Headspace solid phase microextraction applied to the analysis of organophosphorus insecticides in strawberry and cherry juices

Isolation of organophosphate pesticides from water using gold nanoparticles doped magnetic three-dimensional graphene oxide

Pesticides are a large group of pristine organic contaminants, which are widely discharged into environmental water due to agricultural activities. Hence, extraction, determination, and removal of pesticides from water resources are necessary for human health. In this study, novel adsorbent was developed based on three-dimensional magnetic graphene coated with gold nanoparticles (3D-MG@AuNPs) for extraction of chlorpyrifos, dicrotophos, fenitrothion, and piperophos as four specific organophosphorus pesticides (OPPs) from wastewater and tap water samples. The proposed nanocomposite was characterized; FTIR and EDX are performed for the expected functional groups and elemental analysis, SEM showed the unique and spherical AuNPs are well dispersed over graphene sheets. In this investigation, the important parameters that have effect on the extraction efficiency, including the desorbing solvent, desorbing solvent volume, vortex time, the extraction time, adsorbent dosage, pH of sample solutions, and salt effect were evaluated. In conclusion, the measured amounts of the chosen OPPs were determined using the gas chromatography microelectron capture (μECD-GC) method. Limits of quantification (S/N ratio of 10) and detection (S/N ratio of 3) were attained at concentrations of 0.26-0.43 μg.L^-1 and 0.08-0.14 μg.L^-1, respectively. According to the results of the investigations, the synthesized 3D-MG@AuNPs did not require any complicated sample preparation methods; therefore, it is a very good choice for solid magnetic phase extraction studies.

Preparation of Polyacrylonitrile/Ni-MOF electrospun nanofiber as an efficient fiber coating material for headspace solid-phase microextraction of diazinon and chlorpyrifos followed by CD-IMS analysis

Herein, an electrospun polyacrylonitrile/nickel-based metal-organic framework nanocomposite (PAN/Ni-MOF) coating on a stainless steel wire was synthesized and employed as a novel nanosorbent for headspace solid-phase microextraction (HS-SPME) of organophosphorus pesticides (OPPs), diazinon (DIZ), and chlorpyrifos (CPS) from the diverse aqueous media followed by corona discharge ion mobility spectrometry (CD-IMS). Under the optimum experimental conditions, the calibration plots were linear in the range of 1.0-250.0 ng mL^-1 for DIZ and 0.5-300.0 ng mL^-1 for CPS with r² > 0.999. The detection limits (S/N = 3) were 0.3 and 0.2 ng mL^-1 for DIZ and CPS, respectively. The intra-day relative standard deviations (RSDs%) (n = 5) at the concentration levels of 20.0, 40.0, and 100.0 ng mL^-1 were ≤ 5.2%. To investigate the extraction efficiency, PAN/Ni-MOF was employed to analyze various juice samples, including orange, apple, and grape juices, and in three water samples where it led to good recoveries ranged between 87% and 98%.

Employing Solid Phase Microextraction as Extraction Tool for Pesticide Residues in Traditional Medicinal Plants

HS-SPME was optimised using blank plant sample for analysis of organochlorine pesticides (OCPs) of varying polarities in selected medicinal plants obtained from northern part of Botswana, where OCPs such as DDT and endosulfan have been historically applied to control disease carrying vectors (mosquitos and tsetse fly). The optimised SPME parameters were used to isolate analytes from root samples of five medicinal plants obtained from Maun and Kasane, Botswana. The final analytes determination was done with a gas chromatograph equipped with GC-ECD and analyte was confirmed using electron ionisation mass spectrometer (GC-MS). Dieldrin was the only pesticide detected and confirmed with MS in the Terminalia sericea sample obtained from Kasane. The method was validated and the analyte recoveries ranged from 69.58 ± 7.20 to 113 ± 15.44%, with RSDs ranging from 1.19 to 17.97%. The method indicated good linearity (R² > 0.9900) in the range of 2 to 100 ng g^-1. The method also proved to be sensitive with low limits of detection (LODs) ranging from 0.48 ± 0.16 to 1.50 ± 0.50 ng g^-1. It can be concluded that SPME was successfully utilized as a sampling and extraction tool for pesticides of diverse polarities in root samples of medicinal plants.

