Rapid Determination of Invert Cane Sugar Adulteration in Honey Using FTIR Spectroscopy and Multivariate Analysis

ABSTRACT: Fourier transform infrared spectroscopy with an attenuated total reflection sampling accessory was combined with multivariate analysis to determine the level (1% to 25%, wt/wt) of invert cane sugar adulteration in honey. On the basis of the spectral data compression by principal component analysis and partial least squares, linear discriminant analysis (LDA), and canonical variate analysis (CVA), models were developed and validated. Two types of artificial neural networks were applied: a quick back propagation network (BPN) and a radial basis function network (RBFN). The prediction success rates were better with LDA (93.75% for validation set) and BPN (93.75%) than with CVA (87.50%) and RBFN (81.25%).     

Application of Fast Gas Chromatography and Fourier Transform Infrared Spectroscopy for Analysis of Lard Adulteration in Virgin Coconut Oil

Lard (LD) and virgin coconut oil (VCO) share some similarities such as having transparent to yellowish color and are solid at room temperature; hence, as a consequent, LD may be a potential oil adulterant in VCO. This study highlights the application of fast gas chromatography with surface acoustic wave detector (GC-SAW system) and Fourier transform infrared (FTIR) spectroscopy combined with chemometrics to analyze the presence of LD in VCO. Binary admixtures of LD in VCO in various percentage concentrations ranging from 1% to 50% (v/v) were assayed using the fast GC-SAW system and FTIR spectroscopy. Using the fast GC-SAW system, ten different chromatogram peaks were identified as the adulterant peaks. One peak in the fast GC-SAW system chromatogram was found to have the best relationship, with a coefficient of determination (R ²) value of 0.9344. Furthermore, FTIR spectroscopy coupled with partial least square (PLS) and discriminant analysis (DA) can be successfully developed for quantification and classification of LD in VCO. The results showed that PLS able to predict the LD contents in VCO with equation of y = 0.999 ×+ 0.006 y = 0.{999} \times + 0.00{6} , for the correlation between actual value of LD (x) and FTIR predicted value (y) with R ² of 0.9990 at frequency regions of 3,020–3,000 cm⁻¹ and 1,120–1,000 cm⁻¹. DA can classify VCO and that adulterated with LD using the FTIR spectra at the same frequency regions used in quantification.     

高效液相色谱法快速筛查与测定葡萄酒中纽甜

建立一种高效液相色谱法快速定性筛查与准确定量检测葡萄酒中人工合成甜味剂纽甜的方法。采用WatersNova-Pak C18反相色谱柱,以离子对试剂缓冲液:乙腈=60:40(V/V)为流动相,在218nm波长处,对样品进行筛查,纽甜出峰时间约在13.4min;疑似阳性样品在梯度洗脱条件下进行定量检测,纽甜出峰时间约在15.9min,检出限为0.37μg/mL,平均回收率在99%～101%之间,相对标准偏差均小于1.0%(n=5)。本方法简便、准确、实用,在批量样品检测时可节省约50%的分析时间。     

Rapid Discrimination and Determination of Polyunsaturated Fatty Acid Composition in Marine Oils by FTIR Spectroscopy and Multivariate Data Analysis

A rapid analytical approach for discrimination and quantitative determination of polyunsaturated fatty acid (PUFA) contents, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), in a range of oils extracted from marine resources has been developed by using attenuated total reflection Fourier transform infrared spectroscopy and multivariate data analysis. The spectral data were collected without any sample preparation; thus, no chemical preparation was involved, but data were rather processed directly using the developed spectral analysis platform, making it fast, very cost effective, and suitable for routine use in various biotechnological and food research and related industries. Unsupervised pattern recognition techniques, including principal component analysis and unsupervised hierarchical cluster analysis, discriminated the marine oils into groups by correlating similarities and differences in their fatty acid (FA) compositions that corresponded well to the FA profiles obtained from traditional lipid analysis based on gas chromatography (GC). Furthermore, quantitative determination of unsaturated fatty acids, PUFAs, EPA and DHA, by partial least square regression analysis through which calibration models were optimized specifically for each targeted FA, was performed in both known marine oils and totally independent unknown n???3 oil samples obtained from an actual commercial product in order to provide prospective testing of the developed models towards actual applications. The resultant predicted FAs were achieved at a good accuracy compared to their reference GC values as evidenced through (1) low root mean square error of prediction, (2) good coefficient of determination close to 1 (i.e., R ²≥ 0.96), and (3) the residual predictive deviation values that indicated the predictive power at good and higher levels for all the target FAs.     

