A TLC-HPLC Method for Determination of Thiamphenicol in Pig,Chicken, and Fish Feedstuffs

An effective thin-layer chromatography (TLC) purification procedure coupled to high-performance liquid chromatography (HPLC) method was developed for the determination of thiamphenicol (TAP) in pig, chicken, and fish feedstuffs. The feedstuff samples were extracted with ethyl acetate, defatted with n-hexane saturated with acetonitrile, and further purified by TLC. The chromatographic separation was performed on a Waters Symmetry C₁₈ column using an isocratic procedure with acetonitrile-water (21.7:78.3, v/v) at 0.6 mL/min. The ultraviolet (UV) detector was set at a wavelength of 225 nm. The TAP concentrations in feedstuff samples were quantified using a standard curve. Good linear correlations (y?=?162,630x???2381.7, r?>?0.9998) were achieved within the concentration range of 0.05–10.00 μg/mL. The recoveries of TAP spiked at levels of 1, 10, and 100 μg/g ranged from 82.0 to 114.9% with the intra-day and inter-day relative standard deviation (RSD) less than 9.0%. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.02 and 0.03 mg/kg for pig feedstuffs, 0.02 and 0.04 mg/kg for chicken feedstuffs, and 0.02 and 0.03 mg/kg for fish feedstuffs, respectively. This reliable, simple, and cost-effective method could be applied to the routine monitoring of TAP in animal feedstuffs.     

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.     

Effect of Tannin Extracts on Biofilms and Attachment of <Emphasis Type="Italic">Escherichia coli</Emphasis> on Lettuce Leaves

Lettuce is often involved in foodborne outbreaks caused by pathogenic Escherichia coli. Current control strategies have often proved ineffective to ensure safe food production. For that reason, the present study compared the efficacy of tannin extracts and chlorine treatments on the reduction of E. coli ATCC 25922 adhered to lettuce leaves. E. coli was inoculated artificially on leaf surfaces of fresh crisp lettuce. Effectiveness of water, chlorine (200 mg/L), and three commercial available tannin extracts from Acacia mearnsii De Wild. (tannin AQ (2 %, w/v), tannin SG (1 %, v/v) and tannin SM (1 %, v/v)) treatments was evaluated using the viable plate count method and scanning electron microscopy (SEM). SEM results revealed that bacterial cells are attached as individual cells and in clusters to the leaf surface after 2 h of incubation. Biofilm formation was observed after 24 h of incubation. The tannin SM treatment was able to reduce counts in approximately 2 log CFU/cm² on leaf segments. However, treatment was less effective in the reduction of E. coli counts after 24 h of incubation when compared to 2 h incubation of the same extract. The results suggest that the tannin SM extract diminishes E. coli counts adhered to and under biofilm formation on lettuce leaves and its effect is similar to the use of chlorine solutions.     

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.     

High-Performance Liquid Chromatography with Fluorescence Detection for Simultaneous Analysis of Retinoids (Retinyl Palmitate,Retinyl Acetate,and Free Retinol) and α-, β-, γ-, and δ-Tocopherols in Foods

A method based on high-performance liquid chromatography with fluorescence detection for the simultaneous analysis of retinoids (vitamin A) and tocopherols (vitamin E) was developed. This method consists of an isocratic solution using hexane/ethyl acetate (85:15, v/v) as the mobile phase and fluorescence detection using a time program that sets the excitation (Ex) and emission (Em) wavelengths at adequate elution times for retinoids (Ex 342 nm, Em 476 nm) and tocopherols (Ex 298 nm, Em 325 nm), respectively. The separation of three retinoids (retinyl palmitate, retinyl acetate, and free retinol) and four tocopherol homologs was achieved with sufficient reproducibility and quantitative ability. Additionally, the necessity of saponification was considered. As a result, saponification was not used in this method because of the complexity of the procedure and the loss of free retinol. The retinoid and tocopherol contents of various foods were evaluated using the developed method. Our method could evaluate the retinoid and tocopherol contents of fish (eel, Anguilla japonica, and amberjack, Seriola dumerili) muscle and liver, roasted soybean (Glycine max) flour, and Japanese torreya seed (Torreya nucifera). Additionally, our method could be applied to the determination of retinoids and tocopherols not only in foods but also in supplements and cosmetics.     