Optimization of Headspace Sampling Using Solid-Phase Microextraction (SPME) for Volatile Components in Starfruit Juice

Volatiles are important flavor compounds of fruit juices and beverages. In this study, a headspace Solid-phase microextraction (SPME) gas chromatography-mass spectrometry (GC-MS) was used to analyze the volatile components in starfruit juices. Several experimental parameters (e.g. adsorption temperature, adsorption time, and sample volume) were optimized to improve sampling efficiency in two aspects; maximum adsorption and selective adsorption of volatile components onto SPME fiber. The following conditions were found to be optimal for selectivity and sensitivity: adsorption temperature of 50°C for 30 min, with a 65 μm divinylbenzene /polydimethylsiloxane (DVB/PDMS)-coated fiber with a sample volume of 15 g in a 30-ml vial. The proposed technique could be applied for the analysis of volatile compounds that contribute to starfruit juices flavor in different cultivars, and also their ripening stages.

Chemical composition and sensory profile of pomelo (Citrus grandis (L.) Osbeck) juice

Two cultivars (Citrus grandis (L.) Osbeck PO 51 and PO 52) of Malaysian pomelo juices were studied by examining their physicochemical properties (i.e. pH, °Brix and titratable acidity), volatile and non-volatile components (sugars and organic acids). Using solvent extraction and headspace solid-phase microextraction, 49 and 65 volatile compounds were identified by gas chromatography-mass spectrometer/flame ionisation detector, respectively. Compared to pink pomelo juice (cultivar PO 52), white pomelo juice (cultivar PO 51) contained lower amount of total volatiles but higher terpenoids. Descriptive sensory evaluation indicated that white pomelo juice was milder in taste especially acidity. Furthermore, principal component analysis and partial least square regression revealed a strong correlation in pomelo juices between their chemical components and some flavour attributes (i.e. acidic, fresh, peely and sweet). Hence, this research enabled a deeper insight into the flavour of this unique citrus fruit.

Pesticide residue analysis of fruit juices by LC-MS/MS direct injection. One year pilot survey

For this work, thirteen types of fruit juices (orange, pineapple, peach, apple, multifruit, mango, strawberry, tomato, pear, mandarin, grape, banana and grapefruit) were selected to develop an analytical method for the analysis of 53 pesticides by direct injection in LC-MS/MS. The preparation of the samples was very simple: an aliquot of the juice was centrifuged and it was ten-times diluted prior to analysis, which allowed reducing considerably the time and cost of the analyses. Besides, dilution of the samples permits reducing the amount of matrix going into the system, and thus, decreasing the matrix effects, so common in this type of commodities, opening the possibility to perform quantification with solvent based standards. Validation of the method was carried out in accordance with EU guidelines. Calibration curves covering three orders of magnitude were performed, and they were linear over the concentration range studied for all the matrices (from 0.1 to 100 μg L(-1)). Practical limits of quantification were in the low μg L(-1) range, far below the maximum residue levels (MRLs) of the EU regulations, which do not set specific MRLs for juices, and in this cases of processed food, MRLs of the raw product are applied. Repeatability of the instrumental method was studied in all matrices, obtaining good intra- and inter-day relative standard deviations (RSDs). The proposed method was applied to 106 real fruit juice samples purchased in different local markets during a one-year survey in order to validate the suitability for routine analysis. 43% of the analysed samples gave positive results (higher than the practical limits of quantification).

Determination of postharvest fungicides in fruit juices by solid-phase extraction followed by liquid chromatography electrospray time-of-flight mass spectrometry

A multiresidue method using liquid chromatography-time-of-flight mass spectrometry (LC-TOFMS) has been developed for the quantitative analysis of five widely used postharvest fungicides (carbendazim, thiabendazole, imazalil, prochloraz, and iprodione) and two of their transformation products (imazalil and prochloraz metabolites) in fruit juices. LC-TOFMS in positive electrospray ionization mode was used to quantify and confirm trace levels of these fungicides in fruit juices. The proposed method consists of a sample treatment step based on solid-phase extraction using hydrophilic-lipophilic-balanced polymer-based reverse-phase SPE cartridges (Oasis HLB) and methanol as an eluting solvent. Fruit-juice extracts spiked at different fortification levels (10 and 20 microg L(-1)) yielded average recoveries in the range of 71-109% with RSD (%) below 15%. Subsequent identification, confirmation, and quantitation were carried out by LC-TOFMS analysis. The confirmation of the target species was based on accurate mass measurements of protonated molecules ([M+H]+) and fragment ions, obtaining routine accuracy errors lower than 2 ppm in most cases. The obtained limits of detection (LODs) of the proposed method were in the range of 0.08-0.45 microg L(-1). Finally, the proposed method was successfully applied to the analysis of 23 fruit juice samples collected from different European countries and the United States, showing the potential applicability of the method in routine analysis. Over 50% of the samples tested contained pesticide residues, but relatively low concentration levels were found.

