Uptake of the cyanobacterial toxin cylindrospermopsin in Brassica vegetables

Toxin-producing cyanobacterial species are increasingly being found in freshwater systems. However, literature on the impact of many cyanobacterial toxins on plants is scarce. Cylindrospermosin (CYN), a secondary metabolite of cyanobacteria such as Cylindrospermopsis and Aphanizomenon species, is a potent hepatotoxin and protein synthesis inhibitor. Worryingly, CYN is increasingly found in surface and drinking water worldwide causing human and animal intoxications. Further, exposure of crop plants to CYN by irrigation with contaminated water has already been shown. Therefore, in this study, horticulturally important and highly consumed Brassica species were investigated to determine the level of CYN in the leaves after exposure of the roots to the toxin. Treatment of Brassica oleracea var. sabellica, Brassica juncea, and Sinapis alba under varying experimental conditions showed significant CYN uptake, with CYN levels ranging from 10% to 21% in the leaves compared to the CYN concentration applied to the roots (18–35 μg/l). In seedlings, CYN concentrations of up to 49 μg/g fresh weight were observed. Thus, crop plants irrigated with CYN-containing water may represent a significant source of this toxin within the food chain.     

Analysis of nisin A,nisin Z and their degradation products by LCMS/MS

The peptides nisin A and nisin Z belong to type-A lantibiotics applied as preservatives in cheese production. The present study optimised and validated a liquid chromatography–tandem mass spectrometry (LCMS/MS) method for the analysis of nisin A in cheese. Since nisin A was not detectable in nisin-containing commercial cheese samples, an additional LCMS/MS method for the quantification of nisin Z was developed and validated. Quantification was performed by external calibration and standard addition. The latter method provided a non-significantly higher recovery rate for the tested cheese matrix. During the production of processed cheese, nisin A and nisin Z undergo significant degradation. Six degradation products of nisin A or nisin Z, respectively, were detected and assigned to nisin A/Z + H₂O, nisin A/Z^1–32, and nisin A/Z^1–32 + H₂O. In two out of eight commercial processed cheese samples, 1.6, resp. 1.7 mg nisin Z/kg cheese was measured, whereas nisin A was not detectable in any of the samples.     

Determination of quinolone residues in tilapias (Orechromis niloticus) by HPLC-FLD and LC-MS/MS QToF

A method for the simultaneous determination of flumequine, oxolinic acid, sarafloxacin, danofloxacin, enrofloxacin, and ciprofloxacin in tilapia (Orechromis niloticus) fillet, using high-performance liquid chromatography with fluorescence detection (HPLC-FLD) is presented. The quinolones were extracted from the food matrix with a solution of 10% trichloroacetic acid and methanol (80:20 v/v). Clean-up of the extract was performed using polymeric solid-phase extraction cartridges. Identification of the quinolones was confirmed by liquid chromatography-tandem mass spectrometry. The HPLC-FLD method was validated in-house and the following analytical parameters were obtained: linearity higher than 0.99 for all the quinolones; intra- and inter-assay precisions were lower than 3.5% and 10.9%, respectively; and recoveries ranged from 73% to 110%. The limit of quantification was below the maximum residue limit established by the Joint Expert Committee on Food Additives (JECFA), which indicates that the method is appropriate for the determination of quinolones in fish fillet.     

Microwave pretreatment and gas chromatography–mass spectrometry determination of herbicide residues in onion

A rapid multi-residue method was developed for the determination of 16 herbicides in onion. The analytical procedure was based on preventing formation of sulfur-containing compounds in onion by microwave inactivation of the enzyme alliinase. The onion samples which had been pretreated were extracted with acetonitrile and cleaned by solid-phase extraction. The herbicide residues in onion were detected by gas chromatography/mass spectrometry with selected ion monitoring. The recoveries of 16 herbicides ranged from 69.2% to 105.0% with the relative standard deviations (RSD) below 10.7%. The limit of quantitation (LOQ) ranged from 0.003 to 0.015 mg kg⁻¹. The method was applied to the analysis of herbicide residues in onion samples.     

Characterisation of volatile and non-volatile metabolites in etiolated leaves of tea (Camellia sinensis) plants in the dark

Aroma is an essential factor affecting the quality of tea (Camellia sinensis) products. While changes of volatile compounds during tea manufacturing have been intensively studied, the effect of environmental factors on volatile contents of fresh tea leaves has received less attention. We found that C. sinensis var. Yabukita kept in darkness by shading treatment for 3 weeks developed etiolated leaves with significantly increased levels of volatiles, especially volatile phenylpropanoids/benzenoids (VPBs). Upstream metabolites of VPBs, in particular shikimic acid, prephenic acid, and phenylpyruvic acid, showed lower levels in dark treated than in control leaves, whereas the contents of most amino acids including l-phenylalanine, a key precursor of VPBs, were significantly enhanced. In addition, analysis by ultra performance liquid chromatography-time of flight mass spectrometry, capillary electrophoresis–time of flight mass spectrometry, high performance liquid chromatography, and gas chromatography–mass spectrometry indicated that volatile and non-volatile metabolite profiles differed significantly between dark treated and untreated leaves.     

