[Determination of tetrodotoxin in urine by liquid chromatography-tandem mass spectrometry with internal standard calibration].

OBJECTIVE: An analytical method was developed for tetrodotoxin(TTX) in urine by liquid chromatography-tandem mass spectrometry(LC-MS/MS) with internal standard calibration. METHODS: TTX in the sample was extracted with the mixture of acetic acid/methanol/acetonitrile(0.005 mL/0.8 mL/1.8 mL), cleaned by solid phase extraction(SPE) with cation exchange cartridge, eluted with 50% acetonitrile/water containing 0.3% hydrochloric acid, and neutralized with ammonia. The extract was separated by a Waters XBridge~(TM) BEH Amide column(150 mm×3.0mm, 1.7 µm) and measured by MS/MS. By optimizing sample extraction and SPE cleanup conditions, the problems of low recovery and strong suppression effects of MS signal for TTX in urine were resolved when cleaned with cation exchange cartridge. RESULTS: Quantitatively calibrated by the internal standard of Kasugamycin, good linear relationship was found for TTX in urine at the range of 0.2-200 µg/L with the correlation coefficient(r~2) of 0.997. The limits of detection and quantitation for TTX in sample matrix were 0.1 and 0.2µg/L, respectively. The average recoveries at three spiking levels(0.2, 10.0 and 200 µg/L) were 89.3%-95.3% with relative standard deviation(n=6) less than 5.1%. The concentrations of TTX in urine from 11 poisoning patients were 0.4-138 µg/L. The detection rate was 100% in urine collected within 3 days after poisoning. CONCLUSION: The established method was simple, accurate and sensitive. It can provide reliable technical support for the rapid treatment of TTX poisoning events and the study of toxin metabolism in vivo.

[Fat-soluble vitamins in different eggs and egg products in Hangzhou City].

OBJECTIVE: To analyze the contents of fat-soluble vitamins in different kinds of eggs and egg products in Hangzhou City. METHODS: The contents of fat-soluble vitamin A, vitamin E, vitamin K_1 and vitamin K_2(menaquinone-4, menaquinone-7 and menaquinone-9) in eggs and egg products were determined by the high-performance liquid chromatography method. The contents of vitamin D were determined by high performance liquid chromatography-tandem mass spectrometry. The determined contents were compared with the corresponding nutrient reference values. RESULTS: The contents of vitamin A, vitamin D, vitamin E and vitamin K in different eggs and egg products were 64-278 µg RAE/100 g edible, 0. 2-9. 6 µg/100 g edible, 0. 59-2. 31 mg α-TE/100 g edible and 9. 5-84. 8 µg/100 g edible, respectively, accounting for 4%-192% of the corresponding nutrient reference values. The contents of fat-soluble vitamin A, vitamin D, vitamin E and vitamin K in duck, goose and quail eggs were higher than those in chicken eggs and pigeon eggs. CONCLUSION: There are some differences in fat-soluble vitamin A, vitamin D, vitamin E and vitamin K in different eggs and egg products, but there is no significant difference between groups.

[Eight vitamin E congeners in seafood and aquatic products in Zhejiang Province].

OBJECTIVE: Comparison and analysis of α-, ß-, γ-, δ-tocopherol(T) and α-, ß-, γ-, δ-tocotrienol(T3) in 44 species of seafood and aquatic products is under processed to enrich the database of food composition in China and provide a scientific reference for dietary intake choice. METHODS: Quantitative and correlation analysis of eight vitamin E isomers were based on external calibration method with reversed-phase high-performance liquid chromatography-fluorescence detector, after hot saponification with alkaline and liquid-liquid extraction. RESULTS: The content of α-tocopherol equivalent(α-TE) in seafood and aquatic products varied greatly(from 0. 10 to 4. 01 mg/100 g edible), as well as the isomer forms. Aspect of vitamin E forms in aquatic fish, detection rates of α-T and α-T3 were both 100%, while the rates of γ-T and γ-T3 were 31. 58% and 68. 42%, respectively. Aspect of vitamin E forms in sea fish, detection rates α-T3, γ-T and γ-T3 were 28. 57%, 28. 57% and 35. 71%, respectively, while the rate of α-T was 100%. The form of vitamin E isomers in fish was at some extent different when they raise up in wild and farming environment, whereas there was no significant different in content of isomers. For shrimp and crabs, the content of α-TE was also various(from 0. 31 to 14. 27 mg/100 g edible), whereas α-T was the primary vitamin E form. And the content of α-T in female crabs was a little higher than that in male crabs, without statistic difference. With respect to correlation analysis, there was a strong correlation between γ-T and α-T3 in sea fish, while weak correlation of isomers in aquatic fish and certain correlations of isomers in shrimp and crab. CONCLUSION: The level of vitamin E content in seafood and aquatic products are quite different. Thus, it will bring in different effects on total activity and intake of vitamin E isomers by consumption of different species of seafood and aquatic products.

