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.     

Comparison of HPLC Separation of Phenylalanine Enantiomers on Different Types of Chiral Stationary Phases

HPLC separation of phenylalanine by using chiral stationary phases (CSPs) with chiral selectors β-cyclodextrin, isopropylcarbamate cyclofructan 6, teicoplanin, and ristocetin were studied. The effects of mobile phase composition and column temperature from 0 to 30 °C on the retention and resolution of enantiomers were investigated. β-cyclodextrin and isopropylcarbamate cyclofructan 6 CSPs showed chiral recognition in normal phase separation mode. The sufficient enantioseparations (resolution values 1.59 and 2.75) were reached using teicoplanin and ristocetin-based stationary phases at 23 °C in reversed-phase mode with mobile phases consist of acetonitrile and water at ratios 75/25 and 60/40 (v/v), respectively. Chiral HPLC system coupled with circular dichroism and polarimetry detector could be used to determine enantiomeric elution order. The optimized and validated HPLC-UV method with teicoplanin-based chiral stationary phase was applied for determination of phenylalanine in real samples. Both of the enantiomeric forms were detected in samples of dietary supplements and L-phenylalanine in samples of energy drinks. Obtained recoveries were higher than 82% with an RSD less than 10%. The HPLC method showed good linearity (correlation coefficients >?0.998) in concentration range 0.1–500 μg mL^?1. The limit of detection was 0.1 μg mL^?1 for both enantiomers.     

Rapid Screening and Determination of the Residues of Hormones and Sedatives in Milk Powder Using the UHPLC-MS/MS and SPE

A method based on the ultra-high-performance liquid chromatography tandem mass spectrometry for determination of the residues of sex hormones, glucocorticoids, and sedatives in milk powder was developed. The sample was extracted with the acetic acid-acetonitrile (1:99, v/v) twice, purified by the PRiME hydrophilic-lipophilic balance (HLB) cartridges and analyzed by the ultra-high-performance liquid chromatography-tandem mass spectrometry. The analytes were separated by the Waters Acquity UPLC? BEH C18 column (50 mm?×?2.1 mm, 1.7 μm) and determined using the electrospray ionization in the positive mode with the multiple reaction monitoring (MRM). The developed method was validated with the specificity, linearity and range, matrix effects, recovery, and precision. The results showed that the analytes were linear with the correlation of determinations (R²) higher than 0.991 in the corresponding ranges. The limits of detection (LODs) and limits of quantification (LOQs) were in the range of 0.1–1.1 μg kg^?1 and 0.3–3.8 μg kg^?1, respectively. The average recoveries of the analytes ranged from 78.5 to 107.0% with the relative standard deviations lower than 15%. The practical applicability was tested by analyzing real samples and the progesterone was observed in two samples.     

Analysis of Ochratoxin A in Wine by High-Resolution UHPLC-MS

A method for determination of ochratoxin A (OTA) in wines using a new-solid phase extraction clean-up procedure followed with ultra performance liquid chromatography (UHPLC)-Orbitrap MS based on two scan events (full-scan Fourier transform mass spectrometer [FTMS] and higher energy-induced collision dissociation[HCD] data-dependent MS/MS) in positive ionization mode has been developed. The limit of detection (LOD) was estimated at 0.46 μg l^?1 for white wine, 0.53 and 0.54 μg l^?1 for rosé and red wines, respectively. The limit of quantification (LOQ) was estimated at 1.57 μg l^?1 in white wine, 1.77 and 1.81 μg l^?1 in rosé and red wines. Recovery experiments were carried out with spiked samples at three concentration levels (2, 5 and 10 μg l^?1). The OTA recoveries in spiked white wine samples varied from 69.6 % to 99.8 %, while the recoveries for rosé and red wine samples were in the range of 63.0–110.2 % and 63.6–103.2 %, respectively. Finally, based on the results, it is concluded that the combination of C18 cartridge with conventional particle packed columns and UHPLC LTQ-Orbitrap XL is an appropriate procedure for OTA analysis in wines.     

