Application of capillary electrophoresis-nano-electrospray ionization-mass spectrometry for the determination of N-nitrosodimethylamine in pharmaceuticals

A voltammetric method for determining N-nitrosodimethylamine in losartan and olmesartan drugs

Recently, the National Health Surveillance Agency (ANVISA) of Brazil recalled several lots of sartan drugs due to the presence of N-nitrosodimethylamine (NDMA). NDMA is a highly potent carcinogenic contaminant that harms human health; therefore, the presence of NDMA in sartan drugs must be checked through appropriate analytical methods. This work successfully developed a new analytical method for determining NDMA without chemical pretreatment of losartan and olmesartan drug samples. The method uses the square-wave anodic stripping voltammetric (SWASV) technique, a boron-doped diamond electrode (BDDE), and a standard additions procedure (SAP). The proposed SWASV-BDDE-SAP method provided a linear response in the concentration range between 250 and 2500 nmol L-1 (R2 = 0.995, n = 10), a limit of detection (LOD) of 67.6 nmol L-1, satisfactory accuracy (94.3% - 104.7%) without bias, and with good reproducibility (standard deviation = 5.6 %). The results obtained in determining NDMA in losartan and olmesartan drugs using the proposed and reference methods (HPLC-DAD) did not show a statistically significant difference, applying the paired t-test at a confidence level of 95%. In addition, the proposed method uses instrumentation with low acquisition, operation, and maintenance costs and enables rapid determination of NDMA in sartan drugs with great sensitivity, reproducibility, and stability. As the proposed SWASV-BDDE-SAP method does not use chemical pretreatment of samples, such as derivatization and/or extraction with reagents and/or organic solvents, it can be considered a promising eco-friendly alternative for determining NDMA in routine analysis, thus contributing to green analytical chemistry.

Miniaturized nanoelectrospray interface for coupling capillary electrophoresis with mass spectrometry detection

A miniaturized electrospray interface consisting of a microfluidic nanosprayer and nanospray module is reported in the presented short communication. The nanosprayer was fabricated using silicon (Si) technology suitable for cost-efficient high-volume mass production. The nanospray module enabled the positioning of the nanosprayer in front of a mass spectrometry entrance and its coupling with capillary electrophoresis based on the liquid junction principle. A case study of top-down and bottom-up proteomic analyses of intact cytochrome c and its tryptic digest demonstrates the practical applicability of the developed interface.

Recent developments in electromigration techniques related to pharmaceutical and biomedical analysis - A review

The analysis of pharmaceutical compounds is an important research topic as the use of different drugs affects people's daily life for the treatment of diseases. In addition to the widespread use of the internet, counterfeit drugs have appeared in the market. The development of modern analytical techniques, reliable, precise, sensitive, and rapid methods, has provided powerful means of analysis used in various fields such as drug production, quality control, determination of impurities and/or metabolites, biochemistry, pharmacokinetics, etc. Analytical techniques so far used in the pharmaceutical analysis include high-performance liquid chromatography (HPLC), gas chromatography (GC), super/sub-critical fluid chromatography (SFC), and capillary electromigration techniques such as capillary electrophoresis (CE) and rather rarely capillary electrochromatography (CEC). CE has some advantages over other techniques, e.g., very high efficiency, reduced costs (use of minute volumes of solvents and samples), the possibility to use different separation mechanisms, etc. In this review paper, the main features and limitations of the capillary electromigration techniques (especially CE) are discussed. Some selected applications of CE to the analysis of pharmaceutical compounds published in the period 2021-2023 (May) are reported.

Investigation of Carcinogenic Impurities of N-Nitrosamines in Sartan Pharmaceutical Products Marketed in Brazil: Development and Validation of Method Based on High-Performance Liquid Chromatography-Tandem Mass Spectrometry

N-nitrosamines (NA) impurities have unexpectedly been found in sartan products, angiotensin II receptor antagonists that are used to control hypertension, representing an urgent concern for industry, global regulators and for the patients. In this study, an HPLC-MS/MS method was developed and validated for the quantification of six NA (N-nitrosodimethylamine, N-Nitroso-N-methyl-4-aminobutyric acid, N-Nitrosodiethylamine, N-ethyl-N-nitroso-2-propanamine, N-nitroso-diisopropylamine and N-nitroso-di-n-butylamine) in losartan, valsartan, olmesartan, irbesartan, candesartan and telmisartan products. The method was validated in terms of sensitivity, linearity, accuracy, precision, robustness and stability. The limits of quantification were 100, 31.25, 250, 33, 312.5 and 125 µg kg^-1 in losartan, valsartan, olmesartan, irbesartan, candesartan and telmisartan samples, respectively, which met the sensitivity requirements for the limits set by Food and Drug Administration of the United States. The standard curves showed good linearity. The recoveries ranged from 93.06 to 102.23% in losartan matrix, 83 to 85.9% in valsartan, 96.1 to 101.2% in olmesartan, 89.2 to 97.5% in irbesartan, 93.4 to 132.0% in candesartan and 62.3 to 106.2% in telmisartan matrix. The other parameters met the validation criteria, the good sensitivity and precision, high accuracy and simple and fast analysis provides a reliable method for quality control of NA in sartan pharmaceutical products. The developed method was successfully applied for the determination of N-nitrosamines in 71 sartan products marketed in Brazil.