[Determination of thiram, propineb and metiram in mushroom by gas chromatography-mass spectrometry].

OBJECTIVE: To establish a method for determination of thiram, propineb and metiram in mushroom samples by gas chromatography-mass spectrometry(GC-MS). METHODS: Insoluble heavy metal salts were converted into water-soluble sodium salts by alkaline buffer with strong chelating agents. Dithiocarbamates can be converted into different methyl ester compounds with ion pair methylation. The GC separation was performed on a DB-5 MS capillary column(30 m×0. 25 mm, 0. 25 µm). The pesticides were detected by GC-MS with selective ion monitoring(SIM) and quantified by external standard of working curve method. Methodsological verification was carried out based on optimized sample pretreatment and GC-MS condition. RESULTS: The concentrations of dithiocarbamates exhibited a good linear relationship with GC-MS within a certain range. The limits of detection of thiram, propineb and metiram were 0. 01, 0. 05 and 0. 05 mg/kg, respectively. Furthermore, the average recoveries were from 76. 98% to 93. 52%, and the maximum relative standard deviation was 11. 54%(n=6). CONCLUSION: This method is simple, sensitive, accurate and reliable. All the indices meet the requirements of pesticide residue detection.

[Analysis of multi-minerals in seafoods in Zhejiang Province].

OBJECTIVE: To analyze the contents of Ca, K, Na, Mg, Fe, Zn, Cu and Mn in 33 kinds of marine products, such as fish, shrimp, crab, shellfish and mollusk. METHODS: The national standard GB 5009. 268-2016 Determination of multi elements in foods was used for determination. The correlation between multi elements was statistically analyzed. RESULTS: The highest level of Ca was found in clam(510. 2 mg/100 g edible), K in mackerel(444. 4 mg/100 g edible), Na in clam(487. 6 mg/100 g edible), Mg in conch(132. 7 mg/100 g edible). The highest level of Fe and Mn was in conch(37. 35 and 2. 6 mg/100 g edible). The highest level of Zn and Cu was in oyster(15. 92 and 8. 58 mg/100 g edible). The correlation analysis showed that Mn-Ca was highly correlated in fish and shrimp(r=0. 9438 and 0. 8585, P < 0. 05), while Cu-Mg, Cu-Zn, Zn-Na were highly correlated in shellfish(r=-0. 9102, 0. 8501 and 0. 8428, P < 0. 05). CONCLUSION: There are rich mineral elements in different seafood, which can provide reference for the reasonable diet of residents.

[Determination of 22 antibiotics in disinfection products by ultra-performance liquid chromatography tandem mass spectrometry].

OBJECTIVE: To develop a method for simultaneous determination of 5 nitroimidazole antibiotics and 17 sulfonamides antibiotics in disinfection products by ultra-performance liquid chromatography tandem mass spectrometry(UPLC-MS/MS). METHODS: Samples were spiked with isotope internal standard, and then extracted by 2% formic acid solution and acetonitrile with ultrasonic, followed by MCX column to remove matrix interference and for enrichment. The supernatants were diluted with 2% formic acid solution before loading on the columns, then washed with 2% formic acid solution and methanol respectively, eluted with 5% ammonium methanol. The separation was performed on a CORTECS~(TM) UPLC C_(18)(100 mm×2. 1 mm, 1. 6 µm) column by using 0. 1% formic acid solution and 0. 1% formic acid acetonitrile as mobile phase with gradient elution. The antibiotics were analyzed by UPLC-MS/MS. RESULTS: The linear ranges of 22 antibiotics were 0. 05-5. 0 ng/mL and the correlation coefficients were greater than 0. 999. The limits of detection(LODs) were 0. 03-0. 15 µg/kg and the recoveries were 84. 3%-121. 2% with the relative standard deviations were 1. 13%-8. 43%(n=6). The method was successfully used to detect the content of antibiotics in 20 disinfection products, 45% of samples had been detected positively. CONCLUSION: This method is simple, sensitive, selective and accurate, and could be applied for simultaneous detection of antibiotics in disinfection products.