Modification of Multiresidue QuEChERS Protocol to Minimize Matrix Effect and Improve Recoveries for Determination of Pesticide Residues in Dried Herbs Followed by GC-MS/MS

An accurate, rapid, and reliable multiresidue QuEChERS method based on gas chromatography coupled with tandem mass spectrometry was developed for the determination of 235 pesticides in challenging, dry, complex herb matrices (Centaurea cyanus L., Matricaria chamomilla L., Thymus vulgaris L.). Sample mass and the type of cleanup sorbent used to estimate the procedure’s effectiveness were optimized. Purification steps with ChloroFiltr, ENVI-Carb, GCB, octadecyl, PSA, and Z-Sep as cleanup sorbents and a step without purification were compared. To minimize the matrix effect and obtain acceptable recoveries for pesticides, 2 g of herb sample and 10 mL acetonitrile, followed by d-SPE cleanup step with a combination of 150 mg PSA/45 mg ENVI-Carb/900 mg MgSO₄, and additionally 50 μL of 5% formic acid and some droplets of dodecane, were needed. Matrix effects for the vast majority of pesticides were reduced (>?20%), showing suppression or enhancement. Most recoveries were in the range of 70–120% (RSD < 18%), reaching the quantification limit of 0.001 to 0.002 mg kg^?1. There was excellent linearity within the range from 0.001 to 2.00 μg mL^?1, and a correlation coefficient higher than 0.999 was obtained. Expanded measurement uncertainty was estimated to be between 4 and 43%. Finally, the developed method was successfully employed to identify and quantify pesticide residues in the analysis of 46 real herb samples.     

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.     

Speciation Determination of Selenium in Seafood by High-Performance Ion-Exchange Chromatography-Hydride Generation-Atomic Fluorescence Spectrometry

A high-performance ion-exchange chromatography coupled with hydride generation-atomic fluorescence spectrometry (HPIEC-HG-AFS) method was developed for simultaneous speciation of selenium in seafood. Three selenium species including of selenocystine (Se-Cys), selenome-thionine (Se-Met), and selenite Se(IV) were separated on an anion-exchange column (PRP-X100) with eluent of 30 mM NH₄H₂PO₄ and methanol (39:1, v/v) in 10 min at the flow rate of 1.0 mL min^?1. Variables affecting the HG-AFS detection of selenium species were optimized. The optimum conditions found were the following: reducing agent, 2.0 % of KBH₄, and 5.0 % of HCl; lamp current, 90 mA; photomultiplier tube voltage, 280 V; flow rate of carrier gas, 300 mL min^?1; and shielding gas, 800 mL min^?1. Under the optimized conditions, the good linearity of calibration curves (R ²?>?0.999) between signal of fluorescence and concentration of selenium species was obtained in the range of detection limits (DLs), 80 μg L^?1, and the DLs of Se-Cys, Se-Met, Se(IV) were 1.66, 0.990, 1.10 μg L^?1, respectively. The repeatability of the method, expressed as relative standard deviation, was less than 5.0 % (n?=?10), and the average recoveries for spiked test were from 87.3 to 103 % for three analytes in real seafood samples. The developed HPIEC-HG-AFS method was successfully applied for the speciation of selenium in seafood samples.     

Simultaneous Determination of Cyclamate,Acesulfame, and Aspartame in Beverages by Titania-Based RP-HPLC

This paper aims at establishing a rapid method for simultaneous separation and determination of the sweeteners including cyclamate, acesulfame, and aspartame in beverages by titania-based reversed-phase high-performance liquid chromatography. The chromatographic conditions were as follows: a titania Sachtopore-RP C18 column (250?×?4.6 mm; 5 μm) as a separation column, a mixture of water and methanol at a volume ratio of 95:5 containing 1.0 % phosphate acid used as mobile phase, flow rate of 1.0 mL min^?1, and the detection wavelength was 205 nm. The linear ranges of cyclamate and aspartame were 0.02–8.0 mg mL^?1 with limits of detection (LODs) of 16.35 and 19.56 μg mL^?1, respectively, and their limits of quantitation (LOQs) were 55.50 and 68.50 μg mL^?1, respectively. The recoveries of cyclamate were between 93.52 and 103.54 %. The recoveries of aspartame were between 93.31 and 102.63 %. The linear range of acesulfame was 0.125–50 μg mL^?1 with LOD of 0.08 μg mL^?1 and LOQ of 0.25 μg mL^?1. The recoveries of acesulfame were between 94.34 and 103.21 %. Relative standard deviation (n?=?8) for all determinations was less than 0.72 %.     

