characterization, homogeneity, and stability. The certified value was 98.9% ± 0.4% (k = 2) with 12 months stability under −18°C condition and 5 days stability at room temperature. The CRM was sufficiently homogeneous between and within bottles. It can be used for quality control and method validation to ensure the accuracy and reliability of GLA measurements for quality monitoring in the food and pharmaceutical industries.

In this study, a new purity certified reference material (CRM) of gamma‐linolenic acid methyl ester (GLA‐ME) (GBW (E) 091214) was first developed. The preparation, structure determination, characterization, homogeneity test, stability test, and uncertainty evaluation of the GLA‐ME purity CRM have been investigated. The mass balance (MB) and quantitative proton nuclear magnetic resonance (qNMR) methods were used for characterizing the CRM. The certified value was 98.9% ± 0.4%, with a coverage coefficient k value of 2.