Microfluidic device integrating single-cell extraction and electrical lysis for mass spectrometry detection of intracellular compounds

Analysis of cellular composition and metabolism at a single-cell resolution allows gaining more information about complex relationships of cells within tissues or whole living organisms by resolving the variance stemming from the cellular heterogeneity. Mass spectrometry (MS) is a perfect analytical tool satisfying the demanding requirements of detecting and identifying compounds present in such ultralow-volume samples of high chemical complexity. However, the method of sampling and sample ionization is crucial in obtaining relevant information. In this work, we present a microfluidic sampling platform that integrates single-cell extraction from MS-incompatible media with electrical cell lysis and nanoESI-MS analysis of human erythrocytes. Hemoglobin alpha and beta chains (300 amol/cell) were successfully identified in mass spectra of single-erythrocyte lysates.

Thymol-Based Hydrophobic Deep Eutectic Solvents as a Green Approach for Screening Polar Nitrosamines in Sartans Pharmaceutical Products by Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Combined with HPLC-DAD

Nitrosamines are carcinogens substances firstly detected in sartans drugs in 2018, leading to new regulations and monitoring programmes that raised the costs and challenges to the pharmaceutical industry. Therefore, reliable and cost-effective methods for screening nitrosamines in medicines are highly desirable. Hydrophobic deep eutectic solvents (HDES), a novel "eco-friendly" alternative to solvents commonly used in microextraction techniques, can meet these requirements. In this study, a simple and rapid method of ultrasound-assisted dispersive liquid-liquid microextraction using thymol-based HDES followed by HPLC-DAD detection was developed for the determination of n-nitrosodimethylamine (NDMA) and n-nitroso-n-methylamino butyric acid (NMBA) from candesartan, irbesartan, losartan, olmesartan, telmisartan and valsartan drug substances, and from losartan tablets. Various influencing factors (such as HDES type, HDES:sample ratio, salt addition and sample pH) were investigated. Best extraction efficiencies were achieved with thymol:benzyl alcohol HDES. Under optimal conditions, the linearities ranged from 15 to 1000 ng mL^-1 for both NDMA and NMBA (R² > 0.99), with recoveries between 81.8-104.2% and precision from 0.2 to 14.6%. The limits of detection were 17.3 - 220.0 ng g^-1 and 16.3 - 290.0 ng g^-1 for NDMA and NMBA, consecutively. Finally, the proposed method was successfully applied in spiked sartans drug substances and in losartan potassium tablets collected in the market.

Metformin as an emerging concern in wastewater: Occurrence, analysis and treatment methods

Metformin is a wonder drug used as an anti-hypoglycemic medication; it is also used as a cancer suppression medicament. Metformin is a first line of drug choice used by doctors for patients with type 2 diabetes. It is used worldwide where the drug's application varies from an anti-hypoglycemic medication to cancer oppression and as a weight loss treatment drug. Due to its wide range of usage, metformin and its byproducts are found in waste water and receiving aquatic environment. This leads to the accumulation of metformin in living beings and the environment where excess concentration levels can lead to ailments such as lactic acidosis or vitamin B12 deficiency. This drug could become of future water treatment concerns with its tons of production per year and vast usage. As a result of continuous occurrence of metformin has demanded the need of implementing and adopting different strategies to save the aquatic systems and the exposure to metformin. This review discuss the various methods for the elimination of metformin from wastewater. Along with that, the properties, occurrence, and health and environmental impacts of metformin are addressed. The different analytical methods for the detection of metformin are also explained. The main findings are discussed with respect to the management of metformin as an emerging contaminants and the major recommendations are discussed to understand the major research gaps.

Current applications of capillary electrophoresis-mass spectrometry for the analysis of biologically important analytes in urine (2017 to mid-2021): A review

Capillary electrophoresis coupled online with mass detection is a modern tool for analyzing wide ranges of compounds in complex samples, including urine. Capillary electrophoresis with mass spectrometry allows the separation and identification of various analytes spanning from small ions to high molecular weight protein complexes. Similarly to the much more common liquid chromatography‐mass spectrometry techniques, the capillary electrophoresis separation reduces the complexity of the mixture of analytes entering the mass spectrometer resulting in reduced ion suppression and a more straightforward interpretation of the mass spectrometry data. This review summarizes capillary electrophoresis with mass spectrometry studies published between the years 2017 and 2021, aiming at the determination of various compounds excreted in urine. The properties of the urine, including its diagnostical and analytical features and chemical composition, are also discussed including general protocols for the urine sample preparation. The mechanism of the electrophoretic separation and the instrumentation for capillary electrophoresis with mass spectrometry coupling is also included. This review shows the potential of the capillary electrophoresis with mass spectrometry technique for the analyses of different kinds of analytes in a complex biological matrix. The discussed applications are divided into two main groups (capillary electrophoresis with mass spectrometry for the determination of drugs and drugs of abuse in urine and capillary electrophoresis with mass spectrometry for the studies of urinary metabolome).