Application of MALDI-TOFMS Combined with Partial Least Square Regression for the Determination of Mercury and Copper in Canned Tuna,Using Dithizone as the Complexing Agent and Ag(I) as Internal Standard

In this work, a procedure for the determination of mercury and copper in canned tuna samples is presented, based on the extraction of their respective dithizone complexes and quantification by conventional MALDI-TOFMS with the aid of partial least square regression (PLS2). Methanolic dithizone solution (1 ml, 0.01% m/v) containing Ag(I) as internal standard was added to the calibration solutions and to the acid-digested samples (5 ml, pH 3); copper, mercury, and silver complexes were extracted to cyclohexane (1.5 ml), and after evaporation, the residues were re-constituted in acetone (100 μl). The samples were prepared by dried droplet crystallization with α-cyano-4-hydroxycinnamic acid. The experimental and MALDI-TOFMS instrument operating conditions were set up under criteria of as high as possible detectability and repeatability. When univariate calibration was carried out using the most intense ion of Cu or Hg complex normalized by internal standard, determination seemed feasible yet precision of the results was poor. Taking baseline-corrected spectra in m/z range 560–725, PLS2 model was constructed for the prediction of two elements with the method quantification limits 63 μg kg^?1 for Cu and 75 μg kg^?1 for Hg, respectively. For different brands of canned tuna, the results obtained by MALDI-TOFMS combined with PLS2 and by ICP-MS were in good agreement. The proposed procedure is an attractive alternative for the determination of trace metals in foods because of the procedural simplicity, micro-scale dimension, high speed of data acquisition/processing, and the cost of instrument operation lower as compared to any atomic spectrometry technique.     

Simultaneous Determination of Eight Tranquilizers in Pork by Ultra-Performance Liquid Chromatography Coupled with Electrospray Tandem Mass Spectrometry

An ultra-performance liquid chromatography/electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) method was developed and validated for quantification of eight tranquillizers (chlorpromazine, imipramine hydrochloride, diazepam, nitrazepam, nordazepam, oxazepam, flurazepam, and haloperidol) in pork. Sample pretreatment consisted of extraction by acetonitrile, defatted by n-hexane, and further solid phase extraction by hydrophilic-lipophilic balance (HLB) extraction cartridges. The triple quadrupole mass spectrometer was operated in positive ion mode, and multiple reaction monitoring was used for drug quantification. The method was validated over the concentration ranges of 1.0 ～ 250 μg kg^?1 for the eight tranquillizers. The calibrations were performed in sample matrices, and the interference effect of sample matrices on the ionization was effectively eliminated. Good linear relationship (R ² > 0.99) was observed within the concentration range of 1.0–250 μg kg^?1. The average recoveries of the eight tranquillizers spiked at three levels ranged from 63.7 to103.2 % with the relative standard deviation below 11.8 %. The limits of detection were between 0.06 and 0.30 μg kg^?1, and the limits of quantification were between 0.2 and1.0 μg kg^?1 for all analytes in pork. This validated method has been successfully used to quantify the concentration of the eight tranquillizers in pork samples.     

Automated Sequential Injection Method for Determination of Caffeine in Coffee Drinks

An automated sequential injection analysis spectrophotometric assay for the determination of purine alkaloids in coffee drinks was developed. The sample was treated with a carrez reagent for matrix suppression followed by filtration; subsequently, alkaloids were separated from organic acids using a short C18 monolithic column (10 × 4.6 mm). The flow rate of the separation step was 10 μL s^?1 with 10% v/v of methanol as the mobile phase. The sum of alkaloids evaluated as caffeine was detected at 274 nm. The influence of the main parameters affecting the quantification of purine alkaloids was optimized. One sample analysis lasted 15 min when aspirated in triplicate. The linear range was 1–15 mg L^?1, and the determination coefficient (r ²) was 0.9969. The limit of detection and limit of quantitation were 0.128 and 0.425 mg L^?1, respectively. The repeatability evaluated as the relative standard deviation (RSD) was 3.58% (n = 12, 10 mg L^?1). Under optimal conditions, the method was successfully applied to determine purine alkaloids in different real samples including soluble coffee, coffee from an espresso machine, and brewed coffee drinks.     

