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.     

多壁碳纳米管基质固相分散-高效液相色谱测定牛奶中6种四环素

以多壁碳纳米管为吸附材料,建立基质固相分散萃取高效液相色谱法测定牛奶中6种四环素。将多壁碳纳米管、EDTA、草酸和样品研磨混匀装柱,经含甲酸的甲醇洗脱后HPLC多波长紫外检测。6种四环素的检出限0.01～0.03μg/mL,回收率78.7%～105.2%,相对标准偏差小于12%。多壁碳纳米管基质固相分散萃取牛奶中四环素的回收率优于C18,可推广到食品等复杂样品中其他农兽药多残留分析。     

Application of microemulsion electrokinetic chromatography for the detection of preservatives in foods

In this study, a microemulsion electrokinetic chromatographic (MEEKC) method was used to separate seven preservatives which are commonly used as additives in various food products. The RSDs were in the range of 0.64–0.95% for migration time and 0.18–1.21% for reproducibility of sample injection, thus indicating the separation performance was very good even though sample preparations contained high levels of organic solvent (methanol) (up to 20 (v/v)%). Although the separation of soy sauce and wine samples required a C8 solid phase extraction as a pretreatment step in order to reduce matrix interference, this MEEKC method proved to be successful in determining preservatives found in various food products, such as soft drinks, soy sauces and wines.     

Isotope Internal Standard Method for Determination of Four Acrylamide Compounds in Food Contact Paper Products and Food Simulants by Ultra-High Performance Liquid Chromatography Tandem Mass Spectrometry

A new method was developed for the determination of four acrylamide compounds (acrylamide, methacrylamide, N-methylol acrylamide, N-(Methoxymethyl)methacrylamide) in food contact paper products, three kinds of water-based food simulants, and dry food simulant (modified polyphenylene oxide, MPPO) by using ultra-high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Acetonitrile was used as the extraction solvent for different kinds of samples. The extraction solution of paper products was purified with QuEChERS technology. Four analytes were separated by gradient elution in a UPLC HSS T3 column (100 mm?×?2.1 mm, 1.8 μm) with methanol and 0.1 % formic acid water as mobile phases, and then detected in electrospray ionization mode of MS/MS with multiple reaction monitoring (MRM). Under the optimal conditions, the calibration curves for four analytes were linear within the range of 1.0–200 μg/L and the correlation coefficients were higher than 0.998. The quantitation limits of the method (S/N?=?10) of four analytes were in the range of 0.3–20 μg/kg. The mean recoveries for five sample matrixes at three spiked concentration levels of 0.3–200 μg/kg were in the range of 81–108 % with the relative standard deviations (RSDs, n?=?6) values ranging from 2.5 to 7.1 %. The developed method is accurate, simple and rapid, which can be applied to the determination of acrylamide compounds in food contact paper products and food simulants.     

Simultaneous determination of nine preservatives in food by liquid chromatography with the aid of coagulant in the clean-up process

ABSTRACT

A simple HPLC method was developed for the simultaneous analysis of nine preservatives in food including benzoic acid, sorbic acid, dehydroacetic acid, methyl paraben, ethyl paraben, isopropyl paraben, propyl paraben, isobutyl paraben and butyl paraben. Samples were extracted with 60 v/v% methanol containing poly-aluminium chloride (PAC) and sodium hydroxide prior to analysis. PAC, which is normally used as a coagulant, was successfully applied to remove interfering substances from the samples. The method showed good linearity with coefficients of determination higher than 0.999 over the range of 0.2–5 µg ml^–1 for all target preservatives. LOQs of the method were in the range of 0.002–0.008 g kg^–1. Method performance was evaluated in a variety of foods demonstrated to have quantitative recoveries of 81.7–102.5% with satisfactory intra-day precision of < 3.7% and inter-day precision of < 6.5%. The method also demonstrated applicability to real foods containing preservatives.     

