Determination of mepiquat chloride in grape, wine and juice by liquid chromatography with electrospray tandem mass spectrometry

A simple and rapid method was developed for the analysis of mepiquat chloride in grape, wine and juice by high-performance liquid chromatography with electrospray tandem mass spectrometry (LC/MS/MS). Mepiquat chloride was extracted with water-methanol (1:1). Extracted solution was adjusted to pH 10 with ammonia solution. A part of the extracted solution was cleaned up on a styrenedivinylbenzene (SDVB) cartridge for LC/MS/MS. The LC separation was performed on a C18 column (50 mm x 2 mm i.d.) using 0.1% IPCC-MS7-methanol (60:40) as the mobile phase at a flow rate of 0.2 mL/min. The mass spectral acquisition was done in the positive ion mode by applying selected reaction monitoring (SRM). The recoveries of mepiquat chloride from fresh grape, wine and juice fortified at 5 microg/kg and 50 microg/kg were 84.5-96.1%. The lower limit of quantification was 1 microg/kg. Fourteen fresh grape samples, 14 wines (white), 36 wines (red) and 11 juice samples were analyzed by this method. Mepiquat chloride was detected in 5 fresh grape samples, 3 wines (white) and 1 wine (red) at the level of 12.8-199 microg/kg, 5.7-47.7 microg/kg and 24.1 microg/kg, respectively.     

Simple determination of main organic acids in grape juice and wine by using capillary zone electrophoresis with direct UV detection

An accurate, simple and rapid capillary zone electrophoresis (CZE) method with direct UV detection has been set up for the determination of main organic acids in grape juice and wine. The determination of tartaric, malic, and citric acids in grape juices and tartaric, malic, succinic, acetic, lactic and citric acids in wines can be achieved in less than 3 min with only a simple dilution and filtration treatment of the sample. Validation parameters of the method as detection and quantification limits, linearity, precision (intraday and interday analysis) and recovery were also studied in grape juice, white wine, rose wine and red wine, separately. The proposed method decreases the analysis times of the previous reported CZE methods and allows the rapid control of the grape maturity, the winemaking processes and the detection of wine alterations and/or illnesses.     

Determination of 13 Phenolic Compounds in Rice Wine by High-Performance Liquid Chromatography

Rice wines are widely consumed by the general public in Asian countries, while comprehensive studies focused on the individual phenolic compounds in rice wines are limited. A rapid method for simultaneous determination of 13 phenolic compounds in rice wines by high-performance liquid chromatography (HPLC) was developed and validated, and the phenolic compounds in commercial rice wine samples (Chinese rice wine, Japanese sake, and Korean makgeolli) were determined in this paper. The identified compounds contained gallic acid (GA), protocatechuic acid (PRCA), vanillic acid (VA), syringic acid (SRA), caffeic acid (CA), ferulic acid (FA), p-coumaric acid (pCA), sinapic acid (SA), chlorogenic acid (CHA), (+)-catechin (CAT), (?)-epicatechin (EPI), quercetin (QUE), and rutin (RUT). Phenolics were separated with a C18 reversed-phase column at 38 °C by gradient elution using 3 % acetic acid aqueous solution (solvent A) and acetonitrile (solvent B) (0 min, 5 % B; 5 min, 8 % B; 10 min, 15 % B; 20 min, 25 % B; and 25 min, 5 % B) as the mobile phase at 280 nm with flow rate of 1.0 mL min^?1. With direct injection of rice wine samples, the chromatograms of all analytes were observed within 20 min, all calibration curves were linear (R ²?>?0.995) within the range, limits of detection (LOD) ranged from 0.02 to 0.06 μg mL^?1, and good recoveries (88.07–106.80 %) and precision (relative standard deviation (RSD)?<?5.36 % ) were obtained for all compounds. This method was applied to quantify phenolic compounds in commercial rice wine samples (Chinese rice wine, Japanese sake, and Korean makgeolli), and good separation peaks were observed and catechin was the predominant phenolic in the samples. The average values of total phenolic contents of the three groups of rice wine were significantly different (p?<?0.01). In conclusion, this procedure can be used to determine the phenolic compounds in various types of rice wines, as well as to characterize and differentiate rice wine samples.     