Screening of Phenolic Antioxidants in Edible Oils by HPTLC-DPPH Assay and MS Confirmation

The cytotoxicity of phenolic antioxidants had attracted marked attention, posing serious challenges to food safety. This paper presented a screening method for two major phenolic antioxidants (butylated hydroxytoluene and tert-butylhydroquinone) added in edible oils. To specifically visualize the targeted compounds after developing with toluene/ethyl acetate/methanol 8:1:1 (v/v/v) to 70 mm solvent front, the plate was subjected to a standardized 1,1-diphenyl-2-picrylhydrazyl assay. In addition to synoptical eye inspection, accurate quantification was realized by modified densitometric measurements: fluorescence mode, excitation wavelength 530 nm (D₂ and W lamp) without optical filter, which offered satisfactory sensitivity (8.5–17.5 mg/kg) and acceptable linearity (R²?>?0.999 within 50–200 ng/zone). Moreover, the established method was validated with edible oil samples, against EU Directive 2006/52/EC. Apart from that, the unambiguous confirmation of positive results was conveniently achieved by TLC-MS interface-mediated mass spectrometry. Featuring the merits of screening conception, the proposed method not only reached the goal of accurate quantification and conclusive identification of multi-phenolic antioxidants, but also excellently balanced the simplicity, detectability, and throughput of the screening workup. Therefore, it might be an attractive alternative to conventional methods.     

Design of Sonotrode Ultrasound-Assisted Extraction of Phenolic Compounds from <Emphasis Type="Italic">Psidium guajava</Emphasis> L. Leaves

Psidium guajava L. has gained a special attention as health plant due to the presence of phenolic compounds. Box-Behnken design (BBD) has been applied for the extraction of target compounds from guava leaves via sonotrode ultrasound-assisted extraction (UAE). Different extraction times (5, 30, and 55 min), ratios of ethanol/water (50, 75, and 100% (v/v)), and ultrasound (US) power (80, 240, and 400 W) were tested to find their effect on the sum of phenolic compound (SPC), flavonols and flavan-3-ols via HPLC-ESI-QqQ-MS, and antioxidant activity (DPPH and TEAC assays). The best process conditions were as follows: 40 min, 60% ethanol/water (v/v), and 200 W. Established method has been used to extract phenolic compounds in two guava leaves varieties (pyrifera and pomifera). Pyrifera var. showed greater values of the SPC via HPLC-ESI-QqQ-MS (49.7 mg/g leaf dry weight (d.w.)), flavonols (12.51 mg/g d.w.), flavan-3-ols (7.20 mg/g d.w.), individual phenolic compounds, and antioxidant activity (8970 ± 5 and 465 ± 6 μmol Trolox/g leaf d.w, respectively) than pomifera var. Conventional extraction showed lower amounts of phenolic compounds (7.81 ± 0.03 and 4.64 ± 0.01 mg/g leaf d.w. for flavonols and flavan-3ols, respectively) in comparison to the ultrasound-assisted ones.     

Validated RP-HPLC Method for Simultaneous Determination of Tocopherols and Tocotrienols in Whole Grain Barley Using Matrix Solid-Phase Dispersion

