Determination of pesticides and their degradation products in soil: critical review and comparison of methods

Pesticides are applied widely to protect plants from disease, weeds and insect damage, and usually come into contact with soil, where they undergo a variety of transformations that provide a complex pattern of metabolites. This article reviews the most relevant analytical methods for determining pesticides and their transformation products in soils. We address some recent advances in sampling and sample-preparation technologies for soil analysis. We discuss and critically evaluate procedures, such as liquid extraction methods (pressurized liquid extraction or microwave-assisted extraction) and solid-phase based methods (headspace solid-phase microextraction, solid-phase microextraction or matrix-solid-phase dispersion). Analysis of pesticides is generally carried out by gas chromatography (GC) or liquid chromatography (LC) coupled to different detectors, especially to mass spectrometers (MSs). However, alternative and/or complementary methods, using capillary electrophoresis (CE), biosensors and bioassays have emerged recently. We also consider the advantages and the disadvantages of the various methodologies.     

Modern Methods of Sample Preparation for GC Analysis

Today, a wide variety of techniques is available for the preparation of (semi-) solid, liquid and gaseous samples, prior to their instrumental analysis by means of capillary gas chromatography (GC) or, increasingly, comprehensive two-dimensional GC (GC × GC). In the past two decades, a large number of ‘modern’ sample-preparation techniques has been introduced, which have partly superseded their ‘classical’ counterparts. These novel techniques include off-line and on-line (sometimes semi- or fully automated) procedures, and exhaustive extraction as well as equilibrium techniques. In order to improve overall performance, aspects such as essentially organic solvent-less approaches, large-volume injection and miniaturization receive increasing attention. In most recent applications, mass spectrometric or element-selective detection have been used. The present review discusses the advantages and disadvantages, and relative performance, of most of the modern sample-preparation techniques and cites a number of illustrative applications for each of them.     

Determination (monitoring) of PAHs in surface waters: why an operationally defined procedure is needed

The results of interlaboratory studies on the determination of selected PAHs in samples of pure water and water containing suspended matter are presented and discussed in this study. Determinations were performed by independent analytical laboratories which used different sample-preparation procedures, i.e. liquid-liquid extraction and solid-phase extraction with columns and speedisks. The study indicates that the results of PAHs determination depend on the type of isolation technique and the final determination procedure used by a given laboratory. Differences among the determined concentrations of specific PAHs reached 700%. In this work it has been shown that modern analysis does not offer isolation techniques for PAHs which would secure their speciation in the aquatic environment.     

Solid-phase analytical derivatization: enhancement of sensitivity and selectivity of analysis.

Analytical derivatizations enhance the sensitivity and selectivity of determinations for organic compounds. Classical techniques are often based on solution chemistry. Most modern sample preparation techniques, however, are based on solid-phase extractions. Solid-phase analytical derivatization bridges this gap and facilitates sample preparation by combining the isolation step with the derivatization. The solid-phase retains both reagents and derivatized analytes and often permits facile separation of excess reagent or selective elution of the desired products. The most recent solid-phase extraction techniques have been used in conjunction with analytical derivatization to automate the analysis. In this review, analytical derivatizations are presented as functional group analysis.     

Monolithic methacrylate packed 96-tips for high throughput bioanalysis

In the pharmaceutical industry the growing number of samples to be analyzed requires high throughput and fully automated analytical techniques. Commonly used sample-preparation methods are solid-phase extraction (SPE), liquid–liquid extraction (LLE) and protein precipitation. In this paper we will discus a new sample-preparation technique based on SPE for high throughput drug extraction developed and used by our group. This new sample-preparation method is based on monolithic methacrylate polymer as packing sorbent for 96-tip robotic device. Using this device a 96-well plate could be handled in 2–4 min. The key aspect of the monolithic phase is that monolithic material can offer both good binding capacity and low back-pressure properties compared to e.g. silica phases. The present paper presents the successful application of monolithic 96-tips and LC–MS/MS by the sample preparation of busulphan, rescovitine, metoprolol, pindolol and local anaesthetics from human plasma samples and cyklophosphamid from mice blood samples.     

