Project description:Mercury in plants or animal tissue is supposed to occur in the form of complexes formed with biologically relevant thiols (biothiols), rather than as free cation. We describe a technique for the separation and molecular identification of mercury and methylmercury complexes derived from their reactions with cysteine (Cys) and glutathione (GS): Hg(Cys)(2), Hg(GS)(2), MeHgCys, MeHgGS. Complexes were characterised by electrospray mass spectrometry (MS) equipped with an ion trap and the fragmentation pattern of MeHgCys was explained by using MP2 and B3LYP calculations, showing the importance of mercury-amine interactions in the gas phase. Chromatographic baseline separation was performed within 10 min with formic acid as the mobile phase on a reversed-phase column. Detection was done by online simultaneous coupling of ES-MS and inductively coupled plasma MS. When the mercury complexes were spiked in real samples (plant extracts), no perturbation of the separation and detection conditions was observed, suggesting that this method is capable of detecting mercury biothiol complexes in plants.
Project description:Toxic elements (Cd, Pb, and As) accumulate into the environment by industrialization and natural phenomena and then pass to organisms. Analysis of toxic elements in food must be accurately carried out on a regular basis so as to avoid any adverse impact. Salted foods are difficult samples and accurate analysis of As is not easy due to salt interference. In this study, analysis of As was carried without influence of salts in three types of salted foods via an analytical method, which was validated using spiking recovery experiments and by analyzing certified reference materials. As a result, toxic elements were detected in all samples but none of these exceeded the World Health Organization recommended limits. Among the As species, arsenobetaine (AsB) was the most abundant, while inorganic As was below the detection limit in all samples. All the analyzed salted food samples appeared to be safe for consumption. In addition, the analysis of sea shrimp, freshwater shrimp, and seawater verified As bioaccumulation in these organisms from the environment.
Project description:Arsenic (As) compounds can be classified as organic or inorganic, with inorganic arsenic (iAs) having significantly higher toxicity than organic As. As may accumulate in food materials that have been exposed to As-contaminated environments. Thus, the "Sanitation Standard for Contaminants and Toxins in Foods" published by the Ministry of Health and Welfare set the standard limits for iAs content in rice, seaweed, seafood, and marine oils to safeguard public health. Therefore, a robust analytical method must be developed to selectively and quantitatively determine iAs content in rice, seaweed, seafood, and marine oils. Herein, we reported and verified the method of combined high-performance liquid chromatography/inductively coupled plasma-mass spectrometry (HPLC/ICP-MS) to determine iAs content in a wide variety of food. The fish oil samples were spiked with different concentrations of the As(III) standard solution, and their iAs analyzes were obtained via extraction procedures using the 1% (w/w) nitric acid (HNO3) solution containing 0.2 M hydrogen peroxide (H2O2) under sonication. The extracts were subsequently analyzed for their As(V) contents using HPLC/ICP-MS with aqueous ammonium carbonate as the mobile phase. The As(III) species had completely oxidized into the As(V) species, which prevented interferences between organic and iAs during chromatography. The method showed good extraction efficiencies (generally >90%) for the iAs samples, and their limits of quantification in fish oil were 0.02 mg/kg. The method was verified via the iAs speciation analytes of rice, seaweed, seafood, and marine oil matrices. The average recoveries for the fortified samples of each matrix ranged from 87.5 to 112.4%, with their coefficients of variation being less than 10%. Surveillance studies were conducted on the iAs contents of food samples purchased from local Taiwanese markets. The results showed that the only Hijiki (Sargassum fusiforme) higher than the maximum limit of the sanitation standard for iAs in seaweed, whereas the remaining samples met their corresponding requirements. This method is quick and straightforward, and it can be applied for the routine analysis of iAs content in a wide variety of food products to ensure public health safety.