Bivariate Correlation Analysis of the Chemometric Profiles of Chinese Wild Salvia miltiorrhiza Based on UPLC-Qqq-MS and Antioxidant Activities.

To better understand the mechanisms underlying the pharmacological actions of Salvia miltiorrhiza, correlation between the chemical profiles and in vitro antioxidant activities in 50 batches of wild S. miltiorrhiza samples was analyzed. Our ultra-performance liquid chromatography-tandem mass spectrometry analysis detected twelve phenolic acids and five tanshinones and obtained various chemical profiles from different origins. In a principal component analysis (PCA) and cluster analysis, the tanshinones cryptotanshinone, tanshinone IIA and dihydrotanshinone I exhibited higher weights in PC1, whereas the phenolic acids danshensu, salvianolic acids A and B and lithospermic acid were highly loaded in PC2. All components could be optimized as markers of different locations and might be suitable for S. miltiorrhiza quality analyses. Additionally, the DPPH and ABTS assays used to comprehensively evaluate antioxidant activities indicated large variations, with mean DPPH and ABTS scavenging potencies of 32.24 and 23.39 µg/mL, respectively, among S. miltiorrhiza extract solutions. Notably, samples that exceeded the mean IC50 values had higher phenolic acid contents. A correlation analysis indicated a strong correlation between the antioxidant activities and phenolic acid contents. Caffeic acid, danshensu, rosmarinic acid, lithospermic acid and salvianolic acid B were major contributors to antioxidant activity. In conclusion, phenolic compounds were the predominant antioxidant components in the investigated plant species. These plants may be sources of potent natural antioxidants and beneficial chemopreventive agents.

High-performance liquid chromatographic determination of multi-mycotoxin in cereals and bean foodstuffs using interference-removal solid-phase extraction combined with optimized dispersive liquid-liquid microextraction.

A novel pre-treatment was proposed for the simultaneous determination of aflatoxins, ochratoxin A and zearalenone in foodstuffs using high-performance liquid chromatography with fluorescence detection. The analytical procedure was based on a first step using a quick, easy, cheap, effective, rugged, and safe based extraction procedure, followed by salting out and purification with a C18 solid-phase extraction column as interference removal clean-up. Subsequently, collected supernatant was subjected to dispersive liquid-liquid microextraction. Response surface methodology based on central composite design was employed to optimize conditions in the microextraction procedure. Under the optimum conditions, satisfactory analytical performance with recoveries ranging from 63.22 to 107.6% were achieved in different types of cereals and beans, as well as desirable precisions (0.81-8.13%). Limits of detections and quantifications for these six mycotoxins ranging from 0.03 to 13 µg/kg and 0.22 to 44 µg/kg, respectively, were obtained. Finally, the established method was successfully validated by four certified reference materials (P = 0.897 > 0.05) and applied to 79 samples from local markets.

Simultaneous and rapid determination of deoxynivalenol and its acetylate derivatives in wheat flour and rice by ultra high performance liquid chromatography with photo diode array detection.

A simple and reliable method of ultra high performance liquid chromatography coupled with photo-diode array detection has been proposed for the simultaneous determination of deoxynivalenol and its acetylated derivatives in wheat flour and rice, especially focusing on the optimization of sample extraction, cleanup, and chromatographic separation conditions. Sample pretreatment consisted of a first step using a quick, easy, cheap, effective, rugged, and safe based extraction procedure and a subsequent cleanup step based on solid-phase extraction. The method was extensively validated in wheat flour and rice, obtaining satisfactory analytical performance with good linearity (R(2) ≥ 0.999), acceptable recoveries (80.0-104.4%), and repeatability (RSDs 1.3-10.7%). The limits of detection (21.7-57.4 µg/kg) and quantitation (72.3-191.4 µg/kg) for deoxynivalenols were lower than those usually permitted by various countries' legislation in these food matrices. The method was applied to 34 wheat and rice samples. The results were further compared with results of ultra high performance liquid chromatography with electrospray ionization tandem mass spectrometry.