QuEChERS结合GC-MS/MS法快速测定小麦中20种农药残留量（网络首发、推荐阅读）

建立QuEChERS结合气相色谱-串联质谱法（GC-MS /MS）检测小麦中20种农药残留量的方法。在实验过程中对不同含量净化吸附剂对小麦样品提取液的净化效果进行了研究,并且考察了小麦中20种农药的基质效应。结果表明：（1）与GB 23200.113—2018中7.1.2前处理方法相比,通过对净化吸附剂的优化,节约了无水MgSO4、PSA、C18的用量,将无水MgSO4添加量从1 200 mg减少到了400 mg,将PSA的添加量从400 mg减少到了100 mg,将C18的添加量从400 mg减少到了200 mg,另外加入了100 mg GCB可以有效去除小麦提取液中的色素。（2）小麦中20种农药在GC-MS/MS上色谱峰响应值与其质量浓度（5~500 ng/mL）之间线性关系良好,相关系数超过0.99,检出限范围是0.01~0.16 μg/kg,定量限范围是0.04~0.52 μg/kg;另外20种农药的基质效应强度差异较大;（3）在添加水平为80、200、400 μg/kg时20种农药平均回收率分别在75.24%~98.29 %、82.01%~105.71%、94.91%~ 106.14%范围内,RSD分别为0.57%~3.13%、0.67%~3.98%、1.26%~3.08 %,符合农药残留分析要求。     

Determination of Nitrite in Food Samples by Kinetic Spectrophotometric Data and Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS)

Herein, a method for spectrophotometric determination of nitrite in food samples with complex matrices is developed. The method is based on the standard addition and collecting kinetic data of the reaction of nitrite with 4-amino-3-hydroxynaphthalene-1-sulfonic acid (AHNSA) and 1-naphthylamine. Standard additions were made based on the linear range of the method using the above reagents. Kinetic data of different standard additions were augmented and subsequently analyzed by multivariate curve resolution-alternating least squares (MCR-ALS) to achieve second-order advantage. The proposed method was applied to real samples, and 19.86, 19.68, 1.38, 2.50, and 4.00 mg kg^?1 of nitrite was found in cheese, tomato paste, sausage, hamburger, and kielbasa, respectively. The results were validated by a standard method.     

欧盟RASFF系统食品风险预警的数据分析研究

欧盟成员国在预防食品和饲料的安全问题时,愈来愈重视和依靠欧盟的食品与饲料快速预警系统(RASFF),该系统已经成为欧洲地区保障食品安全重要的信息交流平台。自2001年伊始,欧盟RASFF系统每年发布一次年度报告,2009年已经涉及到全球121个国家。本文以RASFF系统的年度报告为基础,根据2008年以来的数据,分析RASFF系统的信息报告种类、关注的热点问题和重大事件、针对中国的报告等,以及数据所表征的风险变化、趋势和欧洲食品安全新的预警进展。     

表面活性剂增敏差分脉冲阳极溶出伏安法测定食品中痕量铅

在0.1mol/L NaNO_3和适量十六烷基三甲基溴化铵(CTAB)介质中,采用玻碳汞膜电极作为工作电极,差分脉冲阳极溶出伏安法测定金属Pb的增敏效果可达10倍左右,其溶出峰为-0.47V(V.S.Ag/AgCl 1mol/L KCl),线性范围为0～100ppb,其准确度和回收率分别在4.6%～9.9%和92%～114%之间。     