Determination of Bisphenol A and Alkylphenols in Soft Drinks by High-Performance Liquid Chromatography with Fluorescence Detection

A highly sensitive and selective method was developed for the purification and determination of bisphenol A and alkylphenols in soft drinks by using 2-(11H-benzo[a]carbazol-11-yl) ethyl chloroformate (BCEC-Cl) as pre-column labeling reagent followed by high-performance liquid chromatography (HPLC) with fluorescence detection. The HPLC sensitivity of bisphenol A and alkylphenols was greatly enhanced through the introduction of BCEC-Cl moiety with excellent fluorescence property into the target molecules. Meanwhile, the introduction of highly hydrophobic BCEC-Cl moiety into the analytes also greatly increased the hydrophobicity of the target compounds and distinguished them from hydrophilic matrices. Therefore, little interference was observed. Solid-phase extraction with C18 cartridges was applied to sample purification procedure with recoveries of higher than 82 %. When 20 mL of sample was used for analysis, the limits of quantifications of the analytes were between 0.06 and 0.1 μg?L^?1. The proposed method was successfully applied to the determination of the target compounds in soft drink samples with a much higher sensitivity than traditional HPLC methods.     

Simultaneous determination of deltamethrin,permethrin and malathion in stored wheat samples using continuous sample drop flow microextraction followed by HPLC–UV

Wheat (Triticum aestivum) is an important staple food worldwide used for the manufacture of flour-derived foodstuffs such as bread and noodles. The purpose of this study was to investigate common pesticides in stored wheat at Kermanshah province’s silos in Iran. Continuous sample drop flow microextraction coupled with high-performance liquid chromatography–ultraviolet (HPLC–UV) detection was applied for this purpose. In this technique, a few microliter of organic solvent is transferred to the bottom of a conical test tube and the aqueous solution transforms in form fine droplets while passing through the organic solvent. After extraction, 20 μL of organic solvent containing target analytes was injected into the HPLC–UV. The extraction conditions (including type and volume of extraction solvent, sample solution flow rate, sample solution volume, pH and salt addition) were varied to achieve optimized performance. Under the optimum conditions, the calibration graphs are linear in the range of 0.5–1000 µg kg^?1 and limit of detections (LODs) are in the range of 0.2–0.5 µg kg^?1. Repeatability (intra-day) and reproducibility (inter-day) of method based on seven replicate measurements of 100 µg kg^?1 of target pesticides were in the range of 3.2–5.1% and 4.7–7.2%, respectively. Three out of 36 wheat grain samples contained permethrin exceeding safety levels, but the levels of the other two pesticides in all samples were below the maximum residue levels based on Europe standard level.     

Solid-Phase Extraction and Procedure for Determination of Phenolic Compounds in Maple Syrup

A solid phase extraction procedure was developed for the extraction of phenolic compounds from maple syrup. The list of targeted chemicals contains phenolic acids as well as aldehydes, flavanols and others such as coniferyl alcohol and 5-hydroxymethyl furfural. The procedure consists in passing a small quantity of maple syrup, 1 g diluted in 2 ml deionized water, through an Oasis HLB cartridge of 200 mg. The cleanest extracts were obtained by rinsing the cartridge load with formic acid 2 %/methanol (9:1). The analytes eluted with methanol were passed in an high-performance liquid chromatography (HPLC)-DAD system for analysis. The method performances show good recoveries; excluding gallic acid measured at 49 %, the chemical recoveries ranged from 81 to 119 %. Moreover, the method repeatability is less than 12 % (RSD) relative standard deviation for all chemicals except for epicatechin (20 %). The analysis method was applied for the determination of phenolic compounds in maple syrups from different color classes (Extra Light to Amber). Results show that concentrations of phenolic compounds vary among syrup classes and the greatest concentration was observed for the Amber syrups.     

超声萃取- 高效液相色谱法同时测定进出口食品中常见6 种防腐剂

使用超声萃取- 反相高效液相色谱(HPLC)技术,建立同时分离和检测食物中苯甲酸、山梨酸、对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯和对羟基苯甲酸丁酯6 种防腐剂的方法。水- 甲醇(5:95,V/V)作为提取溶剂进行超声萃取,采用Supelco Discovery C18 反相色谱柱,流动相为乙腈- 乙酸铵缓冲溶液(pH4.4)进行梯度洗脱,在1ml/min 的流速和254nm 的检测波长下14min 内6 种防腐剂得到良好分离。6 种防腐剂线性范围从5μg/ml 到100μg/ml,相关系数(r)为0.9997～1.0000。方法的平均回收率为90.1%～106.3%,精密度和稳定性的RSD分别为0.58%～1.79%、0.15%～1.65%,检出限的范围为0.012～0.43μg/ml。本方法的预处理过程简便、快速,应用于30 种进出口食品中防腐剂的分析检测,检测结果灵敏、可靠。     