Sorptive sample preparation -- a review

Most sample-enrichment procedures currently available rely on adsorption of the analytes of interest by a suitable adsorbent material. Although good performance can be obtained for many practical problems, in some cases the applicability of adsorptive sample preparation falls short, particularly for the enrichment of polar and/or high-molecular-weight compounds, especially in combination with thermal desorption. Because of the very strong retention of adsorbent materials, undesired effects such as incomplete desorption and artifact formation are observed. Polar solutes are easily adsorbed but readily undergo surface-catalyzed reactions and on desorption yield compounds different than those originally sampled. High-molecular-weight compounds cannot be desorbed because of extremely strong interactions with the adsorbent and their low volatility.To overcome some of these problems sample-preparation techniques based on polydimethylsiloxane sorption have been developed over the past 15 years. In contrast with adsorptive trapping, sorption is based on dissolution of the analytes in a liquid polymeric material. This is a much more inert means of solute retention which overcomes some of the limitations encountered when working with adsorbents. In this contribution, the basic principles of sorption, the different instrumentation used, and applications of the technique will be reviewed. The review covers the sorptive sample-preparation techniques, open-tubular trapping (OTT), solid-phase microextraction (SPME), gum-phase extraction (GPE), equilibrium gum-phase extraction (EGPE), and stir-bar-sorptive extraction (SBSE). Because of the nature of sorptive sample-preparation techniques, which perform particularly well in combination with thermal desorption, this review focuses strongly on gas chromatography as the means of chemical analysis.     

Recent developments in sample preparation techniques for chromatography analysis of traditional Chinese medicines

Traditional Chinese medicines (TCMs) have a long history dating back thousands of years. Recently, there has been increasing interest worldwide in the use of TCMs for the prevention and treatment of various illnesses. In China, a large number of analytical tools, especially chromatographic techniques have been used to analyze the constituents of TCMs in order to control their quality and discover new bioactive compounds. In this paper, recent developments in sample preparation techniques for the extraction, clean-up, and concentration of analytes from TCMs are compared. These techniques include headspace solid-phase microextraction (HS-SPME), headspace liquid-phase microextraction (HS-LPME), microwave-assisted extraction (MAE), supercritical-fluid extraction (SFE), pressurized-liquid extraction (PLE), and microwave distillation (MD).     

Determination of berberine and strychnine in medicinal plants and herbal preparations by pressurized liquid extraction with capillary zone electrophoresis.

A simple and rapid method for the determination of berberine and strychnine in medicinal plants and herbal preparations for regulatory purposes using a home-made pressurized liquid extraction (PLE) system with capillary zone electrophoresis (CZE) using ultraviolet detection at 254 nm was developed. The effects of pH, concentration of buffer, and organic modifiers in the electrophoretic separation were investigated. The buffer used for CZE contained 50 mM ammonium acetate, pH 3.1. The effect of temperature on the extraction efficiency of strychnine in medicinal plants by PLE was demonstrated. Comparable or higher extraction efficiency was achieved with PLE for strychnine in medicinal plants and berberine in herbal preparations compared to soxhlet extraction. The effect of matrix interference in medicinal plants and herbal preparations containing a number of medicinal plants samples using CZE was investigated by standard additional experiments. The reproducibility of the method using PLE with CZE was found to vary between 2.4 and 10.7% (n = 5/6) for different types of samples on different days.     

Application of functionalized magnetic nanoparticles in sample preparation

Functionalized magnetic nanoparticles have attracted much attention in sample preparation because of their excellent performance compared with traditional sample-preparation sorbents. In this review, we describe the application of magnetic nanoparticles functionalized with silica, octadecylsilane, carbon-based material, surfactants, and polymers as adsorbents for separation and preconcentration of analytes from a variety of matrices. Magnetic solid-phase extraction (MSPE) techniques, mainly reported in the last five years, are presented and discussed.     