Dispersive Liquid-Liquid Microextraction for the Determination of Emerging <Emphasis Type="Italic">Fusarium</Emphasis> Mycotoxins in Water

A new method was optimized for the determination of emerging Fusarium mycotoxins enniatins (ENs) and beauvericin (BEA) in different types of water. Mycotoxin analysis was performed by dispersive liquid-liquid microextraction (DLLME) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Mycotoxins were efficiently extracted from water into carbon tetrachloride by DLLME technique using acetonitrile as disperser solvent. Detection limits were in the range of 0.06–0.17 μg L^?1. Quantification was performed using matrix-matched calibration curves over a linear range from limit of quantification (LOQ) to 200 μg L^?1. Acceptable recoveries were obtained between 78.5 and 100.1 % with relative standard deviations of <14 %. The proposed method may be advised as an easy, sensitive, and accurate method for determining emerging Fusarium mycotoxins in water. The method was successfully applied to the analysis of different kinds of water. No detectable levels were achieved in surface, ground, tap, and bottled water. Concentration levels up to 50 μg L^?1 were detected in cooking water related to the pasta cooking process.     

Simultaneous Determination of Multiclass Pesticides and Antibiotics in Honey Samples Based on Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

A simple, fast, and efficient method was developed for simultaneous determination of 79 pesticides and 13 antibiotics compounds of different chemical classes of pesticides and antibiotics in honey samples by ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS). The sample preparation procedure includes homogenization with McIlvaine buffer 0.1 mol L^?1 (pH 4), followed by extraction with acetonitrile and cleanup with florisil, using dispersive solid phase extraction (d-SPE). The proposed method was validated with good results, such as linearity (r ²?>?0.9901), normality, and independence of the evaluated data, as well as recoveries between 70 and 120 % with relative standard deviation (RSD) <20 % for most of the compounds spiked from 0.1 to 200 μg kg^?1. The experimental method limits of detection and quantification were from 0.03 to 1.51 μg kg^?1 and from 0.1 to 5 μg kg^?1, respectively, for the pesticides. For the antibiotics, the decision limits (0.1 to 2 μg g^?1) and the detection capacity (0.12 to 2.81 μg g^?1) were below the maximum residue limits (MRLs) established for honey by the Brazilian and European legislation. The method was successfully applied to real samples from different botanical and geographic origins. From them, 44 % presented residues from 0.12 to 10 μg kg^?1 of one or more analytes. The proposed method combines the advantages of a quick sample preparation step with the selectivity and sensitivity of the UHPLC-MS/MS and proved to be suitable for routine analyses.     

Direct Determination of Trace Elements in Meat Samples via High-Resolution Graphite Furnace Atomic Absorption Spectrometry

This work presents a direct and straightforward approach for the determination of trace elements in fish muscle, oyster, and bovine liver via direct solid sample analysis (SS) using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The preliminary studies revealed the presence of spectral interferences at the analytical line of Ni at 231.096 nm, which could be corrected subtracting the spectrum of SiO and PO from the sample spectra using least-squares background correction. Moreover, all meat samples were proven homogeneous according to the homogeneity factor (H _e) (all values were <10 mg^½). Pyrolysis (Tp) and atomization (Ta) temperatures were studied and optimized as 800 °C (Tp) and 2500 °C (Ta) for Mn, 700 °C (Tp) and 2600 °C (Ta) for Ni, and 600 °C (Tp) and 2500 °C (Ta) for Rb. Calibration against aqueous standards was proven feasible for Mn determination, whereas Ni and Rb required calibration against solid standards for their quantification. The detection limits achieved were demonstrated adequate for application to food analysis (0.005 μg g^?1 for Mn, 0.002 μg g^?1 for Ni, and 0.1 μg g^?1 for Rb). The developed method was successfully applied for the elemental analysis of fish muscle, oyster, and bovine liver and three certified reference materials, demonstrating good agreement with the certified values and with the reference technique at a 95 % statistical confidence level.     

Synergistic Processing of Skim Milk with High Pressure Nitrous Oxide,Heat, Nisin,and Lysozyme to Inactivate Vegetative and Spore-Forming Bacteria