Simultaneous Analysis of Nicarbazin, Diclazuril, Toltrazuril, and Its Two Metabolites in Chicken Muscle and Eggs by In-Syringe Dispersive Solid-Phase Filter Clean-Up Followed by Liquid Chromatography-Tandem Mass Spectrometry.

Nicarbazin (NICA) and triazine anticoccidial drugs (diclazuril (DIZ) and toltrazuril (TOZ)) are the primary strategy for preventing and treating coccidiosis. To prevent the development of drug resistance and mitigate the potential chronic toxicity to humans resulting from prolonged exposure, a liquid chromatography-tandem mass spectrometry method with high reliability and sensitivity was developed to determine NICA, DIZ, TOZ, and its two metabolites in chicken muscle and eggs. Upon establishing the extraction conditions involving 10 mL of acetonitrile and 10 min of sonication, in-syringe dispersive solid-phase extraction with silica was performed in combination with n-hexane clean-up. The selection of isotope peaks of precursor ions and low-mass range scanning allowed the two transitions for the quantification of all compounds. The limits of detection for DIZ and NICA were both 0.1 µg/kg, and for TOZ and metabolites, they were 0.3 µg/kg; the limits of quantitation were 0.3 and 1 µg/kg, respectively. The linear range was 0.25-50 ng/mL with a correlation coefficient r > 0.999. The average recoveries at three spiking levels in muscle and eggs were 90.1-105.2% and 94.0-103.7% with the relative standard deviations of 3.0-8.1% and 3.1-14.4%, respectively. The precision, accuracy, and stability were evaluated by three quality control samples.

[Effects of hemoperfusion on the patients with acute toxication of 2, 4-dinitrophenol].

OBJECTIVE: To explore the management strategies of acute toxication of 2, 4-dinitrophenol by hemoperfusion. METHODS: A total of 14 patients with acute toxication of 2, 4-dinitrophenol were admitted on September 14, 2009. And they were divided into severe and mild groups according to the severity of clinical manifestation. All patients in both groups received 2-hour blood perfusion within 2 hour post-admission. Their clinical manifestations, laboratory parameters and 2, 4-dinitrophenol levels were carefully observed before and after each perfusion. And oxygenation, intravenous use of furosemide, corticosteroids and symptomatic therapies were simultaneously given to improve general conditions. RESULTS: In serious group, the levels of before and after the first perfusion were 28.21(15.56-45.23) and 16.11(10.10-27.52) mg/L (P < 0.05), respectively. In both groups, all levels of 2, 4-dinitrophenol were significantly reduced before and after each perfusion (all P < 0.05). The patients in severe group would get relieved after 3 vs 2 perfusions in mild group. In severe group, there was a remarked decrease in neutrophil and platelet count after perfusion than those in mild group. The liver enzymes and blood lipids in both groups after therapy significantly elevated than those before therapy (all P < 0.05). CONCLUSION: Crucial for managing acute toxication of 2, 4-dinitrophenol, early hemoperfusion reduces mortality.

Construction of a Brain-specific SLC23A2 Gene Knockout Mice Model.

