Modern microextraction techniques for natural products

Paper-based ligand fishing method for rapid screening and real-time capturing of α-glucosidase inhibitors from the Chinese herbs

Identifying medicinally relevant compounds from natural resources generally involves the tedious work of screening plants for the desired activity before capturing the bioactive molecules from them. In this work, we created a paper-based ligand fishing platform to vastly simplify the discovery process. This paper-based method exploits the enzymatic cascade reaction between α-glucosidase (GAA), glucose oxidase (GOx), and horseradish peroxidase (HRP), to simultaneously screen the plants and capture the GAA inhibitors from them. The designed test strip could capture ligands in tandem with screening the plants, and it features a very simply operation based on direct visual assessment. Multiple acylated flavonol glycosides from the leaves of Quercus variabilis Blume were newly found to possess GAA inhibitory activities, and they may be potential leads for new antidiabetic medications. Our study demonstrates the prospect of the newly discovered GAA ligands as potential bioactive ingredients as well as the utility of the paper-based ligand fishing method.

Efficient extraction based on a polydimethylsiloxane/bimetallic ZnCo-MOF carbonization sponge coupled with GC-MS for the rapid analysis of volatile compounds in cumin

A novel porous polydimethylsiloxane/bimetallic ZnCo-MOF carbonization (PDMS/ZnCo-MOF@C) sponge was successfully fabricated, followed by its utilization in GC-MS for the high efficiency extraction and determination of volatile compounds in cumin. The PDMS/ZnCo-MOF@C sponge exhibits outstanding properties with a considerable adsorption capacity, high surface area, and large pore volume and has shown potential as an ideal adsorbent for the separation and preconcentration of trace volatile compounds. The effect of different parameters on the extraction efficiency were investigated. Excellent analytical performances were achieved for the representative compounds (β-pinene, p-cymene, γ-terpinene, cuminaldehyde, and linalyl acetate), including wide linearity (2.31-440.1 ng) with high correlation coefficients (R2 ≥ 0.9979), low LODs (1.02-3.11 ng) and LOQs (2.45-7.08 ng), and satisfactory precision (intra-day RSDs ≤ 2.89% and inter-day RSDs ≤ 4.14%). The optimal method was applied for the analysis of cumin from different regions and 44 volatile compounds were identified. The correlation between the different regions of cumin and volatile compounds was explored using multivariate statistical analysis. These results demonstrated that PDMS/ZnCo-MOF@C is an efficient, simple and sensitive material for use in the pretreatment technique for the determination of the volatile compounds in aromatic plants.

Microextraction of essential oils: A review

Liquid phase microextraction (LPME) and solid phase microextraction (SPME) are popular extraction techniques for sample preparation due to their green and highly efficient single-step extraction efficiency. With the increasing attention to essential oils, their evaluation and analysis are significant in analytical sciences. In this review, starting from a brief description of the recent advances in the last decade, the attention has been focused on the up-to-date research works and applications based on liquid and solid phase microextraction for essential oil analyses. Particular attention has been given to the approaches using ionic liquids, eutectic solvents, gas flow assisted, and novel composite materials. In the end, the technological convergence of novel microextraction of essential oils in the future has been prospected.

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.

Advances on Hormones in Cosmetics: Illegal Addition Status, Sample Preparation, and Detection Technology

Owing to the rapid development of the cosmetic industry, cosmetic safety has become the focus of consumers' attention. However, in order to achieve the desired effects in the short term, the illegal addition of hormones in cosmetics has emerged frequently, which could induce skin problems and even skin cancer after long-term use. Therefore, it is of great significance to master the illegal addition in cosmetics and effectively detect the hormones that may exist in cosmetics. In this review, we analyze the illegally added hormone types, detection values, and cosmetic types, as well as discuss the hormone risks in cosmetics for human beings, according to the data in unqualified cosmetics in China from 2017 to 2022. Results showed that although the frequency of adding hormones in cosmetics has declined, hormones are still the main prohibited substances in illegal cosmetics, especially facial masks. Because of the complex composition and the low concentration of hormones in cosmetics, it is necessary to combine efficient sample preparation technology with instrumental analysis. In order to give the readers a comprehensive overview of hormone analytical technologies in cosmetics, we summarize the advanced sample preparation techniques and commonly used detection techniques of hormones in cosmetics in the last decade (2012-2022). We found that ultrasound-assisted extraction, solid phase extraction, and microextraction coupled with chromatographic analysis are still the most widely used analytical technologies for hormones in cosmetics. Through the investigation of market status, the summary of sample pretreatment and detection technologies, as well as the discussion of their development trends in the future, our purpose is to provide a reference for the supervision of illegal hormone residues in cosmetics.

Determination of volatile components in cumin by microwave-assisted PDMS/GO/DES headspace solid phase extraction combined with GC-MS

A novel approach based on polydimethylsiloxane/graphene oxide/deep eutectic solvent (PDMS/GO/DES) sponge headspace solid phase extraction followed by GC-MS was successfully developed to determine the volatile components in cumin. The PDMS/GO/DES exhibits outstanding properties with high adsorption capacity and good chemical stability, and has shown its potentiality as an ideal adsorbent for the extraction of volatile compounds. The influence factors of the extraction process were investigated. Excellent analytical performances were achieved, including wide linearity (0.60-107.72 ng) with high correlation coefficients (R² ≥ 0.9951), low LODs (0.23-9.23 ng) and LOQs (0.54-18.47 ng), satisfactory precision (intra-day RSDs ≤ 2.85% and inter-day RSDs ≤ 3.92%). Under the optimal extraction conditions, the volatile components in 17 cumin samples from four origins in Xinjiang were analyzed and 31 compounds were identified. PCA was used to establish the relationship between the origins and the volatile compounds for further discriminant analysis. The results showed that the PDMS/GO/DES method was a rapid, simple and sensitive technique for the analysis of volatile components in spices.

Simultaneous capture of hydrophilic and hydrophobic compounds from complex plants by biosurfactant-assisted mechanical amorphous dispersion extraction

A biosurfactant-assisted mechanical amorphous dispersion extraction (BA-MADE) procedure was established for the simultaneous capture of hydrophilic phenolic acids and hydrophobic tanshinones from Salvia miltiorrhiza. Single-factor experiments and the response surface methodology were used to optimize and analyze the crucial parameters for the method, such as the type and amount of amorphous-dispersion extractants, grinding time, extraction time and solid-to-liquid ratio. The optimized parameter values for the BA-MADE process were 407.02 mg of sodium chenodeoxycholate, a grinding time of 4.87 min, an extraction time of 4.92 min, and a solid-to-liquid ratio of 0.5:10 g/mL. The calibration curves of danshensu, rosmarinic acid, lithospermic acid, salvianolic acid B, salvianolic acid A, dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone II A exhibited good linearity in the range of 1-500 μg/mL (R² ≥ 0.9990). The limits of detection of nine analytes ranged from 5.46 to 130 ng/mL, the relative standard deviations (RSDs) of intraday and interday precision were less than 1.95 and 3.56%, respectively, and the recoveries of the real sample were in the range of 85-113%, with RSD% below 3.21%. The BA-MADE method was compared with previously reported methods, such as heating reflux extraction, ultrasonic extraction and microwave-assisted micellar extraction, and the results demonstrated that the developed method has significant advantages in the simultaneous extraction of hydrophilic and hydrophobic active components from Salvia miltiorrhiza.