Solvent extraction remains one of the fundamental sample preparation techniques in the analysis of environmental solid samples, but organic solvents are toxic and environmentally harmful, therefore ...one of the possible greening directions is its miniaturization. The present review covers the relevant research from the field of application of microextraction to the sample preparation of environmental solid samples (soil, sediments, sewage sludge, dust etc.) published in the last decade. Several innovative liquid-phase microextraction (LPME) techniques that have emerged recently have also been applied as an aid in sample preparation of these samples: single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid-liquid microextraction (DLLME). Besides the common organic solvents, surfactants and ionic liquids are also used. However, these techniques have to be combined with another technique to release the analytes from the solid sample into an aqueous solution. In the present review, the published methods were categorized into three groups: LPME in combination with a conventional solvent extraction; LPME in combination with an environmentally friendly extraction; LPME without previous extraction. The applicability of these approaches to the sample preparation for the determination of pollutants in solid environmental samples is discussed, with emphasis on their strengths, weak points and environmental impact.
Polar benzotriazoles are corrosion inhibitors with widespread use; they are environmentally characterized as emerging pollutants in the water system, where they are present in low concentrations. ...Various extraction methods have been used for their separation from various matrices, ranging from classical liquid⁻liquid extractions to various microextraction techniques, but the most frequently applied extraction technique remains the solid-phase extraction (SPE), which is the focus of this review. We present an overview of the methods, developed in the last decade, applied for the determination of benzotriazoles in aqueous and solid environmental samples. Several other matrices, such as human urine and plant material, are also considered in the text. The methods are reviewed according to the determined compounds, sample matrices, cartridges and eluents used, extraction recoveries and the achieved limits of quantification. A critical evaluation of the advantages and drawbacks of the published methods is given.
The intoxication due to unintentional or intentional ingestion of plant material containing tropane alkaloids is quite frequent. GC-MS method is still widely used for the identification of these ...toxicologically important substances in human specimen. During general unknown analysis, high temperature of inlet, at least 270 °C, is commonly used for less volatile substances. Unfortunately, both tropanes are thermally unstable and could be overlooked due to their degradation. The temperature-related degradation of tropanes atropine and scopolamine was systematically studied in the inlet of a GC-MS instrument in the range 110–250 °C by increments of 20 °C, additionally also at 275 °C, and in different solvents. At inlet temperatures not higher than 250 °C, the degradation products were formed by elimination of water and cleavage of atropine’s ester bond. At higher temperatures, elimination of formaldehyde became predominant. These phenomena were less pronounced when ethyl acetate was used instead of methanol, while n-hexane proved unsuitable for several reasons. At an inlet temperature of 275 °C, tropanes were barely detectable. During systematic toxicological analysis, any tropanes’ degradation products should indicate the possible presence of atropine and/or scopolamine in the sample. It is not necessary to prepare thermally stable derivatives for confirmation. Instead, the inlet temperature can be decreased to 250 °C, which diminishes their degradation to a level where their detection and identification are possible. This was demonstrated in several case studies.
Mycotoxins are a group of compounds produced by various fungi and excreted into the matrices on which they grow, often food intended for human consumption or animal feed. The high toxicity and ...carcinogenicity of these compounds and their ability to cause various pathological conditions has led to widespread screening of foods and feeds potentially polluted with them. Maximum permissible levels in different matrices have also been established for some toxins. As these are quite low, analytical methods for determination of mycotoxins have to be both sensitive and specific. In addition, an appropriate sample preparation and pre-concentration method is needed to isolate analytes from rather complicated samples. In this article, an overview of methods for analysis and sample preparation published in the last ten years is given for the most often encountered mycotoxins in different samples, mainly in food. Special emphasis is on liquid chromatography with fluorescence and mass spectrometric detection, while in the field of sample preparation various solid-phase extraction approaches are discussed. However, an overview of other analytical and sample preparation methods less often used is also given. Finally, different matrices where mycotoxins have to be determined are discussed with the emphasis on their specific characteristics important for the analysis (human food and beverages, animal feed, biological samples, environmental samples). Various issues important for accurate qualitative and quantitative analyses are critically discussed: sampling and choice of representative sample, sample preparation and possible bias associated with it, specificity of the analytical method and critical evaluation of results.
•Graphite-glass working electrode for portable electrochemical sensors.•An effective pretreatment protocol for removing silver contamination from SPEs.•Simplified and universal approach for enhancing ...working electrode performance.
