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Sample Preparation Techniques to Isolate and Recover Organics and Inorganics
Published in Paul R. Loconto, Trace Environmental Quantitative Analysis, 2020
QUECHERS is an abbreviation for the phrase: Quick, Easy, Cheap, Rugged, Effective, Safe whose origins go back to pioneer work done at a United States Department of Agriculture (USDA) laboratory.130 This author unknowingly applied what came to be known as QUECHERS when he developed a LLE approach while attempting to find a way to extract three polar organic compounds: 2-aminoethanol, N-methyl-2-aminoethanol and N,N’-dimethyl-2-aminoethanol from an aqueous solution. He was advised to add enough Na2SO4(s) to 4 mL of a deep-blue liquid (copper (II) hydroxide complexed 2-aminoethanol) to saturate the solution followed by adding 2 mL of 2-propanol (isopropyl alcohol). After shaking this mixture and allowing it to settle, an upper phase developed!131 The schematic shown in Figure 3.60 which describes the first step in implementing the QUECHERS sample prep technique. When the ionic strength of an aqueous solution is significantly increased, the degree to which a polar molecule such as 2-propanol interacts intermolecularly with water is significantly reduced. The reader would do well at this point to go back and review Figures 3.44 and 3.45.
Sample Preparation Methods for Determination of Pollutants in Solid and Complex Environmental Matrices
Published in Leo M. L. Nollet, Dimitra A. Lambropoulou, Chromatographic Analysis of the Environment, 2017
Carlos Gonçalves, Maria Augusta D. Sousa, Vasilios G. Samaras, C. Marisa R. Almeida, M. Clara P. Basto
The quick, easy, cheap, effective, rugged, and safe technique, known by the acronym QuEChERS, gained popularity in recent years for the determination of organic pollutants in vegetables and biota samples, the name being explanatory of the claimed advantages. This technique uses both solvent extraction and sorbent-trapping processes. In general, this methodology consists of two steps: (i) extraction of the analytes from the matrix with a solvent by shaking or agitation in a vortex apparatus and (ii) dispersive solid-phase extraction (dSPE) cleanup. The original QuEChERS consisted of extraction of the sample with acetonitrile (ACN), adding MgSO4 and NaCl to enhance the partition of the analytes and reduce polar interferences. After centrifugation, the extract was cleaned up by shaking with PSAs and MgSO4. Later modifications of this procedure include the addition of buffers (acetic acid, anhydrous sodium acetate, or sodium citrate) to preserve base-sensitive analytes and adsorbents (C18 or GCB) and to reduce matrix interferences (Bragança et al., 2012). This procedure uses inexpensive and widely available apparatus in the laboratory. Furthermore, it is relatively fast and simple and provides an extract ready for analysis. The advantages of this procedure were thoroughly described by Bragança et al. (2012). QuEChERS has been adopted by official bodies as a standard method (AOAC 2007.01 and EN 15662).
Determination of Pesticides in Soil
Published in José L. Tadeo, Analysis of Pesticides in Food and Environmental Samples, 2019
Beatriz Albero, Rosa Ana Pérez, José L. Tadeo
The QuEChERS method, an acronym for “quick, easy, cheap, effective, rugged, and safe”, is a sample preparation technique that was developed in 2003 for the analysis of pesticides in fresh fruits and vegetables and consists of a partitioning with acetonitrile in the presence of salts, followed by dispersive solid-phase extraction. Its first application in the analysis of soil was reported in 2008 and it has become very popular taking into account the number of works in the scientific literature. Tables 8.1 through 8.3summarize representative published papers on the analysis of pesticides in soil using those extraction techniques.
Emerging contaminants in the atmosphere: Analysis, occurrence and future challenges
Published in Critical Reviews in Environmental Science and Technology, 2019
Pedro José Barroso, Juan Luis Santos, Julia Martín, Irene Aparicio, Esteban Alonso
As in the case of other solid environmental samples, in order to facilitate sample pre-treatment, new extraction procedures based on instrumental techniques such as MAE and PLE should be tested (Clark et al., 2015; Subedi et al., 2015). Microwave heating is very efficient and it is worth highlighting that its use provides a better control of the experimental conditions and shorter analysis times, preventing degradation issues. Also, in recent years, the quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction technique has gained special attention due to its suitability for multiresidue analysis in matrices such as soils and plants (Abdel-Ghany, Hussein, El Azab, El-Khatib, & Linscheid, 2016; Xiu-Ping, Lin, Lan-Qi, Jian-Bo, & Li, 2017). The QuEChERS procedure mainly involves four steps: (1) Initial extraction step with an organic solvent; (2) Extraction/partitioning step with the addition of a salt mixture; (3) Clean-up step of an aliquot of the raw extract materials; and (4) Direct analysis of the obtained final organic extract with the instrumental system. A recent application of the QuEChERS method conducted by Ribeiro et al. (2017) was developed for the simultaneous measuring of 11 SMF and 2 organic UV-filters in five coastline bush species collected in 15 beaches of Matosinhos and Vila Nova de Gaia (Portugal). The resulting extracts were analyzed by GC-MS. The obtained recoveries were around 93% and the relative standard deviation (RSD) was generally less than 15%. SMCs were detected at levels ranging from 1.56 to 350 ng g−1 dw and UV-filters from 2.9 to 264 ng g−1 dw.
Polycyclic aromatic hydrocarbons in aquatic animals: a systematic review on analytical advances and challenges
Published in Journal of Environmental Science and Health, Part A, 2022
Ivelise Dimbarre Lao Guimarães, Francielli Casanova Monteiro, Júlia Vianna da Anunciação de Pinho, Paloma de Almeida Rodrigues, Rafaela Gomes Ferrari, Carlos Adam Conte-Junior
The process utilized to extract the samples in the various types allied to other techniques included the QuEChERS that can retain the ability to of this method and add very useful quantification features. This procedure was first developed to extract a broad spectrum of pesticides from fruits and vegetables and has been shown to yield a high recovery of apolar compounds from various plant materials. The technique has since been extended to other analytes, including PAHs in fish tissue with recoveries of >90%.[42,43] QuEChERS is a sample preparation method, based on a step of extracting the analytes of interest using a water-miscible solvent, usually acetonitrile, followed by a partition step, promoted by the addition of salts (e.g., magnesium sulfate [MgSO4] and sodium chloride [NaCl]), but requires dSPE for further sample cleanup and purification. In dSPE procedures, primary, secondary amine (PSA) adsorbent is typically used to remove organic acids, while C18 or graphitized carbon black can be included to remove fats and pigments.[44] Another form is the ME technique commonly referred to as SBSE, which initially was used to extract compounds from liquid matrices.[45,46] This technique employs 1–2 cm magnetic stir bars coated with a 0.5 or 1.0 mm film of polydimethylsiloxane (PDMS), a commonly used sorptive material, to extract compounds with high octanol: water partition coefficients (logK●/w > 2). SBSE is easy to use, and parts per billion detection levels for apolar pollutants, like PAHs, in aqueous solutions, are possible when combined with GC/MS.[45,47–49]