食品中杀草强残留量的检测方法研究

建立了一套检测食品中杀草强的液相色谱及液相色谱- 质谱分析方法,采用高效液相色谱荧光检测器(LCFLD),在激发波长380nm、发射波长484nm 条件下,高效液相色谱串联四级杆质谱配大气压电离源(LC-MS/MSAPCI),在多反应监测(MRM)模式下,母离子m/z 85、定量子离子m/z 43、定性子离子m/z 57、碰撞能量m/z85 ＞ m/z 57 为56.9/11eV、m/z 85 ＞ m/z 43 为58.1/11eV、裂解电压100V 条件下,分别对杀草强残留量进行检测,其中液相色谱荧光检测器法杀草强的检出限0.01mg/kg;液相色谱串联质谱法杀草强的检出限为0.005mg/kg。该方法简便、快速,分析结果准确、可靠,两种仪器条件可灵活选择,适用于食品中杀草强残留量的快速检测。     

Influence of extraction procedures on phenolic content and antioxidant activity of Cretan barberry herb

The main goal of present study was the development, optimization and application of different extraction protocols, especially those employing green technologies, in order to obtain from Berberis cretica extracts with high antioxidant capacity. For this purpose, the applied methods: maceration, ASE and SFE coupled with ASE were incorporated. The antioxidant assessment was carried out using DPPH and total phenolic content (Folin–Ciocalteu) assays. Major constituents were elucidated using HPLC-DAD and UHPLC–HRMS/MS (hybrid IT-Orbital trap spectrometer) equipped with an ESI probe.     

Germination induces the glucosylation of the Fusarium mycotoxin deoxynivalenol in various grains

In food, the mycotoxin deoxynivalenol (DON) often occurs in conjunction with its 3-β-d-glucopyranoside (D3G). The transformation of DON to D3G through glucosylation is catalysed by plant enzymes, however, the exact circumstances are not well understood. In order to investigate the role of enzymatic glucosylation in germinating grains, DON treated kernels were steeped and germinated under laboratory conditions. Furthermore, the effect of malting on the DON content of the contaminated barley was investigated. In all cases, DON and its derivatives were quantified by HPLC-MS/MS before, during and after the experiments. Amongst the six tested cereals; wheat, rye, barley, spelt, and millet transformed DON to D3G during germination whilst the oats were inactive. For wheat, barley, and spelt the initial DON content was reduced by 50%, with the loss being almost entirely accounted for by D3G formation. As D3G might be cleaved during digestion, the elevated D3G concentration may obscure the toxicologically relevant DON content in processed food and beer. The germination process has a major influence on the “masking” of DON, leading to high quantities of D3G that may be missed in common mycotoxin analyses.     

Matrix effects on the bioavailability of resveratrol in humans

The pharmacokinetics of resveratrol in 11 healthy male volunteers has been assessed in a randomized, crossover, controlled clinical trial after the administration of three grape products: red wine (250 mL), grape juice (1/L), or tablets (red wine extracts enriched with trans-resveratrol). Doses of trans-resveratrol independently of the product administered, were about 14 μg/kg. Biological samples were collected and analysed by capillary gas chromatography–mass spectrometry. cis-Resveratrol, trans-resveratrol and dihydroresveratrol were determined in plasma and urine. Plasma concentration of trans-resveratrol after hydrolysis increased as a response to all grape products and that of cis-resveratrol after wine and grape juice. Free forms of these phenolic compounds were deemed undetectable in plasma. Despite similar trans-resveratrol doses being administered, its bioavailability from wine and grape juice was 6-fold higher, than that from tablets. Resveratrol was better absorbed from natural grape products than from tablets, pointing out the importance of the matrix in its bioavailability.     

