Ultrasound assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography designated for bioavailability studies of felodipine combinations in rat plasma

Greenness assessment of microextraction techniques in therapeutic drug monitoring

Aim: In this study, we evaluated the greenness and whiteness scores for microextraction techniques used in therapeutic drug monitoring. Additionally, the cons and pros of each evaluated method and their impacts on the provided scores are also discussed. Materials & methods: The Analytical Greenness Sample Preparation metric tool and white analytical chemistry principles are used for related published works (2007-2023). Results & conclusion: This study provided valuable insights for developing methods based on microextraction techniques with a balance in greenness and whiteness areas. Some methods based on a specific technique recorded higher scores, making them suitable candidates as green analytical approaches, and some others achieved high scores both in green and white areas with a satisfactory balance between principles.

Recent Advances in Dispersive Liquid-Liquid Microextraction for Pharmaceutical Analysis

Sample clean-up and pre-concentration are critical components of pharmaceutical analysis. The dispersive liquid-liquid microextraction (DLLME) technique is widely recognized as the most effective approach for enhancing overall detection sensitivity. While various DLLME modes have been advanced in pharmaceutical analysis, there need to be more discussions on pre-concentration techniques specifically developed for this field. This review presents a comprehensive overview of the different DLLME modes used in pharmaceutical analysis from 2017 to May 2023. The review covers the principles of DLLME, the factors affecting microextraction, the selected applications of different DLLME modes, and their advantages and disadvantages. Additionally, it focuses on multi-extraction strategies employed for pharmaceutical analysis.

Recent developments in sample preparation techniques combined with high-performance liquid chromatography: A critical review

This review article compares and contrasts sample preparation techniques coupled with high-performance liquid chromatography (HPLC) and describes applications developed in biomedical, forensics, and environmental/industrial hygiene in the last two decades. The proper sample preparation technique can offer valued data for a targeted application when coupled to HPLC and a suitable detector. Improvements in sample preparation techniques in the last two decades have resulted in efficient extraction, cleanup, and preconcentration in a single step, thus providing a pathway to tackle complex matrix applications. Applications such as biological therapeutics, proteomics, lipidomics, metabolomics, environmental/industrial hygiene, forensics, glycan cleanup, etc., have been significantly enhanced due to improved sample preparation techniques. This review looks at the early sample preparation techniques. Further, it describes eight sample preparation technique coupled to HPLC that has gained prominence in the last two decades. They are (1) solid-phase extraction (SPE), (2) liquid-liquid extraction (LLE), (3) gel permeation chromatography (GPC), (4) Quick Easy Cheap Effective Rugged, Safe (QuEChERS), (5) solid-phase microextraction (SPME), (6) ultrasonic-assisted solvent extraction (UASE), and (7) microwave-assisted solvent extraction (MWASE). SPE, LLE, GPC, QuEChERS, and SPME can be used offline and online with HPLC. UASE and MWASE can be used offline with HPLC but have also been combined with the online automated techniques of SPE, LLE, GPC, or QuEChERS for targeted analysis. Three application areas of biomedical, forensics, and environmental/industrial hygiene are reviewed for the eight sample preparation techniques. Three hundred and twenty references on the eight sample preparation techniques published over the last two decades (2001-2021) are provided. Other older references were included to illustrate the historical development of sample preparation techniques.

Recent applications of microextraction sample preparation techniques in biological samples analysis

Analysis of biological samples is affected by interfering substances with chemical properties similar to those of the target analytes, such as drugs. Biological samples such as whole blood, plasma, serum, urine and saliva must be properly processed for separation, purification, enrichment and chemical modification to meet the requirements of the analytical instruments. This causes the sample preparation stage to be of undeniable importance in the analysis of such samples through methods such as microextraction techniques. The scope of this review will cover a comprehensive summary of available literature data on microextraction techniques playing a key role for analytical purposes, methods of their implementation in common biological samples, and finally, the most recent examples of application of microextraction techniques in preconcentration of analytes from urine, blood and saliva samples. The objectives and merits of each microextration technique are carefully described in detail with respect to the nature of the biological samples. This review presents the most recent and innovative work published on microextraction application in common biological samples, mostly focused on original studies reported from 2017 to date. The main sections of this review comprise an introduction to the microextraction techniques supported by recent application studies involving quantitative and qualitative results and summaries of the most significant, recently published applications of microextracion methods in biological samples. This article considers recent applications of several microextraction techniques in the field of sample preparation for biological samples including urine, blood and saliva, with consideration for extraction techniques, sample preparation and instrumental detection systems.

Meloxicam quantification in rabbit plasma by RP-HPLC: optimization and application to pharmacokinetic study

Background

The goal of the proposed study was to validate a rapid, simple, an accurate, robust, and sensitive bioanalytical method for quantifying Meloxicam and Lornoxicam (as internal standard) in rabbit plasma.

Result

Limit of detection and limit of quantification for Meloxicam were found to be 0.0081 and 0.1035 μg mL−1, respectively. The bioanalysis was continued according to standard guidelines and successfully used for bioavailability studies of meloxicam after single dose administration of pure drug and the formulation in rabbit plasma. Finally, obtained results proved its simplicity and an efficiency to be applied for the therapeutic drug monitoring and bioequivalence studies.

