Ionic Liquid-Based Dispersive Liquid–Liquid Microextraction Following High-Performance Liquid Chromatography for the Determination of Fungicides in Fruit Juices

This paper described an ionic liquid-based dispersive liquid–liquid microextraction (IL-DLLME) combined with high-performance liquid chromatography (HPLC) method to determine fungicides in fruit juices. In this method, 1-hexyl-3-methyli-midazolium hexafluorophosphate (HMIMPF₆) was used as extraction solvent, which dispersed into the fruit juices under vigorously shaking with the vortex. The effects of experimental parameters, such as extraction solvent volume, disperser solvent and its volume, vortex time, centrifugation time, sample pH, on the extraction efficiency were investigated. Under the optimum conditions, the linear correlation coefficients ranged from 0.9902 to 0.9979 for concentration levels of 0.02–2 mg l^?1, the extraction recoveries were ranged 66.2–92.9 % except pyrimethanil (39.5–44.6 %), The relative standard deviations (RSDs; n?=?6) ranged from 2.2 % to 11.6 %, and the limits of detection (LODs) for the fungicides were between 3.1 and 10.2 μg l^?1. Two real samples including apple and grape juices, spiked at two concentration levels were analyzed and yielded recoveries ranging from 71.3–93.1 % and 65.4–87.7 %, respectively.     

Hydroxymethylfurfural in fruit puree and juice: preconcentration and determination using microextraction method coupled with high-performance liquid chromatography and optimization by Box–Behnken design

In the present study, a sensitive and rapid method for separation and determination of hydroxymethylfurfural (HMF) in fruit puree and juices was proposed. Dispersive liquid–liquid microextraction (DLLME) coupled with high-performance liquid chromatography (HPLC) was used for extraction and quantitative determination of HMF in fruit puree and juices. The effective parameters such as the type and volume of extraction and dispersive solvents, pH and salt amount (NaCl) were studied and optimized with the aid of response surface methodology based on Box–Behnken design to obtain the best condition for HMF extraction. At the optimized conditions, parameter values were 60 µL extracting solvent, 600 µL dispersive solvent, 2 g NaCl and pH 5. Repeatability of the method, described as the relative standard deviation, was 3.1% (n?=?6) and the recovery was 98.4%. The limit of detection and limit of quantitation were 1.47 and 5.28 µg L^?1, respectively. The merit figures of DLLME–HPLC–UV method showed that the proposed method can be noticed as a new, fast and good alternative method for investigation of HMF in various fruit puree and juice samples.     

Rapid and Selective Determination of Trace Benzimidazole Fungicides in Fruit Juices by Magnetic Solid-Phase Extraction Coupled with High-Performance Liquid Chromatography-Fluorescence Detection

In this paper, a new method was established for the determination of benzimidazole fungicides in fruit juices by magnetic solid-phase extraction coupled with high-performance liquid chromatography-fluorescence detection. The extraction adsorbent was synthesized to form a core–shell Fe₃O₄@SiO₂ structure surface functionalized with benzenesulfonic acid. The negative charges of the benzenesulfonic acid groups can promote strong electrostatic interaction with positively charged analytes to exhibit efficient and selective extractive ability. After the extraction, the magnetic adsorbent can be rapidly isolated from the matrix by an external magnet. Main factors influencing the extraction efficiency including amount of adsorbent, solution pH, extraction time, and volume of desorption solution were studied and optimized. Under the optimal conditions, recoveries of the spiked samples ranged from 83 to 96 % with the relative standard deviations lower than 10 %. The limits of detection were 0.55 and 0.14 μg?kg^?1 for carbendazim and thiabendazole, respectively. The proposed method was successfully applied for selective and efficient determination of benzimidazole fungicides in various juice samples.     