Individual and combined effects of high pressure nitrous oxide (HPN₂O), heat, and antimicrobials on the inactivation of Escherichia coli, Listeria innocua, and Bacillus atrophaeus endospores in milk were all evaluated after 20-min treatments. Stand-alone milk treatments with HPN₂O (15.2 MPa), heat (45 and 65 °C), or nisin (50 and 150 IU mL^?1) resulted in log₁₀ reductions ranging only from 0.1 to 2.1 for E. coli and L. innocua. Combining HPN₂O (15.2 MPa) with heat (65 °C) inactivated 6.0 and 5.1 log₁₀ in the vegetative bacteria, respectively. Similarly, reductions of 5.9 and ≥ 6.0 log₁₀ of respective E. coli and L. innocua cells in milk were achieved through a combination of HPN₂O (15.2 MPa), heat (65 °C), and nisin (150 IU mL^?1). A 2.5 log₁₀ cycle inactivation of spores was obtained by HPN₂O, nisin (at both 50 and 150 IU mL^?1), and lysozyme (50 μg mL^?1) at 85 °C. Combining these processing techniques resulted in significantly greater microbial inactivation (p < 0.05) than the sum of individual reductions from each treatment alone, indicating synergistic effects. HPN₂O irrespective of processing temperatures did not cause any occurrence of sub-lethally injured cells or disruption in colloidal stability of milk at 65 and 85 °C (p ≥ 0.05). Color and pH changes in milk following the most demanding treatment conditions were minimal.     

Application of High-Performance Liquid Chromatography with Diode Array Detector for Simultaneous Determination of 11 Synthetic Dyes in Selected Beverages and Foodstuffs

A simple, inexpensive and robust high-performance liquid chromatography diode array detector (HPC-DAD) procedures are proposed to analyse food dyes in beverages, hard candy and fish roe samples. An ether-linked phenyl stationary phase provides sufficient selectivity and chromatographic performance for separation of 11 sulfonated azo dyes. Beverage samples were only diluted (and degassed when needed) before analysis. Solid-phase extraction (SPE) or matrix solid-phase dispersion (MSPD) procedures are proposed for efficient extraction of the analytes from candies or fish roe samples, respectively. Limits of detection (LODs) were from 0.005 to 0.013 μg mL^?1 and limits of quantification (LOQs) between 0.014 and 0.038 μg mL^?1. HPLC-DAD method was validated in terms of intra- and inter-day accuracy and precision at three concentration levels 2, 1, and 0.1 μg mL^?1. Validation was also performed for SPE and MSPD extraction procedures including intra- and inter-day accuracy (Recovery %) and precision (RSD%), as well as intra-laboratory reproducibility. Application to analysis of beverages and food samples available to consumers proved that described methods are suitable for the routine analysis of dyes in food products.     

Development of CO<Subscript>2</Subscript>-Mediated Switchable Hydrophilicity Solvent-Based Microextraction Combined with HPLC-UV for the Determination of Bisphenols in Foods and Drinks

In traditional dispersive liquid-liquid microextraction procedures, both extraction and dispersive solvents are required, and thus, it increases the consumption of organic solvent. Herein, we reported a CO₂-mediated switchable hydrophilicity solvent-based microextraction (SHS-BME) for the determination of bisphenol compounds (BPCs) in complex milk and drink samples. N,N-Dimethylcyclohexylamine was used as a switchable hydrophilicity solvent; it can switch reversibly between one form that is miscible with water and another that forms a biphasic mixture with water, and thus allow extraction of the analytes in a homogeneous phase without dispersive solvent. Several important parameters were screened and optimized by single factor experiments and central composite design as follows: 782 μL of switchable solvent, 375 μL of NaOH solvent, and 1.1:1 switchable solvent/water (v/v). Under the optimized SHS-BME conditions, the limit of detections (LODs) for BPCs in milk, orange juice, and energy drink samples were in the range of 0.27–0.40 μg L^?1 for BPE, 0.17–0.30 μg L^?1 for BPA, and 0.50–0.67 μg L^?1 for BPB, respectively, and the extraction recoveries for BPCs were in the range of 79.5–103.4% in milk, of 84.5–97.5% in orange juice, and of 91.9–101.2% in energy drinks. The precision of the method, based on relative standard deviations (RSDs), ranged from 1.7 to 4.8% and from 2.1 to 5.7% for intra-day and inter-day comparisons, respectively. In total, this SHS-BME method possesses many advantages, such as high extraction recovery and high detection sensitivity (low LODs and RSDs), no requirement of dispersive solvent, simple operational procedure, reducing the pretreatment time and workload, and so on. Therefore, it has a great potential application value for detection of trace BPCs in routine food tests.     