Determination of Psoralens in Child Food (Soups and Baby Food) from Brazil by High-performance Liquid Chromatography (HPLC)

Psoralens are considered natural toxins, present in edible plants, which act as protectors against fungi, insects, and herbivores. In this study, an analytical procedure suitable for sample preparation and an HPLC-UV method were developed for the quantification of psoralens in child food (soups and baby food). The samples were lyophilized and 5.00 g of solid was extracted with 25 mL of MeOH:HCl (1000:1), under magnetic stirring at 40 °C for 30 min. Separation was carried out on a C18 column with a mobile phase consisting of acetonitrile (20 to 100%) and water. Spectrophotometric detection with a wavelength of 246 nm was used. The method to determine psoralens in child food showed adequate linearity, repeatability, and accuracy. The limits of detection (LOD) and quantification (LOQ) obtained for psoralens were 0.02 and 0.08 μg g^?1, respectively. The concentrations (minimum–maximum in μg/100 g) of psoralens in the samples ranged from 71.9 to 877.4. The intake of approximately 45-mg psoralen and UVA exposure can result in various skin lesions. Therefore, the results showed that the developed method is simple, fast, and reliable for the determination of psoralens in child food (soups and baby food).     

A Fast and Reliable UHPLC-PDA Method for Determination of Patulin in Apple Food Products Using QuEChERS Extraction

A fast and reliable method for the quantification of patulin using ultra high performance liquid chromatography coupled to a photodiode array detector was developed and validated for the analysis of several apple-based foodstuffs. Sample preparation was based on the QuEChERS procedure. Samples were extracted with acetonitrile and partitioned with a mixture of sodium citrate, NaCl, and Mg₂SO₄. The cleanup step was performed using dispersive SPE mixed with Mg₂SO₄ and PSA. This step was carried out twice in order to improve chromatographic results. The method was validated in spiked cloudy apple juice, apple puree, apple yogurt, beer with apple juice, and cider and applied to 24 commercial samples. The limits of detection and limits of quantification were ≥0.4 and ≥2 ng/g, respectively. Both were below the maximum legal limit established by the European Union. Recoveries for all the matrices were between 78.4 and 94.7 % while relative standard deviations were between 3.8 and 10.4 %. Patulin was detected on four apple juices from concentrate, one cloudy apple juice from an eco-store, and one beer. Nevertheless, the highest concentration found was 25.4 ng/g.     

Zeta Potential (ζ) Analysis for the Determination of Protein Content in Rice Flour

Zeta potential (ζ) analysis was investigated as a means of rapid determination of residual protein content of rice flour during processing of rice starch. A rice flour sample was suspended in 0.3% sodium hydroxide solution to obtain rice flour slurry which was subjected to protein extraction by a decanter for five cycles. The samples from all cycles were collected, neutralized, dried, sieved through a 200 mesh sifter and subjected to ζ analysis. The data from ζ values (y) and chemical analysis of protein content (x) from six samples of rice flour were used in a regression analysis to develop an empirical equation to express the protein content of rice flour based on ζ value alone. The result of ζ value obtained from six samples of different protein contents suspended in a buffer solution of pH 12 yielded a standard linear equation of y = –1.29x–12.51. In another method of ζ analysis, the sample was suspended in DI (deionized) water without buffer by varying pH from 2 to 8 for the ζ measurement. A linear relationship between ζ and pH was obtained together with the constant value k (slope) which could be converted into protein content (x) of rice flour by a standard linear equation of k = –1.15x –4.90.     

