Determination of 2,4,6-trichloroanisole and 2,4,6-tribromoanisole on ng L-1 to pgL-1 levels in wine by solid-phase microextraction and gas chromatography-high-resolution mass spectrometry

A gas chromatography-high-resolution mass spectrometry (GC-HRMS) method using solid-phase microextraction (SPME) for the determination of 2,4,6-trichloroanisole (TCA) and 2,4,6-tribromoanisole (TBA) in wine at low ng L(-1) levels was developed. A robust SPME method was developed by optimizing several different parameters, including type of fiber, salt addition, sample volume, extraction and desorption time. The quantification limit for TCA and TBA in wine was lowered substantially using GC-HRMS in combination with the optimized SPME method and allowed the detection of low analyte concentrations (ng L(-1)) with good accuracy. Limits of quantification for red wine of 0.3 ng L(-1) for TCA and 0.2 ng L(-1) for TBA with gas chromatography-negative chemical ionization mass spectrometry and 0.03 ng L(-1) for TCA and TBA were achieved using GC-HRMS. The method was applied to 30 wines of which 4 wines were sensorically qualified as cork defected. TCA was found in three of these wines with concentrations in the range 2-25 ng L(-1). TBA was not detected in any of the samples.     

Effective analysis of rotundone at below-threshold levels in red and white wines using solid-phase microextraction gas chromatography/tandem mass spectrometry

Rotundone is an oxygenated sesquiterpene belonging to the family of guaianes, giving the 'peppery' aroma to white and black pepper and to red wines. Here we describe a novel, convenient protocol for the synthesis of rotundone, starting from a commercially available compound and requiring only two reaction steps, and an improved, faster method of GC separation (30 min) with selective quantisation of rotundone using tandem mass spectrometry in multiple reaction monitoring (MRM) mode with d(5)-rotundone as internal standard. With limits of detection (LODs) of 1.5 ng/L in white wine and 2.0 ng/L in red wine, intraday repeatability CV values of 6% and 5% at 50 ng/L and 500 ng/L and interday repeatability CV values of 13% and 6% at 50 ng/L and 500 ng/L, respectively, the improved protocol provides the desired sensitivity and selectivity for routine analysis of rotundone in both white and red wines. Initial application of this method highlighted the presence of unexpectedly high concentrations of rotundone, thus explaining the origin of the distinctive peppery aroma in Schioppettino and Vespolina red wines and in Gruener Veltliner white wines.     

Comparative study of two chromatographic methods for quantifying 2,4,6-trichloranisole in wines

Here we present the validation and the comparative study of two chromatographic methods for quantifying 2,4,6-trichloroanisole (TCA) in wines (red, rosé and white wines). The first method involves headspace solid-phase microextraction and gas chromatography with electron-capture detection (ECD). The evaluation of the performance parameters shows limit of detection of 0.3 ng l(-1), limit of quantification of 1.0 ng l(-1), recoveries around 100% and repeatability of 10%. The second one implies a headspace solid-phase microextraction and gas chromatography with mass spectrometric detection. The performance parameters of this second method are limit of detection of 0.2 ng l(-1), limit of quantification of 0.8 ng l(-1) and repeatability of 10.1%. From the comparative study we can state that both methods provide similar results and the differences between them are the better sensitivity of the GC-ECD method and the very shorter chromatogram running time of the GC-MS method. The two methods are able to quantify TCA below the sensorial threshold in red, rosé and white wines using just a calibration graph, thus they could be a very good tool for quality control in wineries.     

Direct determination of 2,4,6-tricholoroanisole in wines by single-drop ionic liquid microextraction coupled with multicapillary column separation and ion mobility spectrometry detection

This article evaluates the capability of single drop ionic liquid microextraction coupled with multicapillary column (MCC) and ion mobility spectrometry (IMS) for the determination of 2,4,6-trichloroanisole (2,4,6-TCA) in wines. The proposed methodology permits the direct analysis of the samples without any additional treatment other than dilution. This is achieved thanks to the selectivity provided by the ionic liquid selected as extractant, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide, as well as the response of the analyte in the IMS working in negative ionization mode. Moreover, the multicapillary column avoids the interference of ethanol in the ion mobility spectra. The analysis of the sample takes ca. 35 min to be completed. The limit of detection was low as 0.01 ng L(-1) using 2 mL of wine sample. Different calibration curves were constructed using aqueous standards, red and white wines, being the signals comparable, with an RSD similar to the method variability. Finally, a set of samples of different nature and packed in different containers were analysed. It was found than those with cork stoppers presented the highest concentration of 2,4,6-TCA.     