The vitamers of vitamin E such as α-, β-, γ-, and δ-tocotrienol and α-, β-, γ-, and δ- tocopherol are important phytochemical compounds with antioxidant activity and with potential benefits for human health. A high-performance liquid chromatography with fluorescence detection (HPLC-FLD) method was validated for their determination in whole grain barley samples. Tocol extraction was performed by an optimized matrix solid-phase dispersion (MSPD) protocol with neutral alumina (0.5 g) as the dispersion agent and methanol (5 mL) as the elution solvent. The analytical column was an Eclipse XDB C18 column (150?×?4.6 mm, 5 μm) and it was operated at room temperature. Mobile phase was consisted of methanol/acetonitrile/i-propanol (55:40:5?v/v?%) and the elution was isocratic at a flow rate of 0.8 mL/min. Total analysis time was 12 min, and the detection of the tocols was performed with a fluorimetric detector where the excitation and emission wavelengths were set at 295 and 335 nm, respectively. Method validation was performed by means of intra-day (n?=?5) and inter-day accuracy and precision (n?=?8), sensitivity, and linearity. The linear regression coefficient (R ²) was higher than 0.99. The recoveries of the tocols from barley samples with the proposed extraction method were in an acceptable level (74–91 %) where the relative standard deviation ranged from 4.2 to 15.0 %. Limits of detection (LODs) and limits of quantification (LOQs) varied from 0.03 to 0.11 mg kg^?1 and 0.11 to 0.34 mg kg^?1, respectively.     

Determination of Seven <Emphasis Type="Italic">N</Emphasis>-nitrosamines in Agricultural Food Matrices Using GC-PCI-MS/MS

The quantitative analytical methods for seven N-nitrosamines including N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), N-nitrosodiethylamine (NDEA), N-nitrosodibutylamine (NDBA), N-nitrosopiperidine (NPIP), N-nitrosopyrrolidine (NPYR), and N-nitrosomorpholine (NMOR) were established for agricultural food matrices. Four food matrices were used for the method development: rice soup as a fatless solid matrix, apple juice as a fatless liquid matrix, corn oil as a fat-rich liquid matrix, and 20 % alcohol as an alcohol matrix. A combination of solid-supported liquid-liquid extraction (SLLE) using Extrelut NT and a solid phase extraction (SPE) using Florisil was employed for fatless matrices. For an alcohol matrix, only SLLE was used without SPE, and liquid-liquid extraction (LLE) was established for a fat-rich matrix. The extract was analyzed by gas chromatography-positive chemical ionization-tandem mass spectrometry (GC-PCI-MS/MS) using ammonia gas as an ion source. Linearity, recovery, repeatability, inter-day precision, reproducibility, and uncertainty were evaluated for method validation using four matrices. Method detection limits for all of the investigated N-nitrosamines were ranged from 0.10 to 0.18 μg/kg for the rice soup, from 0.10 to 0.19 μg/kg for the apple juice, 0.10 μg/kg for the corn oil, and from 0.10 to 0.25 μg/kg for 20 % alcohol, depending on N-nitrosamines. Established methods were applied to determine seven N-nitrosamines in some agricultural food products.     

Simultaneous Determination of Ractopamine,Chloramphenicol, and Zeranols in Animal-Originated Foods by LC-MS/MS Analysis with Immunoaffinity Clean-up Column

A novel analytical method employing immunoaffinity column (IAC) clean-up coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for simultaneous determination of ractopamine, chloramphenicol, and zeranols (α-zearalanol, β-zearalanol, zearalanone, α-zearalenol, β-zearalenol, and zearalenone) in animal-originated foods. The sample was first digested by β-glucuronidase/sulfatase and then extracted with ethyl acetate-diethyl ether (9:1, v/v). The extracted solution was evaporated to dryness and then the residue was dissolved by 2 mL of 50% acetonitrile solution. After filtration, 1 mL filtrate was diluted to 10 mL with PBS. The reconstituted solution was cleaned up with immunoaffinity column and then analyzed by high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The established method was shown to be sensitive efficient and reliable as indicated by the linearity (r ² ≥ 0.9994), precision (RSD ≤ 1.7%), average recovery (72.3–103.2%), and the limit of detection (0.05–0.10 μg/kg). The method can be used for determination of trace residues of ractopamine, chloramphenicol, and zeranols in animal-originated foods.     