Determination of Eugenol in Aquatic Products by Dispersive Solid-Phase Extraction and Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry

A novel procedure, dispersive solid-phase extraction coupled with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), was developed for the determination of eugenol in aquatic products (shrimp, crab, and carp). Aquatic products were extracted with acetonitrile and primarily purified by dispersive solid-phase extraction with graphitized carbon black as absorbent. The pretreated acetonitrile extract was detected by UHPLC-MS/MS. UHPLC was carried out on Dikma Endeavorsil C₁₈ (30 mm × 2.1 mm, 1.8 μm) column eluted by methanol and water (80:20 v/v) at a rate of 0.30 mL min^?1. Tandem mass spectrometry was performed by electrospray ionization in negative ion mode to identify and quantify eugenol during multiple reaction monitoring. Under optimized analytical conditions, the matrix-matched spiked calibration sample demonstrates good linearity between 5.0 and 500.0 μg kg^?1 with a linear regression coefficient of 0.9996. The average recovery of eugenol from aquatic products is 95.3–103.4% at spiked levels between 5 and 50 μg kg^?1 with a relative standard deviation (n = 6) less than 5.4%. The limits of detection and quantification for eugenol were calculated to be 1.47 and 4.91 μg kg^?1, respectively. In comparison with those reported, the proposed method has advantages in low detection limit, high recovery, and short analysis time, meeting the requirements for the determination of trace eugenol residue in aquatic products.     

Reusable 2-(Dimethylamino)ethyl Methacrylate Polymers On-line Solid-Phase Extraction Coupled to Liquid Chromatography Tandem Mass Spectrometry for Rapid Determination of Acidic Pesticides in Foods

A rapid and easy method was developed for the sensitive determination of six acidic pesticides (2,4,5-trichlorophenoxyacetic acid, acifluorfen, methyl-4-chlorophenoxyacetic acid, fluroxypyr, haloxyfop, and bispyribac-sodium) in pear, apple, cucumber, and rice samples. This method was a full automatic platform using a novel polymeric monolith-based on-line solid-phase extraction (SPE) coupled to liquid chromatography-tandem mass spectrometry (LC-MS/MS). A poly(2-(dimethylamino)ethyl methacrylate-co-ethylene dimethacrylate) monolith was fabricated as the sorbent, and the morphology, surface area, and extraction performance of the polymers were characterized. With the addition of 10.0 mL of acetonitrile and 1.0 to 5.0 g of anhydrous NaCl, the food samples were homogenized and centrifuged. The extracted samples were directly loaded and cleaned on the polymers using a 5 mmol L^?1 ammonium acetate solution and subsequently eluted into the analytical column for next separation with an acetonitrile-1.5% formic acid solution as eluting solvent. The detection limit (S/N?=?3) was 0.2 to 2.0 μg kg^?1 for the analytes, and the intra- and inter-day recoveries in pear, apple, cucumber, and rice samples ranged from 80 to 104%, and 83 to 115% with relative standard deviations of less than 13.5%. The developed on-line SPE LC-MS/MS protocol permits an automated and high-throughput determination in only 15 min. Moreover, the intra-batch (n?=?5) and inter-batch precisions (n?=?3) for the preparation of the polymers were lower than 11.6% and the sorbent was sufficiently stable for 500 extraction cycles without a significant loss in the extraction efficiency. The developed method was successfully applied to monitor six acidic pesticides in vegetable, fruit, and cereal samples.     

Dispersive Liquid–Liquid Microextraction Followed by Capillary High-Performance Liquid Chromatography for the Determination of Six Sulfonylurea Herbicides in Fruit Juices

In this study a simple, rapid, and efficient method has been developed for the determination of six sulfonylurea herbicides (SUHs): triasulfuron, metsulfuron-methyl, chlorsulfuron, flazasulfuron, chlorimuron-ethyl, and primisulfuron-methyl in commercial grape and apple juice samples, using dispersive liquid–liquid microextraction coupled with capillary high-performance liquid chromatography with diode array detection. Various parameters that influence the extraction efficiency, such as the type and volume of extraction and disperser solvents, sample pH, and salt addition, were investigated and optimized. Under the optimum conditions, limits of detection and quantification of the method were in the ranges of 2–9 and 8–29 μg L^?1, respectively, lower than the maximum residue limits set by the European Union for the raw fruits, such as grape and apple. The intra- and inter-day relative standard deviations varied from 1.0 to 8.2 and 1.8 to 9.8 %, respectively, with recoveries between 72.0 and 109.5 % for commercial grape (both white and red) and apple juice samples, showing satisfactory accuracy for the determination of SUHs in fruit juices.     