高效液相色谱-电喷雾离子阱质谱法测定红葡萄酒中酚类物质

建立了高效液相色谱-质谱联用(HPLC-MS)技术检测葡萄酒中酚类物质的方法,并评价其定量分析的准确性、线性、重复性和检出限,结果显示:16种酚类物质除芦丁和白藜芦醇糖苷外,平均加标回收率大于78%;相关系数R2>0.999,线性关系良好;保留时间和峰面积在日内(n=10)与日间(n=6)重复性的相对标准偏差(RSD)均分别低于2.0%和5.0%;检出限为0.05~1.0 mg/L。利用该方法对6个红葡萄酒中16种酚类物质进行了定性定量分析,其相对标准偏差(CV%)均小于5.0%,说明本方法简便、准确、灵敏、重现性好,可用于葡萄酒产品质量监控。     

Low pressure chemical ionization in ion trap mass spectrometry

This article presents the specificities of low pressure chemical ionization in ion trap mass spectrometry. One main feature is the ability to perform chemical ionization with liquid reagents as readily as with "conventional" gases (methane, isobutane and ammonia). The reactivities and analytical applications of gas and liquid reagents are summarized from literature data and are compared when possible.     

Fluorescence polarization immunoassay for rapid screening of ochratoxin A in red wine

A fluorescence polarization (FP) immunoassay, based on a monoclonal antibody and an ochratoxin A (OTA)-fluorescein tracer, has been developed for rapid screening of OTA in red wine. Wine samples were diluted with methanol and passed through aminopropyl solid-phase extraction columns prior to the FP assay. Average recoveries from samples spiked with OTA at levels of 2.0 and 5.0 ng/mL were 79% with RDS of 11% (n = 6). The limit of detection of the FP immunoassay was 0.7 ng/mL OTA, and the whole analysis was performed in less than 10 min. The assay was tested on 154 red wine samples (naturally contaminated or spiked at level ranging from 0.1 to 5.0 ng/mL) and compared with an high-performance liquid chromatography/immunoaffinity column clean-up method, showing a good correlation (r = 0.9222). Their compliance with the European regulation (2.0 ng/mL OTA maximum permitted level) was correctly assessed for 70% of the analyzed samples of red wine, whereas confirmatory analyses were required for the remaining ones with OTA levels close to the regulatory limit. No false-negative or positive results were observed using the FP immunoassay. The proposed FP assay is a useful screening method for OTA in red wines, when high throughput is required, that could also be used for white and rosé wines, which are known to contain less interfering compounds such as polyphenols.     

Determination of pesticide residues in red wines with microporous membrane liquid–liquid extraction and gas chromatography

A sample pretreatment method based on microporous membrane liquid-liquid extraction (MMLLE) was developed for the subsequent gas chromatographic determination of pesticides in wine. MMLLE provided efficient and selective extraction with enrichment factors in the range 3-13. The gas chromatographic separation was carried out using on-column injection and flame ionization detection. The method was linear, repeatable and sensitive. The limits of quantification were better than 0.006 mg/L for all the analytes except for iprodione (0.37 mg/L). The method was applied to the determination of pesticides in several red wines of different origin.     

Detection and identification of thyreostats in the thyroid gland by gas chromatography-mass spectrometry

