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.     

Analytical methods for the assessment of endocrine disrupting chemical exposure during human fetal and lactation stages: A review

In the present work, a review of the analytical methods developed in the last 15 years for the determination of endocrine disrupting chemicals (EDCs) in human samples related with children, including placenta, cord blood, amniotic fluid, maternal blood, maternal urine and breast milk, is proposed. Children are highly vulnerable to toxic chemicals in the environment. Among these environmental contaminants to which children are at risk of exposure are EDCs —substances able to alter the normal hormone function of wildlife and humans—. The work focuses mainly on sample preparation and instrumental techniques used for the detection and quantification of the analytes. The sample preparation techniques include, not only liquid–liquid extraction (LLE) and solid-phase extraction (SPE), but also modern microextraction techniques such as extraction with molecular imprinted polymers (MIPs), stir-bar sorptive extraction (SBSE), hollow-fiber liquid-phase microextraction (HF-LPME), dispersive liquid–liquid microextraction (DLLME), matrix solid phase dispersion (MSPD) or ultrasound-assisted extraction (UAE), which are becoming alternatives in the analysis of human samples. Most studies focus on minimizing the number of steps and using the lowest solvent amounts in the sample treatment. The usual instrumental techniques employed include liquid chromatography (LC), gas chromatography (GC) mainly coupled to tandem mass spectrometry. Multiresidue methods are being developed for the determination of several families of EDCs with one extraction step and limited sample preparation.     

Overview of nanosorbents used in solid phase extraction techniques for the monitoring of emerging organic contaminants in water and wastewater samples

In this article, we have critically overviewed some interesting articles published in 2015–2019 about the use of the nanosorbents for the extraction of emerging organic contaminants (EOCs) from various environmental samples. Properties, advantages, disadvantages, and the applicability of different categories of nanosorbents used for the extraction of EOCs are evaluated and discussed. The potential applications of these nanomaterials as adsorptive phase in solid-phase extraction (SPE) based techniques are reviewed.     

Sample treatment and determination of pesticide residues in fatty vegetable matrices: A review

A demanding task in pesticide residue analysis is yet the development of multi-residue methods for the determination of pesticides in vegetables with relatively high fat content (i.e. edible oils and fatty vegetables). The separation of pesticides and other chemical contaminants from high-fat food samples prior to subsequent steps in the analytical process is yet a challenging issue to which much effort in method development has being applied. This review addresses the main sample treatment methodologies for pesticide residue analysis in fatty vegetable matrices. Even with the advent of advanced hyphenated techniques based on mass spectrometry these complex fatty matrices usually require extensive sample extraction and purification. Current methods involve the use of one or the combination of some of the following techniques for both the sample extraction and clean-up steps: liquid-liquid partitioning, solid-phase extraction (SPE), gel-permeation chromatography (GPC), matrix solid-phase dispersion (MSPD), etc. An overview of methods developed for these contaminants in fatty vegetables matrices is presented. Sample extraction and purification techniques are discussed and their most recent applications are highlighted. This review emphasizes that sample preparation is a critical step, but also the determination method is, and cannot be treated separately from sample treatment. In recent years, the appearance and use of new, more polar pesticides has fostered the development of liquid chromatography/mass spectrometry (LC-MS) besides gas chromatography. The main features of LC-MS for the analysis of multi-class pesticides in fatty vegetable samples will be also underlined, with an emphasis on the multi-class, multi-residue strategy and the difficulties associated.     

Analytical methods for the determination of emerging organic contaminants in the atmosphere

Concerns over the occurrence and transport of emerging organic contaminants (EOCs) from local sources to remote regions have resulted in wide developments in sampling strategy and analytical methodology for the determination of trace concentrations of EOCs in the atmosphere. This article discusses developments in the determination of EOCs in ambient air which includes polyfluorinated alkyl substances (PFASs), brominated-flame retardants (BFRs), synthesis musk fragrances, and alkylphenols (APs). References were mainly summarized from the past 5 years (2002 up to present) on new developments of sampling methods, extraction, separation/fractionation and/or applications of new technologies for sampling and determination.     

