Automated Magnetic Solid-Phase Extraction for Synthetic Food Colorant Determination

A new automated magnetic solid-phase extraction (MSPE) method was developed and combined with high-performance liquid chromatography (HPLC) and spectrophotometry for off-line and on-line quantitative enrichment and determination of synthetic food colorants in food samples. Fe₃O₄-poly (ionic liquid) core-shell microspheres were prepared as a sorbent to quickly extract analytes from aqueous samples. The entire MSPE process, including extraction, separation, elution, and cleaning, was automated using common equipment. The main parameters affecting the performance of MSPE and the automated process, such as absorbent, sample pH, eluent, flow rate, elution time, etc., were investigated in detail. Under the optimum experimental conditions, the limits of detection ranged between 4.1 and 14 ng/mL by off-line HPLC and were 220 ng/mL for the determination of amaranth by on-line spectrophotometry, with excellent reproducibility (intra- and inter-day relative standard deviations were less than 3.2 %). The developed method was successfully applied to the determination of colorants in food samples.     

Development of Multiresidue Analysis for 21 Synthetic Colorants in Meat by Microwave-Assisted Extraction–Solid-Phase Extraction–Reversed-Phase Ultrahigh Performance Liquid Chromatography

A novel ultrahigh performance liquid chromatographic method is developed for analysis of 21 synthetic colorants with different acid–base property, solubility, and polarity. The meat samples were extracted by microwave-assisted extraction followed by cleanup with solid-phase extraction. The effective separation of the colorants in meat matrixes was achieved, and no interfering peaks could be detected at the retention time of the analytes. The calibration curves showed good linearity with correlation coefficients of 0.9940–0.9999. The limits of quantification were 0.48–7.19 μg/kg. The average recovery of the 21 analytes from meat samples spiked with 25 and 75 μg?kg^?1 was 61.29–116.1 % with relative standard deviation (RSD) of <11 %. For blank beef sausage spiked with 50 μg?kg^?1 for each analyte, the intraday precision (as RSD) for 21 analytes was 1.45–9.21 % for six determinations within a day. This method has the advantages of being rapid, sensitive, accurate, and with high-throughput and can be applied for multiresidue analysis of meat samples, including six allowable azo food colorants, ten banned azo food colorants, four banned triphenylmethanes, and rhodamin B food colorant.     

Application of Ultrasound-Assisted Extraction Followed by Solid-Phase Extraction Followed by Dispersive Liquid-Liquid Microextraction for the Determination of Chloramphenicol in Chicken Meat

In the present study, a simple and efficient preconcentration method was developed using ultrasound-assisted extraction followed by solid-phase extraction followed by dispersive liquid-liquid microextraction for the extraction and determination of trace amount of chloramphenicol in chicken meat. The sample was extracted with acetonitrile and EDTA-McIlvaine buffer under ultrasonication, followed by solid-phase extraction and dispersive liquid-liquid microextraction. In order to obtain high extraction efficiency, the parameters affecting the proposed method were evaluated and optimized. Under the optimized conditions, the calibration curve was linear in the range of 0.3–200 μg kg^?1 with good linearity (r ² > 0.995). Finally, applicability of the proposed method was successfully confirmed by extraction and determination of the chloramphenicol in chicken meat samples. Comparing to the traditional methods, the proposed method exhibits high sensitivity and high preconcentration as well as good precision.     

Determination of Sulfonamides in Chicken Meat by Magnetic Molecularly Imprinted Polymer Coupled to HPLC-UV

In this work, Fe₃O₄ magnetic nanoparticles were synthesized and modified by a molecularly imprinted polymer for easy and selective extraction and determination of sulfonamides in chicken meat samples. Imprinted polymer magnetic nanoparticles were characterized by Fourier transform infrared spectroscopy, X-ray diffraction pattern, thermal analysis, and scanning electron microscope micrograph. The template was removed by methanol elution. The effective parameters on extraction and determination of sulfonamides on the sorbent such as eluent type, extraction solvent, and adsorption and desorption times were optimized. Sulfonamide separation and determination were performed by high-performance liquid chromatography–UV. The linear ranges for sulfonamides were 0.5–150 μg/L and the limits of detection were 0.1–0.5 μg/L. Relative standard deviations were within 4.3–5.4 %. The method showed good selectivity for extraction of sulfonamides in real samples.     