Because thyreostatic compounds, also named thyreostats, are banned in Europe (directive 86/469/EEC), methods have to be developed to prevent the illegal use of these substances. The analytical procedure described herein involves the detection and identification at the low ng g⁻¹ level of the main thyreostats known to be used for growth promotion by gas chromatography coupled to mass spectrometry (GC-MS). The assay is based on a liquid/liquid extraction of the thyroid gland, derivatization with pentafluorobenzyl bromide (PFBBr), purification on a silica solid phase extraction column and finally a trimethylsilylation prior to GC-MS. Good thyreostat recoveries were obtained (from 40% to 70%) as well as at acceptable repeatability. The target analytes were detectable below the 1 ng g⁻¹ level on a quadrupole mass spectrometer with negative chemical ionization (NCI) using ammonia as reagent gas and the selected ion monitoring (SIM) acquisition mode. This limit of detection was also reached in the SIM high resolution mode. An improved specificity (more diagnostic ions) was obtained under electronic impact (EI) conditions and positive chemical ionization (PCI) with methane as reagent gas. Identification of thyreostats according to the EU (European Union) criteria (93/256/EEC decision) was made on the basis of two independent GC-MS techniques; the limit of identification was close to 5 ng g⁻¹ for most thyreostats, which represents a real improvement for their control.     

Determination of ochratoxin A in wine by means of immunoaffinity column clean-up and high-performance liquid chromatography

A new and accurate method to quantify ochratoxin A (OA) in table wine has been developed. The method uses commercial immunoaffinity columns for clean-up and high-performance liquid chromatography (HPLC) with fluorescence detection for quantification of the toxin. Wine was diluted with a solution containing 1% polyethylene glycol (PEG 8000) and 5% sodium hydrogencarbonate, filtered and applied to an OchraTest immunoaffinity column. The column was washed with a solution containing sodium chloride (2.5%) and sodium hydrogencarbonate (0.5%) followed by water. OA was eluted with methanol and quantified by reversed-phase HPLC with fluorometric detection (excitation wavelength 333 nm, emission wavelength 460 nm) using acetonitrile-water-acetic acid (99:99:2) as mobile phase. Average recoveries of OA from white, rosé and red wine samples spiked at levels from 0.04 to 10 ng/ml ranged from 88% to 103%, with relative standard deviations (RSDs) between 0.2 and 9.7%. Detection limit was 0.01 ng/ml based on a signal-to-noise ratio of 3:1. The method was applied successfully to 56 samples of red (38), rosé (8), white (9) and dessert (1) wine. The levels of OA ranged from <0.01 to 7.6 ng/ml with red wines more contaminated than rosé and white wines. A good correlation (r=0.987) was found by comparative analysis of 20 naturally contaminated samples using this method and the method of Zimmerli and Dick with better recoveries of OA and better performances for the new method. Several advantages of this method with respect to the actually available methods have been pointed out, with particular reference to red wine which appears to be the most difficult to analyze.     

Coacervative extraction of Ochratoxin A in wines prior to liquid chromatography/fluorescence determination

Coacervates made up of reverse micelles of decanoic acid were assessed as a new strategy for the simplification of wine sample treatment in the determination of Ochratoxin A (OTA). Simultaneous extraction/concentration of this contaminant was based on both hydrophobic and hydrogen bond OTA:coacervate interactions. Parameters affecting extraction efficiency and concentration factors were studied. Concentrations of decanoic acid and tetrahydrofuran (THF) were the most influential parameters, being 0.5% of acid and 5% of THF the selected ones. The procedure was very robust, so that the extractions were not influenced by the pH and the nature or concentration of matrix components. OTA recoveries from different types of wines (white, rosé and red) ranged between 85 and 100% and the actual concentration factors varied from 105 to 125 for sample volumes of 15 mL. The detection limits for OTA, after liquid chromatography/fluorimetry (LC/FL) analysis of the coacervate (20 microL), were 4.5 ng L(-1) in white and rosé wines and 15 ng L(-1) in red wines, values which were far below the threshold limit established for OTA by EU directives (2.0 microg L(-1)). No clean-up of the extracts was required for any of the samples analysed. The overall sample treatment took about 15-20 min and several samples could be simultaneously treated using conventional lab equipment. The precision of the method, expressed as relative standard deviation, was about 5%. The approach developed was successfully applied to the determination of OTA in different wine samples from the South of Spain. The concentrations found ranged between 0.015 and 0.091 microg L(-1).     