Recent Advances in Sample Preparation for Cosmetics and Personal Care Products Analysis

The use of cosmetics and personal care products is increasing worldwide. Their high matrix complexity, together with the wide range of products currently marketed under different forms imply a challenge for their analysis, most of them requiring a sample pre-treatment step before analysis. Classical sample preparation methodologies involve large amounts of organic solvents as well as multiple steps resulting in large time consumption. Therefore, in recent years, the trends have been moved towards the development of simple, sustainable, and environmentally friendly methodologies in two ways: (i) the miniaturization of conventional procedures allowing a reduction in the consumption of solvents and reagents; and (ii) the development and application of sorbent- and liquid-based microextraction technologies to obtain a high analyte enrichment, avoiding or significantly reducing the use of organic solvents. This review provides an overview of analytical methodology during the last ten years, placing special emphasis on sample preparation to analyse cosmetics and personal care products. The use of liquid–liquid and solid–liquid extraction (LLE, SLE), ultrasound-assisted extraction (UAE), solid-phase extraction (SPE), pressurized liquid extraction (PLE), matrix solid-phase extraction (MSPD), and liquid- and sorbent-based microextraction techniques will be reviewed. The most recent advances and future trends including the development of new materials and green solvents will be also addressed.     

Thermal characterization of dried extract of medicinal plant by DSC and analytical techniques

The increased search for herbal products has generated an increasing interest in improving the quality control of dried extracts by pharmaceutical industry since these are raw materials of great importance by their quality and versatility. This work aimed at the application of various analytical techniques (thermal analysis, X-ray diffraction, scanning electron microscopy, and infrared Fourier transform spectroscopy) in the characterization of dried extracts of two plants from the Brazilian semiarid region with medicinal properties. The DSC curves for the dried extracts of Ximenia americana L. and Schinopsis brasiliensis Engl. showed that thermal processes occur between 33.50 and 118.58 °C and between 39.17 and 126.14 °C. The X-ray powder diffraction revealed high degree of amorphization, but the dried extract of X. americana L. showed some diffraction peaks of high intensity. The IR spectra showed high variety of metabolites in the extracts dried. Through this study it was possible to verify the feasibility of applying these techniques in the characterization of raw materials from medicinal plants for use in the herbal medicines production.     

Identification of volatile components in Angelica species using supercritical-CO2 fluid extraction and solid phase microextraction coupled to gas chromatography-mass spectrometry

As a part of our search for environmentally friendly solvents to extract the active components of medicinal plants, two sampling techniques, supercritical fluid extraction (SFE) using CO(2) and solid-phase microextraction (SPME) were compared for their efficacy in the analysis of volatiles rhizome components emitted from the medicinal herbs Angelica gigas NAKAI (Korean danggui), Angelica sinensis (Chinese danggui), and Angelica acutiloba (Japanese danggui). A total of 54 compounds released from all of these varieties of Angelica rhizomes were separated and identified by gas chromatography-mass spectrometry (GC-MS). The composition of supercritical extracts from these plants was very different from the solid-phase microextraction products. More compounds were detected by SPME-GC-MS (41) than by SFE-GC-MS (17). The results of these analyses suggest that SFE may be useful for detecting the main components, decursinol angelate and decursin in Korean danggui, and butylidene dihydro-phthalide in both Chinese and Japanese danggui, whereas the results for SPME did not. The SFE method required specialized instrumentation, required little time to prepare the sample, and had a small sample size and no organic solvent. In sum, these results suggest that SFE is useful for extracting the volatile main components of danggui cultivars. Its simplicity, low cost and speed may allow SPME to increase the recovery of volatile components in general without disturbing the main components of the plant.     