Evolution of dispersive liquid–liquid microextraction method

Dispersive liquid–liquid microextraction (DLLME) has become a very popular environmentally benign sample-preparation technique, because it is fast, inexpensive, easy to operate with a high enrichment factor and consumes low volume of organic solvent. DLLME is a modified solvent extraction method in which acceptor-to-donor phase ratio is greatly reduced compared with other methods. In this review, in order to encourage further development of DLLME, its combination with different analytical techniques such as gas chromatography (GC), high-performance liquid chromatography (HPLC), inductively coupled plasma-optical emission spectrometry (ICP-OES) and electrothermal atomic absorption spectrometry (ET AAS) will be discussed. Also, its applications in conjunction with different extraction techniques such as solid-phase extraction (SPE), solidification of floating organic drop (SFO) and supercritical fluid extraction (SFE) are summarized. This review focuses on the extra steps in sample preparation for application of DLLME in different matrixes such as food, biological fluids and solid samples. Further, the recent developments in DLLME are presented. DLLME does have some limitations, which will also be discussed in detail. Finally, an outlook on the future of the technique will be given.     

Solventless sample preparation techniques based on solid- and vapour-phase extraction

The main objective of this review is to critically evaluate recent developments in solventless sample preparation techniques. The potential of a variety of sample preparation techniques based on solid- and vapour-phase extraction techniques is evaluated. Direct thermal extraction and derivatization processes to facilitate the extraction of analytes in different areas are included. The applicability, disadvantages and advantages of each sample preparation technique for the determination of environmental contaminants in different matrices are discussed.     

Determination of pesticide transformation products: A review of extraction and detection methods

Pesticides are widely applied and they can produce a variety of transformation products (TPs), through different pathways and mechanisms. Nowadays there is a growing interest related to the determination of pesticide TPs in several matrices (environmental, food and biological samples), due to these compounds can be more toxic and persistent than parent compounds, and some of them can be used as markers of exposure to different pesticides. Although solid-phase extraction (SPE) is mainly used for the extraction of TPs, alternative techniques such as solid-phase microextraction (SPME) and liquid-phase extraction (LPE) can be used. These TPs are mainly determined by liquid chromatography (LC) due to the recent developments in this technique, especially when it is coupled to mass spectrometry (MS) detectors, allowing the determination of known and/or unknown TPs. Furthermore, MS is a very valuable tool for the structural elucidation of unknown TPs. This review discusses all phases of analytical procedure, including sample treatment and analysis, indicating the main problems related to the extraction of TPs from several matrices due to their high polarity, as well as the different alternatives found for the simultaneous determination of parent compounds and TPs, using chromatographic techniques coupled to MS detection.     

Uranium determination using atomic spectrometric techniques: An overview

This review focuses on the determination of uranium using spectroanalytical techniques that are aimed at total determination such as flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS), inductively coupled plasma optical emission spectrometry (ICP-OES); and inductively coupled plasma mass spectrometry (ICP-MS) that also enables the determination of uranium isotopes. The advantages and shortcomings related to interferences, precision, accuracy, sample type and equipment employed in the analysis are taken into account, as well as the complexity and costs (i.e., acquisition, operation and maintenance) associated with each of the techniques. Strategies to improve their performance that employ separation and/or preconcentration steps are considered, with an emphasis given to solid-phase extraction because of its advantages compared to other preconcentration procedures.     

食品中邻苯二甲酸酯类化合物的分析方法研究进展

邻苯二甲酸酯是应用最广泛的增塑剂,具有生殖、发育毒性及致癌性,是近年来食品污染的一个重要来源。该类化合物种类多、同系物和同分异构体性质接近、在基体中含量范围宽,高效样品前处理、高选择性分离和高灵敏检测、降低本底干扰等技术是食品中邻苯二甲酸酯类化合物准确测定面临的挑战。本文综述了液液萃取、液液微萃取、固相萃取、固相微萃取、基质固相萃取等传统及新型的提取与净化技术在食品样品分析中的应用,比较分析了气相色谱、液相色谱、串联质谱、高分辨质谱以及酶联免疫、离子迁移谱等快速检测技术的特点,并展望了发展趋势。     

Carbon nanotubes as solid-phase extraction sorbents prior to atomic spectrometric determination of metal species: A review

New materials have significant impact on the development of new methods and instrumentation for chemical analysis. From the discovery of carbon nanotubes in 1991, single and multi-walled carbon nanotubes – due to their high adsorption and desorption capacities – have been employed as sorption substrates in solid-phase extraction for the preconcentration of metal species from diverse matrices. Looking for successive improvements in sensitivity and selectivity, in the past few years, carbon nanotubes have been utilized as sorbents for solid phase extraction in three different ways: like as-grown, oxidized and functionalized nanotubes. In the present paper, an overview of the recent trends in the use of carbon nanotubes for solid phase extraction of metal species in environmental, biological and food samples is presented. The determination procedures involved the adsorption of metals on the nanotube surface, their quantitative desorption and subsequent measurement by means of atomic spectrometric techniques such as flame atomic absorption spectrometry, electrothermal atomic absorption spectrometry or inductively coupled plasma atomic emission spectrometry/mass spectrometry, among others. Synthesis, purification and types of carbon nanotubes, as well as the diverse chemical and physical strategies for their functionalization are described. Based on 140 references, the performance and general properties of the applications of solid phase extraction based on carbon nanotubes for metal species atomic spectrometric determination are discussed.     