超高效液相色谱-串联质谱法检测畜肉及内脏中苯甲酸和马尿酸残留

建立超高效液相色谱-串联质谱技术对畜肉及内脏中苯甲酸和马尿酸进行检测。通过加标回收优化提取溶剂和净化方式,最终选择纯甲醇提取,经PRiME HLB固相萃取小柱净化,采用多反应监测模式检测,外标法定量。结果表明：苯甲酸在20～1 000 ng/mL、马尿酸在4～200 ng/mL质量浓度范围内线性关系良好,线性相关系数均大于0.99,检出限分别为12.5?μg/kg和2.5?μg/kg,定量限分别为50?μg/kg和10?μg/kg;在3个添加水平的回收率在70.5%～99.7%之间,精密度相对标准偏差在0.3%～7.1%之间（n=6）;方法具有良好的重复性和日内、日间稳定性,相对标准偏差不大于7.2%。该方法前处理简单、准确灵敏、回收率好,可为畜肉及内脏中苯甲酸和马尿酸残留量的监管提供技术支持。     

Study of hydroxycinnamic acids and malvidin 3-monoglucoside derivatives using capillary zone electrophoresis and ultra-performance liquid chromatography

Model solutions (pH = 3.5, 12% ethanol) of malvidin 3-O-glucoside (Mv3glc), the most common free anthocyanin in grapes and red wines from Vitis vinifera, and three free hydroxycinnamic acids present in wines (caffeic, ferulic and p-coumaric acids) were studied.     

Comparison of GC and colorimetry for the determination of alkylresorcinol homologues in cereal grains and products

Cereal alkylresorcinols (ARs), a group of phenolic lipids mainly found in the outer parts of wheat and rye kernels, are currently being studied for possible use as biomarkers of intake of whole grain wheat and rye foods. Several different techniques have been used for quantitative AR analysis over the years, but with limited attempts to compare them. In this present study, two commonly used methods, gas chromatography and colorimetry, were evaluated and compared. Gas chromatographic and the colorimetric methods showed good agreement. The GC-method provides the total amount of AR and relative homologue composition, whereas the colorimetric method, which is based on azo-coupling of a Fast Blue salt to the hydroxyl group(s) in the alkylresorcinol molecule, only provides the total amount, but is much faster and does only requires a UV-spectrophotometer.     

Rapid determination of organophosphorous pesticides in leeks by gas chromatography–triple quadrupole mass spectrometry

A rapid multi-residue method was developed for the determination of 20 organophosphorous pesticide residues in leeks by gas chromatography coupled to triple quadrupole mass spectrometry (GC–QqQ-MS/MS). The method was based on the modified QuEChERS sample preparation method. After microwave pre-treatment, leek samples were extracted with acetonitrile containing acetic acid 0.1% and cleaned by dispersive solid phase extraction. The QqQ analyser acquired data in selected reaction monitoring (SRM) mode. Recoveries of 20 organophosphorous pesticides ranged from 81.0% to 109.4% with the relative standard deviations (RSD) below 10.4%. The limits of detection (LODs) were 0.07–1.5 μg/kg. The limits of quantitation (LOQs) ranged from 0.25 to 5 μg/kg. Ten leek samples were analysed for method application.     

Development and validation of an HPLC-method for determination of free and bound phenolic acids in cereals after solid-phase extraction

Whole cereal grains are a good source of phenolic acids associated with reduced risk of chronic diseases. This paper reports the development and validation of a high-performance liquid chromatography–diode array detection (HPLC–DAD) method for the determination of phenolic acids in cereals in either free or bound form. Extraction of free phenolic acids and clean-up was performed by an optimised solid-phase extraction (SPE) protocol on Oasis HLB cartridges using aqueous methanol as eluant. The mean recovery of analytes ranged between 84% and 106%. Bound phenolic acids were extracted using alkaline hydrolysis with mean recoveries of 80–95%, except for gallic acid, caffeic acid and protocatechuic acid. Both free and bound phenolic extracts were separated on a Nucleosil 100 C₁₈ column, 5 μm (250 mm × 4.6 mm) thermostated at 30 °C, using a linear gradient elution system consisting of 1% (v/v) acetic acid in methanol. Method validation was performed by means of linearity, accuracy, intra-day and inter-day precision and sensitivity. Detection limits ranged between 0.13 and 0.18 μg/g. The method was applied to the analysis of free and bound phenolic acids contents in durum wheat, bread wheat, barley, oat, rice, rye, corn and triticale.     

The interactive effects of irrigation,nitrogen fertilisation rate,delayed harvest and storage on the polyphenol content in red grape (Vitis vinifera) berries: A factorial experimental design

Polyphenol concentrations, including anthocyanidins, flavonols, flavan-3-ols and stilbenes, were quantified by liquid chromatography/mass spectrometry in two cultivars of red grapes for daily consumption, which were subjected to different kinds of water supply and nitrogen fertilisation rates. Samples from the same vineyards were also analysed after a 6 week storage in a refrigerator and 6 week delayed harvesting. Berry skins and seeds were analysed separately.     

