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Given the extensive use of pesticides in modern times, residues are frequently detected in water samples. Therefore, this study developed and validated a method utilizing solid-phase extraction (SPE) with a polymeric sorbent for sample preparation in combination with ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The aim was to determine a variety of current-use pesticides (CUPs) in different types of water. The preconcentration step, employing the polymeric sorbent Oasis HLB (60 mg), combined with the high selectivity and sensitivity of the UHPLC-MS/MS analysis, enabled the multiclass determination of pesticide residues in water samples at very low concentrations. The proposed method underwent validation, demonstrating satisfactory linearity, precision, and accuracy. The accuracy results, determined through recovery assays at varying spike levels (0.04-0.4 μg L-1), ranged from 71 to 117%, with precision expressed as relative standard deviations consistently below 19%. The practical limits of detection and quantification for most compounds were 0.01 and 0.04 μg L-1, respectively. This method was effectively employed to analyze drinking water, artesian well water, dam water, and river water, leading to the detection of various pesticides at concentrations of up to 2.24 μg L-1.

ELECTROSPINNING APPLIED TO THE DEVELOPMENT OF ADSORBENT NANOFIBERS AIMING AT IMPROVING SOLID PHASE (MICRO)EXTRACTION TECHNIQUES. The limitations and challenges associated with the complex analyte-matrix-interfering interactions make the development of new sorbent materials an attractive line in several research areas, ranging from the synthesis and characterization to the application of these materials. Among the different strategies for manufacturing sorbent nanomaterials, the electrospinning of nanofibers based on polymeric solutions incorporated into Metal-Organic Frameworks (MOFs), Molecularly Imprinted Polymers (MIPs) and Nanoparticles (NPs) have represented in recent years, one of the methods more versatile and promising with regard to obtaining materials with large surface area and potential for functionalization and chemical modification. In this sense, the objective of this contribution is to highlight recent work aimed at the synthesis of electrospun nanofibers applied in adsorption and sample preparation processes, highlighting the synthetic nanofiber strategies based on MOFs, MIPs and NPs and the main challenges and perspectives of the applications, although little explored, of these materials in solid phase extraction and microextraction techniques.

Food safety is a constant and necessary concern due to the worldwide increase of the food demand. The monitoring of quality parameters demands the development of accurate, easy and fast procedures. The aim of this work was to develop a cheap, miniaturized and trustworthy salting-out assisted liquid-liquid extraction (SALLE) procedure for the determination of pesticides in wines. Sample and acetonitrile were mixed and the addition of NaCl and CH3COONa were used for separation of aqueous and organic phases. After centrifugation, the organic phase was directly injected into a liquid chromatograph. The developed SALLE procedure consumed at least 25-fold less reagent compared to conventional QuEChERS procedure. Additionally, the d-SPE step of the QuEChERS method was suppressed, without efficiency losses. The developed procedure was compared to the conventional methodology and no significant difference was observed. It was successfully applied to the determination of three pesticides in wines by liquid chromatography. Low consumption of sample and solvent, low residues generation, simple instrumentation are notable advantages. The suppression of the d-SPE step simplified the process and the risk of analyte losses.

Sample preparation is commonly considered a key step to achieve selective, sensitive, and reliable chemical analyses, particularly those involving complex matrices. Although the application of electric fields to improve the speed and efficiency of sample preparation methods has been proven, this approach is still considered to be state-of-the-art; hence, further development is necessary to improve future applications. This review describes the fundamentals, advances, applications, and perspectives of using electric fields to enhance sample preparation techniques such as liquid-liquid and solid-liquid extractions in conventional and microscale devices.

This paper describes the evaluation of a new method of sample preparation using a cold finger system with continuous water flow for rice analysis by flame atomic absorption spectrometry. The limits of detection for Cu, Fe, Mn and Zn for the proposed method were 0.36, 1.84, 2.12 and 0.16 mg kg-1, respectively. The RSDs were lower than 6.0% for all elements and the CRM analyzed showed values with 95% agreement. The proposed method is simple and safe for the proposed objective and does not require the use of mixtures of acid or special equipment for sample preparation.

This paper describes the development of methods in micro-scale for the determination of K, Mg, Na and Zn in meat by atomic spectrometry techniques. The limits of detection (LOD) for K and Na by microdigestion were 0.18 and 0.20 mg g-1, respectively whereas LOD for Mg and Zn by microsolubilization with TMAH were 2.40 and 18.4 µg g-1, respectively. The RSD values were lower than 6.0% and the CRMs analyzed showed values with 95% agreement. The proposed methods are simple, fast and use small amounts of sample (around 10 mg) yet do not require special equipment for sample preparation.