Comparative performance of extraction strategies for polycyclic aromatic hydrocarbons in peats

The assessment of historical trends in atmospheric deposition of organic contaminants by using peat samples has been reported on several occasions because these samples represent an almost ideal medium for recording temporal changes in organic contaminant deposition rates. The determination of polycyclic aromatic hydrocarbons (PAHs) in peat samples is complicated due to the high content of organic matter in peat, which affects both extraction efficiency and analytical quality. A rapid and simple method is proposed for the determination of 10 US Environmental Protection Agency indicator PAHs in complex matrices such as peat. This article reviews and addresses the most relevant analytical methods for determining PAHs in peat. We discuss and critically evaluate three different extraction procedures, such as ultrasound-assisted solvent extraction (UASE), shaking and pressurized liquid extraction (PLE). Clean-up of extracts was performed by solid-phase extraction using silica cartridges. Detection of the selected PAHs was carried out by high-performance liquid chromatography coupled with fluorescence detection for determination. Optimization of the variables affecting extraction by the selected extraction techniques was conducted, concluding that the UASE extraction method using hexane:dichloromethane (80:20) as extractant was robust enough to determine the selected PAHs in peat samples with estimated quantification limits between 0.050 and 3.5 μg/kg depending on the PAH. UASE did not demand sophisticated equipment and long extraction times. PLE involved sophisticated equipment and showed important variations in the results. The method proposed was applied to the determination of PAHs in peat samples from Xistral Mountains (Galicia, Spain).     

Developments in single-drop microextraction

Single-drop microextraction (SDME) has become a very popular liquid-phase microextraction technique because it is inexpensive, easy to operate and nearly solvent-free. Essentially, SDME combines extraction (and conceivably, cleanup) and concentration in a minimum number of steps, and thereafter, direct extract introduction into an analytical system. In this review, in order to encourage further development of SDME, we focus on its recent developments in its various guises. Its applications when used in combination with different analytical techniques, such as gas chromatography, high-performance liquid chromatography, inductively-coupled plasma mass spectrometry, capillary electrophoresis, mass spectrometry and electrothermal atomic absorption spectrometry, are summarized. SDME does have some limitations, and these are also discussed as well. Finally, an outlook on the future of the technique is given.     

Simultaneous determination of 3-monochloropropane-1,2-diol and acrylamide in food by gas chromatography-triple quadrupole mass spectrometry with coupled column separation

Both 3-monochloropropane-1,2-diol (3-MCPD) and acrylamide are contaminants found in heat-processed foods and their related products. A quantitative method was developed for the simultaneous determination of both contaminants in food by gas chromatography-triple quadrupole mass spectrometry (GC–MS/MS). The analytes were purified and extracted by the matrix solid-phase dispersion extraction (MSPDE) technique with Extrelut NT. A coupled column (a 3 m Innowax combined with a 30 m DB-5 ms) was developed to separate both compounds efficiently without derivatization. Triple quadrupole mass spectrometry in multiple reaction monitoring mode (MRM) was applied to suppress matrix interference and obtain good sensitivity in the determination of both analytes. The limit of detection (LOD) in the sample matrix was 5 μg kg⁻¹ for 3-MCPD or acrylamide. The average recoveries for 3-MCPD and acrylamide in different food matrices were 90.5–107% and 81.9–95.7%, respectively, with the intraday relative standard deviations (RSDs) of 5.6–13.5% and 5.3–13.4%, respectively. The interday RSDs were 6.1–12.6% for 3-MCPD and were 5.0–12.8% for acrylamide. Both contaminants were found in samples of bread, fried chips, fried instant noodles, soy sauce, and instant noodle flavoring. Neither 3-MCPD nor acrylamide was detected in the samples of dairy products (solid or liquid samples) and non-fried instant noodles.     