Dispersive Liquid–Liquid Microextraction Combined With Micellar Electrokinetic Chromatography for the Determination of Some Photoinitiators in Fruit Juice

A fast and simple technique composed of dispersive liquid–liquid microextraction (DLLME) and micellar electrokinetic chromatography (MEKC) with diode array detector (DAD) was developed for the determination of multi-photoinitiators in fruit juice. Seven photoinitiators were separated in MEKC using a 25 mM borate buffer of pH 8.0, containing 24 mM sodium dodecyl sulfate (SDS), 10 mM β-cyclodextrin (β-CD), and 12.5 % acetonitrile (v/v). A CD-modified MEKC made this method more suitable for the determination of isopropylthioxanthone (ITX) isomers including 2-IXT and 4-ITX than the recently prescribed methods. A DLLME procedure was used as an offline preconcentration strategy. The satisfactory recoveries obtained by DLLME spiked at two spiked levels ranged from 85.6 to 124.7 % with relative standard deviations (RSDs) below 14 %. The limits of quantification (LOQs) ranged from 2.1 to 6.0 μg kg^?1.     

Determination of Triazoles in Tea Samples Using Dispersive Solid Phase Extraction Combined with Dispersive Liquid–Liquid Microextraction Followed by Liquid Chromatography–Tandem Mass Spectrometry

In this study, dispersive solid phase extraction (DSPE) combined with dispersive liquid–liquid microextraction (DLLME) method was developed for the determination of triazole fungicide residues in tea samples. DSPE with ODS C₁₈, primary secondary amine, and florisil as sorbents was applied to clean up and minimize matrix interference from tea samples; it was followed with the enrichment of target compounds in the DLLME procedure and detection with liquid chromatography–tandem mass spectrometry (LC-MS/MS). The effects of various experimental parameters on the DSPE and DLLME procedures were studied systematically, such as the kinds and volume of sorbents, extraction and dispersive solvents, and extraction time. Under optimum conditions, the method was validated in a tea matrix. The matrix-matched calibration curves of three triazoles had good linearity in the range of 0.0125–50 μg kg^?1, and the linear regression coefficients (r) ranged from 0.9998 to 0.9999. The limits of quantification (S/N?=?10) for penconazole, tebuconazole, and triadimenfon were 4.0, 7.8, and 31.6 ng kg^?1, respectively. The intra-day and inter-day relative standard deviations varied from 3.6 to 18.6 %. Recoveries in three concentration levels were between 91 and 118 %. The obtained results show that the proposed DSPE-DLLME-LC-MS method has the potential to analyze trace fungicides in a complex sample matrix.     

Rapid Analysis of Styrene in Drinking Water and Tea Samples Using Dispersive Liquid-Liquid Microextraction Combined with Liquid Chromatography-Ultraviolet Detection

In this project, a simple, low-cost and rapid procedure based on dispersive liquid–liquid microextraction (DLLME) technique coupled with high performance liquid chromatography-ultraviolet detector (HPLC-UV) has been used for the extraction and determination of styrene in aqueous solutions. Several factors, such as type of extraction and dispersive solvents and their volumes, salt addition, and pH were optimized. Under optimal conditions, the recoveries of styrene for tea and water samples spiked with 10 and 15 ng mL^?1 were in the range of 91.4–97.8 %, whereas the temperature was set at 0, 4, 20, 70 and 91 °C for 15, 30, 60, 1440, and 14,400 min. The linear range was obtained in the interval of 1.86–50 ng mL^?1. The limits of detection (S/N = 3) and quantitation (S/N = 10) were 0.6 and 1.86 ng mL^?1, respectively. The relative standard deviations (RSDs) for three replicated analysis of styrene in aqueous samples ranged from 0.01 to 0.3 %.     