In the last decades, a significant amount of research has been focused on the development of miniaturized and portable electrochemical sensors in the form of screen-printed electrodes (SPEs). When performing voltammetric measurements using SPEs, especially in the case of carbon-based electrodes, additional peaks can appear and overlap with analytes’ signals or otherwise interfere with results. Therefore, the development of pretreatment methods that enable the removal of interferences is of great importance for SPEs utilization, e.g. for sensor applications. Moreover, electrode pretreatment can also be used to improve electron transfer kinetics, including reversibility of the studied redox processes. In this work, we present the evaluation of different pretreatment methods using cyclic voltammetry and potentiostatic anodization, applied on an in-house graphite-glass composite working electrodes. With the use of X-ray photoelectron spectroscopy and scanning electron microscopy it was confirmed that the surface of working electrode was contaminated by sub-micrometer sized silver particles, which resulted in two interference peaks. Several strong acids, including H2SO4, HNO3, and HCl, as well as phosphate buffer solution, were evaluated as electrolytes for electrochemical pretreatment. A rapid, simple, and low-cost pretreatment protocol that enables the removal of the interference peaks, as well as improved voltammetric signals for Fe(CN)63−/4− redox probe was developed. We propose the optimal pretreatment method in H2SO4 as a protocol that could be universally applied for carbon, carbon-glass, or similar types of SPEs before performing voltammetric experiments and/or further modifications of SPEs.
Emerging environmental pollutants are becoming a global concern, since the acceptable concentrations are currently not set by legislation in EU or elsewhere. Benzotriazoles are an important group of ...emerging pollutants found in low μg/L concentrations, entering the environment through wastewater treatment facilities due to their insufficient removal, and through industrial and other use. Two new dispersive liquid-liquid microextraction (DLLME) methods were developed for the extraction of hydrophilic and hydrophobic benzotriazoles from environmental waters. Liquid chromatographic method coupled to tandem mass spectrometric detection (LC-MS/MS) was developed and validated for surface water. Validation parameters were satisfactory and the overall DLLME-LC-MS/MS method was found to be applicable to analysis of the chosen analytes in environmental waters. It was used to determine benzotriazoles in surface water and wastewater from a municipal wastewater treatment plant. In surface waters, concentration was below the limit of detection, while concentrations determined in wastewater were estimated between 2.7 and 12.0 μg/L.
In this study, a method was developed for the determination of five neonicotinoid pesticides (acetamiprid, clothianidin, imidacloprid, thiacloprid, and thiamethoxam) in propolis. Two sample ...preparation methods were tested: solid-phase extraction and the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method. The identities of analytes were confirmed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the selected reaction monitoring mode. Solid-phase extraction resulted in cleaner extracts; therefore, the SPE-LC-MS/MS method was validated according to the SANTE protocol in triplicate at two spiking levels (10 ng/g and 50 ng/g). The average recoveries of analytes ranged from 61% to 101%, except for clothianidin (10-20%). The LOD ranged from 0.2 ng/g to 4.4 ng/g, whereas the LOQ was in the range of 0.8 ng/g-14.7 ng/g. In order to compensate for the matrix effect, matrix-matched calibration was used. Good accuracy (relative error: 1.9-10.4%) and good linearity (R
> 0.991) were obtained for all compounds. The optimised method was applied to 30 samples: 18 raw propolis and 12 ethanol tinctures. Acetamiprid, imidacloprid, and thiacloprid were detectable in seven samples but were still below the LOQ. This study is the first to report the determination of several neonicotinoid residues in propolis.
In the present work the LC–MS/MS method with solid phase extraction for simultaneous determination of bioflavonoids rutin, quercetin, hesperidin, hesperetin and kaempferol in some food samples (red ...onion, orange peel and honey) was developed and the matrix effect accompanying this determination was quantified.
The matrix effect evaluated using a postextraction addition method was found to be negative in the range −44 to −0.5%, indicating ionization suppression and strongly depended on bioflavonoid concentration. The observed matrix effect was explained taking into account the co-elution of phenolic acids, in terms of their acid–base and hydrophilic properties. The efficacy of extraction expressed as the absolute recoveries of flavonoids were 88–96%, indicating very good efficiency of extraction.