Subcritical Water Extraction of Salvia miltiorrhiza

In this work, a green extraction technique, subcritical water extraction (SBWE), was employed to extract active pharmaceutical ingredients (APIs) from an important Chinese medicinal herb, Salvia miltiorrhiza (danshen), at various temperatures. The APIs included tanshinone I, tanshinone IIA, protocatechualdehyde, caffeic acid, and ferulic acid. Traditional herbal decoction (THD) of Salvia miltiorrhiza was also carried out for comparison purposes. Reproduction assay of herbal extracts obtained by both SBWE and THD were then conducted on Caenorhabditis elegans so that SBWE conditions could be optimized for the purpose of developing efficacious herbal medicine from Salvia miltiorrhiza. The extraction efficiency was mostly enhanced with increasing extraction temperature. The quantity of tanshinone I in the herbal extract obtained by SBWE at 150 °C was 370-fold higher than that achieved by THD extraction. Reproduction evaluation revealed that the worm reproduction rate decreased and the reproduction inhibition rate increased with elevated SBWE temperatures. Most importantly, the reproduction inhibition rate of the SBWE herbal extracts obtained at all four temperatures investigated was higher than that of traditional herbal decoction extracts. The results of this work show that there are several benefits of subcritical water extraction of medicinal herbs over other existing herbal medicine preparation techniques. Compared to THD, the thousand-year-old and yet still popular herbal preparation method used in herbal medicine, subcritical water extraction is conducted in a closed system where no loss of volatile active pharmaceutical ingredients occurs, although analyte degradation may happen at higher temperatures. Temperature optimization in SBWE makes it possible to be more efficient in extracting APIs from medicinal herbs than the THD method. Compared to other industrial processes of producing herbal medicine, subcritical water extraction eliminates toxic organic solvents. Thus, subcritical water extraction is not only environmentally friendly but also produces safer herbal medicine for patients.     

Chromatographic separation techniques and data handling methods for herbal fingerprints: a review

As herbal medicines have an important position in health care systems worldwide, their current assessment and quality control are a major bottleneck. Over the past decade, major steps were taken not only to improve the quality of the herbal products but also to develop analytical methods ensuring their quality. Nowadays, chromatographic fingerprinting is the generally accepted technique for the assessment and quality control of herbal products. This paper briefly considers the evolution of the regulations and guidelines on the quality control of herbal medicines, and reviews the established analytical techniques for herbal fingerprinting with an emphasis on the most recent developments, such as miniaturized techniques, new stationary phases, analysis at high temperatures and multi-dimensional chromatography. Accessory to the new analytical techniques, the chemometric data handling techniques applied are discussed. Chemometrics provide scientists with useful tools in understanding the huge amounts of data generated by the analytical advances and prove to be valuable for quality control, classification and modelling of, and discrimination between herbal fingerprints.     

A capsule review of recent studies on the application of mass spectrometry in the analysis of Chinese medicinal herbs

Chinese herbal medicine is gaining increasing popularity worldwide as an alternative approach to the development of pharmaceuticals in therapeutic applications. Chemical characterization and compositional analysis of Chinese medicines provide the necessary scientific basis for the discovery and development of new drugs of natural origin. Applications of mass spectrometry in the analysis of Chinese herbal medicines have been growing rapidly in recent years owing to the rapid technical advances and increasing availability of the instrumentation. This paper reviews the current status of how different mass spectrometric techniques are being used to support research studies of Chinese medicines. The focus is on crude herbal medicines and their derived products. The review is not meant to be exhaustive, but rather to provide a general overview of the various research activities in this rapidly expanding field. In the discussion of specific herbs, the emphasis is placed on ginseng and Danshen, two of the herbs for which active experimental work is on-going in the authors' laboratories. Other selected herbs will be discussed only briefly, aiming primarily to illustrate the current status of research in the area.     

Modern microextraction techniques for natural products

Natural product analysis has gained wide attention in recent years, especially for herbal medicines, which contain complex ingredients and play a significant clinical role in the therapy of numerous diseases. The constituents of natural products are usually found at low concentrations, and the matrices are complex. Thus, the extraction of target compounds from natural products before analysis by analytical instruments is very significant for human health and its wide application. The commonly used traditional extraction methods are time-consuming, using large amounts of sample and organic solvents, as well as expensive and inefficient. Recently, microextraction techniques have been used for natural product extraction to overcome the disadvantages of conventional extraction methods. In this paper, the successful applications of and recent developments in microextraction techniques including solvent-based and sorbent-based microextraction methods, in natural product analysis in recent years, especially in the last 5 years, are reviewed for the first time. Their features, advantages, disadvantages, and future development trends are also discussed.     

