Tomasz Tuzimski

A review of recent developments and trendsin the QuEChERS sample preparation approach

Abstract A comprehensive review is presented on the recent developments and trends in the QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation approach. This technique involves liquid-liquid partitioning using acetonitrile and purifying the extract using dispersive solid-phase extraction (d-SPE). Originally, the QuEChERS was introduced for pesticides residues analysis in high moisture fruits and vegetables, but more recently it is gaining significant popularity in the analysis of broad spectrum of analytes in huge variety of samples. The wide range of the technique applications is possible due to introducing various modifications based on the use of different extraction solvent and salt formulation and buffer additions for salting-out partitioning step and the application of various d-SPE sorbents for clean-up step. Therefore, the QuEChERS approach is useful for analysis of, among others pesticides, veterinary drugs and other pharmaceuticals, mycotoxins, polycyclic aromatic hydrocarbons (PAHs), dyes, acrylamide, synthetic musks and UV filters, bisphenols, polybrominated diphenyl ethers and other flame retardants, endocrine disruptors, and other chemical compounds. Thanks to the QuEChERS approach, high-throughput multiresidue methods operate in a routine contaminant control of food products, feedstuff, and environmental samples. Graphical Abstract

Correlation of retention parameters of pesticides in normal- and reversed-phase systems and their utilization for the separation of a mixture of 14 triazines and urea herbicides by means of two-dimensional thin-layer chromatography

The selectivities of TLC systems were compared by use of correlations between RF(II) and RF(I) (by analogy with two-dimensional TLC). The greatest spread of points, indicative of individual selectivity, was obtained for nonaqueous mobile phases on silica and aqueous mobile phases on octadecyl silica adsorbent wettable with water (RP-18 W). The correlation of RF values in normal- and reversed-phase systems was utilized in the practical separation of a mixture of 14 triazines and urea herbicides using two-dimensional thin-layer chromatography on a Multi-K CS5 dual phase (3 cm strip of octadecyl silica parallel to silica layer). The plate was videoscanned showing the real picture of the plate.

Application of different modes of thin-layer chromatography and mass spectrometry for the separation and detection of large and small biomolecules

Biomolecules are widespread throughout the world. A biomolecule is any organic molecule produced by a living organism, including large polymeric molecules such as proteins, polysaccharides and nucleic acids. Many sample preparation techniques are used in biomolecule analysis; the method selected depends on the complexity of the sample, the nature of the matrix and the analytes, and the analytical technique available. This review covers the current state of knowledge on thin-layer chromatography and mass spectrometry for qualitative analysis of biomolecules. In the first part of the paper the reader will gain useful information to avoid some problems about performing various modes of thin-layer chromatography combined with mass spectrometry experiments and in the second part he will find useful information for application of these techniques for separation, detection, and qualitative investigation of structures and quantitative determination of biomolecules such as proteins, peptides, oligonucleotides, amino acids, DNA, RNA, and lipids.

Application of HPLC–DAD after SPE/QuEChERS with ZrO2-based sorbent in d-SPE clean-up step for pesticide analysis in edible oils

In this study, the solid-phase extraction/quick, easy, cheap, effective, rugged and safe (SPE/QuEChERS) technique was adapted to develop a simple sample treatment for multi-residue pesticide analysis of edible oils. The proposed method is based on liquid-liquid partitioning with acetonitrile followed by dispersive solid phase extraction using zirconia-coated silica particles for extract purification. To evaluate the described method, 21 pesticides belonging to different chemical classes were analysed using high performance liquid chromatography with diode-array detection (HPLC-DAD). For validation purposes, recovery studies were performed at 75 ng g(-1), 125 ng g(-1), 250 ng g(-1), 500 ng g(-1) and 1000 ng g(-1) levels. Recoveries were over the range of 50-130% for most of the analytes, with relative standard deviations less than 15% being observed. HPLC-DAD provided suitable linearity, precision and accuracy. The validated method was successfully applied to the analysis of edible oil samples selected from the market.

Use of a Database of Plots of Pesticide Retention (RF) against Mobile-Phase Composition. Part I. Correlation of Pesticide Retention Data in Normal- and Reversed- Phase Systems and their Use to Separate a Mixture of Ten Pesticides by 2D TLC

SummaryTen pesticides have been completely separated by two-dimensional (2D) development on TLC plates coated with coupled layers of octadecyl silica (reversed-phase, RP) and plain silica (normal-phase, NP). The binary mobile phases, aqueous-organic for RP chromatography and nonaqueous for NP chromatography, were chosen from plots ofRF against mobile-phase composition and graphicalRF(RP)-RF(NP) correlations. The different selectivity of the RP and NP systems enabled dispersion of spots over the plate area and good separation.

