Optimization of two-dimensional gas chromatography time-of-flight mass spectrometry for separation and estimation of the residues of 160 pesticides and 25 persistent organic pollutants in grape and wine

Two-dimensional gas chromatography (GC × GC) coupled with time-of-flight mass spectrometric (TOFMS) method was optimized for simultaneous analysis of 160 pesticides, 12 dioxin-like polychlorinated biphenyls (PCBs), 12 polyaromatic hydrocarbons (PAHs) and bisphenol A in grape and wine. GC × GC–TOFMS could separate all the 185 analytes within 38 min with >85% NIST library-based mass spectral confirmations. The matrix effect quantified as the ratio of the slope of matrix-matched to solvent calibrations was within 0.5–1.5 for most analytes. LOQ of most of the analytes was ≤10 μg/L with nine exceptions having LOQs of 12.5–25 μg/L. Recoveries ranged between 70 and 120% with <20% expanded uncertainties for 151 and 148 compounds in grape and wine, respectively, with intra-laboratory Horwitz ratio <0.2 for all analytes. The method was evaluated in the incurred grape samples where residues of cypermethrin, permethrin, chlorpyriphos, metalaxyl and etophenprox were detected at below MRL.     

An innovative multistage, physiologically structured, population model to understand the European grapevine moth dynamics

We present a multistage, physiologically structured, population model for studying the dynamics of one of the most important grapevine insect pests. Growth of the population at each stage is modeled considering the climatic variations and the grape variety. A result of existence and uniqueness of solutions is presented for this original hyperbolic system as well as simulations of experimental field data.     

巴豆种子油的GC-MS分析

巴豆种子经石油醚或无水乙醇提取得巴豆种子油，通过气相色谱－质谱联用仪（GC－MS）测定其中的化学夸分，结果显示，巴豆种子油中含有26个组分，本文确定了其中22个组分的结构。     

CIEL*a*b* parameters of white dehydrated grapes as quality markers according to chemical composition,volatile profile and mechanical properties

In the oenological sector, the withering process is of particular importance in the production of dry and sweet dessert wines due to the total or partial use of overripe and/or dehydrated grapes.     

Glucose and fructose levels on grape skin: interference in Lobesia botrana behaviour

The vineyard produces one of the most important crops in Portugal and is affected by various pests, such as the Lobesia botrana moth, which can be attracted chemically by compounds on the grape skin.In this study, the sugar contents (glucose and fructose) on grape skin were analysed for five Portuguese Vitis vinifera grape varieties and compared in grape juice and whole grapes. Samples were harvested in July, August and September of 2001 and 2002.The quantification was attained employing a new methodology, which comprised the preparation of a methanol solution to extract the compounds from the grape skin and further chromatographic analyses by liquid chromatography (LC) with refractive index (RI) detection. The samples designated by whole grapes were homogenised, centrifuged and filtrated, while the juice was obtained by crushing and filtration.Grape skin has shown higher levels of glucose than fructose, but both compounds increased from green berry (July) to veraison (August) and had a slight decrease from veraison to harvest (September).As expected, the glucose and fructose contents (total sugar) were higher in the whole grape than in the juice and much higher than in the grape skin itself. For Loureiro and Trajadura varieties, the levels of both sugars on grape skin were very similar. This resemblance strengthened the statement of the decisive role of this parameter in female L. botrana oviposition behaviour.     

贵州主产区薏苡仁及非种仁部位薏苡仁多糖的测定

采用蒽酮-硫酸法,以无水葡萄糖为对照品,于582nm处测定吸光度,测定薏苡仁及非种仁部位薏苡仁多糖含量。葡萄糖在3.314×10-3—1.988×10-2mg/mL范围内与吸光度呈良好线性关系,相关系数r=0.9995,该方法准确,重复性好。各主产区薏苡仁中薏苡仁多糖含量均大于非种仁部位,非种仁部位薏苡仁多糖含量无明显差异,本文为非种仁部位资源的综合开发利用提供科学依据。     

原子吸收光谱法测定葡萄酿酒副产物中的化学元素

原子吸收光谱法测定葡萄皮、葡萄籽和葡萄酒泥中的化学元素.称取5份粉碎的葡萄酿酒副产物加入一定量硝酸:高氯酸(V/V=4 ∶ 1)混合溶液置电热板上加热消解,在仪器工作条件下用3％稀硝酸做空白测定12种元素的吸光度.原子吸收光谱法测定的标准曲线相关系数为0.9979-0.9999.加标回收率在96.2％-100.2％之间...     

固相萃取气相色谱-质谱法测定葡萄酒中118种农药残留量

样品(10g)先后用20mL及15mL乙腈超声波提取118种农药残留,经盐析并离心除水液液分配,所得提取液经40℃旋转蒸干,残渣溶于乙腈甲苯(3+1)混合溶液5mL中,溶液经Carb/PSA双层固相萃取小柱净化,淋出液蒸至近干并溶于丙酮-正己烷(1+1)混合溶液1.0mL中,供气相色谱质谱分析。分析中采用HP-5MS毛细管色谱柱及EI离子源和选择离子扫描方式,外标法定量。方法的测定下限(10S/N)在0.01～0.031mg·kg~(-1)之间,在加标水平为0.05mg·kg~(-1)时,方法回收率为67%～124%,相对标准偏差(n=5)小于12.2%。     

Method for simultaneous analysis of eight vitamin E isomers in various foods by high performance liquid chromatography and fluorescence detection

The objective of this study was to optimize a method to investigate the occurrence and to quantify the full isomeric composition of vitamin E (α-, β-, γ- and δ-tocopherols and tocotrienols) in 6 vegetables (raw and cooked), 3 herbs/spices, raw and cooked eggs, vegetable oils (canola, olive and soybean), flaxseed and sorghum (flour and seeds) and soy (flour) by HPLC with fluorescence detection. Different conditions of extraction and analysis were tested. The optimized method consisted of direct extraction with solvent (hexane:ethyl acetate, 85:15, v/v). For analysis normal phase column was used with mobile phase consisting of hexane:isopropanol:acetic acid (98.9:0.6:0.5) with isocratic elution and fluorescence detection. Excellent separation of all isomers was obtained along with adequate quantification in the foods analyzed. Recovery rates of standards ranged from 91.3 to 99.4%. The linearity range for each isomer varied from 2.5 to 137.5 ng/mL (R2 greater than 0.995 in all cases). Detection limits ranged from 21.0 to 48.0 ng/mL for tocopherols and from 56.0 to 67.0 ng/mL for tocotrienols, while quantification limits ranged from 105.0 to 240.0 ng/mL for tocopherols and from 280.0 to 335.0 ng/mL for tocotrienols. The optimized method was considered simple, fast and reliable, and also preserved vitamin E isomers when compared to validated methods involving saponification.     

Preliminary study to determine the phenolic maturity stage of grape seeds by computer vision

The applications of computer vision technology for acquiring and analysing images have been extended to the quality evaluation in food industry. This technique involves great advantages for the objective, rapid, non-contact and automated quality inspection and control. The aim of this work was to evaluate the potential of the computer vision to determine the phenolic maturity stage of grape seeds. Up to 21 phenolic compounds were determined by HPLC–DAD-MS in order to obtain reference values to develop the model. The CIELAB parameters, area, aspect, roundness, length, width and heterogeneity of seeds were analysed using a DigiEye^® system. The technique reported in this work can be a good and rapid tool for taking decisions at harvest time. Notwithstanding, a comprehensive study should be made in order to develop more robust models.