Supported ionic liquid adsorbent and ELSD–HPLC method as an alternative procedure for exogenous fatty acid analysis in breast milk

Development of matrix certified reference material for accurate determination of docosahexaenoic acid in milk powder

A novel matrix certified reference material (CRM) of docosahexaenoic acid in milk powder [GBW (E) 100641] was first developed. The CRM candidates was prepared by adding appropriate levels of docosahexaenoic acid to cow's milk, then powder sprayed, lyophilized, mixed, dispensed and sterilized. An optimized acetylchloride-methanol method was proposed and used for the characterization. The CRM characterization was carried out in six laboratories in accordance with ISO Guide 35 requirements. The certified value of CRM was 0.69 mg/g with an uncertainty of 0.08 mg/g (k = 2). The CRM was sufficiently homogeneous between and within bottles and stable up to 6 month at -20℃ and 7 days below 50 ℃. The uncertainty was evaluated by combing the contributions from characterization, homogeneity and stability. Thus, the CRM can be used for quality control and method validation to ensure the accurate and reliable measurements of docosahexaenoic acid in milk for quality monitoring.

An overview of poly (amide-amine) dendrimers functionalized chromatographic separation materials

Chromatography is one of the most important separation techniques in analytical chemistry. In which, the separation materials are the core for good separation results. Poly (amide-amine) dendrimers with regular three-dimensional structure, abundant terminal groups, controllable molecule chains, and unique cavities appear to have a positive impact on chromatographic separation materials. In the past decades, poly (amide-amine) grafted adsorbents and stationary phases have presented high grafting efficiency, controllable surface structure, good dispersion, and wide practical applications. In this review, the prepared poly (amide-amine) functionalized separation materials and their applications are systematically summarized. Functions, significance, structure-actvity relationships and benefits of poly (amide-amine) dendrimers in the proposed separation materials are discussed in detail. And we hope to provide a useful reference for the future development of chromatographic separation materials and inspire new discoveries in the study of poly (amide-amine) functionalized materials.

Validation of an HPLC Method for Pretreatment of Steviol Glycosides in Fermented Milk

Steviol glycosides are used in food and beverages worldwide as natural sweeteners, serving as a low-calorie sugar substitute. The acceptable daily intake of steviol is 0-4 mg/kg body weight. The rising demand for dairy products has led to a corresponding increase in the use of steviol glycosides in such products. Therefore, it is important to analyze the levels of steviol glycosides in dairy products. Dairy products have high fat contents and unique emulsion characteristics, conferred by a mixture of fat globules, casein micelles, whey proteins, and numerous other small molecules. These characteristics may interfere with the estimation of steviol glycoside levels; therefore, dairy samples require pretreatment. We aimed to develop an objective test for measuring the levels of steviol glycosides through the development of an efficient pretreatment method. In this study, the steviol glycoside content in dairy products was evaluated by using various methods, and an optimal pretreatment method was determined. We used high-performance liquid chromatography to assess the selectivity, linearity, limit of detection, limit of quantification, accuracy, precision, and recovery rate. Calibration curves were linear in the range of 1-50 mg/kg, with a coefficient of determination of ≥0.999. The limit of detection and limit of quantification were in the ranges of 0.11-0.56 and 0.33-1.69 mg/kg, respectively. The relative standard deviation (%) represents the precision of a measurement. The RSD relative standard deviationof recovery varied between 0.16% and 2.83%, and recovery of the analysis varied between 83.57% and 104.84%. These results demonstrate the reliability of the method for measuring the steviol glycoside content. This method can be used for the simple pretreatment of steviol glycosides and can provide an accurate determination of steviol glycoside content in emulsified food matrices, such as dairy products.