Classification of juices and fermented beverages made from unripe,ripe and senescent apples based on the aromatic profile using chemometrics

The aim of this study was to assess differences between apple juices and fermented apple beverages elaborated with fruits from different varieties and at different ripening stages in the aroma profile by using chemometrics. Ripening influenced the aroma composition of the apple juice and fermented apple. For all varieties, senescent fruits provided more aromatic fermented apple beverages. However, no significant difference was noticed in samples made of senescent or ripe fruits of the Lisgala variety. Regarding the juices, ripe Gala apple had the highest total aroma concentration. Ethanal was the major compound identified in all the samples, with values between 11.83 mg/L (unripe Lisgala juice) and 81.05 mg/L (ripe Gala juice). 3-Methyl-1-butanol was the major compound identified in the fermented juices. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied and classified the juices and fermented juices based on physicochemical and aroma profile, demonstrating their applicability as tools to monitor the quality of apple-based products.     

Determination of THMs in soft drink by solid-phase microextraction and gas chromatography

In this study, a simple and fast method was developed for the analysis of trihalomethanes (THMs) in soft drink samples using headspace solid-phase microextraction coupled with gas chromatography (HS-SPME–GC). The influence of factors, such as, extraction temperature, extraction time, addition of sodium chloride and agitation speed on extraction yield was studied through an univariate experimental design strategy. Satisfactory recoveries (?90%) and precision, calculated as the relative standard deviations (RSD ? 11%), were obtained. The limit of detection (LOD) between 0.22 and 0.46 μg L⁻¹ was achieved for THMs along with a wide linear range of concentrations. The applicability of the proposed method was demonstrated by analysing 74 real soft-drink samples. Since no matrix effects were observed, quantification could readily be carried out by external calibration with deionized water standards.     

Characterization of rum using solid-phase microextraction with gas chromatography–mass spectrometry

Headspace solid-phase microextraction was used to extract and analyze volatile compounds in different aged rums. The interference of ethanol was resolved with a dilution of the sample at 12% v/v. The extraction procedure, using a 100 μm PDMS fibre with 35 min at 30 °C, permitted the isolation of a large quantity of volatile compounds. One hundred and eighty-four volatile compounds were identified, including 64 esters, 47 benzenic compounds, 16 terpenoids, 14 alcohols, 10 acetals, 9 aldehydes, 6 phenols, 6 ketones, 6 furans, 3 acids and 3 benzopyrans.     

Differentiation of “Claret”, Rosé, Red and Blend wines based on the content of volatile compounds by headspace solid-phase microextraction and gas chromatography

We studied 46 samples of wine from Denomination of Origin of La Rioja: 8 rosé, 8 “claret”, 10 red, 10 artificial blend and 10 ungrouped wines (3 rosé, 2 “claret”, 2 red and 3 blend). The samples were analysed by gas chromatography using headspace-solid-phase microextraction (HS-SPME) with a Carbowax-divinylbenzene (CW/DVB) fibre. The variables considered were 3-methyl butyl acetate, 3-methyl-1-butanol, ethyl hexanoate, 1-hexanol, ethyl octanoate, diethyl succinate, hexanoic acid, 2-phenylethanol, octanoic acid, decanoic acid and geraniol, all significant for distinguishing the types of wines except 3 metil-1-butanol and 1-hexanol. The different wine samples were classified by multivariate statistical methods. Good differentiation between the different groups of samples was achieved by means of principal component analysis and hierarchical cluster analysis. Linear discriminant analysis was used to differentiate and classify these wines. 3-methyl-butyl acetate, ethyl octanoate, diethyl succinate, hexanoic acid, 2-phenylethanol and decanoic acid were the most discriminant variables and gave 100% recognition ability and 100% prediction ability.     