Recent developments in headspace microextraction techniques for the analysis of environmental contaminants in different matrices

Headspace microextraction procedures such as solid-phase microextraction (SPME) and single drop microextraction (SDME) or liquid-phase microextraction (LPME) are increasingly used for the extraction of environmental organic pollutants from a variety of aqueous, viscous, semisolid and solid environmental and biological matrices. In this article, recent analytical applications of these methodologies when used as an isolation and trace enrichment step prior to the analysis of organic pollutants (pesticides, polycyclic aromatic hydrocarbons, polychlorinated compounds, organotin compounds, phenolic derivatives, aromatic amines, phthalates, etc.) by gas and liquid chromatography are reviewed. The applicability and inherent limitations of headspace microextraction are also discussed. The future direction of research in this field and general trends toward commercial applications are considered.

Methods of sample preparation for determination of pesticide residues in food matrices by chromatography-mass spectrometry-based techniques: a review

Much progress has been made in pesticide analysis over the past decade, during which time hyphenated techniques involving highly efficient separation and sensitive detection have become the techniques of choice. Among these, methods based on chromatographic separation with mass spectrometric detection have resulted in greater likelihood of identification and are acknowledged to be extremely useful and authoritative methods for determination of pesticide residues. Even with such powerful instrumental techniques, however, the risk of interference increases with the complexity of the matrix studied, so sample preparation before instrumental analysis is still mandatory in many applications, for example food analysis. This article summarizes the analytical characteristics of the different methods of sample-preparation for determination of pesticide residues in a variety of food matrices, and surveys their recent applications in combination with chromatographic mass spectrometric analysis. We discuss the advantages and the disadvantages of the different methods, address instrumental aspects, and summarize conclusions and perspectives for the future.

Rapid gas chromatographic method for the determination of famoxadone, trifloxystrobin and fenhexamid residues in tomato, grape and wine samples

Trifloxystrobin, fenhexamid and famoxadone belong to the generation of fungicides acting against a broad spectrum of fungi and widely used in Integrated Pest Management strategies in different agricultural crops but mainly in viticulture. In the present work, a gas chromatographic (GC) method for their determination was developed and validated on tomato, grape and wine matrices. The method was based on a simple one step liquid-liquid microextraction with cyclohexane/dichloromethane (9+1, v/v) and determination of fungicides by gas chromatography with nitrogen phosphorous (NP-) and electron capture (EC-) detection, and ion trap mass spectrometry (ITMS) for confirmation. The method was validated by recovery experiments, assessment of matrix effect and calculation of the associated uncertainty. Recoveries for GC-NPD and GC-ECD were found in the range of 81-102% with RSD <12%, while matrix-matched calibration solutions were imposed for quantification. LOQs ranged from 0.005 to 0.05 mg/kg and 0.01 to 0.10 mg/kg for the GC-ECD and GC-NPD, respectively, depending on the sensitivity of each compound with trifloxystrobin being the most sensitive. The expanded uncertainty, calculated for a sample concentration of 0.10 mg/kg, ranged from 4.8 to 13% for the GC-ECD and from 5.4 to 29% for the GC-NPD. The concentration levels for famoxadone residues found in tomato and grape samples from field experiments were clearly below the EU established MRL values, thus causing no problems in terms of food safety.

Evaluation and interlaboratory validation of a GC-MS method for analysis of pesticide residues in teas

A method was described for simultaneous determination of nine organic heterocyclic pesticide residues by gas chromatography-mass spectrometry-selected ion monitoring. Atrazine, vinclozolin, procymidone, triflumizole, imazalil, buprofezin, propiconazole, fenarimol, and pyridaben were clearly separated from each other, extracted with acetone—hexane mixture, purified with graphitized carbon black cartridge and neutral Al2O3 cartridge, eluted with acetone—hexane mixture, simultaneously determined by GC-MS, and then quantified with an external standard method. Recoveries of pesticides ranged from 73 % to 116 % at the spiked level of 0.01–30 mg kg−1, while the relative standard deviation was between 3 % and 27 %. In addition, the limits of determination (0.01 mg kg−1 to 5.0 mg kg−1) and linearity (0.02–40 μg mL−1) revealed that simultaneous determination of multi-residues in Chinese teas (like Oolong tea, green tea, red tea, etc.) was possible. Furthermore, an interlaboratory study among 5 labs was conducted to further validate the method, and the results were satisfactory.