Vitamin C (VC) is a key antioxidant of the Central Nervous System (CNS) and SLC23A2 (SVCT2) is the only transporter that actively transports VC into the brain. While the existing animal models of VC deficiency are in the whole body, the essential role of VC in brain development remains elusive. In our study presented here, the CRISPR/Cas9 technology was applied for the construction of a C57BL/6J-SLC23A2 em1(flox)Smoc mouse model, which was crossed with the Glial fibrillary acidic protein-driven Cre Recombinase (GFAP-Cre) genotype mice to generate a conditional knockout model of SLC23A2(SVCT2) gene in mice brain (GFAP-Cre;SLC23A2 flox/flox) after generations of crossbreeding. Our results showed that the expression of SVCT2 in GFAP-Cre;SLC23A2 flox/flox (Cre;svct2 f/f) mice brain was significantly decreased, and consistently, the expression of Neuronal nuclei antigen (NeuN), Glial fibrillary acidic protein (GFAP), calbindin-28k, brain-derived neurotrophic factor (BDNF) was down-regulated but Ionized calcium binding adapter molecule 1 (Iba-1) was up-regulated in Cre;svct2 f/f mice brain tissues. On the other hand, the levels of Glutathione, Reduced (GSH), myeloperoxidase (MDA), 8-isoprostane, tumor necrosis factor-α (TNF-α) and interleukin-6(IL-6) were significantly increased, but the levels of VC in brain tissue of the model group were decreased in Cre;svct2 f/f mice brain tissues, indicating the protective effect of VC against oxidative stress and inflammation during pregnancy. Thus, the conditional knockout of the SLC23A2 gene in the brain of mouse was successfully established by the CRISPR/Cas9 technology in our study, providing an effective animal model for studying the role of VC in fetal brain development.

Multiple mycotoxins in commonly used edible oils: Occurrence and evaluation of potential health risks.

In this study, the contamination of 51 mycotoxins in 416 edible oils were determined by UPLC-MS/MS. Totally, twenty-four mycotoxins were detected and nearly half of the samples (46.9%, n = 195) were contaminated simultaneously with six to nine kinds of mycotoxins. The predominant mycotoxins and contamination characteristics varied depending on the type of oils. More specifically, four enniatins, alternariol monomethyl ether (AME) and zearalenone were the most frequent combination. Overall, peanut and sesame oils (10.7-11.7 mycotoxins on average) were found to be the most contaminated matrices whereas camellia and sunflower seed oils (1.8-2.7 species) were the opposite. Dietary exposure risks of mycotoxins were acceptable in most cases, however, the ingestion of aflatoxins (especially aflatoxin B1) through peanut and sesame oil (margin of exposure: 239.4-386.3 < 10000) exceeded the acceptable carcinogenic risk level. Meanwhile, the risks of cumulative ingestion through the food chain should be of great concern, especially sterigmatocystin, ochratoxin A, AME and zearalenone.

A novel single step solid-phase extraction combined with bromine derivatization method for rapid determination of acrylamide in coffee and its products by stable isotope dilution ultra-performance liquid chromatography tandem triple quadrupole electrospray ionization mass spectrometry.

This work aimed to establish a novel determination method for acrylamide in coffee and its products by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Acrylamide in samples were prepared by a single-step solid-phase extraction clean-up using mixed mode sorbents. The bromine derivatization efficiency of acrylamide and its internal standard were improved at an acidic condition. After derivation, the retention capability of acrylamide and its resistance to interference were significantly improved. The limit of detection (LOD) and the limit of quantification (LOQ) were 1.2 and 4 µg/kg for roasted and instant coffees, while they were 0.24 and 0.8 µg/kg for ready-to-drink coffees. The average recoveries for acrylamide ranged from 99.3 to 102.2% in coffee and its products. All the results showed that the developed method was simple, quick, specific and suitable for screening and determination of acrylamide in batch samples of coffee and its products.

Quantitative determination of bovine caseinoglycomacropeptide in infant formulas by ultra-high-performance liquid chromatography-electrospray-ionization mass spectrometry.

An ultra-high-performance liquid chromatography-electrospray ionization coupled to mass spectrometry method has been developed for determining caseinoglycomacropeptide (CGMP) in infant formulas by selected ion reaction and area monitoring modes. The present study focused on the optimization of sample pretreatment, chromatographic resolution and mass spectrometry parameters. After a simple sample pretreatment, the two genetic variants of caseinoglycomacropeptide, CGMP(A) and CGMP(B), were separated using a BEH300 C(18) column by gradient elution. The established method was extensively validated by determining the linearity (R(2)>0.999), average recovery (95.8-118.4%), inter-day precision (relative standard deviation ≤7.81%) and intra-day precision (relative standard deviation ≤6.99%) based on two scan modes. To further verify the applicability of the method, 21 brands of commercial available infant formulas were analyzed. The results showed that the present method is selective, sensitive and reliable for separating and quantifying two genetic variants (CGMP(A) and CGMP(B)) of caseinoglycomacropeptide in infant formulas with complex matrix.