Occurrence of ochratoxin A in Australian wine

A survey of 601 samples of Australian wine for the presence of ochratoxin A (OA) was undertaken. The study sampled predominantly bottled wines, approximately equal numbers of red and white wines, wines made from a range of grape varieties and wines from all the major producing areas and some of the minor ones. A validated HPLC assay that did not utilise expensive immunoaffinity columns was developed for quantifying OA in wine, with limits of detection and quantification of 0.02 and 0.05 μg/L respectively. OA was detected in 90 (15.0%) of the 601 samples, but at uniformly low levels, with 85% of positive samples containing less than 0.2 μg/L OA. Only one sample exceeded 0.5 μg/L OA and no sample exceeded 1.0 μg/L OA. No region of Australia appeared more or less likely to produce wines containing OA.     

Optimisation of the Amido Black assay for determination of the protein content of grape juices and wines

While the heat/chill stability of white wines cannot be predicted from the total protein concentration, this information is useful in assessing the effectiveness of fining treatments. We have adapted the Amido Black assay for use in grape juice and wine. The response of bovine serum albumin (BSA) was similar in water, model wine and model juice. The linear range of the assay (<100 mg l^?1) extends beyond protein concentrations typically found in grape juices and wines. The limit of quantification was 11.1 mg l^?1 for BSA in model wine and 7.6 mg l^?1 in model juice, while the limit of detection was found to be less than 3 mg l^?1 in either solution. In contrast to other methods of protein determination, this assay is not affected by common wine phenolic and pectic compounds or by glutathione. The mean response of BSA was similar in model juice and red and white grape juices. The mean response of BSA in red wine was lower than in white wine and model wine (p < 0.001), and there was considerable variation in response among wines. Protein concentrations determined using this method were reproducible (CV < 10%). This optimised assay can be used to monitor protein levels in grape juices and wines. © 2001 Society of Chemical Industry     

Analysis of Ochratoxin A in Wine by High-Resolution UHPLC-MS

A method for determination of ochratoxin A (OTA) in wines using a new-solid phase extraction clean-up procedure followed with ultra performance liquid chromatography (UHPLC)-Orbitrap MS based on two scan events (full-scan Fourier transform mass spectrometer [FTMS] and higher energy-induced collision dissociation[HCD] data-dependent MS/MS) in positive ionization mode has been developed. The limit of detection (LOD) was estimated at 0.46 μg l^?1 for white wine, 0.53 and 0.54 μg l^?1 for rosé and red wines, respectively. The limit of quantification (LOQ) was estimated at 1.57 μg l^?1 in white wine, 1.77 and 1.81 μg l^?1 in rosé and red wines. Recovery experiments were carried out with spiked samples at three concentration levels (2, 5 and 10 μg l^?1). The OTA recoveries in spiked white wine samples varied from 69.6 % to 99.8 %, while the recoveries for rosé and red wine samples were in the range of 63.0–110.2 % and 63.6–103.2 %, respectively. Finally, based on the results, it is concluded that the combination of C18 cartridge with conventional particle packed columns and UHPLC LTQ-Orbitrap XL is an appropriate procedure for OTA analysis in wines.     

Detection of ochratoxin A in tropical wine and grape juice from Brazil

BACKGROUND: Ochratoxin A (OTA) is the main mycotoxin found in grapes, wines and grape juices and is considered one of the most harmful contaminants to human health. In this study, samples of tropical wines and grape juices from different grape varieties grown in Brazil were analysed for their OTA content by high‐performance liquid chromatography. RESULTS: The detection and quantification limits for OTA were 0.01 and 0.03 µg L^?1 respectively. OTA was detected in 13 (38.24%) of the samples analysed, with concentrations ranging from < 0.03 to 0.62 µg L^?1. OTA was not detected in any of the grape juice samples. Most of the red wine samples proved to be contaminated with OTA (75%), while only one white wine sample was contaminated. However, the OTA levels detected in all samples were well below the maximum tolerable limit (2 µg L^?1) in wine and grape juice established by the European Community and Brazilian legislature. CONCLUSION: The results of this study indicate a low risk of exposure to OTA by consumption of tropical wines and grape juices from Brazil. © 2012 Society of Chemical Industry     

Ochratoxin A in wine and grape juice sold in Canada.

