A capillary electrophoresis method for free fatty acids screening and acidity determination in biodiesel

Recent advances in lipid analysis by capillary electromigration methods, 2019-2024

Following a long period during which Capillary Electrophoresis (CE) was little used for lipid analysis (see Poinsot et al., Electrophoresis, 40, 2019, 190-211), the last five years have seen an increase in publications on this subject. Micellar Electrokinetic Chromatography (MEKC) can now compete with Gas Chromatography (GC) for the analysis of fatty acids, while non-aqueous capillary electrophoresis (NACE) now allows the study of fatty acids as well as phospholipids or glycolipids. As NACE also allows easy coupling to Mass Spectrometry (MS) in both positive and negative Electrospray Ionization (ESI), the technique has now become sufficiently robust, and for laboratories equipped with GC or Liquid Chromatography (LC) to consider using CE, particularly as it presents the advantage of much faster sample preparation than with GC for fatty acids and a resolution identical to LC for phospholipids and glycolipids. In this article, we will therefore describe the advances made in this area over the last five years.

Fatty acids analysis by capillary electrophoresis: Fundamentals, advantages and applications

This review covers the know-how of the Grupo de Química Analítica e Quimiometria regarding the analysis of fatty acids by capillary electrophoresis acquired over its 20 years of existence. Therefore, the fundamentals, advantages, and applications of this technique for analyzing different fatty acids in samples such as food, oils, cosmetics, and biological matrices are presented and discussed. Capillary electrophoresis is, thus, shown as an interesting and valuable separation technique for the target analysis of these analytes as an alternative to the gas chromatography coupled to flame ionization detection, as it offers advantages over the latter such as low analysis times, low sample and reagent consumption, the use of a nondedicated column, and simpler sample preparation. In addition, the methods shown in this literature review can be useful for quality control, adulteration, and health-related research by regulatory agencies.

Strategies for capillary electrophoresis: Method development and validation for pharmaceutical and biological applications-Updated and completely revised edition

This review is in support of the development of selective, precise, fast, and validated capillary electrophoresis (CE) methods. It follows up a similar article from 1998, Wätzig H, Degenhardt M, Kunkel A. "Strategies for capillary electrophoresis: method development and validation for pharmaceutical and biological applications," pointing out which fundamentals are still valid and at the same time showing the enormous achievements in the last 25 years. The structures of both reviews are widely similar, in order to facilitate their simultaneous use. Focusing on pharmaceutical and biological applications, the successful use of CE is now demonstrated by more than 600 carefully selected references. Many of those are recent reviews; therefore, a significant overview about the field is provided. There are extra sections about sample pretreatment related to CE and microchip CE, and a completely revised section about method development for protein analytes and biomolecules in general. The general strategies for method development are summed up with regard to selectivity, efficiency, precision, analysis time, limit of detection, sample pretreatment requirements, and validation.

Determination of creatinine in urine and blood serum human samples by CZE-UV using on-column internal standard injection

Creatinine is a well-stablished biomarker for kidney malfunctions and for normalization parameter of urinary quantitative information. Recently, metabolic studies have been discovering other functionalities for creatinine tests in human urine and blood serum. In this work we present an enhanced capillary electrophoresis (CE) based protocol for determination of creatinine. CE is a high-throughput separation technique that have been getting attention through the last decades and might be considered to be adopted as an analytical instrumentation for clinical purposes. In the proposed method, we performed a short injection program with on-column addition of internal standard. Additionally, the method allows a simultaneous screening of non-proteinogenic amino acids that could be considered for metabolomics purposes. We design a pilot study that successfully estimated the creatinine value in 100 urine samples with (2.85 ± 1.78) mg dL^-1 LOD; (8.24 ± 5.93) mg dL^-1 LOQ and 82.4% accuracy. Considering that serum creatinine is also included in the clinical laboratory routines for estimated Glomerular Filtration Rate dosage, the method was complementary applied to 10 blood serum samples, which resulted in a model with (0.4 ± 0.2) mg dL^-1 LOD; (2.0 ± 0.6) mg dL^-1 LOQ and 83.8% of accuracy. All results were in agreement with reference values. The proposed method promotes a great analytical frequency and reproducibility with enhanced specificity compared with the ongoing protocol by Jaffe's reaction, thereby proving to be useful as an alternative for creatinine exams that might help complete a diagnosis of a series of health-related issues.

Separation of unsaturated C18 fatty acids using perfluorinated-micellar electrokinetic chromatography: I. Optimization and separation process

Ammonium perfluorooctanoate (APFOA) was used as a surfactant for the separation of free unsaturated C18 fatty acids by micellar electrokinetic chromatography. A simple background electrolyte of 50 mM APFOA water/methanol (90:10, v/v) at pH = 10 enabled the repeatable separation of oleic acid, elaidic acid, linoleic acid, and alpha-linolenic acid in less than 20 min. Separation conditions were optimized regarding various parameters (organic solvent, counterion, APFOA concentration, and pH). Because the repulsive interactions between fluorocarbon chains and hydrogenated chains are known to lead to segregation and phase separation, the choice of perfluorinated micelles to separate such perhydrogenated long-chain acids could appear astonishing. Therefore, the critical micelle concentration, the charge density, and the mobility of the micelles have been determined, resulting in a first description of the separation process.