Analysis of Ascorbic Acid and Isoascorbic Acid in Orange and Guava Fruit Juices Distributed in Thailand by LC-IT-MS/MS

This work describes the determination of ascorbic acid (AA) and isoascorbic acid (IAA) in fruit juices by liquid chromatography coupled with ion trap tandem mass spectrometry (LC-IT-MS/MS), with a reversed phase column (C₁₈) and simple isocratic conditions of 0.1 % formic acid. The negative ion mode of electrospray ionization (ESI) and the MS/MS transition of m/z 175 were used for the quantitation of AA- and IAA-generated product ions with m/z 115. The method was validated in terms of linearity, limit of detection (LOD), limit of quantitation (LOQ), precision, and accuracy. Good linearity was achieved with 0.6 and 1.8 μg/mL for the LOD and LOQ, respectively. The intraday and intermediate precisions were approximately 4 and 7 %, respectively. Recovery percentages ranged from 88 to 108 %. All validation parameters were found to be within the acceptable range for both AA and IAA. Hence, the proposed method is suitable for simultaneously determining AA and IAA. Fourteen fruit juice samples were analyzed including fruit juices from supermarkets, local markets, and laboratory preparations. Ten fruit juice samples (100 %) from different brands in the supermarkets were investigated for AA and IAA content. AA could be detected in all the samples, ranging from 5.2?±?2 to 44.4?±?1.3 μg/mL, and the values of vitamin C in 4 guava samples were less than the values specified by the manufacturer. IAA was observed in 4 of 10 samples ranging from 3.4?±?0.9 to 78.3?±?3.9 μg/mL, and the highest value of IAA was approximately two fold higher than the highest value of AA. For freshly prepared fruit juices, AA was detected in both local market- and laboratory-prepared juices. The value ranged from 13.2?±?0.9 to 105.1?±?1.3 μg/mL. In addition, the AA stability after opening the package was evaluated. The results showed that after 4 days of storage in the refrigerator, approximately 30 and 15 % losses of AA were observed for the orange and guava juices, respectively. Fresh fruit juices were thus demonstrated to be good sources of AA, with the highest value observed for guava juice prepared in the laboratory.     

Dispersive Liquid–Liquid Microextraction Followed by Magnetic Solid-Phase Extraction for Determination of Four Parabens in Beverage Samples by Ultra-performance Liquid Chromatography Tandem Mass Spectrometry

In this study, a two-step extraction technique was developed for extraction and preconcentration of parabens from beverage samples using ionic liquid dispersive liquid–liquid microextraction (IL-DLLME) and magnetic solid-phase extraction (MSPE). In this IL-DLLME followed by MSPE method, ionic liquid (IL, 1-octyl-3-methylimidazolium hexafluorophosphate) formed hydrophobic microdroplets in beverage samples as an extractant of parabens; after the IL-DLLME process was completed, graphene modified Fe₃O₄ nanoparticles (Fe₃O₄@G) were placed to adsorb and isolate IL from the sample solution. After the supernatant was carefully moved, acetonitrile was added to elute the IL containing parabens from Fe₃O₄@G. The experimental variables affecting the extraction procedure have been systematically studied. Under optimal conditions, the detection limits were less than 1.53 ng/mL and the linear detection ranges were 2–500 ng/mL (R ² ≥ 0.998) for these analytes. The recoveries for spiked samples were 58.8–89.2% and satisfactory precision (RSD ≤ 4.8%) were obtained.     

