Current Analytical Chemistry - Volume 19, Issue 5, 2023

The recent development of microfluidics and lab-on-a-chip technology has substantially raised interest in analytical chemistry. Since, they have demonstrated to be extraordinarily adept at precise fluid control, cell manipulation, and signal output, microfluidic chips are a useful tool for quick and in-depth single-cell investigation. This technique is cost-effective, less time-consuming, automatic, high mobility, and fast separation technique. Due to the internal chip sizes, which range from micrometers to millimeters, consumption of the samples and reagents occurs at the nanoliter and picoliter levels. The microfluidic device can fit a variety of functions onto a few centimeter-long chips. In this article, we discussed numerous preparations of microfluidic chip electrophoresis and its recent advancements. This method is useful for the detection of various small amounts of content with less time and greater efficacy. It is also useful in cancer studies, 3D inkjet printing, immunoassay investigation in cell-cell interactions, analysis of nanoparticles, dielectrophoretic particle separation, plant alkaloids, and forensic science applications. This review, therefore, examines the use of various microfluidic chips in electrophoretic separation during 2017–2022. There are various papers found by search, indicating continuous activity in the research area along with studies to explain its material, method, and its efficacy.

In recent years, size exclusion chromatography (SEC) has gained valuable and impactable recognition among various chromatographic techniques. Also addressed as other names, viz. gel permeation chromatography, steric-exclusion chromatography, etc., SEC is typically taken into consideration for the fractionation and molecular weight determination of biomolecules and large macromolecules (proteins and polymers) using porous particles. A homogenous mixture of molecules dispersed in the mobile phase is introduced to the chromatographic column, which provides a solid support in the form of microscopic beads (the stationary phase). The beads act as “sieves” and purify small molecules, which become temporarily trapped inside the pores. Some of the advantages that SEC offers over other chromatographic techniques are short analysis time, no sample loss, good sensitivity, and requirement for less amount of mobile phase. In the proposed manuscript, we have deliberated various proteomic applications of size exclusion chromatography, which include the isolation of extracellular vesicles in cancer, isolation of human synovial fluid, separation of monoclonal antibodies, as well as several tandem techniques, such as deep glycoproteomic analysis using SEC-LC-MS/MS, analysis of mammalian polysomes in cells and tissues using tandem MS-SEC, SEC-SWATH-MS profiling of the proteome with a focus on complexity, etc.

Introduction: The current investigation's objective was to develop an HPLC method along with a validated stability-indicating method and analyzing the behavior of levocetirizine degradation under various ICH-suggested stress conditions using LC-UV and LC-MS with a triple quadrupole mass analyzer. Methods: Levocetirizine was exposed to various stressors while performing degradation studies. Using LC-UV and LC-MS methods, the degradation products formed in different stress environments were studied. The drug and degradation products were successfully separated using a Thermo Hypersil BDSC18 column having a dimension of 250 mm length, 4.6 mm internal diameter, and a particle size of 5.0 μm. The isocratic green mobile phase contained methanol:water in the proportion of 65:35 at a flow rate of 1 mL/min, and the selected wavelength for the UV detector was 230 nm. Results: Significant degradation was found in acidic, alkaline, and oxidative conditions, whereas in photo and neutral conditions, no degradation products were formed. The drug was fairly stable in the solid state. Conclusion: The values of m/z obtained from LC-MS after exposing the drug to different stress conditions were used to study fragmentation patterns, characterize the structure of the degradation product, and design the degradation pathway.

Introduction: The objective of this study is to provide a rapid, sensitive, consistent, and costeffective method for quantifying isradipine using ultra-fast liquid chromatography. Methods: Quality by Design principles will form the basis of this approach, grounded on response surface analysis. Shimadzu liquid chromatographic system equipped with a photodiode array detector and LC solution software was used to conduct the RP-UFLC method development and validation. An ODS C18 (250 x 4.6 mm; 5 μm) UFLC column was used to complete the analysis. The RSM methodology utilized a central composite design to perform the optimization studies. Results: The mobile phase ratio and flow rate were considered crucial method parameters, as well as the peak area, retention time, and USP plate were considered critical analytical attributes. The optimal conditions for chromatographic separation were followed using 80% acetonitrile and water (20% v/v) as mobile phase, a 1 mL/min flow rate, an injection volume of 20 μL, 40°C of column oven temperature, and maximum absorption at λmax 254 nm using graphical optimization technique. When examining concentrations between 5 and 150 ng/mL, linearity was observed with an R² of 0.999. The method created was validated by employing stability testing per the recommendations provided by ICH Q2 (R1). The analysis of blood serum was modified so that it could be used to examine the pharmacokinetic parameters. Conclusion: As a result, high accuracy, precision, sensitivity, linearity, and robustness were established for predicting the amount of isradipine present in its freeze-dried nano-formulations.

Introduction: The present work fits in the context of verifying the safety of some food contact materials (FCMs) declared sustainable, checking for the presence of different classes of contaminants and their possible migration. Background: Alternative packaging materials have started to step in the market in substitution to plastic for several years. Most of them come from natural, biological sources to meet biodegradability and compostability. Nevertheless, some contaminants can be present and concerning for human health. Objective: To pursue the goal, we focused on brominated flame retardants, in particular new brominated flame retardants and bromophenols, as they are considered emerging contaminants, and no legislation has been enacted yet. Methods: After the evaluation of their presence in the seven investigated samples, we adopted migration tests into proper simulants recommended by the legislation. The analyses were carried out both by gas chromatography-mass spectrometry and by high-performance liquid chromatography-tandem mass spectrometry. Results: All the items taken into consideration contained detectable concentrations of the investigated compounds. The total amount of new brominated flame retardants were considered irrelevant to proceed with the migration study, whereas the migration of bromophenols was studied in deep due to the greater amount present. Conclusion: In overall, the findings obtained on real samples showed that, except in one case the percentage of chemicals migration measured was very low, to be considered not concerning for human health in most of the cases.

Introduction: UPLC coupled with a high-resolution mass analyzer i.e, Q-TOF analyzer with electrospray ionization (ESI) source using collision-induced dissociation (CID) method was applied to study the characteristic product ions of azilsartan protonated ion. Method: The experimental results of high-resolution mass spectra explained the elemental compositions of product ions accurately and reasonable fragmentation pathways were proposed for azilsartan protonated ions. Calculated mass error in parts per million (ppm) for molecular ions and product ions and results of mass error found from this study from 0.2 ppm to 3.5 ppm. Result: The characteristic fragmentation pathways were helpful to analyze and interpret the stability and possible degradation pathway of the parent ion. Conclusion: The present study explains the significant role of high-resolution mass spectrometry in the structural analysis of the protonated ion of azilsartan.