Method development and validation for cyprodinil and fludioxonil in blueberries by solid-phase microextraction gas chromatography,and their degradation kinetics

A method of analysis for residues of cyprodinil and fludioxonil in blueberries was developed. Fungicide residues were determined by solid-phase microextraction coupled to GC with nitrogen-phosphorous detection. The effect of pH values and fibre coatings was studied. The solid-phase microextraction fibre coating selected was 100 µm polydimethylsiloxane. The method was selective, with adequate precision and high accuracy and sensitivity. Apparent recoveries ranged within the 99–101% range for cyprodinil and the 98–100% range for fludioxonil; LODs and LOQs were 1.2 and 3.9 µg/kg for cyprodinil and 0.4 and 1.3 µg/kg for fludioxonil, respectively. Statistical parameters indicated a matrix effect; consequently, calibration was performed on spiked samples. Degradation of cyprodinil and fludioxonil was studied in a blueberry field located in Concordia (Argentina), with fruit from Emerald and Jewel varieties. The degradation of these fungicides in both blueberry varieties studied followed first-order rate kinetics for both fungicides, and the half-life for cyprodinil was 2.2 and 3.4 days for Emerald and Jewel cultivars, respectively, and for fludioxonil was 12.7 and 16.3 days, respectively.     

Evaluation of chemical indicators for monitoring freshness of food and determination of volatile amines in fish by headspace solid-phase microextraction and gas chromatography-mass spectrometry

A headspace solid-phase microextraction and gas chromatography–mass spectrometric (HS-SPME-GC-MS) method was developed to monitor methylamine (MA), dimethylamine (DMA) and trimethylamine (TMA) in fish. The alkylamines were extracted using carboxen/divinylbenzene/polydimethylsiloxane (CAR/DVB/ PDMS) fibres at 25 °C and exposure time of 5 min. Calibration curves showed good linearity in the concentration range of 0.5–10 μg ml⁻¹ and the corresponding coefficients of correlation were all above 0.99. Detection limits were estimated to be 0.10 μg ml⁻¹ for MA and DMA; and 0.15 μg ml⁻¹ for TMA. Intra-day and inter-day variation of spike samples at 2.0 μg g⁻¹ were 4.3–6.2% and 5.4–10%, respectively. Recovery of the method for TMA was found to be comparable to that of a standard titration method with the mean deviation of the two methods being 6.7%. The validated method was applied to study the decay profiles of the concerned alkylamines in two fish species that were stored at 0 and −20 °C; and the results obtained were compared with that obtained by using the classical parameter of total volatile basic nitrogen (TVBN).     

An accurate quantitative method for the analysis of terpenes in milk fat by headspace solid-phase microextraction coupled to gas chromatography–mass spectrometry

HS-SPME analysis of terpenes does usually have inherent quantification problems when working with complex samples, especially due to the matrix effect of the substrate or the calibration solution. Three different terpene carrier matrices were compared: methanol, synthetic oil and milk fat obtained by centrifugation from milk cream. Considerable differences in calibration sensitivity parameters were observed depending on the matrix used and on the type of terpene standard analysed. For milk sample quantification purposes internal standard method was preferred using milk fat as calibration matrix. Linearity range, repeatability, recovery and limits of detection and quantification were determined. Validation parameters were different depending on the concentration and molecular structure of each terpene analysed, particularly between mono- and sesquiterpenes. The method was useful to determine in an accurate manner the terpene content in milk samples from pasture fed animals, and it will help to establish objective terpene levels to differentiate milks from specific production systems.     

气相色谱法检测苹果中氟环唑、咪鲜胺及其代谢物的残留

目的建立气相色谱法检测苹果中咪鲜胺及其代谢物2,4,6-三氯苯酚和氟环唑残留的分析方法。方法匀浆样品加入1%乙酸乙腈振荡,再加入3 g NaCl、2 g无水Na2SO4高速振荡10 min,以5000 r/min离心5 min提取,之后经N-丙基乙二胺(primary secondary amine,PSA)净化,采用气相色谱法进行检测,外标法定量。结果苹果中3种农药在0.01~2.0 mg/L范围内呈良好线性(r2=0.999)。方法定量限为10~20μg/kg。平均回收率为74%~108%,相对标准偏差为2.90%~9.55%。结论该方法准确、快速、可靠,适用于苹果中咪鲜胺及其代谢物2,4,6-三氯苯酚和氟环唑残留量的检测。     

A headspace solid-phase microextraction method development and its application in the determination of volatiles in honeys by gas chromatography

The first part of the paper presents the detailed optimisation of all steps of the determination procedure of volatiles from Polish honeys by headspace solid-phase microextraction (HS-SPME) as the sample preparation method and gas chromatography/mass spectrometry (GC–MS) as the method of final determination. In the result, the following conditions were applied: CAR/PDMS/DVB SPME fibre, the sample composition (5:1 w/w honey to water ratio), 3 g sample size. The other procedure parameters, like the temperatures of individual stages of the process, were also included.     