Determination of Triazole Fungicides in Liquid Samples Using Ultrasound-Assisted Emulsification Microextraction with Solidification of Floating Organic Droplet Followed by High-Performance Liquid Chromatography

An ultrasound-assisted emulsification microextraction with solidification of organic droplet method followed by high-performance liquid chromatography with diode array detection for six triazole fungicide determination (diniconazole, fluquinconazole, flusilazole, myclobutanil, tebuconazole, and tetraconazole) was developed. After some preliminary experiments, undecanol was chosen as extracting solvent using 50 μL for 10 mL of liquid sample. A central composite design was performed to obtain the best experimental conditions for the following variables NaCl concentration (250 g L^?1), extraction time (18 min), and temperature (30 °C) in ultrasonic bath. After the ultrasound-assisted extraction, two steps considering centrifugation (4,200 rpm, 10 min) and solidification (5 min, 3 °C) were done. Following these conditions, the method showed linearity higher than 0.9930 with the concentration ranged from 20 to 890 μg L^?1. The limits of detection obtained using calibration curves were from 10.9 to 17.2 μg L^?1 and the intra- and inter-day repeatability at two levels showed RSD values between 1.9 and 10.6 %. The enrichment factors for the studied triazoles were between 226 (flusilazole) and 255 (tebuconazole). Recovery studies at two spiked levels in apple and grape juices gave values from 64 to 112 %.     

温控辅助离子液体分散液液微萃取-高效液相色谱检测果汁中杀菌剂残留

建立温控辅助离子液体分散液液微萃取结合高效液相色谱-二极管阵列检测器法检测果汁中7 种杀菌剂农药残留的新方法。对影响萃取效果的因素萃取剂和分散剂类型及体积、溶解温度、萃取时间和离心时间进行优化。在优化后的方法条件下,7 种杀菌剂富集倍数可达64～101;方法检出限在4.3～13.0 μg/L之间;在0.02、0.05 mg/L和0.10 mg/L三个水平下加标,果汁（苹果汁、梨汁、葡萄汁、桃汁和橙汁）的平均加标回收率在70.0%～116.2%范围内,相对标准偏差均小于9.8%,能满足多种果汁中杀菌剂农药多残留检测的要求。     

Development of an Enzyme-Linked Immunosorbent Assay for the Detection of Difenoconazole Residues in Fruits and Vegetables

An indirect, competitive enzyme-linked immunosorbent assay (ic-ELISA) for the detection of difenoconazole was developed. Two haptens were designed and successfully synthesized. Hapten 1 had a particular moiety of difenoconazole, while hapten 2 had its full structure. The polyclonal antibodies against hapten-protein conjugates were prepared by immunizing rabbits. After optimization of the conditions, the detection limit (IC₁₅) and sensitivity (IC₅₀) were 4.58 and 29.10 μg L^?1, respectively. The cross-reactivities of the antibody with 11 triazole fungicides were all less than 0.1%, which showed that the antibody had excellent specificity. The recoveries of difenoconazole from the spiked samples ranged from 89.70 to 102.31% with good accuracy. The matrix effect was easily removed using a simple, rapid, and efficient extraction method on fruits and vegetables. The detection limit was all 229 μg kg^?1 in fruits and vegetables. To validate the ic-ELISA, samples were spiked with difenoconazole at three different concentrations and simultaneously analyzed using high-performance liquid chromatography (HPLC). The results showed a good correlation between the ic-ELISA and HPLC data (R ² = 0.9970). As a result, the developed immunosorbent assay is suitable for the quantitative determination of difenoconazole in fruits and vegetables.     

Determination of Sulfonamide Residues in Chicken Liver Using High-Performance Liquid Chromatography

A novel high-performance liquid chromatography method was adopted for determination of sulfacetamide, sulfathiazole, sulfamethazine, and sulfamethoxypyridazine residues in chicken liver based on the coupling of dispersive solid-phase extraction (DSPE) and dispersive liquid-liquid microextraction (DLLME). In the DSPE-DLLME method, chicken livers were firstly extracted with 50 mM phosphoric acid:MeCN (30:70), then cleaned up with a solid adsorbent. One milliliter of the resulting liquid supernatant extract and 650 μL of 1,2-dichloroethane were then added to a centrifuge tube containing 10 mL water. The analytes were extracted under optimized pretreatment conditions. Signal linearity over the concentration range of 0.006–4.00 mg/kg was observed (regression coefficients, 0.9988–0.9992), and limits of detection were in the range of 0.0004–0.0084 mg/kg. The present method was applied to the determination of the sulfonamides in chicken liver samples. The spiked recovery values ranged from 70.2 to 91.4 % and the relative standard deviations were less than 5.35 % (n?=?6).     