Research progress of rapid detection of typical environmental pollutants based on chromatographic technologiesEI北大核心CSCD

对复杂环境介质中的典型污染物进行快速、精准甚至远程连续自动的检测,是控制环境污染、确保环境和生态安全的重要前提。近年来,基于色谱技术的典型环境污染物快速检测方法发展迅猛,主要包括样品快速制备和目标物快速检测两方面。辅助萃取、快速液相萃取、QuEChERS等样品前处理方法具有萃取效率高、溶剂消耗少、操作简便快速等优点。快速检测技术可在几秒到半小时内提供检测结果,主要包括实验室和现场检测。本文综述了2019年以来基于色谱技术的典型环境污染物快速检测研究新进展。介绍了萃取技术和基于试验设计的样品快速制备,实验室快速检测、便携仪器现场检测及遥感技术远程检测,提出了色谱技术快速检测环境污染物的挑战和展望。     

Établissement du profil chromatographique liquide non aqueux des métabolites phytochimiques apolaires des phytomédicaments

Chromatographic profiling of plant metabolites is therefore a good tool for quality control of such herbal medicinal products. Our objective was to propose a protocol for sample preparation and liquid chromatographic profiling of non-polar metabolites for quality assessment of African herbal medicinal products. The methodology is based on the chemometric assessment of liquid chromatographic profiles of non-polar metabolites issued from several batches of leaves of Combretum micranthum and Mitracarpus scaber. Metabolic profiling is carried out by non-aqueous liquid chromatography on porous carbon graphite, coupled with mass spectrometry, after extraction with dichloromethane and removal of chlorophyll. Our method using liquid chromatography, coupled to mass spectrometry can detect non-polar metabolites already identified in the two herbal drugs. Chemometric data analysis of chromatographic profiles using the PLS-discriminant analysis with or without orthogonal signal correction, allowed a distinction between the two herbal drugs.     

Advances in the determination of degradation intermediates of personal care products in environmental matrixes: a review

In this review, recent methods developed for the determination of degradation intermediates of personal care products in environmental matrixes focusing on the extraction and determination steps are discussed. The five classes of personal care products evaluated are stimulants, fragrances, sunscreens, antimicrobials, and insect repellents. Methods are critically reviewed in terms of the analytical steps involved in the analysis, sample pretreatment, separation, and detection as well as the different confirmation strategies employed. Preconcentration from aqueous matrixes was performed by solid-phase extraction, liquid–liquid extraction, or solid-phase microextraction, allowing the simultaneous extraction of parent compounds and their degradation intermediates. Following the extraction and cleanup steps, the identification and quantification of degradation intermediates of personal care products at environmental levels (i.e., parts per trillion to parts per billion range) is usually performed by using mass spectrometry techniques such as single quadrupole mass spectrometry and more recently by time-of-flight mass spectrometry or tandem mass spectrometry. The main scope of this review is to critically evaluate the current state of the art of the analytical techniques used and to identify the research needs in the determination of degradation intermediates of personal care products in environmental matrixes.     

Promising therapeutics with natural bioactive compounds for improving learning and memory - a review of randomized trials

Cognitive disorders can be associated with brain trauma, neurodegenerative disease or as a part of physiological aging. Aging in humans is generally associated with deterioration of cognitive performance and, in particular, learning and memory. Different therapeutic approaches are available to treat cognitive impairment during physiological aging and neurodegenerative or psychiatric disorders. Traditional herbal medicine and numerous plants, either directly as supplements or indirectly in the form of food, improve brain functions including memory and attention. More than a hundred herbal medicinal plants have been traditionally used for learning and memory improvement, but only a few have been tested in randomized clinical trials. Here, we will enumerate those medicinal plants that show positive effects on various cognitive functions in learning and memory clinical trials. Moreover, besides natural products that show promising effects in clinical trials, we briefly discuss medicinal plants that have promising experimental data or initial clinical data and might have potential to reach a clinical trial in the near future.