QuEChERS-based extraction with dispersive solid phase extraction clean-up using PSA and ZrO2-based sorbents for determination of pesticides in bovine milk samples by HPLC-DAD

In this study, a quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction technique was adapted to develop a simple sample treatment for multi-residue pesticide analysis in milk samples. The proposed method is based on liquid-liquid partitioning with acetonitrile followed by dispersive solid phase extraction clean-up using primary secondary amine along with zirconia-coated silica particles for extract purification. Identification and quantification of 30 pesticides was conducted via high performance liquid chromatography with diode-array detection (HPLC-DAD). Recoveries were from 70 to 100% for the vast majority of the analytes, with relative standard deviations less than 20% being observed. HPLC-DAD provided suitable linearity, precision and accuracy. For 28 of 30 analytes in the study method limit of quantification values (mLOQs) comply with the most recent European Union guidelines for the maximum residue levels (MRLs) in milk. Negligible matrix effect was observed due to efficient extract clean-up with ZrO2-based sorbents.

Recent Trends in Sample Preparation and Liquid Chromatography/Mass Spectrometry for Pesticide Residue Analysis in Food and Related Matrixes.

A rising interest by consumers and various governmental organizations towards the quality of food has been continuously observed. Pesticide residue analysis has a significant role in assessing food safety and quality. This article reviews the new analytical approaches for efficient extraction and reliable identification and quantification of pesticides in foodstuffs and related matrixes. Emphasis is given to the new materials used for effective extract purification. We discuss the potential and pitfalls of the different LC/MS approaches, including application of high resolution mass spectrometry in the area of pesticide residue analysis. Untargeted and retrospective screening is outlined, highlighting prospects and achievements as well as its major drawbacks.

Application of SPE-HPLC-DAD and SPE-TLC-DAD to the determination of pesticides in real water samples.

Planar chromatography with diode array scanning (TLC-DAD) and high-performance chromatography with diode array detection (HPLC-DAD) were used to screen water samples for pesticides. Pesticides were enriched from lake water samples by SPE on C18/SDB-1, C18, C18 Polar Plus and cyanopropyl (CN) cartridges. The recovery rates were high for all extraction materials except for all pesticides on CN cartridges, for which the values were lower. SPE was used not only for preconcentration of analytes but also for their fractionation. The analytes were eluted first with methanol and then with dichloromethane. Methanol eluates were analysed by HPLC-DAD, the dichloromethane eluates with TLC-DAD. The method was validated for precision, repeatability and accuracy. The calibration plots were linear between 0.1 and 50.0 microg/mL for all pesticides, the correlation coefficients, r, were between 0.9992 and 1.000 as determined by HPLC-DAD. In the TLC experiments, the best fit for the calibration lines was found when the calibration data were analysed using a second-degree polynomial regression. Calibration plots lay between 0.1 and 17 microg/spot for all pesticides, the correlation coefficients, r, were between 0.9974 and 0.9997 determined by TLC-DAD. The LOD was between 0.04 and 0.65 microg/spot (TLC-DAD) and between 0.02 and 3.68 microg/mL (HPLC-DAD).

Chemometric Characterization of the R F Values of Pesticides in Thin-Layer Chromatography on Silica with Mobile Phases Comprising a Weakly Polar Diluent and a Polar Modifier. Part IV

Relationships between RF values and mobile phase composition have been determined for the last twenty of almost one hundred pesticides studied in this work. Chromatography was performed on silica gel (and other adsorbents) with mobile phases comprising a weakly polar diluent (heptane) and a polar modifier (ethyl acetate, tetrahydrofuran, or dioxane). The relationships obtained constitute a retention database. Group selectivity was compared by use of correlation between RF coefficients, by analogy with two-dimensional TLC. The greatest spread of points, indicative of the highest selectivity, was obtained by use of non-aqueous mobile phases on silica and by use of the aqueous mobile phase methanol-water, 60 + 40 (v/v) on water wettable octadecyl silica (RP-18W). The most selective systems (normal- and reversed-phase) were chosen for separation of a mixture of nine pesticides; these were fully separated by two-dimensional development (2D TLC) on a TLC plate comprising coupled layers of octadecyl silica (reversed-phase, RP) and plain silica (normal-phase, NP).

Application of HPLC-DAD and TLC-DAD after SPE to the Quantitative Analysis of Pesticides in Water Samples

Abstract The objective of this work is to present a new procedure for the analysis of pesticides in water samples with use of solid phase extraction (SPE) and high performance chromatography with diode array detection (HPLC-DAD) and thin layer chromatography with diode array scanning (TLC-DAD). Pesticides were enriched from lakes water samples by solid phase extraction (SPE) on C18/SDB-1, C18, C18 Polar Plus, and CN cartridges. SPE was used not only for preconcentration of analytes but also for their fractionation. The analytes were eluted with methanol, and next with dichloromethane. Methanol eluates were analysed by HPLC-DAD, the dichloromethane eluates with TLC-DAD. The method was validated for precision, repeatability, and accuracy. The calibration plots were linear between 0.1 and 50.0 µg mL−1 for all pesticides, the correlation coefficients, r, were between 0.9992 and 1.000, as determined by HPLC-DAD. In the TLC experiments, the best fit for the calibration lines was found when the calibration data were analyzed using a second degree polynomial regression. Calibration plots lay between 0.1 and 17 µg spot−1 for all pesticides, the correlation coefficients, r, were between 0.9974 and 0.9997, as determined by TLC-DAD. The limit of detection (LOD) was between 0.04 and 0.65 µg spot−1 (TLC-DAD) and between 0.02 and 1.56 µg mL−1 (HPLC-DAD).