Screening method for organophosphorus insecticides and their metabolites in olive oil samples based on headspace solid-phase microextraction coupled with gas chromatography

This work is focused on the effectiveness of headspace solid-phase microextraction (HS-SPME) for the analysis of nine organophosphorus (OPs) insecticides (dimethoate, diazinon, fenitrothion, malathion, fenthion, parathion ethyl, methyl bromophos, methidathion, ethion) and four metabolites (omethoate, malaoxon, fenthion sulfoxide and fenthion sulfone) residues in olive oil samples. The efficiency of six fibre types with different film thickness was compared. PDMS (100 microm) was found to be the most suitable fibre for the analysis of OPs in olive oils. Optimization of SPME conditions (stirring rate, extraction time, temperature, salt addition) was based on previous developed method in the laboratory that was enriched with additional analytes including major metabolites. In addition, the effect of the oil matrix on the pesticide recoveries was evaluated using spiked oil samples of different composition (acidity, fatty acids, triglycerides, sterols). It was found that only acidity and total amount of sterols are the main factors influencing the SPME efficiency. Matrix effects were compensated for, by using the internal standard method for the quantification of pesticides. The recoveries at three spiking levels were between 80% and 106% with R.S.D. (%) values below 10% in most cases. Good linearity (R2>0.985) was observed in the 0.025-0.50 mg kg(-1) concentration range with satisfactory R.S.D. (%) values of 4.5-10.4%. The method allowed detection of the tested compounds at concentrations below 0.010 mg kg(-1) with GC-FTD detection. In addition, intra- and inter-day precision was satisfactory (R.S.D. (%) <10%). The performance results confirm the usefulness of the proposed methodology for the analysis of OPs in olive oils. Moreover, the maximum residue limits required by European and international regulations can be attained without difficulty. Finally, the method was applied to 30 virgin olive oil samples from major olive production areas of Greece in the framework of an extended monitoring survey of OPs residues in olive oil. The most commonly found pesticides were fenthion, dimethoate and ethion in levels that did not exceed the MRLs.

Development and Application of Porous Membrane-Protected Carbon Nanotube Micro-Solid-Phase Extraction Combined with Gas Chromatography/Mass Spectrometry

A novel, multiwalled carbon nanotube (MWCNT)-supported micro-solid-phase extraction (mu-SPE) procedure has been developed. A 6-mg sample of MWCNTs was packed inside a (2 cm x 1.5 cm) sheet of porous polypropylene membrane whose edges were heat-sealed to secure the contents. The mu-SPE device, which was wetted with dichloromethane, was then placed in a stirred sewage sludge sample solution to extract organophosporous pesticides, used here as model compounds. Tumbling of the extraction device within the sample solution facilitated extraction, and the porous membrane acted as a filter to exclude the extraction of extraneous materials. After extraction, analytes were desorbed in hexane and analyzed using gas chromatography/mass spectrometry. Since the porous membrane afforded protection of the MWCNTs, no further cleanup of the extract was required. The pi-pi electrostatic interaction with the analytes and the large surface area of MWCNTs facilitated the adsorption of analytes, with good selectivity and reproducibility. Under the optimized extraction conditions, the method showed good linearity in the range of 0.1-50 mug/L, repeatability of the extractions (RSD 2-8%, n = 4), and low limits of detection (1-7 pg/g). No analyte carryover effect was observed, and each mu-SPE device could be used for up to 30 extractions. Comparison was made with hollow fiber protected solid-phase microextraction and headspace solid-phase microextraction; mu-SPE was demonstrated to be a fast, accurate, and cost-effective pretreatment method for sewage sludge samples.