Gas Purge Microsyringe Extraction Coupled with Dispersive Liquid-Liquid Microextraction for the Determination of Acidic Compounds in Food Packaging Materials

A green, simple and sensitive method was developed for the analysis of volatile carboxylic acids (VFAs) and perfluorocarboxylic acids (PFCAs) in food packaging materials. The acidic compounds in food packaging materials were first extracted by gas purge microsyringe extraction (GP–MSE) with 1.0 mL 0.1 mol·L^?1 NaOH solution, then the analytes were dispersive liquid-liquid microextracted (DLLME) by 50 μL chloroform as extraction solvent and 200 μL acetonitrile as dispersive solvent. The 2-(5-Benzoacridine) ethyl-p-toluenesulfonate (BAETS) with excellent fluorescence property was applied to enhance the high performance liquid chromatography (HPLC) sensitivity. The obtained recoveries for the VFAs ranged from 92.0 to 101 %. The method LODs calculated at a signal-to-noise ratio (S/N) of 3 were in the range of 0.80–3.40 μg·kg^?1, while the LOQs calculated at S/N of 10 were in the range of 2.5–10.2 μg·kg^?1. All compounds were in good linearity with concentration coefficients of higher than 0.997. Perfluorooctanoic acid (PFOA) was found in all of the 15 kinds of samples analyzed with concentrations ranging from 4.86–7.56 μg·kg^?1. Acetic acid, butyric acid, and caprylic acid were found in half of the samples analyzed. The other analytes were also found in more than 30 % samples with concentrations varied between 3.96 and 293 μg·kg^?1.     

A New and Fast HPLC Method for Determination of Rutin, Troxerutin, Diosmin and Hesperidin in Food Supplements Using Fused-Core Column Technology

A new and fast high-performance liquid chromatography (HPLC) method using fused-core column for separation of rutin, troxerutin, diosmin, and hesperidin has been developed and used for determination of these flavonoids in food supplements. Efficient separation of flavonoids and internal standard methylparaben was achieved on the fused-core column Ascentis Express RP-Amide (100?×?3.0 mm), particle size 2.7 μm, with mobile phase acetonitrile/water solution of acetic acid pH?3 (30:70, v/v) at a flow rate of 1.0 mL?min^?1 and at temperature 50 °C. The detection wavelengths were set at 283 nm for hesperidin and at 255 nm for rutin, troxerutin, diosmin, and internal standard methylparaben. Under the optimal chromatographic conditions, good linearity with correlation coefficients in the range (r?=?0.9991–0.9998; n?=?7) for all flavonoids was achieved. Commercial samples of food supplements were extracted with 100 % dimethyl sulfoxide using ultrasound bath for 10 min and then diluted to methanol. A 5-μL sample volume of the filtered solution was directly injected into the HPLC system. Accuracy of the method defined as a mean recovery of flavonoids from food supplement matrix was in the range 96.2–104.4 % for all flavonoids. The intraday method precision was satisfactory, and relative standard deviations of sample analysis including preparation and determination of different food supplements were in the range 0.5–3.5 % for all flavonoids. The developed method has shown high sample throughput during sample preparation process, modern separation approach, and short time (5 min) of analysis.     

Determination of Four Synthetic Phenolic Antioxidants in Edible Oils by High-Performance Liquid Chromatography with Cloud Point Extraction Using Tergitol TMN-6

A cloud-point extraction (CPE) method using Tergitol TMN-6 (TMN-6) non-ionic surfactant was developed for the extraction and preconcentration of propyl gallate (PG), tertiary butyl hydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) in edible oils. The optimum conditions of CPE were 1.5 % (v/v) Tergitol TMN-6, 1 % (w/v) NaCl, ultrasound-assist 15 min at 49 KHz, 20 min equilibrated at 45 °C, and centrifugation for 10 min at 3,000 rpm. The surfactant-rich phase was then analyzed by reversed-phase high-performance liquid chromatography (HPLC) with ultraviolet detection at 280 nm, under gradient separation, using methanol and 1.5 % (v/v) acetic acid. Under the study conditions, four synthetic phenolic antioxidants (SPAs) were successfully separated within 24 min. Limits of detection in the studied edible oils were in the range of 1.6 to 9.0 ng mL^?1. The high recoveries of the spiked edible oils were obtained in the range 90–98 %. The CPE method has been shown to be a potentially useful methodology for the preconcentration of the target analytes, with a preconcentration factor of 25. This method was compared with cloud point extraction (using Triton X-114) and liquid–liquid extraction (using methanol).     