A Preconcentration Procedure for Determination of Ultra-Trace Mercury (II) in Environmental Samples Employing Continuous-Flow Cold Vapor Atomic Absorption Spectrometry

New functionalized magnetic nanoparticles as solid-phase sorbent were prepared and investigated for extraction of ultra-trace amounts of mercury from environmental samples. The Fe₃O₄ magnetic nanoparticles functionalized with dithizone were characterized by Fourier transform infrared spectrometer. X-ray diffraction and scanning electron microscopy confirmed the size of nanoparticles. Effects of several factors on the extraction procedure were investigated. The optimized conditions were established to be 80 mg of polymer, 8.5 for solution pH, 5 min for adsorption time, 5 min for desorption time, 2 mL for HCl (0.1 mol L^?1)/ thiourea 0.05 % as the eluent, 500 mL for breakthrough volume, and without addition of salt. Under the optimal conditions, the limit of detection, maximum capacity, and preconcentration factor were 0.05 ng mL^?1, 0.557 mmol g^?1, and 250, respectively. Limit of quantification was in the range of 0.2–2 ng mL^?1 for various matrices. Accuracy and precision of the method were about ±2.0 and below 11.1 %, respectively. Finally, the present method has been successfully applied to mercury determination in table salt, green tea, vegetables, toothpaste, and water samples. The mercury content found in the real samples was from 0.6 to 15.74 ng mL^?1 without addition of mercury.     

超高效液相色谱—串联质谱测定红烧老抽中六种合成色素的方法

建立了超高效液相色谱-串联质谱法(UPLC/MS/MS)同时测定红烧老抽中日落黄、柠檬黄、苋菜红、胭脂红、诱惑红、亮蓝等6种合成色素的方法。样品用水稀释后经过聚酰胺粉柱子净化,采用超高效液相色谱-串联质谱进行分析。采用0.02mol/L乙酸铵和甲醇作为流动相,梯度洗脱,流速为0.2mL/min,在7min内实现6种合成色素的良好分离。串联质谱条件是正离子模式电离,采用多反应监测模式(MRM)。6种色素在10~1000μg/L的范围内线性良好。6种色素的方法最低检出限是10μg/kg,加标回收率在80.0%～93.4%之间,相对标准偏差在2.4%～6.8%之间(n=6)。本方法分析快速、定性准确、检出限低,应用到基质复杂的老抽类液体复合调味料的检测中效果较佳。     

食品中合成着色剂的提取方式及测定方法研究进展

柠檬黄、日落黄、苋菜红、胭脂红、诱惑红等水溶性偶氮类着色剂,由于其易溶于水、耐酸性、耐热性及耐氧化性的特点,被广泛应用于食品行业。长期过量摄入合成着色剂会对人体健康造成危害,GB 2760-2014规定合成着色剂最大使用量为0.5 mg/kg。目前有关合成着色剂的提取方法和测定方式的研究有很多。本文综述了合成着色剂的提取方式及测定方法,比较分析各种方法和方式的差异性、共性和适用性,为检测不同食品中合成着色剂提取方式和测定方法的选择提供了指南。     

A Rapid Quantification of β-Carotene in Fruits and Vegetables by Dispersive Liquid–Liquid Microextraction Coupled with UV–Vis Spectrophotometry: Optimized by Response Surface Methodology

A simple, fast, and efficient method consisted of optimized dispersive liquid–liquid microextraction (DLLME) followed by UV–vis spectrophotometry was developed for determination of β-carotene in fruits and vegetables. Chloroform and methanol were chosen as extraction and disperser solvents, respectively. The extraction process was optimized using a central composite design (CCD) with the optimum points of 115 μL for volume of extraction solvent and 6.5 % (w/v) for salt concentration. Under the optimal conditions, the relative standard deviation (RSD, C?=?500 μg L^?1, n?=?5), limit of detection (LOD), linear dynamic range (LDR), and coefficient of determination (R²) were 1.08 %, 2 μg L^?1, 50–1,500 μg L^?1, and 0.991, respectively. The present method consisted of a simple and fast sample preparation procedure without any antioxidant addition, saponification, and purification was used.     

A Novel Cationic Surfactant-Assisted Switchable Solvent-Based Dispersive Liquid–Liquid Microextraction for Determination for Orange II in Food Samples

In this research, a new and green procedure based on the cationic surfactant-assisted switchable solvent-based dispersive liquid–liquid microextraction (CS-SS-DLLME) with UV-vis spectrophotometry was used for the extraction and determination of the Orange II dye in food samples. The main feature of the switchable solvent is the simple and reversible conversion of polarity protonated triethylammonium carbonate (P-TEA-C, ionic) to triethylamine (TEA, nonionic) by adding NaOH. This extraction method is based on hydrophilicity switchable solvent and ion pair effect of cationic surfactant. Simplicity, high-performance extraction, rapidity of the process, increase of stability, and reduction of the extractive phase volatility are other advantages of the proposed method. The parameters including the extraction and preconcentration of Orange II were studied and optimized. Under optimal conditions, the calibration curve was linear within the range of 2–450 μg/L and the detection limit was 0.9 μg/L and the relative standard deviation (RSD) for 80 μg/L of Orange II was 1.68%. This developed method was used successfully for the determination of Orange II in food samples.     