Application and Optimization of Microwave-Assisted Extraction and Dispersive Liquid–Liquid Microextraction Followed by High-Performance Liquid Chromatography for the Determination of Oleuropein and Hydroxytyrosol in Olive Pomace

In the present study, a new method based on microwave-assisted extraction and dispersive liquid–liquid microextraction (MAE–DLLME) followed by high-performance liquid chromatography (HPLC) was proposed for the separation and determination of oleuropein (Ole) and hydroxytyrosol (HyT) from olive pomace samples. The effective factors in the MAE–DLLME process such as microwave power, extraction time, the type and volume of extraction, and dispersive solvents were studied and optimized with the aid of response surface methodology (RSM) based on a central composite design (CCD) to obtain the best condition for Ole and HyT extraction. At the optimized conditions, parameter values were 220 W microwave power, 12 min extraction time, 60 μL extracting solvent, and 500 μL dispersive solvent. The calibration graphs of the proposed method were linear in the range of 10–500,000 μg L^?1, with the coefficient of determination (R²) higher than 0.99 for Ole and HyT. Repeatability of the method, described as the relative standard deviation (RSD), was 4.12–5.63% (n?=?6). The limits of detection were 35 and 20 μg L^?1 for Ole and HyT, respectively. The recoveries of these compounds in the spiked olive pomace sample were from 93 to 98%. The proposed method, MAE–DLLME–HPLC–UV, was an accurate, rapid, and reliable method when compared with previous methods.     

Simple and Fast Determination of Acrylamide and Metabolites in Potato Chips and Grilled Asparagus by Liquid Chromatography Coupled to Mass Spectrometry

The purpose of this study was to evaluate an analytical procedure for the determination of acrylamide in different starchy foods such as potato chips and grilled asparagus. The method is based on high-performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry (HPLC-QqQ-MS/MS). A solid–liquid extraction procedure, using water as extraction solvent, has been developed followed by a cleanup procedure based on solid-phase extraction (SPE) or dispersive solid-phase extraction (d-SPE). Polymeric cartridges (Oasis HLB) and aluminum oxide (Al₂O₃) were used for potato and asparagus matrices, respectively. The optimized procedures were validated, and limits of detection and quantitation were 4 and 12 μg/kg for potato chips and 2 and 5 μg/kg for grilled asparagus, respectively. Recoveries were evaluated, and good values were obtained, ranging from 90 to 117 % for potato chips and from 90 to 116 % for grilled asparagus. The method was applied to real samples, and concentrations ranged from 105 to 860 μg/kg in potato chips, whereas higher values were detected in grilled asparagus (from 292 to 1469 μg/kg). Furthermore, single-stage Orbitrap high-resolution mass spectrometry has been used for the putative identification of acrylamide-N-acetyl-S-(2-carbamoylethyl)-l-cysteine (AAMA) in urine.     

Determination of 21 Free Amino Acids in Fruit Juices by HPLC Using a Modification of the 6-Aminoquinolyl-<Emphasis Type="Italic">N</Emphasis>-hydroxysuccinimidyl Carbamate (AQC) Method