Ochratoxin A (OTA) was determined in 251 samples of wines and grape juice collected over 3 years in Canada. In total, 25/84 samples of red wine, 22/96 samples of white wine, 3/46 red grape juices and 1/25 white grape juices contained OTA levels above the limit of quantitation (LOQ). Canadian wines, when compared with imported products, showed both a lower OTA occurrence, noted as positive (19 versus 48% above the limit of detection (LOD) for wines), and a lower level of OTA contamination (upper bound mean of 17.5 versus 163pg ml(-1) for wines). Wines from the USA contained no quantifiable levels of ochratoxin A. OTA was found in Canadian and US grape juice samples, with 12.9% above the LOD and an upper bound mean of 13.3pg ml(-1). It was extracted from a wine or grape juice sample by passing it through an immunoaffinity column. The sample matrix was washed off the column with water. OTA was eluted from the column with methanol and quantitatively determined by liquid chromatography using a fluorescence detector. The presence of OTA was confirmed by esterification with boron trifluoride-methanol. The LOQ of OTA was estimated as 20 pg ml(-1) in white wine (S/N 10:1) and 40 pg ml(-1) in red wine, white grape juice and red grape juice (S/N 20.1). The LOD was estimated as 4pgml(-1) for white wine and 8pgml(-1) for red wine and white and red grape juices (S/N 3:1).     

进口西拉葡萄酒的HPLC-DAD-MS特征指纹图谱

建立进口西拉葡萄酒的高效液相色谱-二极管-离子阱质谱指纹图谱分析方法。样品采用乙酸乙酯萃取,旋转蒸发仪浓缩,甲醇溶解,高效液相色谱-离子阱质谱分析测定。色谱柱采用MG Ⅱ C18柱（150 mm×2.0 mm,5 μm）,以pH 3.0水-乙腈为流动相,梯度洗脱,流速0.25 mL/min,多波长检测,离子阱质谱采用负离子模式,扫描范围m/z 50～1 200,可对没食子酸等11 个组分进行定性和定量。维拉西拉葡萄酒的15 个共有峰在60 min内得到良好分离,通过与标准品比较,对其中6 个峰进行了确证,10 批次维拉西拉葡萄酒的相似度均大于0.9。方法简便、灵敏、稳定、精确,生成的葡萄酒指纹图谱能够用于进口西拉葡萄酒的质量评价。     

Proteins in white wine, I: Procyanidin occurrence in soluble proteins and insoluble protein hazes and its relationship to protein instability

The presence of procyanidins in wine protein fractions was established by a chemical assay and by pyrolysis DI-EI MS/MS of proteins. The chemical assay, involving acid-catalysed oxidative degradation of the procyanidins, gave cyanidin which was specifically quantified by HPLC. The assay was calibrated with purified grape seed tannin (GST); procyanidin was expressed in μg GST. Cyanidin yields were little altered by the presence of a large excess of protein. The limit of detection of the assay was 1 μg GST and the limit of quantification 3.5 μg GST. Both heat-induced and natural hazes isolated from various white wines were all shown to contain procyanidins, with a content ranging from < 0.02 to 4.9% (w/w). Although a crude soluble protein isolate from white wine contained a detectable amount of procyanidins, none were found in fractions separated chromatographically from this isolate. This observation, and the absence of procyanidins in resolubilised heat-induced haze, demonstrated that procyanidins are only weakly associated with both heat-induced hazes and soluble wine proteins. Nevertheless, procyanidins appear to be implicated in the formation of protein hazes in wine, because many soluble wine proteins that had been rendered free of procyanidins would precipitate to give haze in wine but not in model wine which was devoid of phenolic compounds.     