Conclusion

Therefore, the set RP-HPLC bioanalysis is simple, convenient, and acceptable to analyze meloxicam in bulk and pharmaceutical formulations in rabbit plasma.

Graphical abstract

Development of a UHPLC-MS method for inhibitor screening against α-L-1,3-fucosidase

α-L-Fucosidase (AFU) is a promising therapeutic target for the treatment of inflammation, cancer, cystic fibrosis, and fucosidosis. Some of the existing analytical methods for the assessment of AFU activity are lacking in sensitivity and selectivity, since most of them are based on spectrofluorimetric methods. More recently, mass spectrometry (MS) has evolved as a key technology for enzyme assays and inhibitor screening as it enables accurate monitoring of the conversion of substrate to product in enzymatic reactions. In this study, UHPLC-MS has been utilized to develop a simple, sensitive, and accurate assay for enzyme kinetics and inhibition studies of AFU3, a member of the AFU family. A reported method for analyzing saccharide involving a porous graphitic carbon column, combined with reduction by NaBH₄/CH₃OH, was used to improve sensitivity. The conversion of saccharide into alditol could reach nearly 100% in the NaBH₄ reduction reaction. In addition, the bioanalytical quantitative screening method was validated according to US-FDA guidance, including selectivity, linearity, precision, accuracy, stability, and matrix effect. The developed method displayed a good accuracy, high sensitivity (LOD = 0.05 mg L^-1), and good reproducibility (RSD < 15%). The assay accurately measured an IC₅₀ value of 0.40 μM for the known AFU inhibitor, deoxyfuconojirimycin, which was consistent with results reported in the literature. Further validation of the assay was achieved through the determination of a high Z'-factor value of 0.89. The assay was applied to screen a marine-derived chemical library against AFU3, which revealed two marine-oriented pyrimidine alkaloids as potential AFU3 inhibitors. Graphical abstract.

Validated RP-HPLC method for quantification of felodipine in rabbit plasma: Application in a bioequivalence study

OBJECTIVE

The aim of present study was to develop a simple, rapid, selective, sensitive and robust reverse phase high performance liquid chromatographic method for quantification of felodipine in rabbit plasma at the wavelength of 360nm.

METHOD

Protein was precipitated from rabbit plasma sample by addition of acetonitrile as a vehicle. An isocratic elution of samples was performed on capcell pak C₈ DD S5 column (4.6mm×250mm particle size 5μm) column with mobile phase consisting 5mM Phosphate Buffer (pH 4.8 adjusted with dilute ortho-phosphoric acid solution): acetonitrile (25:75:v/v) delivered at flow rate 1.0mLmin^-1.

RESULT

A good linear response was achieved over the range of 0.25-20.00μgmL^-1. LODs and LOQs for felodipine were found to be 0.055 and 0.201μgmL^-1, respectively. The method was quantitatively evaluated in terms of linearity, precision, accuracy (recovery), selectivity robustness and stability study as per standard guidelines. The validated RP-HPLC method was successfully applied for the bioavailability studies of felodipine. The pharmacokinetic parameters were calculated for all the investigated drugs in rabbit after single-dose administrations of pure drug and formulation of felodipine. Finally, the obtained results for the application of the proposed RP-HPLC method proved its efficiency to be applied to the therapeutic drug monitoring (TDM) and bioequivalence (BE) studies.

CONCLUSION

Thus, developed method is simple, convenient and suitable for the analysis of felodipine in bulk and pharmaceutical formulations.

Solvent-terminated dispersive liquid-liquid microextraction: a tutorial

Solvent-terminated dispersive liquid-liquid microextraction (ST-DLLME) is a special mode of DLLME in which a demulsifying solvent is injected into the cloudy mixture of sample/extractant to break the emulsion and induce phase separation. The demulsification process starts by flocculation of the dispersed microdroplets by Ostwald ripening or coalescence to form larger droplets. Then, the extractant either floats or sinks depending on its density as compared with that for the aqueous sample. The demulsifier should have high surface activity and low surface tension in order to be capable of inducing phase separation. The extraction efficiency in ST-DLLME is controlled by the same experimental variables of normal DLLME (n-DLLME) such as the type and volume of the extractant as well as the disperser. Other parameters such as pH and the temperature of the sample, the stirring rate, the time of extraction and the addition of salt are also important to consider. Along with these factors, the demulsifier type and volume and the demulsification time have to be optimized. By using solvents to terminate the dispersion step in DLLME, the centrifugation process is not necessary. This in turn improves precision, increases throughput, decreases the risk of contamination through human intervention and minimizes the overall analysis time. ST-DLLME has been successfully applied for determination of both inorganic and organic analytes including pesticides and pharmaceuticals in water and biological fluids. Demulsification via solvent injection rather than centrifugation saves energy and makes ST-DLLME easier to automate. These characteristics in addition to the low solvent consumption, the reduced organic waste and the possibility of using water in demulsification bestow green features on ST-DLLME. This tutorial discusses the principle, the practical aspects and the different applications of ST-DLLME.