The present paper reports the application of an optimized pre-column derivatization procedure with aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) to the determination of 21 free amino acids in fruit juices. The method permitted the optimal separation of 21 amino acids and ammonium in 30 min. Excellent response linearity was obtained from 2 to 1,000 μM for all amino acids, except tryptophan, for which the linearity was 5–1,000 μM. The fluorescence detection limits ranged from 0.08 pmol (phenylalanine) to 0.69 pmol (cysteine), except for tryptophan (7.89 pmol), for a signal-to-noise ratio of 3. The relative standard deviations of peak areas ranged from 0.1 to 0.4 % for intraday analysis and from 2.1 to 5.0 % for interday analysis. The method was applied to analyze the free amino acids in six fruit juices, and the recoveries of the proposed method were 90.4 to 103.3 %. The total free amino acid content ranged from 56.97 mg L^?1 (apple) to 469.45 mg L^?1 (longan) in six fruit juices. Aspartic acid (Asp), glutamic acid (Glu), asparagine (Asn), serine (Ser), and glutamine (Gln) were present in higher levels in most samples, whereas cysteine (Cys) was below the detection limit in the selected samples. Notable advantages of this method include its speed, ease, low cost, good repeatability, high sensitivity, excellent precision and accuracy, and anti-interference in high-sugar matrices.     

Simultaneous Determination of Nine Plant Growth Regulators in Navel Oranges by Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry

A new and reliable method for the simultaneous determination of nine plant growth regulators in navel oranges was developed by liquid chromatography-triple quadrupole tandem mass (QqQ LC/MS). Extraction was performed by acetone and ethyl acetate (v/v, 1:2) with microwave-assisted extraction technique. Cleanup of extracts was performed with dispersive-solid phase extraction (d-SPE) using active carbon as the sorbent. The identification of each analyte was established by chromatographic retention time, analyte-specific fragmentation patterns, and relative peak area ratios of precursor/production pairs. Under the optimized conditions, the average recoveries (six replicates), except for methyl naphthacetate, were in the range of 61.0–109.4 % and limits of detection ranging from 0.01 to 162.2 μg kg^?1. The results demonstrated that the developed QqQ LC/MS, extraction and purification method is highly effective for analyzing trace amounts of target plant growth regulators (PGRs) in navel orange samples.     

A Powerful Analytical Strategy Based on QuEChERS-Dispersive Solid-Phase Extraction Combined with Ultrahigh Pressure Liquid Chromatography for Evaluating the Effect of Elicitors on Biosynthesis of <Emphasis Type="Italic">trans</Emphasis>-Resveratrol in Grapes

A powerful methodological approach based on modified quick, easy, cheap effective, rugged, and safe (QuEChERS) extraction technique, followed by cleanup dispersive solid-phase extraction (dSPE) and combined with ultrahigh pressure liquid chromatography (UHPLC), is presented in this paper, for the rapid determination of the health-promoting phytoalexin, trans-resveratrol, in grapes. This is the first time, to our knowledge, that the combination QuEChERS-dSPE/UHPLC-PDA has been used for trans-resveratrol quantification in grapes. The method has been validated according to European Union Decision 2002/657/EC, in terms of selectivity, linearity, sensitivity, instrument LOD and method LOQ, accuracy, precision, extraction efficiency, and interference assessment. Validation experiments revealed sufficient linearity (R ²?=?0.9931) within the established concentration range confirmed by Mandel’s fitting test. The sensitivity was good with method detection limit (LOD) of 0.003 μg/mL and quantification limit (LOQ) of 0.010 μg/mL. Optimum QuEChERS-dSPE/UHPLC-PDA conditions led to recoveries of the target analyte in grape samples ranging between 75.1 and 99.7 % and precisions in the 0.9–4 % range (RSD, n?=?18). The method also afforded satisfactory results in terms of extraction efficiency and interference assessment and provides a valuable and promising tool for determination of trans-resveratrol in grapes with a high resolution within 8 min and a total analysis time of 11 min. The validated methodology was applied to evaluate the effect of the use of elicitors, namely benzothiadiazole and methyl jasmonate, in trans-resveratrol biosynthesis on Vitis vinifera Monastrell grapes. The results obtained revealed an increase of trans-resveratrol level of 2-fold for grapes treated with benzothiadiazole and 3.5-fold for grapes treated with methyl jasmonate.