High throughput residue analysis of paraquat and diquat involving hydrophilic interaction liquid chromatographic separation and mass spectrometric determination

A selective, sensitive and robust LC-MS/MS method is reported for the determination of the residues of paraquat and diquat in various fruit matrices, including grape, apple and pomegranate. The extraction with acidified water (0.1 M HCl) at 80°C (15 min) offered superior recoveries for both analytes with a significantly lower matrix effects as compared to the extraction with acidified methanol by the methods reported in the existing literature. The optimised HPLC conditions on hydrophilic interaction liquid chromatography (HILIC) columns, when coupled with electrospray ionisation-tandem mass spectrometry, offered their limit of quantification at 0.01 mg kg^?1. The analysis on an XBridge HILIC column required a thorough optimisation of the gradient programme to induce chromatographic separation and minimise matrix effects. This was not necessary when a CORTECS HILIC column was used, which provided selective and sensitive analysis within 5 min runtime using isocratic flow. Isotopically labelled internal standards corrected the recoveries of both analytes within 70–120% (RSD < 20%). For the first time, the applications of high resolution accurate mass analysis in the ‘time of flight – multiple reaction monitoring’ mode have been demonstrated as a complementary means of targeted screening of these compounds at 0.01 mg kg^?1 level. The method has a strong potential for applications in both official control and by those involved in food production for checking compliance with the EU MRLs.     

A Sensitive Method for the Rapid Determination of Underivatized Ethyl Carbamate in Fortified Wine by Liquid Chromatography-Electrospray Tandem Mass Spectrometry

This work presents the optimization of a miniaturized liquid-liquid extraction (mLLE) followed by reversed-phase liquid chromatography-electrospray tandem mass spectrometry (RP-HPLC-MS/MS) for the determination of ethyl carbamate (EC) in fortified wine, without using derivatizing agents. The mLLE was optimized by an experimental design. Thus, 15 mL of wine and 8 mL of ethyl acetate were used for the extraction. After concentration, each extract was injected into the HPLC-MS/MS equipment and the characteristic secondary ion transition of EC (m/z = 90.10 → 62.05) was used for the quantification purposes. The proposed method presented a good linearity (R ² = 0.9999) and a high sensitivity with low limits of detection (LOD) and quantification (LOQ), 0.17 and 0.52 μg L^?1, respectively. The precision (repeatability and reproducibility) never exceeded 8% of variation, and the recoveries varied between 93 and 114%. The applicability of the method was checked through the analysis of 24 fortified wines, with EC values ranging between 23 ± 1 and 194 ± 5 μg L^?1. All chromatograms revealed good peak resolutions. This new method is efficient for the simple, fast, and reliable determination of EC in fortified wines, providing great sensitivity without using derivatizing agents or large volumes of organic solvents.     

Occurrence of ochratoxin A in wine and grape juice marketed in Rio de Janeiro, Brazil.

Ochratoxin A (OA) is receiving attention world-wide because of the hazard it poses to human health. The aim was to test the distribution of OA in grape juice, pulps of frozen grapes, and national and imported table wine obtained from markets in Rio de Janeiro, Brazil. Analytical methodology using immunoaffinity column for OA extraction and clean-up with a final separation on a reversed-phase (C(18)) column and fluorescence detection in high-performance liquid chromatography showed a detection limit of 21 ng l(-1). The mean recovery was 91% for red wines and 82% for white wines; while the mean recoveries for juices and pulps of frozen grapes were 91.6 and 88%, respectively. Of 64 samples of grape juice and frozen pulps, 25% were positive for OA, being the mean content of 37 ng l(-1) with a maximum concentration of 100 ng l(-1). In wines, the mean concentration detected in 80 samples analysed was 34.4 ng l(-1) with 28.75% of positive samples. Red wines showed the highest percentages and levels of contaminated samples: 38% and 37 ng l(-1), respectively. The white wine contained levels above 26 ng l(-1) in 17.75% of the analysed samples. The levels of contamination detected in red wine sold in Río de Janeiro were not enough to surpass the virtually safe dose established as 5 n g kg(-1) body weight of daily intake.     