固相萃取-高效液相色谱法测定食品基质中5种不同合成红色着色剂

目的建立一种固相萃取-高效液相色谱法(solidphaseextraction-highperformanceliquid chromatography,SPE-HPLC)测定食品中5种人工合成红色着色剂(新红、苋菜红、胭脂红、诱惑红、赤藓红)的方法。方法比较ProElut PWA-2, Cleanert PWAX和Sep-Pak Plus QMA 3种不同SPE小柱的净化效果,比较Eclipse XDB C_(18)、Venusil XBP C_(18)及Agilent TC-C_(18) 3种色谱柱对5种着色剂的分离情况,按照GB 5009.35-2016《食品中合成着色剂的测定》对食品中5种着色剂进行测定。结果 Pro Elut PWA-2 SPE固相萃取小柱进行样品净化效果最优, Agilent TC-C_(18)色谱柱在10 min内有较好的分离度。加标浓度为0.5～50 mg/kg时,该方法回收率为90.3%～103.9%,相对标准偏差(relative standard deviation, RSD)值为1.18%～7.11%。结论该方法快速、准确,适合用于不同食品基质中5种合成着色剂定性、定量测定。     

Application of Ion-Imprinted Polymer Nanoparticles for Selective Trace Determination of Palladium Ions in Food and Environmental Samples with the Aid of Experimental Design Methodology

A solid phase extraction method using Pd²⁺ ion-imprinted polymer (Pd²⁺-IIP) nanoparticles combined with flame atomic absorption spectrophotometry (FAAS) was developed for the preconcentration and trace detection of palladium ions. The Pd²⁺-IIP nanoparticles were obtained by precipitation polymerization of 4-vinylpyridine (the functional monomer), ethylene glycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the initiator), Eriochrome Cyanine R (the lead-binding ligand), and palladium ions (the template ion) in acetonitrile solution. The parameters affecting adsorption and desorption steps were optimized by a Box–Behnken design through response surface methodology. Three variables (pH value, extraction time, and amount of the synthesized IIP) were selected as the main factors affecting sorption step, while four variables (type of eluent, volume of the eluent, concentration of the eluent, and elution time) were selected for desorption step in the optimization study. The optimized values by this optimization method were 30 mg, 15 min, 6.0, HCl, 4.0 mL, 1.8 mol L^-l HCl, and 14 min, for amount of polymer, retention time, pH of solution, type, volume, concentration of the eluent, and elution time, respectively. Under the optimized conditions, the detection limit for the proposed method was found to be 0.2 μg L^?1, while the relative standard deviation (RSD) for five replicate measurements was calculated to be <3 %. Finally, the introduced solid phase extraction technique was successfully applied for extraction and determination of Pd²⁺ ions in food and environmental samples.     

A Miniaturized Preconcentration Method Based on Dispersive Liquid–Liquid Microextraction for the Spectrophotometric Determination of Aziridine in Food Simulants

In this work a simple, rapid and sensitive method using dispersive liquid–liquid microextraction (DLLME) combined with UV–Vis spectrophotometry has been developed for the preconcentration and determination of trace amounts of aziridine in food simulants. The method is based on derivatization of aziridine with Folin's reagent (1,2-naphthoquione-4-sulphonic acid) and extraction of color product using DLLME technique. Some important parameters, such as reaction conditions, and type and volume of extraction solvent and disperser solvent were studied and optimized. Under optimum conditions, a linear calibration curve in the range of 2.0–350 ng mL^?1 of aziridine was obtained. Detection limit based on 3S_b was 1.0 ng mL^?1, and the relative standard deviation for 50 ng mL^?1 of aziridine was 2.49c (n?=?7). The proposed method was applied for the determination of aziridine in food simulants.     