Method Development for Sulfonylurea Herbicides Analysis in Rapeseed Oil Samples by HPLC–DAD: Comparison of Zirconium-Based Sorbents and EMR-Lipid for Clean-up of QuEChERS Extract

This study develops a simple, cost-effective and sensitive high-performance liquid chromatography with diode array detector (HPLC–DAD) method for the simultaneous determination of eight sulfonylurea herbicides (oxasulfuron, metsulfuron-methyl, triasulfuron, chlorsulfuron, amidosulfuron, mesosulfuron-methyl, bensulfuron-methyl and tritosulfuron) in rapeseed oil. Extraction of target analytes was performed using quick, easy, cheap, effective, rugged and safe-based procedure followed by solid-phase extraction (SPE) and dispersive solid-phase extraction (d-SPE) clean-up, and presents good performance for all of the analytes with recoveries in the range of 67–133% and relative standard deviations (RSD) less than 15%. No significant matrix interference was observed due to the application of effective zirconium dioxide-based sorbent (Z-Sep). Method LOQs for most of the investigated analytes were set at satisfactory low value of 20 ng g^?1 in food product. The procedure was evaluated in analyses of actual samples. The most important steps of the method optimization are presented. Novel EMR-Lipid clean-up solution for samples with high fat content was evaluated and compared to Z-Sep sorbent.     

Ion-Pair-Based Air-Assisted Liquid–Liquid Microextraction for the Extraction and Preconcentration of Phthalic Acids from Aqueous Samples

In the present study, a rapid, simple, and highly efficient sample preparation method based on ion-pair air-assisted liquid–liquid microextraction using a low-density extraction solvent followed by high performance liquid chromatography–diode array detection has been developed for the extraction, preconcentration, and determination of three phthalic acids (phthalic acid, iso-phthalic acid, and terephthalic acid) in aqueous samples. In this method, a mixture of tri-butyl amine (as an ion-pair reagent) and toluene (as an extraction solvent) is transferred into an aqueous sample solution. Fine organic solvent droplets are formed by aspirating and dispersing of the mixture via syringe needle. After that, the formed ion-pairs are extracted into toluene, and after centrifuging, the obtained collected phase is transferred into a microtube and is evaporated to dryness under a stream of nitrogen at room temperature. The residue is re-dissolved in mobile phase and injected into the separation system for analysis. Under the optimum extraction conditions, the method showed low limits of detection and quantification between 0.09–0.24 and 0.29–0.78 ng mL^?1, respectively. Extraction recoveries and enrichment factors were from 88 to 98 % and 443 to 491, respectively. Relative standard deviations for the extraction of 5 ng mL^?1 of each analyte were less than 8.4 % for intra-day (n?=?6) and inter-days (n?=?5) precisions. Finally, different aqueous samples were successfully analyzed using the proposed method, and the target analytes were determined in some of them at ng mL^?1 level.     

高效液相色谱法测定肉制品中栀子黄色素含量

通过正交试验分析法对肉制品中栀子黄色素提取方法进行优化。利用正交试验设计考察提取溶剂体积、超声时间和提取次数对肉制品中栀子黄色素提取回收率的影响。结果表明,肉制品中栀子黄色素的最优提取条件为：甲醇为提取溶剂、固液比1∶6（g/mL）、超声提取时间20 min、提取2 次;建立高效液相色谱法测定肉制品中栀子黄色素中藏花素和藏花酸方法的线性范围为0.5～50 mg/mL,相关系数大于0.999,检出限不高于0.07 μg/g,加标平均回收率为83.51%～96.00%,相对标准偏差不大于2.94%。该方法准确度高、简单、快速,可适用于肉制品中栀子黄色素中藏花素和藏花酸含量检测。     