Chlorophyll Fluorescence Imaging for Monitoring the Effects of Minimal Processing and Warm Water Treatments on Physiological Properties and Quality Attributes of Fresh-Cut Salads

In this study, chlorophyll fluorescence imaging (CFI) was used to monitor plant stress induced by cutting of mini romaine lettuce (Lactuca sativa L. var. longifolia) and by cutting and washing of endive (Cichorium endivia L.) during storage. Regarding the more detailed study of endive fresh-cut salads, we additionally monitored respiratory activity, phenylalanine ammonia lyase (PAL) activity, contents of plant pigments, and cut edge browning. Determination of maximum quantum efficiency F _v/F _m was feasible through sealed consumer-sized film bags, thus, enabling the non-invasive monitoring of both fresh-cut salad types in the corresponding modified atmosphere during storage. Cutting of romaine lettuce provoked a partially reversible drop of F _v/F _m during the first 24 h. Subsequently, F _v/F _m of cut romaine strongly decreased with elapsing shelf life, whereas intact leaves exhibited only a slight decline. Regarding minimally processed endive, warm water washing progressively reduced F _v/F _m with increasing heat exposure, while respiratory activities and the content of accessory pigments remained unaffected. The heat-dependent decrease of F _v/F _m was correlated to the inhibition of the PAL activity. Mildly warm washing (40 °C, 120 s; 45 °C, 60 s) reduced PAL activities, while F_v/F_m remained widely unaffected and visual quality was only partially improved. However, warm water washing at elevated temperatures (45 °C, 120 s; 50 °C, 30–60 s) enabled maximum visual quality retention, accompanied by a significant decrease of F _v/F _m. CFI may represent a useful tool to monitor the stress conditions due to cutting and warm water treatments, hence, allowing the systematic improvement of fresh-cut produce.     

A Rapid Single-Extraction Method for the Simultaneous Determination of Aflatoxins B1, B2, G1, G2, Fumonisin B1, and Zearalenone in Corn Meal by Ultra Performance Liquid Chromatography Tandem Mass Spectrometry

A single-extraction method to simultaneously determine aflatoxins (B1, B2, G1, G2), fumonisin B1, and zearalenone in corn meal by ultra performance liquid chromatography tandem mass spectrometry, using a triple quadrupole, was optimized, validated, and applied in an occurrence study. Different extraction solutions were tested, with better performance for methanol/acetonitrile/water (60:20:20, v/v/v). Linearity was observed from 0.25 to 1.50 ng/mL for aflatoxins, from 20 to 120 ng/mL for fumonisin, and from 7.00 to 42.00 ng/mL for zearalenone. Significant matrix effects were shown for all groups. Selectivity was demonstrated, as matrix or spectral interferences were not observed at the predicted retention time window of the target analytes. Average recoveries of 87.57, 93.18, 93.35, 94.20, 78.76, and 95.98% were obtained for aflatoxins (B1, B2, G1, and G2) fumonisin and zearalenone, respectively. A z-score of 0.19 was estimated in a corn certified reference material for fumonisin B1. Maximum relative standard deviation values under repeatability and intermediate precision conditions were determined to be 13.6 and 13.6% for aflatoxins, 3.7 and 6.3% for fumonisin, and 3.5 and 4.0% for zearalenone, respectively. In the occurrence study, 50 samples were analyzed and 44% had measurable levels of fumonisin. Zearalenone was detected in 18%. The proposed method showed considerable advantages, considering environmental impacts, efficiency, and reliability.     

Development of a Liquid Chromatography Tandem Mass Spectrometric Method for Simultaneous Determination of 15 Aminoglycoside Residues in Porcine Tissues