Kinetics and mechanism of the degradation of methyl parathion in aqueous hydrogen sulfide solution: investigation of natural organic matter effects

The kinetics of the transformation of methyl parathion have been investigated in aqueous solution containing reduced sulfur species and small concentrations of natural organic matter (NOM) from different sources such as soil, river, and peat. It was shown that NOM mediates the degradation of methyl parathion in aqueous solutions containing hydrogen sulfide. After evaluating and quantifying the effect of the NOM concentration on the degradation kinetics of methyl parathion in the presence of hydrogen sulfide, it was found that the observed pseudo-first-order reaction rate constants (k(obs)) were proportional to NOM concentrations. The influence of pH on the degradation of methyl parathion in the aqueous solutions containing hydrogen sulfide and NOM has been studied. The rate of degradation of methyl parathion was strongly pH dependent. The results indicate k(obs) with a commercially available humic acid has a maximum value at approximately pH 8.3. Two main reaction mechanisms are identified to dominate the degradation of methyl parathion in aqueous solution containing hydrogen sulfide and NOM based on the products aminomethyl parathion and desmethyl methyl parathion. The two mechanisms are nitro-group reduction and nucleophilic attack at the methoxy-carbon. The reduction of the nitro-group is only observed in the presence of NOM. The results of this study form an important base for the evaluation and interpretation of transformation processes of methyl parathion in the environment.

Optimization of a multi-residue screening method for the determination of 85 pesticides in selected food matrices by stir bar sorptive extraction and thermal desorption GC-MS

A multi-residue method to determine 85 pesticides, including organochlorine pesticides, carbamates, organophosphorus pesticides, and pyrethroids, in vegetables, fruit, and green tea, has been developed. The method is based on stir bar sorptive extraction (SBSE) coupled to thermal desorption (TD) and retention time locked (RTL) GC-MS operating in the scan mode. Samples are extracted with methanol and diluted with water prior to SBSE. Dilution of the methanol extract before SBSE was optimized to obtain high sensitivity and to minimize adsorption onto the glass wall of the extraction vessel as well as to minimize sample matrix effects (particularly for the pesticides with high log K(o,w) values). The optimized method consists of a dual SBSE extraction performed simultaneously on respectively a twofold and a fivefold diluted methanol extract. After extraction, the two stir bars are placed in a single glass thermal desorption liner and are simultaneously desorbed. The method showed good linearity (r2 > 0.9900) and high sensitivity (limit of detection: < 5 microg kg(-1)) for most of the target pesticides. The method was applied to the determination of pesticides at low microg kg(-1) in tomato, cucumber, green soybeans, spinach, grapes, and green tea.

Determination of 266 pesticide residues in apple juice by matrix solid-phase dispersion and gas chromatography-mass selective detection

A macro matrix solid-phase dispersion (MSPD) method was developed to extract 266 pesticides from apple juice samples prior to gas chromatography-mass selective detection (GC-MSD) determination. A 10 g samples was mixed with 20 g diatomaceous earth. The mixture was transferred into a glass column. Pesticide residues were leached with a 160 mL hexane-dichloromethane (1:1) at 5 mL/min. Two hundred and sixty-six pesticides were divided into three groups and detected by GC-MSD under selective ion monitoring. The proposed method takes advantage of both liquid-liquid extraction and conventional MSPD methods. Application was illustrated by the analysis of 236 apple juice samples produced in Shaanxi province China mainland this year.

Application of solid-phase microextraction for determining phenylurea herbicides and their homologous anilines from vegetables

Residues of metobromuron, monolinuron and linuron herbicides and their aniline homologous were analyzed in carrots, onions and potatoes by solid-phase microextraction (SPME) performed with a polyacrylate fiber. A juice was obtained from food samples that were further diluted, and an aliquot was extracted after sodium chloride (14%) addition and pH control. At pH 4 only the phenylureas were extracted. A new extraction at pH 11 allowed the extraction of phenylureas plus homologous aniline metabolites. Determination was carried out by gas chromatography with nitrogen-phosporus detection (NPD) the identity of the determined compounds was studied by gas chromatography-mass spectrometry. Limits of quantification (LOQs) obtained with NPD and MS (selected-ion monitoring) were in the microg/kg order allowing determination of maximum residue levels (MRLs) established in the Spanish regulations. MRLs ranged from 0.02 to 0.1 mg/kg depending on the kind of food and herbicide. Under the proposed conditions matrix effects were low enough to permit calibration with samples proceeding from ecological (non-pesticide treated) crops. Twelve commercial samples of each carrots, onions and potatoes were analyzed and only three samples of potatoes contained residues of linuron at levels below MRLs.