Multi-residue analysis of pesticides in tea by online SEC-GC/MS.

A multi-residue method for the analysis of pesticides in tea was developed by online size exclusion chromatography (SEC)-GC/MS with full scan mode. The sample was fortified with chlorpyrifos-d(10) isotope internal standard and extracted by acetonitrile. After purification by primary secondary amine sorbent and solvent exchange by SEC mobile phase, the sample was detected by online SEC-GC/MS. The purification result of the online system was evaluated by comparing the correlation between Chinese cabbage and tea matrix. The factors for method optimization included sample preparation, matrix effects and the instrument parameters of each online component. Scatter plot was introduced in this study to directly illustrate the results of the condition optimization and matrix effects in the online system. For most of the pesticides, the average recoveries ranged from 70 to 130% and the RSD were below 15%. The feasibility of the application of full scan mode in multi-residue determination of trace amounts of pesticides (LODs below 0.01 mg/kg) in a complex matrix was discussed.

[Determination of trace α-amanitin in urine of mushroom poisoning patient by online solid phase extraction-liquid chromatography-tandem mass spectrometry].

An analytical method was established for the determination of trace α-amanitin in the urine of patients suffering from mushroom poisoning by online solid phase extraction-liquid chromatography-tandem mass spectrometry (online SPE-LC-MS/MS). The sample was protein precipitated with formic acid acidified acetonitrile-methanol (5:1, v/v). Reversed-phase liquid-liquid microextraction was used to remove the organic solvent from the sample extract. The toxin was purified by online SPE using an ODS micro column (5 mm×2.1 mm, 5 µm), and separated on an XBridgeTM BEH C18 column (150 mm×3.0 mm, 2.5 µm). Finally, the toxin was measured by MS/MS in the negative electrospray ionization (ESI-) mode. Multiple reaction monitoring (MRM) was used, and the conditions were m/z 917.4>205.1 (quantitative ion transition) and m/z 917.4>257.1. Collision energy for both transitions was 55 eV. A fast valve-switching technique with a quantitative loop was used as an interface between the online SPE and LC-MS/MS modules. The two modules were independent, neither the mobile phase nor the pressure would interfere with each other, thus ensuring the stability of the system. Precise purification by the online system could effectively eliminate the matrix effects in the subsequent MS detection. Weak matrix suppression effects were found, with results of 88.7%-96.5%. The linear range of α-amanitin in urine was 0.1-50 µg/L with a correlation coefficient (r2) of 0.9983. The limit of detection (LOD) and limit of quantification (LOQ) in the sample matrix were 0.03 µg/L and 0.1 µg/L, respectively. The average recoveries at three spiked levels (0.1, 2.0 and 20 µg/L) were 84.3%-91.7% with relative standard deviations (RSDs) of 3.8%-7.2%. The accuracy and precision were evaluated using quality control samples with toxin contents of 0.1 µg/L (LOQ), 0.2 µg/L (2-fold LOQ), 2.0 µg/L (medium level), and 20 µg/L (high level). The calculated average intra-day accuracy was 85.1%-96.0% with the precision of 4.1%-7.8%. The inter-day accuracy was 82.9%-94.8% with the precision of 5.0%-9.5%. The specificity of the method was verified by negative samples derived from patients who suffered only gastroenteritis poisoning, without hepatotoxic symptoms. α-Amanitin was found in urine samples from nine mushroom poisoning patients with hepatotoxic symptoms. The sampling time ranged from 19 h to 92 h. The toxin contents were 0.11-53.1 µg/L. For patients with a high intake of poisonous mushrooms, the toxin content was 53.1 µg/L in a patient's urine sampled 19 h after accidental consumption and 0.19 µg/L in another patient's urine sampled 92 h after poisoning. The content of α-amanitin was only 0.53 µg/L in the urine sample obtained 23 h after consumption for a patient with low intake and 0.11 µg/L in the urine sampled from another patient 40 h after poisoning. Amatoxins can metabolize rapidly in vivo. The laboratory identification of amatoxin poisoning requires a method for trace-level analysis in the biological matrix. It is proved that this method is simple, accurate and sensitive by the application to the analysis of actual samples. The protein precipitation and reversed-phase liquid-liquid microextraction steps are fast and simple. Hence, they can be used as a rapid and effective pre-treatment method for online SPE-LC-MS/MS analysis of water-soluble toxins in biomaterial matrix. Highly sensitive analysis of α-amanitin in urine can be obtained using a precise purification technology via online SPE in this study. The problem of qualitative confirmation of the toxin at trace levels (0.03 µg/L) after poisoning can be solved. The laboratory identification time for amatoxin poisoning in some patients exceeds 90 h. The developed analytical method at trace level (0.1 µg/L of LOQ) can provide reliable technical support for establishing the dose-response relationship of α-amanitin in vivo. It can satisfy for the determination of trace α-amanitin in urine samples from patients with hepatotoxic mushroom poisoning.