食品中脂肪测定国家标准的分析与探讨

食品中脂肪的测定是食品营养成分检测的重要环节,是人们健康饮食的重要保障。国家卫计委于2016年12月23日发布了GB 5009.6-2016《食品安全国家标准食品中脂肪的测定》,替代了9个关于食品中脂肪测定的标准,是国家强制实施的统一的、普适性的脂肪检测标准。但由于食品种类繁多,脂肪形态性状各异,脂肪检测方法原理多样等原因,普适性标准可能存在一些不具体、不适用情况。本文通过比较被替代标准及脂肪检测文献的脂肪检测原理、适用范围及流程,综述了食品中脂肪测定国家标准的制样、取样、萃取、恒重技术控制关键点。     

Multivariate Optimization for the Development of a Fast and Simple Ultrasound-Assisted Extraction Procedure for Multielemental Determination in Tea Leaves by Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES)

The current study describes a fast and efficient procedure of ultrasound-assisted extraction for determination of Ca, Mg, K, Na, Cu, Zn, Mn, and Al in tea leaves by inductively coupled plasma optical emission spectrometry (ICP OES). The variables of procedure were optimized using the Box–Behnken design and the conditions selected were nitric acid concentration (1.0 mol L^?1), sonication time (7 min), and sonication temperature (75 °C). The extraction efficiency was calculated using the analyte concentration obtained by a total digestion procedure as reference. Accuracy was confirmed by analysis of certified reference material of apple leaves (NIST 1515) and spinach leaves (NIST 1570a) using the procedure proposed. A statistical evaluation using Student’s t test showed that there is no significant difference between the value obtained with the proposed procedure and the certified value, at 95% confidence level. The proposed procedure was successfully applied and is a good alternative to conventional acid digestion procedure and can be applied to routine analysis for determination of Ca, Mg, K, Na, Zn, Mn, Cu, and Al in tea leaves used for the preparation of infusions.     

Benzyloxybenzaldehydethiosemicarbazone: Extractive Spectrophotometric Reagent for the Determination of Cu(II) in Food and Water Samples

Benzyloxybenzaldehydethiosemicarbazone (BBTSC) was prepared and developed a new method for the simple, highly selective, and extractive spectrophotometric determination of copper(II) with BBTSC at wavelength 370 nm. The metal ion formed a bluish green colored complex with BBTSC in acetate buffer of pH 5.0, which was easily extractable into n-butanol with 1:1(metal/ligand) composition. The method obeys Beer’s law in the range of 0.5–5.2 ppm. The molar absorptivity and Sandell’s sensitivity were found to be 1.5 × 10⁴ l mol⁻¹ cm⁻¹ and 0.00412 g cm⁻², respectively. The correlation coefficient of the Cu(II)–BBTSC complex was 0.998, which indicated an excellent linearity between the two variables. The repeatability of the method was checked by finding the relative standard deviation (RSD; n = 10), which was 0.377% and its detection limit 0.0204 μg ml⁻¹. The interfering effect of various cations and anions were also studied. The proposed method was successfully applied to the determination of copper(II) in food and water samples. Comparing the results with those obtained using an atomic absorption spectrophotometer tested the validity of the method.     

On the Colorimetric-Sulfuric Acid Analysis of Uronic Acids in Food Materials: Potential Sources of Discrepancies in Data and How to Circumvent Them

The determination of the uronic acid content of biological and food substances is of primary importance when their functionalities are being investigated. To date, three kinds of colorimetric-H₂SO₄ procedures using carbazole, meta-hydroxydiphenyl, and 3,5-dimethylphenol chromogenic compounds are the most currently used to achieve this goal. However, great discrepancies in inter- and intra-procedure data are frequently noted in the literature for the same kinds of raw materials. A scrutiny of a large number of published procedures in combination with personal communication have permitted us to find out several potential results “modifiers,” i.e., the experimental parameters, which modification alone, even slight, can engender significant variations in the final data, compared with the data from the original procedure. No less than a dozen factors have been pin-pointed as critical and discrepancy causing. Therefore, unreliable modification of a parameter at once without concomitant optimization of all the main parameters should completely be avoided.     