超声波提取HPLC-UV法测定人工蛹虫草中8种核苷类物质

蛹虫草中核苷及其代谢化合物的分析检测对于蛹虫草的生理和药理研究是非常重要的。该文采用超声波辅助提取HPLC-UV法,以反相DIAMONSIL C1(8250mm×460mm,5μm)为色谱柱,以水(含0.1%乙酸)和甲醇混合液为流动相进行梯度洗脱,同时测定了人工蛹虫草中的尿嘧啶、次黄嘌呤、鸟嘌呤、胸腺嘧啶、肌苷、鸟苷、腺苷和虫草素等8种化合物。结果表明,超声波提取的最优条件为提取溶剂为甲醇,提取温度25℃,提取时间15min,超声功率100W,料液比1:100,在最优的超声提取和色谱分离条件下,8种核苷类化合物在检测范围内的线性关系较好(r2>0.9995),检出限和定量限最低可达到16.9ng/mL和56.4ng/mL,日内和日间精密度(RSD)分别小于4.1%和4.6%,加样回收率为81.9%~93.7%。此法可用于冬虫夏草及其代用品中核苷类化合物的分析检测。     

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.     

Analysis of lasalocid residues in grease and fat using liquid chromatography-mass spectrometry

A method for the determination of lasalocid, an antibiotic and coccidiostat, in grease and fat is described. The manufacture of lasalocid produces a grease-like residue as a waste byproduct. Recently this byproduct has been shown to have been illegally introduced into the animal feed chain. Therefore, a quantitative and confirmatory procedure to analyse for lasalocid in this matrix is needed. A portion of grease/oil sample was extracted into hexane-washed acetonitrile, and a portion of the extract was then applied to a carboxylic acid solid-phase extraction (SPE) column for concentration and clean-up. The SPE column was washed with additional hexane-washed acetonitrile and ethyl acetate/methanol, after which lasalocid was eluted with 10% ammoniated methanol. The eluate was evaporated to dryness, redissolved in (1:1) acetonitrile–water and filtered through a PTFE syringe filter. Confirmation and quantitation of lasalocid in the final extract employed a triple quadrupole LC-MS/MS. The method was applied to grease and oil samples containing from 0.02 to 34 000 mg kg^?1 of lasalocid.     

Simultaneous determination of dehydroacetic acid,benzoic acid,sorbic acid,methylparaben and ethylparaben in foods by high-performance liquid chromatography

In this study, an analytical method was established and validated to determine the preservatives such as dehydroacetic acid, benzoic acid, sorbic acid, methylparaben and ethylparaben. The level of preservatives was measured by solvent extraction method adding purification process with carrez reagent and by high-performance liquid chromatography (HPLC). The developed analytical method was successfully applied to determine the concentration of preservatives in various food samples including jam, cheese and soy sauce, displaying high accuracy (recoveries between 87.8% and 110%) and precision (%RSD less than 5.92% and 7.72% for intra-day and inter-day, respectively). To verify the applicability of the improved test method, selected 13 food items and collected 521 samples were monitored. As a result, all the cases met the Korea standard guidelines. Consequently, this study is expected to contribute to the safety management of preservatives for domestic distribution and imported food.

     

Simultaneous Determination of 13-HODE, 9,10-DHODE,and 9,10,13-THODE in Cured Meat Products by LC-MS/MS

A method was developed for simultaneous determination of 13-hydroxyoctadecadienoic acid (13-HODE), 9,10-dihydroxyoctadecenoic acid (9,10-DHODE), and 9,10,13-trihydroxyoctadecenoic acid (9,10,13-THODE) in cured meat products. The analytes, extracted with methanol and cleaned by solid phase extraction, were separated on an XBridge C18 column (150*4.6 mm, 5 μm) with a mobile phase consisting of 0.1 % formic acid in water and acetonitrile, followed by detection with an electrospray ionization tandem mass spectrometry in negative-ion mode. The proposed method produced satisfactory reliability, sensitivity, and accuracy. Recoveries of the three analytes within the spiking range of 0.5–40 μg/g were 80.0–97.8 %, and limits of quantification of 13-HODE, 9,10-DHODE, and 9,10,13-THODE were 0.4, 0.025, and 0.05 μg/g, respectively. The method was successfully employed to detect the three fatty acids with hydroxyl(s) in cured meat products. It was shown that all samples contained the three analytes simultaneously, with concentrations ranging 1.40–100.77 μg/g for 13-HODE, 0.13–1.82 μg/g for 9,10-DHODE, and 0.49–10.12 μg/g for 9,10,13-THODE, respectively. The analytical result also indicated there were isomers of analytes, and the real content of fatty acids with hydroxyl(s) from oxidation of LA might be much higher.