Contamination status of bisphenol A and its analogues (bisphenol S, F and B) in foodstuffs and the implications for dietary exposure on adult residents in Zhejiang Province.

An effective method has been developed for the simultaneous determination of four bisphenols (bisphenol A, S, F and B) in various foodstuffs. The contaminants were extracted by QuEChERS-based strategy and subjected to ion-exchange solid-phase extraction for further clean-up. The critical variables were screened by Plackett-Burman design and then optimized by central composite design. Under the optimized conditions, satisfactory accuracy (recoveries 76%-116%) and precision (RSDs < 12%) were achieved. The established method was then used to assess the contamination status of 379 real samples. Bisphenol A was demonstrated to be the predominant bisphenol with highest incidence (79.7%) and average concentration (14.3 µg/kg). The positive rates (mean concentration) of bisphenol S, F and B were 37.7% (1.6 µg/kg), 26.9% (1.4 µg/kg) and 0.0% (not detected), respectively. Finally, the daily dietary intakes of ∑4bisphenolsfor adult residents were estimated (55.9-76.1 ng/kg bw/day) according to the contamination concentrations and the daily recommended intakes.

Simultaneous determination of 24 sulfonamide residues in meat by ultra-performance liquid chromatography tandem mass spectrometry.

The present study used the liquid extraction pretreatment method and developed an ultra-performance liquid chromatography triple quadrupole tandem mass spectrometry (UPLC-MS/MS) for the simultaneous determination of 24 kinds of sulfonamide residues in meat. The meat samples were homogenized, extracted and deproteinized by acetonitrile, defatted by n-hexane, and further liquid-liquid extracted by ethyl acetate. All of 24 sulfonamide residues were simultaneously separated and determined by UPLC-MS/MS within 15 min. The sulfonamide residues were monitored via the ESI(+) ionization method and quantified by six-channel multiple reaction monitoring (MRM). The calibrations were performed in sample matrixes by the isotope dilution method and the interference effect of sample matrixes on the ionization was effectively eliminated. Good linear relationship (R(2)=0.991-0.999) was observed within the concentration range of 0.2-50 microg/kg. Satisfied recoveries (67.8-113.9%) of all the sulfonamides were demonstrated in different standard-spiked levels except sulfanitran (SNT). The analytical category, separation speed, selectivity, sensitivity and repeatability of sulfonamides using UPLC-MS/MS were significantly improved compared to other analytical methods. Quantitative results of 240 meat samples demonstrated that the present method has a convenient operation and good practicability, which can be applied to the quantitative analysis of a large number of samples.

Simultaneous determination of two acute poisoning rodenticides tetramine and fluoroacetamide with a coupled column in poisoning cases.

A coupled column system was developed for the simultaneous determination of both rodenticides fluoroacetamide and tetramine in this paper by gas chromatography/mass spectrometry (GC/MS). A short length of strong polar column (1.5 m of Innowax) was coupled to the top of a 30 m of DB-5 ms with a quartz capillary column connector. Peak width at half height (W(h)) was used to evaluate the band broadening of the coupled column system. The length of the short couple column and oven temperature program were discussed according to W(h). The precisions of the coupled column were analyzed with peak area and retention time. Good linear correlations were found for both rodenticides. Typical samples were discussed for each rodenticide and some poisoning cases were presented.