Primaquine Analysis in Pharmaceutical Formulation Using Multiple and Short-End Injections by Capillary Zone Electrophoresis-Ultraviolet Detection

Novel methods were proposed for determining primaquine (PQN) in tablets by multiple-injection capillary zone electrophoresis (MI-CZE) and by short-end injection CZE (SEI-CZE), both with ultraviolet detection. The background electrolyte (BGE), consisting of 20 mmol/L of tris (hydroxymethyl) aminomethane and 30 mmol/L of hydrochloric acid at pH 2.0, was selected considering a comprehensive study involving the effective mobility versus pH curves of the analytes and BGE components. Experimental designs were applied in methods developments, showing the chemometric tool's applicability in achieving suitable electrophoretic conditions. A baseline resolution in the separation of adjacent peak pairs was obtained by injecting a spacer electrolyte for 18 s, with a voltage of + 15 kV, and the sample can be injected six consecutive times in a single run in less than 3 min, in the MI-CZE method. For the SEI-CZE method, the migration time of PQN was 0.6 min, and the method was applied to a demonstrative forced degradation study. Some validation parameters were evaluated for both methods, and all results were satisfactory, indicating that they can be implemented as PQN determination methods in routine quality control analyses.

Antimalarial analysis of pharmaceutical formulations and biological samples by capillary electrophoresis: the state of the art and applications

Malaria is a serious public health problem, being an endemic disease in 84 countries, mainly in Africa. This review explores the application of capillary electrophoresis (CE) techniques for analyzing antimalarial drugs, highlighting methods from 2000 to 2023 for the analysis of pharmaceutical formulations and human biological samples. The versatility, selectivity, high efficiency, cost-effectiveness, and high analytical frequency of CE techniques have become attractive choices for pharmaceutical analysis, focusing on quality control and impurity analysis applications. The evolution of achiral and chiral electromigration methods has been described based on the features of each mode of separation: capillary zone electrophoresis (CZE), micellar electrokinetic chromatography, microemulsion electrokinetic chromatography, and capillary electrochromatography. As expected, CZE is reported in most articles owing to its compatibility with drug properties and separation mode. However, it is necessary to perform other separation modes for a few drugs that are present in neutral form. After exhaustive research using different databases and statistical analyses, 27 articles using CE techniques for antimalarial drug analysis were found and are mentioned in this review.

Malondialdehyde Analysis in Biological Samples by Capillary Electrophoresis: The State of Art

Lipid peroxidation occurs when substances, such as reactive oxygen species, attack lipids. Polyunsaturated fatty acids are the main targets. Several products are formed, including primary products such as lipid hydroperoxides and secondary products such as malondialdehyde (MDA), the most used lipid peroxidation biomarker. As MDA levels are elevated in several diseases, MDA is an essential indicator for assessing pathological states. The thiobarbituric acid reactive substances assay is the most widely used method for MDA determination. However, it lacks specificity. Capillary Electrophoresis (CE) is a separation technique that has been used to quantify MDA in biological samples. This technique has advantages such as the low amount of biological sample required, absence or low volume of organic solvent, short analysis time, separation of interferents, sample preparation step with only protein precipitation, and the possibility of direct detection of the MDA, without derivatization. To our knowledge, this review article is the first to show the CE background for analyzing MDA in biological samples. Therefore, given the potential of MDA in evaluating pathological states, this article demonstrates the potential of CE to become a reference method for MDA determination in clinical analysis laboratories, which will play a significant role in diagnosing and monitoring diseases.