A quantitative and confirmatory method has been developed for simultaneous determination of 15 aminoglycoside (AG) residues in porcine tissues (muscle, liver and kidney) by liquid chromatography tandem mass spectrometry (LC-MS/MS). The analytes were extracted from different matrices with aqueous trichloroacetic acid solution (5 %, w/v) followed by solid phase extraction (SPE) clean-up under optimised conditions. Due to the different pK _a values of the compounds, two consecutive SPE steps using Oasis HLB cartridges were used to purify all 15 AGs from sample extracts, with 9 AGs quantitatively retained on Oasis HLB cartridges at pH?<1 and the other 6 AGs retained at pH 8.5. The analytes were separated on a reversed-phase C18 column and eluted with water and acetonitrile containing the ion-pair reagent heptafluorobutyric acid (HFBA). The LC-MS/MS method was validated according to Decision 2002/657/EC. The optimised procedure was successfully applied to analyse 100 real porcine tissue samples (60 muscles, 20 livers and 20 kidneys) collected from local markets in southern China, demonstrating that the method is robust and useful for determination of residues of the 15 target AGs in porcine tissue samples.     

Optimization of Extraction Parameters of Total Phenolics from <Emphasis Type="Italic">Annona crassiflora</Emphasis> Mart. (Araticum) Fruits Using Response Surface Methodology

In this study, response surface methodology was used to optimize the extraction temperature (25–75 °C) and ethanol concentration (0–70 %, ethanol/water, v/v) to maximize the extraction of total phenolic compounds (TPC) from araticum pulp. The efficiency of the extraction process was monitored over time, and equilibrium conditions were reached between 60–90 min. A second-order polynomial model was adequately fit to the experimental data with an adjusted R ² of 0.9793 (p < 0.0001) showing that the model could efficiently predict the TPC content. Optimum extraction conditions were ethanol concentration of 46 % (v/v), extraction temperature of 75 °C and extraction time of 90 min. Under the optimum conditions, the araticum pulp showed high TPC content (4.67 g GAE/100 g dw) and also high antioxidant activity in the different assays used (46.56 μg/mL, 683.65 μmol TE/g and 1593.72 μmol TE/g for DPPH IC₅₀, TEAC and T-ORAC_FL, respectively). From our extraction procedure, we successfully recovered a significantly higher amount of TPC compared to other studies in the literature to date (1.5–22-fold higher). Furthermore, TPC and antioxidant activity were present in the fruit in levels that are difficult to find in other common fruits. These results expose a potential approach for improving human health through consumption of araticum fruit.     

Green Approach for Sample Preparation and Determination of Anthocyanins from <Emphasis Type="Italic">Lycium ruthenicum</Emphasis> Murr. Using a <Emphasis Type="Italic">β-</Emphasis>Cyclodextrin-Based Extraction Method Coupled with UPLC-DAD Analysis

This study aimed to develop and optimize a β-cyclodextrin (β-CD)-based technique for extracting anthocyanins from Lycium ruthenicum Murr. and to establish a ultra-high-performance liquid chromatography-diode array detector (UPLC-DAD) method for their analysis. β-CD solutions produced higher extraction yields of petunidin-3-O-(trans-p-coumaroyl)-rutinoside-5-O-glucoside and total anthocyanins from L. ruthenicum fruit than did pure water and aqueous hydroxypropyl-β-cyclodextrin (HPβ-CD) and ethanol and methanol solutions. Extraction at 50 °C for 30 min using 1.65% β-CD solution and a liquid/solid ratio of 15:1 produced the optimal extraction yield of L. ruthenicum anthocyanins. A UPLC-DAD method was developed for the determination of L. ruthenicum anthocyanins using an ethanol-based mobile phase, and the primary anthocyanins were identified using two-dimensional LC-MS/MS. Method validation showed that the developed method was accurate, stable, and reliable for the analysis of petunidin-3-O-(trans-p-coumaroyl)-rutinoside-5-O-glucoside and total anthocyanins from L. ruthenicum fruit. The present study showed that β-CD-based extraction coupled with UPLC-DAD analysis is an efficient and green method for the extraction and analysis of anthocyanins from L. ruthenicum fruit.     