Application of Polypropylene Amine Dendrimers (POPAM)-Grafted MWCNTs Hybrid Materials as a New Sorbent for Solid-Phase Extraction and Trace Determination of Gold(III) and Palladium(II) in Food and Environmental Samples

A new method which utilizes a polypropylene amine dendrimers (POPAM)-grafted multi-walled carbon nanotubes (MWCNTs) hybrid materials as an effective sorbent in solid-phase extraction has been developed for separation and preconcentration of Au(III) and Pd(II) trace levels in food, water and soil samples. The optimum experimental conditions such as pH, flow rates, type, concentration, and volume of the eluent for elution of gold and palladium ions, breakthrough volume, and effect of potentially interfering ions on separation and determination of these noble metals were investigated. The extraction recoveries for the mentioned noble metals were greater than 98 % and the limits of detection were 0.08 and 0.12 ng mL^?1 for gold and palladium, respectively. The relative standard deviations of the method were less than 4 % for eight separate column experiments for determination of 5.0 μg of gold and palladium ions. The adsorption capacity of the modified MWCNT was 92 mg g^?1 for gold and 74 mg g^?1 for palladium on POPAM-grafted MWCNTs. Validation of the suggested method was performed by analyzing certified reference materials. Finally, the proposed method was applied for determination of gold(III) and palladium(II) in real samples, including fish, shrimp, water, and soil.     

2014年欧盟RASFF对华食品通报分析研究

根据2014年欧盟食品和饲料快速预警系统(Rapid Alert System of Food and Feed,RASFF)通报我国输欧食品安全情况,总结我国被通报食品种类、风险因素以及通报国家的分布,并探讨对我国食品安全监管的启示。     

GC-MS检测食品包装用PET中6种潜在添加的小分子化合物

本文建立了气相色谱-质谱串联(GC-MS)同步检测PET食品包装中6种小分子化合物的方法。对二氯甲烷超声波辅助提取法和苯酚/四氯乙烷混合溶液溶解法进行了对比和优化,萃取液经HP-5MS色谱柱分离,质谱检测器检测,标准品保留时间定性,峰面积定量。结果表明二氯甲烷超声辅助提取法在料液比(m:V)为1:15,萃取时长为30 min,次数为1次时萃取效果较好,6种小分子化合物在0.05~2 mg/L的浓度范围内呈良好线性,判定系数R2均大于0.9980,检出限为0.1~20μg/L,定量限为1~25μg/L,加标浓度为200、500、1000μg/L的回收率为71.99%~109.99%,相对标准偏差(RSD)为0.01~8.20%,日内精密度均≤4.74%,日间精密度均≤5.86%。用该方法对市售的25种PET食品包装进行了检测,共有5个样品被检出目标物质甲苯、BHT或DEHP,最高含量分别为308.11 mg/kg、500.31 mg/kg和482.57 mg/kg。该方法前处理简便,分离度好,分析灵敏度高,适用于PET中6种小分子化合物的日常检测。     

CTMAB增敏共振瑞利散射法快速测定面制食品中的Pb

在表面活性剂溴化十六烷基三甲基铵及酸性三羟甲基氨基甲烷-盐酸缓冲介质存在条件下,铬天青S与Pb（Ⅱ）结合,导致共振瑞利散射（resonance Rayleigh scattering,RRS）显著增强,并产生新的RRS光谱。在最大共振瑞利散射峰369 nm波长处,Pb（Ⅱ）的质量浓度在0.002～0.35 mg/L范围内与体系的共振瑞利散射增强程度（ΔIRRS）呈良好的线性关系,定量限为0.024 mg/kg。据此建立了快速、准确、高灵敏的测定Pb（Ⅱ）的RRS新方法,并研究了适宜的反应条件及RRS光谱特征。方法可用于市售面制食品中Pb的快速测定。