UPLC法同时检测新疆葡萄酒中的7种单体酚

建立了一种测定葡萄酒中7种单体酚含量的超高效液相色谱（UPLC）检测方法。采用ACQUITY BEH C18色谱柱,以甲醇/乙酸铵-乙酸缓冲溶液为流动相,0.2 mL/min梯度洗脱,变波长检测,各化合物线性关系较好（R2＞0.993）,不同的添加水平的回收率在84.0%~108.4%范围,方法重复性较好（RSD≤6.08%）。该文利用UPLC法分析了不同地区、不同年份的葡萄酒中7种单体酚的含量,结果表明,葡萄酒中含有丰富的单体酚,单体酚的含量因酒样含糖量、品牌、厂家和原料产地不同而差别很大。     

The application of an improved method for trans-resveratrol to determine the origin of Greek red wines

A rapid and sensitive method has been developed for the determination of trans-resveratrol in wine. This method consists of a solid phase extraction step followed by a rapid HPLC quantification step (30 min). The improvement of this method consists of the washing step of the solid phase extraction method carried out at pH 8.0 (12% ethanol in a phosphate buffer solution), thus permitting a more efficient removal of the interfering phenolic compounds in conjunction with the required low volume of tested sample. Trans-resveratrol content was determined for 29 red Greek wines of appellation of origin. The concentrations found varied between 0.550 and 2.534 mg/l. The wines produced by grape varieties grown in the Greek islands (Rhodes, Crete and Paros) were richer in trans-resveratrol. The grape variety Mandilaria, in particular, was the Greek variety with the highest trans-resveratrol content.     

Simultaneous Determination of Phenolic Compounds in Different Matrices using Phenyl-Hexyl Stationary Phase

A novel unique liquid chromatographic method has been developed consisting of diode array and fluorescence detection, using phenyl-hexyl stationary phase of the column, for the determination of over thirty phenolic compounds (anthocyanins, flavonols, flavan-3-ols, hydroxybenzoic acids, hydroxycinammic acids, and stilbenes). The method was validated including the following parameters: linearity, limits of detection and quantification, precision, and reproducibility. Excellent selectivity and sensitivity have been achieved. Detection levels ranging from 1.79?×?10^?5 mg/L to 0.26 mg/L were obtained. New fluorescence wavelengths for detection of flavan-3-ols (λ _ex?=?225 and λ _em?=?320 nm) were more sensitive than previously published. The new optimized method showed good repeatability and reproducibility, and values for relative standard deviations (RSD) were less than 3 %. Applicability of the method was demonstrated for five different matrices, white and red wine from Vitis vinifera cultivars, apple cider, blackberry wine, and grape skin extracts, showing that method is robust and can be applied for routine analysis.     

GAS CHROMATOGRAPHIC DETERMINATION OF TYROSOL AND TRYPTOPHOL IN WINES AND BEERS

A gas chromatographic method for the determination of tyrosol and tryptophol in wines and beers has been developed. The aromatic fusel alcohols are extracted with ether or ethyl acetate from a sample made alkaline with Na₂CO₃ and saturated with NaCl. In beer determinations the extraction is performed with ethyl acetate in order to avoid complications caused by emulsion. Most of the solvent is removed by distillation and the rest is cautiously allowed to evaporate. The gas chromatographic determination of tyrosol and tryptophol is performed in a 0·5-m. Apiezon M-DEGS column at 190°C. According to the infra-red spectra, both components are eluted without being decomposed at this temperature. In the grape wines investigated, tyrosol was found in amounts of 10–40 mg. per litre, in two Finnish berry wines 10–15 mg. per litre and in two different types of pale lager beers 5–10 mg. per litre. The same samples contained about 1–4 mg. tryptophol per litre. The two white grape wines and one red berry wine were exceptional, with only 0·2–0·3 mg. tryptophol per litre.     