Project description:Arsenic is a well-known carcinogenic, mutagenic and toxic element and occurs in the environment both as inorganic arsenic (iAs) and organoarsenical compounds (oAsCs). Since the toxicity of arsenic compounds depends on their chemical form, the identification and determination of arsenic species are essential. Recently, the European Food Safety Authority, following the European Commission request, published a report on chronic dietary exposure to iAs and recommended the development and validation of analytical methods with adequate sensitivity and refined extraction procedures for this determination. Moreover, the authority called upon new arsenic speciation data for complex food matrices such as seaweeds, grains and grain-based products. Looking at this context, an optimized, sensitive and fast analytical method using high performance liquid chromatography followed by inductively coupled plasma-mass spectrometry (HPLC/ICP-MS) was developed for the determination of iAs (sum of arsenite-AsIII and arsenate-AsV) and the most relevant oAsCs, arsenobetaine, dimethylarsinic acid and monomethylarsonic acid. The method was validated with satisfactory results in terms of linearity, sensitivity, selectivity, precision, recovery, uncertainty, ruggedness and matrix effect, and then successfully applied for the analysis of several matrices, i.e., processed and unprocessed cereal and cereal products, fruits, vegetables, legumes, seaweeds, nuts and seeds. The results obtained indicate that not only seaweed and rice matrices but also many cereals, legumes and plant-based foods for infants and young children contain significant concentrations of iAs and oAsCs. These findings contribute to the data collection necessary to assess the role of these matrices in the total arsenic exposure and if specific maximum limits have to be established.
Project description:BackgroundCordyceps sinensis, one of the most valued traditional herbal medicines in China, contains high amount of arsenic. Considering the adverse health effects of arsenic, this is of particular concern. The aim of this study was to determine and analyze arsenic speciation in C. sinensis, and to measure the associated human health risks.MethodsWe used microwave extraction and high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry to determine and analyze the arsenic content in C. sinensis, and measured the associated human health risks according to the hazard index (HI), lifetime cancer risk (CR), and target hazard quotient (THQ).ResultsThe main arsenic speciation in C. sinensis were not the four organic arsenic compounds, including dimethyl arsenic, monomethyl arsenic, arsenobetaine, and arsenocholine, but comprised inorganic arsenic and other unknown risk arsenic compounds. HI scores indicated that the risk of C. sinensis was acceptable. CR results suggested that the cancer risk was greater than the acceptable lifetime risk of 10-5, even at low exposure levels. THQ results indicated that at the exposure level < 2.0 months/year, the arsenic was not likely to harm human health during a lifetime; however, if the exposure rate was > 3.0 months/year, the systemic effects of the arsenic in C. sinensis was of great concern.ConclusionThe arsenic in C. sinensis might not be free of risks. The suggested C. sinensis consumption rate of 2.0 months/year provided important insights into the ways by which to minimize potential health risks. Our study not only played the role of "cast a brick to attract jade" by which to analyze arsenic speciation in C. sinensis but also offered a promising strategy of risk assessment for harmful residues in traditional herbal medicines.
Project description:Untargeted (NMR) and targeted (RP-HPLC-PDA-ESI-MSn, RP-HPLC-FD) analytical methodologies were used to determine the bioactive components of 19 tea samples, characterized by different production processes (common tea and GABA tea), degrees of fermentation (green and oolong teas), and harvesting season (autumn and spring). The combination of NMR data and a multivariate statistical approach led to a statistical model able to discriminate between GABA and non-GABA teas and green and oolong teas. Targeted analyses showed that green and GABA green teas had similar polyphenol and caffeine contents, but the GABA level was higher in GABA green teas than in regular green tea samples. GABA oolong teas showed lower contents of polyphenols, caffeine, and amino acids, and a higher content of GABA, in comparison with non-GABA oolong teas. In conclusion, the results of this study suggest that the healthy properties of teas, especially GABA teas, have to be evaluated via comprehensive metabolic profiling rather than only the GABA content.