Potential of SPME-GC and chemometrics to detect adulteration of soft fruit purées

The potential of combining solid-phase microextraction (SPME) with gas chromatography and chemometric data analysis to differentiate between pure strawberry samples (Fragraria ananassa) and strawberry samples adulterated with 10, 40, and 70% (v/v) apple purée was investigated. The method involved the extraction of aroma volatiles from the headspace of the purée samples using a SPME fiber followed by GC analysis with flame ionization detection. The principal component analysis (PCA) data matrix consisted of the relative percent peak areas of 37 compounds deemed to be significant in the differentiation of the samples on the basis of adulteration. The PCA results clearly showed that differentiation of the adulterated and unadulterated samples was possible, particularly at the higher levels of adulteration. Partial least-squares regression (PLSR) using a dummy set of Y variables (set to 0 for unadulterated and 1 for adulterated samples) resulted in clear discrimination between unadulterated purées and those containing 40 and 70% (v/v) apple. PLSR using a second set of Y variables, consisting of the actual level of adulteration, enabled quantification of apple purée with a standard error of prediction of 11.6%, implying a minimum detectable level of 25% (v/v) apple. GC-MS analysis enabled identification of the compounds with the greatest influence on sample differentiation. These compounds were identified as hexanoic acid, 2-hexenal, and alpha-farnesene, all of which are key aroma compounds in apples.

Preparation and characteristics of sol–gel-coated calix[4]arene fiber for solid-phase microextraction

5,11,17,23-Tetra-tert-butyl-25,27-diethoxy-26,28-dihydroxycalix[4]arene/hydroxy-terminated silicone oil coated fiber was first prepared and applied for solid-phase microextraction (SPME) with sol-gel technology. The possible sol-gel mechanism was discussed and confirmed by IR spectra. It showed wonderful selectivity and sensitivity to polar (aromatic amines), nonpolar (benzene derivatives, polycyclic aromatic hydrocarbons) and high boiling point compounds (phthalates) and the extraction equilibria were reached quite fast. The coating has high thermal stability (380 degrees C) and solvent stability (organic and inorganic), thus its lifetime is longer than conventional fibers. In addition, it has surprising fiber-to-fiber and batch-to-batch reproducibility. The detection limits were quite low and the linear ranges were pretty broad for all analytes.

Headspace solid-phase microextraction in combination with gas chromatography-mass spectrometry for the rapid screening of organophosphorus insecticide residues in strawberries and cherries

A headspace solid-phase microextraction (HS-SPME) method in combination with GC-MS was used for the extraction and quantification of diazinon, fenitrothion, fenthion, parathion ethyl, bromophos methyl, bromophos ethyl and ethion. The method was developed using a 100-microm poly(dimethylsiloxane) fiber. The obtained results showed higher responses of the insecticides after addition of aliquots of water and solvent to the fruit samples. Calibration curves that were constructed for the analytes spiked into strawberry and cherry samples followed linear relationships with good correlation coefficients (R2 > 0.986). Linearity range was between 50 and 500 microg/kg and the precision was found to be lower than 15% when applying the optimized HS-SPME procedure to fruit samples. Limits of detection in both strawberry and cherry samples using GC-MS (selected ion monitoring mode) were below 13 microg/kg. Moreover, the HS-SPME method was applied to the analysis of fruit samples and compared with liquid-liquid extraction. Results obtained in this study were in good agreement with those obtained using liquid-liquid extraction demonstrating that the recommended procedure was a fast, accurate and stable sample pretreatment method obtaining good efficiency for the extraction of organophosporus insecticides from strawberries and cherries.

Recent applications of sample preparation techniques in food analysis

Even with the emergence of advanced techniques of separation and identification, it is rarely possible to analyse food without manipulation. The traditional techniques for sample preparation are time consuming and require large amount of reagents, which are expensive, generate considerable waste, contaminate the sample and can enrich it for analytes. The more analytical techniques have become highly developed, the more has sample clean-up become important in order to fully take advantage of them. Due to the multiplicity of food matrices, it is not possible to use one sample preparation technique, so many methods have been proposed for meeting all the requirements. The newest variations of wet digestion, solvent and sorbent extraction and membrane separation are summarised and their most recent applications to food analysis are provided.