Antioxidant Activity and Determination of Phenolic Compounds from <Emphasis Type="Italic">Eugenia involucrata</Emphasis> DC. Fruits by UHPLC-MS/MS

Fruits have been the focus of several studies aimed at finding new antioxidant sources for protection against the damage caused by reactive species. In this study, the antioxidant activity and the presence of phenolic compounds in all parts (peel, pulp, and seeds) of Eugenia involucrata DC. fruits were evaluated. DPPH^·, ABTS^·+, and ORAC methods were used to determine the antioxidant activity, and an UHPLC-MS/MS method was developed for determining the phenolic compounds (gallic, chlorogenic, ferulic, p-coumaric and ellagic acids, quercetin, and myricetin). In the determination of both antioxidant activity and phenolic composition, the efficiency of solvents with different polarities—methanol/H₂O (80:20, v/v), ethanol/H₂O (80:20, v/v), methanol/acidified water with phosphoric acid pH 3.00 (80:20, v/v), and ethyl acetate—for the extraction of the phenolic compounds, was also evaluated. All parts of E. involucrata fruits showed antioxidant activity, in the range of 36.68 ± 1.44 to 873.87 ± 18.24 μmol TE g^?1, being the highest values found in the seeds and peel when more polar extraction solvents were used. Six, five, and three phenolic compounds were identified and quantified in the pulp, peel, and seeds, respectively, with the highest abundance as p-coumaric acid (14 ± 2 mg kg^?1) in the pulp, quercetin (47 ± 5 mg kg^?1) in the peel, and gallic acid (74 ± 4 mg kg^?1) in the seeds, also when more polar solvents were used. Although antioxidant activity methods suggested that the peel and seeds have more antioxidant potential, a wider variety of compounds were determined in the pulp.     

Determination of Ultraviolet Absorbers and Light Stabilizers in Food Packaging Bags by Magnetic Solid Phase Extraction Followed by High-Performance Liquid Chromatography

A sensitive and effective extraction technique based on magnetic solid phase extraction (MSPE) was developed for separating and detecting trace amounts of ultraviolet (UV) absorbers and light stabilizers in plastic packaging prior to high-performance liquid chromatography (HPLC). The magnetic Fe₃O₄/Au composites were synthesized by chemical co-precipitation, and a HAuCl₄ solution was added to the Fe₃O₄ NPs, followed by the addition of hydroxylamine hydrochloride as a reducing agent for Au shell formation. The main factors affecting the adsorbability of UV absorbers, such as the effects of pH of the sample solution, the amount of adsorbent, extraction time, and desorption conditions on the magnetic nanoparticles (MNPs), were investigated and optimized. The proposed method showed good linearity in the range from 0.75 to 100 μg/mL with good presenting regression coefficients (R ²) ≥0.9999. Low limits of detection (LODs) were achieved at 0.05, 0.14, and 0.04 μg mL^?1 for 2-hydroxy-4-n-octoxy-benzophenone (UV-531), 2-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)-4-methylphenol (UV-326), and 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV-328), respectively. The mean recoveries were in the range from 88.06 to 100.29% at 2.5, 5, and 10 μg mL^?1 spiked levels, and the relative standard deviations (RSDs) were in the range from 0.98 to 3.56%.     

Determination of Pesticide Residues in Golden Berry (<Emphasis Type="Italic">Physalis peruviana</Emphasis> L<Emphasis Type="Italic">.</Emphasis>) by Modified QuEChERS Method and Ultra-High Performance Liquid Chromatography-Tandem Quadrupole Mass Spectrometry

A fast and effective multiresidue method for the determination of 42 pesticides in golden berry was developed and validated. A modified QuEChERS method was established for sample preparation followed by ultra-high performance liquid chromatographic-tandem mass spectrometry (UHPLC-MS/MS) determination with electrospray ionization in a triple quadrupole system. Validation results were satisfactory, since the method presented recoveries between 70 and 114 % with relative standard deviations (RSD) <20 % for blank samples spiked from 5 to 25 μg kg^?1. The method limit of detection and limit of quantification were 1.5 and 5 μg kg^?1 _, respectively. Matrix effect ranged from ?32 to 218 % and was compensated using matrix-matched calibration. Method linearity was established from 2.5 to 100 μg kg^?1 with r ² ≥ 0.99. The proposed method combines the advantages of a simple and fast sample preparation step by a modified QuEChERS method with the high selectivity and sensitivity of the UHPLC-MS/MS system using selected reaction monitoring. The method was successfully applied to commercial samples, proving to be an efficient alternative for routine analysis. From the 16 analyzed samples, 13 presented residues of one or more pesticides (carbendazim, chlorpyrifos ethyl, dimethoate, propamocarb, and tebuconazole) in the concentration range of 2.0 to 55.6 μg kg^?1.