Formation of the highly stable pyranoanthocyanins (vitisins A and B) in red wines by the addition of pyruvic acid and acetaldehyde

Pyruvic acid (500 mg/l) and acetaldehyde (200 mg/l) were added, either as a large single dose or as smaller weekly doses over a 10 week period, to a young red wine (Vitis vinifera L. cv Tempranillo) in order to study the formation of vitisin A and B, and p-coumaroylvitisin A and B. In a further trial, pyruvic acid and acetaldehyde were added simultaneously as a single administration to test for any synergistic effect on vitisin formation. The addition of pyruvic acid led to the production of higher concentrations of vitisin A (4.08 ± 0.86 mg/l; 2.03% of the total anthocyanin content), while additions of acetaldehyde increased the concentration of vitisin B (2.47 ± 0.09 mg/l; 1.35%). The single, large dose administrations led to greater vitisin formation than did the smaller, weekly doses. Different patterns of formation were seen for vitisin A and B: the highest vitisin A content was achieved during the latter half of the 10 week study period while the highest vitisin B concentration was achieved early. The addition of acetaldehyde produced a greater reduction in monomeric anthocyanins than did the addition of pyruvic acid (loss of total anthocyanins 81.5%). The simultaneous addition of pyruvic acid and acetaldehyde led to less vitisin formation than did the addition of the reagents separately. p-Coumaroylvitisin A reached a maximum concentration of 0.86 ± 0.15 mg/l when the single dose of pyruvic acid was added, while the maximum recorded for p-coumaroylvitisin B was 0.66 ± 0.05 mg/l when the single dose of acetaldehyde was added. All anthocyanins were identified using HPLC/DAD and HPLC/ESI–MS.     

UPLC-MS/MS同时测定铁皮石斛茎、叶、 花中酚类组分的含量

建立超高效液相色谱-串联质谱同时、快速分析18种酚类物质的方法,测定比较铁皮石斛茎、叶、花部位含量差异.样品用甲醇-水溶液提取,提取液中的目标化合物经Waters?T3?C18柱梯度洗脱分离,电喷雾串联三重四极杆质谱仪正、负离子扫描方式多反应监测模式检测.结果表明:以18种酚类物质标准品作为对照,在铁皮石斛样品中共检出...     

Study of volatile organic acids in freeze-dried Cheonggukjang formed during fermentation using SPME and stable-isotope dilution assay (SIDA)

Volatile organic acids in freeze-dried Cheonggukjang were quantified using a stable-isotope dilution assay (SIDA) according to the fermentation period. Five organic acids, acetic acid, propanoic acid, 2-methylpropanoic acid, butanoic acid, and 3-methylbutanoic acid, were identified using solid-phase microextraction (SPME) in conjunction with gas chromatography–mass spectrometry (GC–MS). The contents of volatile organic acids in Cheonggukjang were highly dependent on the fermentation period and they increased during fermentation. Moreover, the branched-chained organic acids (namely 2-methylpropanoic acid and 3-methylbutanoic acid) were formed earlier and were present at much higher contents than the corresponding straight-chained organic acids during Cheonggukjang fermentation.     

A novel method for determination and quantification of 4-methyloctanoic and 4-methylnonanoic acids in mutton by hollow fiber supported liquid membrane extraction coupled with gas chromatography

4-methyloctanoic acid (MOA) and 4-methylnonanoic acid (MNA) are the main compounds responsible for "sweaty" odor of mutton. A novel method for their determination has been developed and validated. Hollow fiber supported liquid membrane (HF-SLM) was applied to selectively extract MOA and MNA prior to gas chromatography (GC) analysis. For HF-SLM, the donor outside the fiber was the acidified supernatant (pH 4) from aqueous mutton slurry. Liquid membrane was 5% tri-n-octylphoshphine oxide in di-n-hexyl ether and 0.3M NaOH aqueous solution filled in the lumen of the fiber was used as the acceptor. The extraction last for 4h. After acidification with HCl, the acceptor was directly analyzed by GC. Importantly, HF-SLM provided high enrichment factors for MOA (133) and MNA (116). The method developed had low detection limits of 0.0007-0.0015mg/kg, good linearity (R(2)>0.9956), reasonable recovery (88.54-122.13%), satisfactory intra-assay (7.83-9.73%) and inter-assay (15.68-16.14%) precision.     

中国食醋中苯乳酸的检测、鉴定及其与醋酸的联合抑菌作用

从我国食醋中分离纯化并采用核磁共振(1H和13C)技术鉴定苯乳酸,建立苯乳酸的超高效液相色谱-三重四极杆串联质谱快速测定方法,分析我国72种食醋中的苯乳酸含量.结果 表明,72种食醋中均可检出苯乳酸,谷物酿造食醋中苯乳酸含量显著高于果醋,平均质量浓度为227.89 mg/L,最高质量浓度为618.69 mg/L.工艺分...