Project description:Fractionation prior to mass spectrometry is an indispensable step in proteomics. In this paper we report the success of performing offline reversed phase high pressure liquid chromatography (HPLC) fractionation on a C18 2.0 mm×150 mm column at the peptide level with microliter per minute flow rates prior to online nano-flow reversed phase liquid chromatography mass spectrometry (nanoLC-MS) using the well-studied fungus Saccharomyces cerevisiae. A C18 75 μm×150 mm column was used online and the online elution gradients for each fraction were adjusted in order to obtain well resolved separation. Comparing this method directly to only performing nanoLC-MS we observed a 61.6% increase in the number of identified proteins. At a 1% false discovery rate 1028 proteins were identified using two dimensions of RPLC versus 636 proteins identified in a single nano-flow separation. The majority of proteins identified by one dimension of nano-LC were present in the proteins identified in our two dimensional strategy. Although increasing analysis time, this non-orthogonal and facile pre-fractionation method affords a more comprehensive examination of the proteome.
Project description:The phytochemical sulforaphane can induce cell cycle arrest and apoptosis in metastatic prostate cancer cells, though the mechanism of action is not fully known. We conducted a global proteome analysis in LNCaP metastatic prostate cancer cells to characterize how global protein signature responds to sulforaphane. We conducted parallel analyses to evaluate semi-quantitative 1-dimensional versus 2-dimensional liquid chromatography tandem mass spectrometry (LC-MS/MS) and their utility in characterizing whole cell lysate. We show that 2-dimensional LC-MS/MS can be a useful tool for characterizing global protein profiles and identify TRIAP1 as a novel regulator of cell proliferation in LNCaP metastatic prostate cancer cells.
Project description:The main aim of the research was to develop a complementary analytical approach consisting of bespoke speciation analysis and non-targeted speciation analysis of As, Sb, and Cr in flavored bottled drinking water samples using HPLC/ICP-DRC-MS and ESI-MS/MS. The scope of two previously developed analytical procedures, (1) multielemental speciation procedure for AsIII, AsV, CrVI, SbIII, and SbV analysis and (2) arsenic speciation procedure for AsB, AsIII, DMA, MMA, and AsV quantification, was extended to the analysis of a new sample type in terms of bespoke speciation analysis. As for the non-targeted speciation, analysis size exclusion chromatography was used with ICP-MS and a complementary technique, ESI-MS/MS, was used for the organic species of As, Sb, and Cr screening. Full validation of procedures 1 and 2 was conducted. Procedure 1 and 2 were characterized with precision values in the range from 2.5% to 5.5% and from 3.6% to 7.2%, respectively. Obtained recoveries ranged from 97% to 106% and from 99% to 106% for procedures 1 and 2, respectively. Expanded uncertainties calculated for procedures 1 and 2 ranged from 6.1% to 9.4% and from 7.4% to 9.9%, respectively. The applicability of the proposed procedures was tested on bottled drinking water samples. Results for the real samples in procedure 1 were in the range from 0.286 ± 0.027 [μg L-1] to 0.414 ± 0.039 [μg L-1] for AsIII, from 0.900 ± 0.083 [μg L-1] to 3.26 ± 0.30 [μg L-1] for AsV, and from 0.201 ± 0.012 [μg L-1] to 0.524 ± 0.032 [μg L-1] for SbV. CrVI and SbIII were not detected in any sample. As for procedure 2, results were in the range from 0.0541 ± 0.0053 [μg L-1] to 0.554 ± 0.054 [μg L-1] for AsB. Results for AsIII and AsV obtained with procedure 2 were in good accordance with results obtained with procedure 1. DMA and MMA were not detected in any sample.
Project description:Zornia brasiliensis Vogel (Leguminosae) is a species popularly known in Brazil as "urinária", "urinana", and "carrapicho", it is popularly used as a diuretic and in the treatment of venereal diseases. A specific methodology to obtain a saponin-enriched fraction and high-performance liquid chromatography coupled with diode array detection, ion trap mass spectrometry, and TOF-MS (HPLC-DAD-ESI-MS/MS) was applied for the analysis of triterpene saponins. The MS and MS/MS experiments were carried out by ionization in negative mode. Molecular mass and fragmentation data were used to support the structural characterization of the saponins. Based on retention times, high-resolution mass determination and fragmentation, 35 oleanane-triterpene saponins were tentatively identified in Z. brasiliensis.