Characterization of Biodegradable Films Based on <Emphasis Type="Italic">Salvia hispanica</Emphasis> L. Protein and Mucilage

Biodegradable films of chia by-products (mucilage and protein-rich fraction (PF)) incorporated with clove essential oil (CEO) were obtained and characterized. The effects of polymer concentration (PC; 1.0–3.0 %, w/v) and CEO concentration (0.1–1.0 %, v/v) were evaluated as well as the pH (7–10), using a 2³ factorial design with four central points. The films exhibited moisture values between 11.6 and 52.1 % (d.b.), which decreased (p?<?0.05) with increasing PC and CEO. The thickness of the films increased (p?<?0.05) with increasing PC. PC and pH influenced (p?<?0.05) the lightness (L) and variation in color between red and green (a). The orientation of the color to yellow-blue hues (b) decreased significantly (p?<?0.05) with increasing PC. Transparency was significantly lower and higher (p?<?0.05) than PC and CEO, respectively. The film surface morphology was evaluated using atomic force miscrocope images, and thermogravimetric analysis (TGA) was performed to study the thermal stability of the films. The displacement and tensile strength were significantly lower (p?<?0.05) at higher concentrations of CEO, this variable being the only one with a significant effect. The chemical composition of the films was confirmed utilizing Fourier transform infrared (FTIR) spectroscopy. The proportion of CEO added to the films had a significant influence on antimicrobial activity, inhibiting the growth of both Escherichia coli and Staphylococcus aureus.     

Novel Intact Bitter Cassava: Sustainable Development and Desirability Optimisation of Packaging Films

Novel biomaterials and optimal processing conditions are fundamental in low-cost packaging material production. Recently, a novel biobased intact bitter cassava derivative was developed using an intrinsic, high-throughput downstream processing methodology (simultaneous release recovery cyanogenesis). Processing of intact bitter cassava can minimise waste and produce low-cost added value biopolymer packaging films. The objective of this study was to (i) develop and characterise intact bitter cassava biobased films and (ii) determine the optimal processing conditions, which define the most desirable film properties. Films were developed following a Box-Behnken design considering cassava (2, 3, 4 % w/v), glycerol (20, 30, 40 % w/w) and drying temperature (30, 40, 50 °C) and optimised using multi-response desirability. Processing conditions produced films with highly significant (p?<?0.05) differences. Developed models predicted impact of processing conditions on film properties. Desirable film properties for food packaging were produced using the optimised processing conditions, 2 % w/v cassava, 40.0 % w/w glycerol and 50 °C drying temperature. These processing conditions produced films with 0.3 %; transparency, 3.4 %; solubility, 21.8 %; water-vapour-permeability, 4.2 gmm/m²/day/kPa; glass transition, 56 °C; melting temperature, 212.6 °C; tensile strength, 16.3 MPa; elongation, 133.3 %; elastic modulus, 5.1 MPa and puncture resistance, 57.9 J, which are adequate for packaging applications. Therefore, intact bitter cassava is a viable material to produce packaging films that can be tailored for specific sustainable, low-cost applications.     

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.     

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.     

Establishment and Application of Infant Formula Fingerprints by RP-HPLC

An efficient method for rapid and simple identification of infant formula quality was investigated so as to prevent brand counterfeit of infant formulas. Reversed-phase, high-performance liquid chromatography (RP-HPLC) method combined with chemometric method was developed for fingerprints analysis. To optimize the RP-HPLC conditions, the RP-HPLC analysis was performed on a C₈ column by using gradient elution with 0.1% (v/v) aqueous trifluoroacetic acid (TFA) in water as mobile phase A and 0.1% (v/v) TFA in acetonitrile as mobile phase B, the flow rate was 0.5 mL min^?1, and the detection wavelength was set at 214 nm. Three different stages of infant formulas of two series (R₁ and R₂) of R brand were analyzed to establish infant formula fingerprints of each series at different stages under optimal conditions. Five major common peaks in each chromatogram of the infant formulas were used in fingerprint analysis. The results showed that the RP-HPLC fingerprints and principal component analysis (PCA) method can effectively differentiate the infant formula of different brands, as well as the different series of infant formulas of the same brand, which provide an effective testing method for authenticity identification and brand protection in infant formulas.