A New Ultrasonic Thermostatic-Assisted Cloud Point Extraction/Spectrophotometric Method for the Preconcentration and Determination of Bisphenol A in Food,Milk, and Water Samples in Contact with Plastic Products

Bisphenol A (BPA) contamination in foods and beverages usually occurs as a result of migration from the packages that contain it. In this context, a simple, easy-to-use, and efficient method was developed for the spectrophotometric determination of BPA in food, milk, and water samples in contact with plastic products after preconcentration by ultrasonic-thermostatic-assisted cloud point extraction (UTA-CPE). The method is based on the charge transfer-sensitive complexation of BPA with 3-methylamino-7-dimethylaminophenothiazin-5-ium chloride (AzB) in the presence of cetyltrimethylammonium bromide (CTAB) at pH 8.5 and then extraction of the formed complex into the micellar phase of polyethylene glycol dodecyl ether (Brij 35). The effects of the analytical variables affecting complex formation and extraction efficiency were systematically studied and optimized. Under optimized conditions, a good linear relationship was obtained in the range of 1.2–160 μg L^?1 with a detection limit of 0.35 μg L^?1. After preconcentration of a sample of 20 mL, a sensitivity enhancement factor was found to be 180. The accuracy and reliability of the method were evaluated by recovery studies from the spiked quality control samples and intraday and interday precision studies. From the studies conducted, the extraction efficiency (E%) was in the range of 94–103% with a relative standard deviation lower than 5.2% (as RSD%, n = 5). The method was successfully applied to the preconcentration and determination of BPA from the selected sample matrices.

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Graphical Abstract Migration of bisphenol A into the foodstuffs

     

Application of Box–Behnken Design in the Optimization of In Situ Surfactant-Based Solid Phase Extraction Method for Spectrophotometric Determination of Quinoline Yellow in Food and Water Samples

In this work, a simple, rapid and sensitive method using in situ surfactant-based solid phase extraction (ISS-SPE) combined with UV–vis spectrophotometry has been developed for the preconcentration and determination of trace amounts of quinoline yellow in food and water samples. The Box–Behnken design was employed to optimize the extraction efficiency. The variables of interest were pH, surfactant volume, extraction time and NaI volume. In the optimal conditions, the calibration graph was linear in the range of 10.0–750 μg L^?1 with a correlation coefficient of 0.9982. The limit of detection (LOD) was 2.1 μg L^?1, and the preconcentration factor was calculated to be 51.8.     

Determination of green,blue and yellow artificial food colorants and their abuse in herb-coloured green Easter beers on tap

Beer is one of the most popular alcoholic beverages worldwide. For consumer acceptance, significant factors are its taste, flavour and colour. This study determines selected synthetic green, blue and yellow food colorants in popular Easter herb-coloured green beers on tap produced in breweries on Holy Thursday. The abuse of beer colouring with Tartrazine (E 102), Quinoline yellow (E 104), Sunset yellow (E 110), Patent blue (E 131), Indigo carmine (E 132), Brilliant blue FCF (E 133), Green S (E 142) and Fast green FCF (E 143) was assessed in 11 green beer samples purchased in local restaurants. HPLC was used for the separation and detection of artificial colorants with diode-array detection and a Chromolith Performance CN 100 × 4.6 mm column with guard pre-column Chromolith CN 5 × 4.6 mm. Separation was performed in gradient elution with mobile phase containing methanol–aqueous 2% ammonium acetate at pH 7.0. The study showed that eight beers (70%) marketed in the Czech Republic contained artificial colorants (Tartrazine and Brilliant blue FCF). The concentration of colorants found in analysed green herb-coloured beers ranged from 1.58 to 3.49 mg l^–1 for Tartrazine, 0.45–2.18 mg l^–1 for Brilliant blue, while Indigo carmine was detected only once at concentration 2.36 mg l^–1. Only three beers showed no addition of the synthetic colorants. However, the levels of artificial colorants found in beers marketed in the Czech region were very low and did not show a serious risk for consumers’ health.     

Simultaneous Determination of Aflatoxin B1 and Aflatoxin M1 in Food Matrices by Enzyme-Linked Immunosorbent Assay

Aflatoxins are a class of highly toxic chemical contaminants occurring in food. Consumption of aflatoxin-contaminated food can lead to harmful effects on human health. A rapid and reliable analysis of aflatoxins in food is crucial. In this study, we generated a broad–specific monoclonal antibody (MAb) 3 C10 against aflatoxin B₁ (AFB₁). The MAb 3 C10 binds specifically to AFB₁ and AFM₁ and has a IC₅₀ of 0.13 μg L^?1 for AFB₁ and 0.16 μg L^?1 for AFM₁. Furthermore, the MAb showed high cross-reactivity to AFB₂, AFG₁, and AFG₂. To enable simultaneous AFB₁ and AFM₁ detection in different food matrices, an indirect competitive enzyme-linked immunosorbent assay (icELISA) based on MAb 3 C10 has been developed and optimized. In addition, the extraction methods of different food matrices (peanut, corn, soybean, wheat flour, rice, soy sauce, vinegar, wine, raw milk, pure milk, skimmed milk, and yogurt) were established. The average recovery ranged from 73 to 121 %, with relative standard deviation values less than 15 %. The limit of detection was 0.52?+?0.36 μg kg^?1 (mean?+?3SD) for AFB₁ in eight agricultural products and 0.031?+?0.015 μg kg^?1 (mean?+?3SD) for AFM₁ in four dairy products. The sensitivity of icELISA was below the limit set by the European Commission for aflatoxin detection in different food matrices and similar to LC–MS/MS method. We demonstrate a rapid, simple, and reliable method for simultaneous screening of AFB₁ and AFM₁ in different food matrices.     