Determination of iodoacetic acid using liquid chromatography/electrospray tandem mass spectrometry

A rapid analytical method based on liquid chromatography/tandem mass spectrometry (LC/MS/MS) using electrospray ionization in negative ion detection mode was developed for the analysis of underivatized iodoacetic acid in water. The method was applied to model reaction mixtures in the study of the formation of iodoacetic acid after chlorinated tap water was boiled in the presence of potassium iodide or iodized table salt. Samples can be directly analyzed by the LC/MS/MS system without extraction or chemical derivatization. Limit of detection was determined to be 0.3 microg/L (or 0.3 ng/mL) and limit of quantitation was about 1 microg/L (1 ng/mL).     

高效液相色谱-串联质谱法检测红葡萄酒中功效成分

建立了高效液相色谱-串联质谱法快速测定葡萄酒中白藜芦醇、黄酮类、多酚类功效成分的分析方法。葡萄酒样品直接稀释后进样,用C18柱进行分离,以乙腈-0.1%(体积分数)甲酸水溶液为流动相进行梯度洗脱,通过多反应监测(MRM)模式进行检测。13种功效成分在各自线性范围内呈良好的线性关系,相关系数均大于0.99。除表没食子儿茶素、没食子儿茶素、儿茶素没食子酸酯、花旗松素的检出限为1.0、1.0、3.0、3.0μg/L外,其他9种化合物的检出限均小于1.0μg/L。回收率为80.9%~112.3%,相对标准偏差小于10%。该方法快速、准确、灵敏度高,适用于葡萄酒中功效成分的快速分析。对实际样品的检测表明,所测葡萄酒样品中均含有儿茶素、表儿茶素、表没食子儿茶素、没食子儿茶素、表儿茶素没食子酸酯/儿茶素没食子酸酯、白藜芦醇、大豆黄素等功效成分,不同品种葡萄酒中这些功效成分含量差异显著。     

A validated HPLC method for the quantitative analysis of trans-resveratrol and trans-piceid in Hungarian wines

A new, simple procedure for the determination of phenolic components of wines, such as resveratrol and piceid isomers, has been elaborated and validated. A set of 70 red wines and 3 white wines from two wineries (Polgar Winery and Bock Winery, Villany, Hungary) are analyzed by reversed-phase high-performance liquid chromatography. The samples are injected without pretreatment and UV-vis and mass spectrometric (MS) detection has been applied. The detection limit for trans-resveratrol and for trans-piceid is found to be 0.9 and 0.6 pmol for the UV-vis detection method and 0.3 and 0.2 pmol for the MS detection method. Trans-resveratrol and trans-piceid are found in red wines from 0.1 to 14.3 mg/L and from 3.8 to 16.4 mg/L concentrations, respectively.     

Chemical ionization mass spectrometry using a glow discharge ion source combined with a nebulizer sampling system

A glow discharge chemical ionization (CI) source equipped with a pneumatic nebulizer for sample introduction has been constructed. A comparative study of the discharge CI and conventional CI by electron impact from a hot filament is made for various polar compounds using oxygen-containing reagents such as water and methanol. The potential utility of the discharge ion source to liquid chromatography/mass spectrometry is also discussed.     

多维气相色谱法检测酒中甲醇

建立了多维气相色谱检测酒中甲醇含量的方法.采用自动进样器将酒类样品直接注入气相色谱进样口,依次经过非极性RTX-5ms色谱柱和极性HP-INNOWax色谱柱,由气相色谱质谱选择离子监测技术进行测定与确证.甲醇在1～10000 mg/L范围内呈线性相关;方法检出限为1 mg/L.各种酒类样品在5,50,250,400和8...     

超高效液相色谱-串联质谱同时检测血液中29种农药

本文采用超高效液相色谱-串联质谱法(UPLC-MS/MS)和固相萃取法(SPE)建立了血液中29种农药同时筛查、定性、定量分析的方法,血液经4%磷酸水溶液稀释后,震荡10min,以8000r·min-1转速离心10min,取上清液过3mL甲醇和3mL水活化好的Oasis Prime HLB(3cc,60mg)固相萃取小柱,使用3mL5%甲醇水淋洗,3mL乙腈甲醇混合溶剂(90:10)洗脱,接收洗脱液后在40℃条件下氮吹仪吹干,使用0.5mL初始流动相复溶,震荡10s后,过0.22μm水膜,装液质小瓶后进样分析。采用ACQUITY UPLC HSS C18色谱柱(150 mm×2.1mm,1.8μm)分离,流动相为0.1%甲酸乙腈-水/甲酸/甲酸铵(5mmol,pH=3),梯度洗脱,电喷雾电离正离子模式(ESI+),多反应选择离子监测模式(MRM)检测。29种农药的检出限为0.1 ng·mL^-1~5 ng·mL^-1,定量限为0.5 ng·mL^-1~10 ng·mL^-1,回收率为62.4%~97.4%,基质效应为82.8%~109%,相对标准偏差小于10.3%,相关系数均大于0.99,线性关系良好范围为10 ng·mL^-1~1000ng·mL^-1。本文方法灵敏度高,可以对血液中29种农药成分进行筛查、定性、定量分析,能够满足实际血液样品中农药成分检测的需求。     