The extracts of food samples obtained either by Soxhlet or ultrasonic extraction were analyzed for bioflavonoid content by the LC–MS/MS method in selected reaction monitoring mode using a triple quadrupole detector and standard addition method, which was found to be the most suitable calibration approach for these samples. The optimized separation was achieved on a Phenomenex Gemini C18 column with gradient elution and mobile phase composition A: 2% acetic acid in water and B: acetonitrile. Rs values were in the range from 1.3 to 3.1, indicating good selectivity of the method. The obtained results (mg/100g fresh weight) for different bioflavonids were for rutin 0.16, for quercetin in the range 0.65–56, for hesperidin 0.016–24, for hesperetin 0.0068–36.4 and for kaempferol 0.14–1.63 and generally show good agreement with published data. Low detection limits (0.014–0.063μg/mL) were obtained with acceptable recoveries (86–114%). Total time of analysis was less than 40min, therefore the proposed method represents significant improvement over existing methods.
► HPLC–MS/MS method for determination of flavonoids in food was developed and optimized. ► Matrix effect was evaluated for each food sample and corrected during method development. ► Extraction procedure was optimized achieving 88–96% of Soxhlet yield. ► Negative matrix effect (−44 to −0.5%) was confirmed and flavonoids were quantified by standard addition method.
Advanced oxidation processes (AOPs) have been introduced to deal with different types of water pollution. They cause effective chemical destruction of pollutants, yet leading to a mixture of ...transformation by-products, rather than complete mineralization. Therefore, the aim of our study was to understand complex degradation processes induced by different AOPs from chemical and ecotoxicological point of view. Phenol, 2,4-dichlorophenol, and pentachlorophenol were used as model pollutants since they are still common industrial chemicals and thus encountered in the aquatic environment. A comprehensive study of efficiency of several AOPs was undertaken by using instrumental analyses along with ecotoxicological assessment. Four approaches were compared: ozonation, photocatalytic oxidation with immobilized nitrogen-doped TiO
thin films, the sequence of both, as well as electrooxidation on boron-doped diamond (BDD) and mixed metal oxide (MMO) anodes. The monitored parameters were: removal of target phenols, dechlorination, transformation products, and ecotoxicological impact. Therefore, HPLC-DAD, GC-MS, UHPLC-MS/MS, ion chromatography, and 48 h inhibition tests on
were applied. In addition, pH and total organic carbon (TOC) were measured. Results show that ozonation provides by far the most suitable pattern of degradation accompanied by rapid detoxification. In contrast, photocatalysis was found to be slow and mild, marked by the accumulation of aromatic products. Preozonation reinforces the photocatalytic process. Regarding the electrooxidations, BDD is more effective than MMO, while the degradation pattern and transformation products formed depend on supporting electrolyte.
Solid-phase extraction (SPE) has gained an essential role in environmental analytical chemistry. Classic off-line SPE coupled with LC-MS/MS systems creates powerful analytical procedures for ...ultratrace analysis of contaminants of emerging concern (CECs) in water. But, being associated with tedious work and large consumption of materials, alternative SPE modes are becoming interesting. As so, the study focuses on development, evaluation, and overall comparison of established and novel SPE modes. Off-line SPE, dispersive micro SPE (DMSPE), and ‘fast’ single-pump on-line SPE were explored, using commercially available sorbents. Their efficiency was evaluated on their performance in water analysis of 20 multiclass CECs.
Hydrophilic-lipophilic sorbent and mixture of C18/C8 sorbents were the best choice for off-line and DMSPE, respectively. All optimized SPE modes coupled with UHPLC-MS/MS reached environmentally-relevant limits of detection (LODs 0.1−12 ng L−1), acceptable repeatability (<20 % RSD), and exhibited less than ±30 % matrix effects in real river water sample. Among all, on-line SPE showed a potential to fully replace the well-established off-line SPE and even improve analytical performance. This was due to the best repeatability (<10 % RSD), automatization, simplicity, the highest multiplexing capacity, as well as comparable LODs of <2 ng L−1. DMSPE is, on the other hand, the most innovative and could be seen as a quick and green alternative to off-line SPE for determination of semi-to-nonpolar CECs, but within sub-10 ng L−1 range.
Overall, the study shows workflow for the exploration of important and promising sample pretreatment techniques in water analysis. Comparison of the developed three SPE-UHPLC-MS/MS methods suggests that alternative SPE modes can compete with the well-established off-line SPE and can even improve the analysis quality if properly applied.
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•Conventional off-line SPE was compared with two simplified and novel SPE modes.•Dispersive micro SPE (DMSPE) is a promising approach that uses sorbent mixtures.•Fast on-line SPE makes SPE process even simpler, automated, and more repeatable.•On-line SPE can replace off-line SPE and improve the analytical performance.•Developed SPE-UHPLC-MS/MS methods reach sub-1 ng L−1 limits of detection.
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