Ochratoxin A in wines,musts and grape juices from Spain

A survey on the occurrence of ochratoxin A (OTA) in 240 grape‐based beverages was carried out. Red and white wines from four different Spanish Designations of Origin (n = 160), musts (n = 20), grape juices (n = 10), ordinary wines (n = 20), special wines (Malaga, muscatel, sherry, vermouth, etc) (n = 20) and sparkling wines (n = 10) were assayed for OTA content using immunoaffinity column clean‐up and high‐performance liquid chromatography with fluorimetric detection (detection limit 0.05 µg l^?1). Forty‐three (17.9%) of the samples tested contained detectable levels of OTA. The overall mean OTA concentration in red and white wines of Designations of Origin was 0.30 and 0.18 µg l^?1 respectively (ranges 0.05–3.19 and 0.05–1.13 µg l^?1 respectively). The percentage of wine samples with detectable amounts of OTA was higher for red (18.3%) than for white (10%) wines. OTA was also found in two of 10 red ordinary wines (0.68 and 4.24 µg l^?1), whereas none of 10 white ordinary wines contained OTA. The mean OTA amount detected in sparkling wines was 0.44 µg l^?1 (range 0.14–0.71 µg l^?1). Two of 20 must samples contained OTA at low levels (0.08 and 0.18 µg l^?1), while none of 10 grape juice samples contained OTA. Highest amounts of OTA were found in special wines (45%), with a maximum of 15.25 µg l^?1 in a muscatel sample. Copyright © 2004 Society of Chemical Industry     

Flow-Based System for the Determination of Titratable Acidity in Wines

A flow injection analysis system with a spectrophotometric detection was arranged in order to develop a simple and fast methodology for the quantification of titratable acidity in different types of wines. In the proposed system, a precise volume of sample is injected in the carrier stream, composed by a mixture of OH^? solution with the pH indicator, bromothymol blue (BTB). Consequently, a change on the colour of the carrier solution is achieved and quantified by spectrophotometry. Therefore, it was possible to establish a linear range up to 0.16 g/L expressed as tartaric acid, with a limit of detection and quantification of 0.01 and 0.05 g/L, respectively. The proposed work has a low sample and reagents consumption, only 96 μg of BTB, 336 mmol de OH^? and 50 μL of sample were needed per assay. At the same time, a high determination rate was achieved, 75 determinations per hour. The developed methodology was applied on the quantification of total acidity in red and white table wine and port wine samples.     

Fast and Selective Determination of Ochratoxin A in Wines Using an Optimized and Validated Liquid Chromatographic Method

Determination of ochratoxin A (OTA) in wines requires a cleanup step using solid phase extraction (SPE). Immunoaffinity columns are commonly the columns of choice but due to its high cost, other SPE columns have been assayed without optimal results. The present work reports an optimized and validated liquid chromatographic method for a fast and selective quantification of OTA in wines using C₁₈ columns for cleanup. Chromatographic conditions were optimized using a central composite design, establishing the following optimal conditions: acetonitrile/water/acetic acid (59.5:39.5:1.0 v/v/v) as mobile phase, flow rate of 1.2 mL min^?1, and column temperature of 30 °C. With these conditions, OTA had a retention time (~4 min) up to five times lower than those reported earlier. Regarding validation, calibration data (n?=?8) fitted a linear regression model with a determination coefficient (R ²) of 0.9992. Repeatability (relative standard deviation (RSD)) and intermediate precision (RSD) in matrix showed values of 1.3 % (n?=?6) and 0.8 % (n?=?3), respectively. Recoveries at five levels ranged from 87.2 to 118.9 % (mean RSD of 7.4 %). Fifty-three samples from different origins were analyzed, finding only seven samples (13 %) with quantifiable OTA content (0.15–0.26 μg L^?1). According to the levels found, the contribution of wine consumption to OTA daily intake was at least 58 times lower than the current tolerable daily intake. In view of optimization and validation results as well as its applicability to real samples, this method could be considered a good alternative for routine analysis of OTA in wines.