Solid-phase extraction and high-performance liquid chromatography mass spectrometry analysis of nitrosamines in treated drinking water and wastewater

N-Nitrosamines, including N-nitrosodimethylamine (NDMA), were identified as chlorination byproducts in drinking water in 1989. Nitrosamines are known rodent carcinogens and probable human carcinogens, and so they are considered disinfection byproducts (DBPs) of public health concern. Epidemiological studies show a potential association of consumption of chlorinated drinking water with an increased risk of bladder cancer. As small, relatively polar DBPs that often occur at low-ng/L concentrations in water, nitrosamines pose analytical challenges for accurate determination. Sample preparation (e.g., the commonly used solid-phase extraction) plays a critical role in achieving reliable determination of nitrosamines at ng/L concentrations. Historically, gas chromatography (GC)-based techniques have been used for nitrosamine analysis. Recently, newly developed liquid chromatography–tandem mass spectrometry (LC-MS²) methods have shown potential advantages in determining polar DBPs. This review focuses on the sample preconcentration methods and LC-MS² determination of nitrosamines in drinking water and wastewater. It also provides a historical perspective on nitrosamines and their occurrence in drinking water.     

New sorbents for extraction and microextraction techniques

This review outlines recent progress in the research on some new classes of sorbents for extraction and microextraction techniques. Carbon nanotubes are allotropes of carbon with cylindrical structure. They are very stable systems having considerable chemical inertness due to the strong covalent bonds of the carbon atoms on the nanotube surface. Some applications of carbon nanotubes are presented in a perspective view. Molecular imprinting has proved to be an effective technique for the creation of recognition sites on a polymer scaffold. By a mechanism of molecular recognition, the molecularly imprinted polymers are used as selective tools for the development of various analytical techniques such as liquid chromatography, capillary electrochromatography, solid-phase extraction (SPE), binding assays and biosensors. Sol–gel chemistry provides a convenient pathway to create advanced material systems that can be effectively utilized to solve the solid phase microextraction fiber technology problems. This review is mainly focused on recent advanced developments in the design, synthesis and application of sol–gel in preparation of coatings for the SPME fibers.     

Recent advances in applications of single-drop microextraction: a review

During the past fifteen years since its introduction, single-drop microextraction has witnessed incessant growth in the range of applications of samples preparation for trace organic and inorganic analysis. This was mainly due to the array of modes that are available to accomplish extraction in harmony with the nature of analytes, and to use the extract directly for analysis by diverse instrumental methods. Whilst engineering of novel sorbent materials has expanded the sample capabilities of rival method of solid-phase microextraction, the single-drop microextraction – irrespective of the mode of extraction – uses common equipment found in analytical laboratories sans any modification, and in a much economic way. The recent innovations made in the field, as highlighted in this review article in the backdrop of historical developments, are due to the freedom in operational conditions and practicability to exploit chemical principals for optimum extraction and sensitive determination of analytes. Literature published till July 2011 has been covered.     

State of the art of environmentally friendly sample preparation approaches for determination of PBDEs and metabolites in environmental and biological samples: A critical review

Green chemistry principles for developing methodologies have gained attention in analytical chemistry in recent decades. A growing number of analytical techniques have been proposed for determination of organic persistent pollutants in environmental and biological samples. In this light, the current review aims to present state-of-the-art sample preparation approaches based on green analytical principles proposed for the determination of polybrominated diphenyl ethers (PBDEs) and metabolites (OH-PBDEs and MeO-PBDEs) in environmental and biological samples. Approaches to lower the solvent consumption and accelerate the extraction, such as pressurized liquid extraction, microwave-assisted extraction, and ultrasound-assisted extraction, are discussed in this review. Special attention is paid to miniaturized sample preparation methodologies and strategies proposed to reduce organic solvent consumption. Additionally, extraction techniques based on alternative solvents (surfactants, supercritical fluids, or ionic liquids) are also commented in this work, even though these are scarcely used for determination of PBDEs. In addition to liquid-based extraction techniques, solid-based analytical techniques are also addressed. The development of greener, faster and simpler sample preparation approaches has increased in recent years (2003–2013). Among green extraction techniques, those based on the liquid phase predominate over those based on the solid phase (71% vs. 29%, respectively). For solid samples, solvent assisted extraction techniques are preferred for leaching of PBDEs, and liquid phase microextraction techniques are mostly used for liquid samples. Likewise, green characteristics of the instrumental analysis used after the extraction and clean-up steps are briefly discussed.