固相萃取-HPLC法同时测定肉制品中苋菜红、胭脂红、日落黄和诱惑红的含量

建立了利用固相萃取-高效液相色谱法同时测定肉制品中4种合成色素的检测方法.样品经乙醇、氨水和水溶液(7∶2∶1,mlm)提取后,固相萃取净化,经C18柱分离,用紫外检测器检测.结果表明:4种合成色素分离良好,加标平均回收率为66.7％～99.7％,相对标准偏差1.9％～3.6％.该方法准确度和精密度较高,可应用于测定肉制品中的合成色素.     

Hybrid Amine-Functionalized Titania/Silica Nanoparticles for Solid-Phase Extraction of Lead,Copper, and Zinc from Food and Water Samples: Kinetics and Equilibrium Studies

In the present study, hybrid amine-functionalized titania/silica nanoparticles were employed as a new and novel adsorbent for solid-phase extraction of Pb²⁺, Cu²⁺, and Zn²⁺ ions prior to their determination using flame atomic absorption spectrometry. Under the best conditions (including adsorbent, 0.4 g; eluent, 5.0 mL nitric acid (HNO₃), 3.0 mol L^?1, 1.0 mL min^?1; and sample, pH 5.0, 3.0 mL min^?1), detection limits, adsorption capacities, and preconcentration factors were 0.12–0.24 μg L^?1, 7.1–20.7 mg g^?1, and 200, respectively. To predict the adsorption isotherms, different isotherm models were studied and the obtained results showed that the Langmuir model is the most suitable one to explain the experimental data. The kinetics of the reaction followed pseudo-second-order kinetic model. Thermodynamic parameters like free energy (ΔG ⁰) and enthalpy (ΔH ⁰) confirmed the spontaneous and exothermic nature of the process. The method was successfully applied for determination of the analytes in different food and water samples.     

Selective Determination of Selenium in Garlic, Mushroom and Water Samples by Chemically Modified Mesoporous Silica Solid Phase Coupled with ICP-OES

A selective sorbent for solid phase extraction (SPE), based on a chemically modified mesoporous silica (SBA-15), followed by inductively coupled plasma-optical emission spectrometry was used for extraction, preconcentration, and determination of selenium in water and food samples. The main parameters of SPE including pH, amount of mesoporous (solid phase), concentration of the eluent (desorption solvent), and equilibrium time were optimized by using a fractional central composite design (f-CCD). The optimum conditions were found to be 3.2 for pH, 21 mg for amount of the mesoporous, 1 mol l^?1 for eluent concentration, and 9 min for equilibrium time. Under the optimal conditions, the limit of detection (LOD) was 2.56 μg l^?1. The linear dynamic range (LDR) was 5–1,000 μg l^?1 with determination coefficient (R ²) of 0.999. Relative standard deviation (C?=?400 μg l^?1, n?=?5) was 3.84 %. The enrichment factor was 20. The maximum sorption capacity of the modified SBA-15 was 15 mg g^?1. The sorbent presented good stability, reusability, high adsorption capacity, and fast rate of equilibrium for sorption/desorption of selenium (IV) ions.     

Magnetic solid-phase extraction coupled with HPLC for the determination of Allura Red in food and beverage samples

A magnetic solid-phase extraction (MSPE) protocol prior to HPLC was developed for the extraction and determination of Allura Red in food samples. Magnetic nanoparticles were coated with tetraethylorthosilicate and 3-aminopropyltriethoxysilane and modified by graphene. Scanning electron microscopy, transmission electron microscopy and Fourier-transform infrared spectrometry were used to characterise the graphene-functionalised sorbents; and the main parameters affecting the extraction such as sample volume, temperature, pH and time were investigated and established. Under optimised conditions, the pre-concentration factor of Allura Red was 200, and the calibration curve was linear at a concentration range of 5–1500 μg kg^?1. The LOD was 2 μg kg^?1, the limit of quantification was 7 μg kg^?1, and the relative standard deviation was 3.3%. The prepared MSPE procedure was simple and fast, and it was successfully applied for the determination of Allura Red in beverages, candy and jelly.