The variability in aflatoxin B1 concentration among peanut subsamples of 4 sample preparation procedures was evaluated. For each procedure, 18 samples were prepared involving dry comminuting/homogenization or dry roughly comminuting followed by the preparation of a aqueous slurry. Ten analytical samples were withdrawn from each sample/procedure and analyzed by thin layer chromatography. The coefficient of variation (CV%) among each set of 10 analytical samples was assumed to be associated with the sample preparation procedure. The procedure that made use of a subsample mill and preparation of a subsample slurry, showed lower variability (CV%) among the analytical subsamples.

The use of thermoanalytical data in sample preparation is described as a tool to catch the students' attention to some details that can simplify both the analysis and the analytical procedure. In this case, the thermal decomposition of eggshells was first investigated by thermogravimetry (TGA). Although the classical procedures suggest long exposure to high temperatures, the TGA data showed that the decomposition of organic matter takes place immediately when the sample is heated up to 800 °C under air atmosphere. After decomposition, the calcium content was determined by flame atomic emission photometry and compared with the results obtained using classical volumetric titration with EDTA.

When organic compounds present in biological fluids are analysed by chromatographic methods, it is generally necessary to carry out a prior sample preparation due the high complexity of this type of sample, especially when the compounds to be determinated are found in very low concentrations. This article describes some of the principal methods for sample preparation in analyses of substances present in biological fluids. The methods include liquid-liquid extraction, solid phase extraction, supercritical fluid extraction and extraction using solid and liquid membranes. The advantages and disadvantages of these methods are discussed.

Dry ashing, dissolution in aqueous medium or wet digestion methods were evaluated for sample preparation of shampoo for the subsequent indirect determination of sulfur by UV-Vis spectrophotometry. Among the sample preparation methods evaluated, microwave-assisted wet digestion using 7 mol L-1 HNO3 was the most suitable method for this purpose. Accuracy of the proposed method was evaluated by recovery test using standard solution, and the recovery was about 96%. Moreover, for comparison of results, S (as SO42-) was also determined by ion chromatography, after microwave-assisted wet digestion using concentrated HNO3, and no significant difference was observed between the obtained results (according to the t-test for a 95% confidence level, p = 0.288). Relative standard deviations were always lower than 10% and the limit of detection was 0.007% w/v. Finally, the proposed method was applied for analysis of sixteen shampoos used to many types of hair, from different brands produced in Brazil, and the concentration of S ranged from 0.78 to 2.82% w/v.

Over the past few years, metabolomics has been employed in a broad range of applications in different research fields. Microbial metabolomics has been applied in several microbiological areas, such as identification of microorganisms, cell mutations, functional gene approach, identification of unique metabolic pathways and microbial engineering, leading to a better understanding of the global metabolism and metabolic regulation of certain systems. Metabolites produced by microorganisms constitute a large promising group with diverse applications; however, most of these systems are still unknown and underexplored. In this context, the overall analysis of metabolites involved in a biological system can be used to discover potential biomarkers or specific metabolic changes due to a biological phenomenon studied. In this sense, this review aims to understand the main challenges faced by each step of the workflow in the metabolic analysis of microorganisms and how these difficulties have been overcome. A critical analysis of the articles published within the last five years will be accomplished in this paper to understand how these studies have contributed to the microbial metabolomics research. Moreover, major trends observed in this area will be highlighted here in order to guide readers interested in microbial metabolomics in their future researches.

There are not reports in the literature of digestion processes of metallic cation carrier microparticles. Multivariate experimental designs were utilized to ensure an appropriate digestion for further analysis by atomic absorption spectroscopy. It was used a heater plate and the polimeric degradation was evaluated utilizing an analyzer of total organic carbon (TOC). For the total carbon (TC) content, the full factorial design 24 pointed the significance of sample volume (VAm), in relation to the variables acid volume (VAc), temperature (T) and digestion time (t). However, according to the normal distribution graph it was noted a possible significance of the T and t effects. The same was observed for TOC, including the VAm × VAc × T effect suggestive of complex behavior. In the central composite design all variables were again studied and the VAM was significant, promoting a TC decreasing at the lower evaluated level. By ANOVA a quadratic model without lack of fit was found, with the significant quadratic term. The best digestion condition was: 5.00 mL of sample, 10.00 mL of nitric acid, 60 ºC and 90 min. The multivariate optimization allowed an efficient digestion, with the initial carbon concentration of 4.60 mg L-1 decreased to 0.55 mg L-1.