Characterisation of sparkling cider by the yeast type used in taking foam on the basis of polypeptide content and foam characteristics

This paper describes the characterisation of sparkling ciders from Asturias, northern Spain, by means of the analysis of their protein content and their foam characteristics. A capillary sieving electrophoretic method was used in the protein analysis to determine molecular mass and the Bradford method to determine total protein content. The foam parameters were measured using the Bikerman method.     

固相萃取-气相色谱法测定螺旋藻中指示性 多氯联苯

目的建立气相色谱法测定螺旋藻中痕量多氯联苯的分析方法,以考查螺旋藻中7种指示性多氯联苯(polychlorinated biphenyls,PCBs)的残留情况。方法乙腈提取样品后,选用弗罗里矽柱对螺旋藻中指示性多氯联苯净化。色谱条件为:DB-17(30 m×0.25 mm,0.25μm)石英毛细管柱,采用程序升温分离,流速为1.0m L/min,进样量为1.00μL,电子捕获检测器检测。结果在优化的条件下,7种指示性多氯联苯在10~50μg/L范围内线性良好,相关系数(r)大于0.999,在螺旋藻空白样品中添加25、35、45μg/kg 3个水平的7种指示性多氯联苯,其加标回收率范围为90.8%~112%,相对标准偏差(RSD)范围为0.526%~3.89%。结论该方法具有操作简便、快速、准确的特点,适用于螺旋藻试样中指示性多氯联苯痕量残留的分析。     

顶空固相微萃取-气相色谱法测定山楂果胶酯化度

利用顶空固相微萃取与气相色谱联用（HS-SPME-GC）的方法测定山楂果胶的酯化度（包括甲酯化和乙酯化）,对影响检测结果的萃取头种类、萃取温度、平衡时间、萃取时间、盐离子浓度、解吸温度、解吸时间进行了优化。结果表明,HS-SPME-GC测定山楂果胶酯化度较优条件为:5 m L山楂果胶溶液中加48.8%硫酸钠,在40℃下平衡20 min,用75μm CAR-PDMS萃取头在40℃下萃取30 min,然后在280℃的GC进样口解析60 s。该方法线性良好r≥0.9983,检出限10¹5 mg/L,加标回收率为95.6%¹16.2%。该方法快速、简便、准确。      

APs气相色谱测定中固相萃取剂的优选

采用固相萃取-气相色谱法检测防水服中烷基酚(APs)类物质,通过比较C18柱、MAX柱、WAX柱和Abselut NEXUS柱四种固相萃取剂的洗脱剂种类、洗脱剂用量、洗脱速率和吸附容量,其结果表明,以Abselut NEXUS柱作为萃取剂,在3 mL甲醇作为洗脱剂,洗脱速率为3 mL/min的条件下,对防水服的水样进行固相萃取,然后用GC进行检测,在0.1~10.0 mg/L范围内线性关系良好。该方法对辛基酚(OP)和壬基酚(NP)检出限分别是0.013 mg/L和0.014 mg/L,加标回收率分别为98.45%和94.06%;相对标准偏差均小于3.5%,能够适用于市售防水服样品的检测。     

Analysis of the headspace volatiles of freshly brewed arabica coffee using solid-phase microextraction

ABSTRACT:  Headspace volatiles of freshly brewed drip coffee were investigated by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/olfactometry (GC/O, CharmAnalysis™) analyses. For this purpose, a solid-phase microextraction (SPME) sampling method for the headspace volatiles of freshly brewed drip coffee was developed. SPME fiber coated with divinylbenzene (DVB)/carboxen/polydimethylsiloxane (PDMS) was selected from 6 types, and sampling time was determined at 2 min. The headspace coffee volatiles stayed constant in proportion for the first 2 min to keep the freshness of the brewed coffee aroma. Using this sampling method, the headspace volatiles of freshly brewed drip coffee (Ethiopian arabica coffee, roast degree: L value; 23) were examined by GC/MS and GC/O analyses. From the GC/O results, 1-(3,4-dihydro-2 H -pyrrol-2-yl)-ethanone (nutty-roast odor) and 4-(4'-hydroxyphenyl)-2-butanone (raspberry ketone, sweet-fruity odor) were newly detected as components in the aroma of coffee.     