Determination of perfluorocarboxylic acids in aqueous matrices by ion-pair solid-phase microextraction-in-port derivatization-gas chromatography-negative ion chemical ionization mass spectrometry

A rapid, selective and simple analytical procedure using tetrabutylammonium as ion pair in conjunction with solid-phase microextraction followed by in-port derivatization-GC-negative ion chemical ionization mass spectrometry was developed. The procedure allows an accurate determination of perfluoroalkylcarboxylic acids in aqueous samples at ng L(-1) levels (i.e. method detection limit 20 ng L(-1) forperfluorodecanoic acid) improving previous GC methods in terms of analysis time and sensitivity. Ammonia as reagent gas in the negative ion chemical ionization mass spectrometry increased the sensitivity at least 3-fold compared to methane for perfluorocarboxylic acid butyl esters. The developed procedure was successfully applied to effluents from wastewater treatment plants (i.e. 0.05-8.2 microg L(-1)) and harbor seawaters.     

Development of a liquid chromatography-electrospray mass spectrometric method for the simultaneous analysis of benzoxazolinones and their degradation products

A new method for the simultaneous analysis of some benzoxazolinones, aminophenoxazinones and malonamic acids was developed based on liquid chromatography (LC) coupled to mass spectrometry (MS), using electrospray ionization (ESI) and operating in positive mode. Different ESI-MS parameters, such as fragmentor voltage, capillary voltage, drying gas flow, nebulizer gas pressure and drying gas temperature, were optimized in order to obtain structural information and to achieve maximum sensitivity. Chromatographic separation was performed by a reversed-phase LC column using a linear gradient of water and methanol. Quality assurance of the developed method was assessed by measuring parameters as linearity, sensitivity, repeatability and reproducibility. Quantification method based on the use of internal standard was developed, selecting synthetic 2-methoxy-2H-1,4-benzoxazin-3(4H)-one as internal standard. Good correlations were obtained for all analytes relative to this compound in the range of 0.05-1.5 ng/microL. Instrumental detection limits were between 0.02 and 0.2 ng/microL. Repeatability and reproducibility studies showed acceptable coefficient of variation values.     

Multi-analyte approach for the determination of ng L(-1) levels of steroid hormones in unidentified aqueous samples

Since the 1970s, many analytical methods for the detection of illegal growth promoters, such as thyreostats, anabolics, beta-agonists and corticosteroids have been developed for a wide range of matrices of animal origin, including meat, fat, organ tissue, urine and faeces. The aim of this study was to develop an analytical method for the determination of ng L(-1) levels of estrogens, gestagens, androgens (EGAs) and corticosteroids in aqueous preparations (i.e. drinking water, drinking water supplements), commercially available on the 'black' market. For this, extraction was performed with Bakerbond C18 speedisk, a technique commonly used in environmental analysis. After fractionation, four fractions were collected using a methanol:water gradient program. Gas chromatography coupled to electron impact multiple mass spectrometry (GC-EI-MS2) screening for the EGAs was carried out on the derivatized extracts. For the detection of corticosteroids, gas chromatography coupled to negative chemical ionization mass spectrometry (GC-NCI-MS) was used after oxidation of the extracts. Confirmation was done by liquid chromatography coupled to electrospray ionization multiple mass spectrometry (LC-ESI-MS2). The combined use of GC and LC coupled to MS enabled the identification and quantification of anabolics and corticosteroids at the low ng L(-1) level. This study demonstrated the occurrence of both androgens and corticosteroids in different commercial aqueous samples.