Mixture design of an electrolyte system for the simultaneous separation of Cl-, SO42-, NO3-, NO2-, and HCO3- in shrimp-farming water by CZE-UV

Shrimp is one of the most traded fishery products in the world. The shrimp-farming water ionic composition is fundamental to the growth and survival of these specimens. Therefore, this study is aimed to develop a method for the simultaneous separation of Cl^-, SO₄^2-, NO₃^-, NO₂^-, and HCO₃^- in this sample by capillary zone electrophoresis with UV indirect detection, without any prior sample treatment, besides dilution. The background electrolyte (BGE) was composed of CrO₄^2- (60 mmol L^-1), cetyltrimethylammonium bromide (CTAB, 2.5 mmol L^-1), acetonitrile (0.875% (v/v)), and methanol (2.625% (v/v)). The mixture design optimized the BGE composition. Acetonitrile and methanol changed the degree of solvation of the anions, which decreased the radius, a phenomenon proven by calculating the radius of anions in all the conditions of the mixture design. The optimized and validated method allowed the simultaneous determination of the five above-mentioned anions in 10 min.

Determination of purity and anionic exchange efficiency of amino acid ionic liquids synthesis by multiple-injection capillary zone electrophoresis

The purity of ionic liquids (IL) is important for its performance, so the methods able to quantify low concentration impurities are necessaries. Therefore, this paper aims to determine the purity and the anionic exchange efficiency for the preparation of amino acids ionic liquids (AAIL). For this, a Multiple-Injection Capillary Zone Electrophoresis (MICZE) method with direct UV detection was developed and optimized for iodide (I^-) determination as impurity of AAIL synthesis, comparing this method with traditional injection modes. Furthermore, this paper aims to demonstrate the use of factorial design methods for the optimization of MICZE method. The method optimization allowed five consecutives I^- injections of sample in a single run, with analysis time of less than 3 min, showing a larger analytical frequency, counting with 31 injections per hour. It was possible to determine the high purity of the prepared and analyzed AAIL, ranging from 89% to 95% and its overall ionic exchange yield varying from 55% to 87%.

Simultaneous separation of artesunate and mefloquine in fixed-dose combination tablets by CZE-UV

A novel method was proposed for simultaneous determination of artesunate (ATS) and mefloquine (MFQ) in fixed-dose combination tablets by capillary zone electrophoresis with simultaneous direct and indirect detection by ultraviolet (CZE-UV). The background electrolyte, consisting of 30/15 mmol L^-1 TRIS/3,5-dinitrobenzoic acid buffer at pH 8.2, a chromophore buffer, was selected taking into account a detailed study involving the effective mobility vs. pH curves of the analytes and electrolyte compounds in association with the very low molar absorptivity of ATS. Suitable separation conditions, considering voltage, temperature and buffer concentration as factors, were achieved through the 3³ Box-Behnken design investigation. The optimum baseline separation conditions were: injection pressure of 30 mbar for 10 s, cartridge temperature of 22.5 °C and positive voltage of +30 kV. The method proved to be rapid (5 minutes), simple, selective, linear (r² > 0.98), precise (relative standard deviation (RSD): ATS < 2.9% and MFQ < 2.2%) and accurate (recoveries: ATS 98.13-102.96% and MFQ 98.75-106.77%), proving to be suitable for routine quality control analysis.

Ratiometric Fluorescent Hydrogel Test Kit for On-Spot Visual Detection of Nitrite

In this work, we proposed a new method based on carbon dots (named m-CDs) for selective and efficient detection of nitrite (NO₂^-), which was based on the interaction between the amine group of m-CDs and NO₂^- via a diazo reaction that produced diazonium salts and induced the fluorescence quenching of m-CDs. The concentration of NO₂^- shows a good linear relationship with a quenched fluorescence intensity from 0.063 to 2.0 μM ( R² = 0.996) with a detection limit of 0.018 μM. In addition, a ratiometric fluorescence probe ( m-CDs@[Ru(bpy)₃]²⁺) was constructed via electrostatic interaction by introducing Ru(bpy)₃Cl₂·6H₂O as an internal reference fluorescent reagent. Interestingly, a transition of the fluorescent color of the ratiometric probe from cyan to red could be visually observed upon increasing the concentration of NO₂^-. Based on these findings, a ratiometric fluorescent-based portable agarose hydrogel test kit was fabricated and applied for on-spot assessment of NO₂^- content within 10 min. As far as we know, this is the first ratiometric fluorescent sensor for visual detection of NO₂^-. It has broad application prospects in environmental monitoring and food safety assessment.