固相萃取净化-气相色谱法检测人乳中 持久性有机氯农药

目的 建立母乳中有机氯农药六六六和滴滴涕的检测方法, 并对北京、兰州和杭州三个地区的蓄积水平现状进行分析。方法 母乳样品用乙腈提取, 经过酸化的硅胶固相萃取柱净化, 浓缩后, 采用气相色谱仪检测。结果 8种农药的线性范围在5~200 ng/mL, 相关系数0.9955~0.9994, 定量限均小于2.6 μg/kg, 平均回收率在70%~122%, 相对标准偏差在3.91%~10.77%。结论 本方法结合磺化法和固相萃取法, 能有效去除基质中的杂质。通过方法学验证证明, 本方法操作简单、精确、快速, 适用于母乳中有机氯的检测。随着六六六、滴滴涕等持久性有机氯农药的禁用或严格限用, 母乳中持久性有机氯农药的蓄积水平明显降低。     

Detection of the adulteration of olive oils by solid phase microextraction and multidimensional gas chromatography

The presence or absence of filbertone in 21 admixtures of olive oil with virgin and refined hazelnut oils obtained using various processing techniques from different varieties and geographical origins was evaluated by solid phase microextraction and multidimensional gas chromatography (SPME–MDGC). The obtained results showed that the sensitivity achievable with the proposed procedure was enough to detect filbertone and, hence, to establish the adulteration of olive oil of different varieties with virgin hazelnut oils in percentages of up to 7%. The very low concentrations in which filbertone occurs in some refined hazelnut oils made difficult its detection in specific admixtures. In any case, the minimum adulteration level to be detected depends on the oil varieties present in the adulterated samples. In the present study, the presence of R- and S-enantiomers of filbertone could be occasionally detected in olive oils adulterated with 10–20% of refined hazelnut oil.     

A sensitive determination method for carbendazim and thiabendazole in apples by solid-phase microextraction−high performance liquid chromatography with fluorescence detection

A new analytical method for the determination of carbendazim (MBC) and thiabendazole (TBZ) in apples is reported, based on solid-phase microextraction (SPME) coupling HPLC with fluorescence detection. The main SPME and HPLC experimental conditions were optimized. The apples were first blended and centrifuged. Then, an aliquot of the resulting solution was subjected to SPME on a 60 µm polydimethylsiloxane/divinylbenzene (PDMS/DVB) fibre for 35 min at room temperature with the solution being stirred at 1100 rev min^–1. The extracted pesticides on the SPME fibre were desorbed in the mobile phase into the SPME/HPLC interface for HPLC analysis. The method was linear over the range 0.01–1 mg kg^–1 in apples for both MBC and TBZ, with detection limits of 0.005 and 0.003 mg kg^–1 and correlation coefficients of 0.9995 and 0.9998, respectively. The average recoveries for MBC and TBZ were 91.5 and 92.3% with the relative standard deviations (RSD) of 4.7 and 4.1% at the 0.1 mg kg^–1 level, and 94.6 and 96.1% with RSD of 3.3 and 3.8% at the 0.5 mg kg^–1 level, respectively. The method is simple, sensitive, organic solvent-free and is suitable for the determination of MBC and TBZ in apples.     

Preparative separation and purification of sulforaphene from radish seeds by high-speed countercurrent chromatography

Sulforaphene, a kind of isothiocyanates, derived from glucoraphenin which is the important ingredient of radish (Raphanus sativus L.) seeds, has shown significant pharmacological activities. In this paper, the separation and purification of sulforaphene from radish seeds, was achieved by high-speed countercurrent chromatography (HSCCC). A two-phase solvent system consisted of n-hexane–ethyl acetate–methanol–water (35:100:35:100, v/v/v/v) was applied. The revolution speed of the separation column, flow rate of the mobile phase and separation temperature were 800 rpm, 2 ml/min and 30 °C, respectively. From about 1000 mg amount of the crude plant extract, 249.4 mg of pure sulforaphene was obtained by one-step separation on a 280 ml HSCCC column. The purified sulforaphene was at a high purity of 96.9% and the mass recovery was more than 95%. The purity of sulforaphene was determined by HPLC analysis and its chemical structure was assessed by MS, ¹H NMR, ¹³C NMR and DEPT-135 NMR.