A fluorescent terbium-metal-organic framework material for high-sensitivity detection of vomitoxin and oxytetracycline hydrochloride in water.

A unique luminescent lanthanide metal-organic framework (LnMOF)-based fluorescence detection platform was utilized to achieve sensitive detection of vomitoxin (VT) and oxytetracycline hydrochloride (OTC-HCL) without the use of antibodies or biomolecular modifications. The sensor had a fluorescence quenching constant of 9.74 × 106 M-1 and a low detection limit of 0.68 nM for vomitoxin. Notably, this is the first example of a Tb-MOF sensor for fluorescence detection of vomitoxin. We further investigated its response to two mycotoxins, aflatoxin B1 and ochratoxin A, and found that their Stern-Volmer fluorescence quenching constants were lower than those of VT. In addition, the fluorescence sensor realized sensitive detection of OTC-HCL with a detection limit of 0.039 µM. In conclusion, the method has great potential as a sensitive and simple technique to detect VT and OTC-HCL in water.

Occurrence and exposure risk assessment of pesticide residues in green tea samples cultivated in Hangzhou area, China.

The concentration of pesticide residues in 105 green tea samples grown in Hangzhou area were investigated. Of the 14 pesticides analysed using gas chromatography-tandem mass spectrometry and the 27 pesticides analysed using liquid chromatography-tandem mass spectrometry, only 18 were detected in the tea samples. The most frequently detected pesticide residues were imidacloprid (35.2%), acetamiprid (26.7%), carbendazim (21.0%), bifenthrin (21.0%), and cyhalothrin (19.1%). Carbofuran was the only pesticide which exceeded in one sample the maximum residue limit. The concentrations of the analytes in tea samples ranged from below the limit of detection (LOD) to 2.64 mg/kg. Their mean concentrations were all below the LOD, except for imidacloprid, acetamiprid, carbendazim, bifenthrin and cyhalothrin. Based on a preliminary long-term exposure assessment, the hazard quotient values of the detected pesticides varied in the range 0.47 × 10-3 - 1.1 × 10-3%, which indicates that these levels did not pose a risk to human health in Hangzhou area.

Monochloropropanediol in edible vegetable oils from Hangzhou market in China: occurrence and exposure risk assessment.

In this study, 241 vegetable-oil food samples were collected from the Hangzhou market in China and analysed for fatty acid esters of 3- and 2-monochloropropanediol (3-MCPD and 2-MCPD) using non-derivative gas chromatography tandem mass spectrometry (GC-MS/MS). Food consumption data were taken from a food consumption survey of urban and rural residents in Hangzhou city performed in 2010-2011. Levels of 3-MCPD esters in edible oil ranged from not detected to 7.98 mg/kg, and the highest mean levels were found in tea seed oil, with concentrations of 2.94 mg/kg. Esters of 2-MCPD levels ranged from not detected to 4.03 mg/kg, and the highest mean levels were also found in tea seed oil, containing 1.49 mg/kg. The range of mean dietary intake of 3-MCPD esters in different groups of edible oil was from 0.096 to 1.54 µg/kg body weight (bw) per day, which is lower than the tolerable daily intake (TDI) established by the European Food Safety Authority (EFSA) (2 µg/kg bw/day). For people aged above 6 years old, the dietary intake of 3-MCPD from edible oil was 0.42 µg/kg bw per day (mean) and 1.22 µg/kg bw per day (P97.5). The range of mean dietary intake of 2-MCPD esters in different groups of edible oil was from 0.025 to 0.79 µg/kg bw/day, and 2-MCPD esters intake was 0.20 µg/kg bw per day (mean) and 0.60 µg/kg bw per day (P97.5). In addition, the dietary intake exposure to 3-MCPD and 2-MCPD esters for urban residents was lower than that for rural residents. The findings indicate that the potential health risks caused by dietary 3-MCPD esters from edible oils were of low concern for most of the Hangzhou residents. However, the exposure risk for consumers with excessive consumption of certain kind of edible oil calls for attention.

Migration of eleven DSD-FWAs from packaging paper to food / 预防医学

Objective@#To observe the migration of 4,4＇-diaminostilbene-2,2＇-disulfonc acid-based fluorescent whitening agents ( DSD-FWAs ) in food packaging paper, so as to provide evidence for quality and safety supervision for paper packaging materials.@*Methods@#Forty-one paper samples with DSD-FWAs positive were made into 6 cm2 pieces and were soaked in four food simulants ( distilled water, 3% acetic acid, 10% ethanol and 95% ethanol, 10 mL each ). The experiment was carried out at the specified soaking temperature and time. The migration amounts of eleven DSD-FWAs were detected by high performance liquid chromatography-fluorescence detection. @*Results@#C.I.220, C.I.24, C.I.210, C.I.85, C.I.113, C.I.264, C.I.353 and C.I.357 were found in all the four food simulants. At the same time and temperature, the migration amount was highest in 10% ethanol, followed by distilled water, 3% acetic acid and 95% ethanol. C.I.220 was dissolved in all four food simulants, in the range of 20-90 ℃, the migration amount increased with soaking temperature; at 20 ℃, 40 ℃ and 60 ℃, the migration amount increased first and then stabilized over time.@*Conclusion@#The higher the storage temperature and the longer the storage time of paper packaging, the easier the DSD-FWAs in packaging paper migrate to food.

Determination of phthalate esters in breast milk before and after frozen storage in milk storage bags.

This study describes the migration of 20 phthalates from breast milk storage bags to breast milk after storage frozen for 1 to 6 months. Analysis of the investigated phthalates was performed by GC-MS/MS. Nine phthalates were found in some of the 27 breast milk storage bags, six phthalates were detected in some of the 40 breast milk samples, but the concentrations were low, except for one sample, which contained dibutyl phthalate (DBP) at the level of 211.2 µg/kg. For most of the breast milk samples stored in breast milk storage bags, the migration of diisobutyl phthalate (DIBP), DBP and di-ethyl-hexyl phthalate (DEHP) increased with increasing storage time, but the migration of DBP and DEHP was lower than the migration limits of 300 µg/kg and 1500 µg/kg from the National Standards of the PRC even after storage for six months. The average daily intakes of DMP, DEP, DIBP, DBP and DEHP were 0.099, 0.39, 0.62, 2.89 and 1.13 µg/kg/d, respectively, and the hazard indices were far below 1.

Determination of vanadium, chromium, nickel, selenium and arsenic in calcium based toothpastes by microwave digestion-ICP-MS/MS / 预防医学

Objective@#To establish analytical method for the determination of vanadium ( V ), chromium ( Cr ), nickel ( Ni ), selenium ( Se ) and arsenic ( As ) in calcium based toothpastes by microwave digestion-inductively coupled plasma tandem mass spectrometry ( ICP-MS/MS ).@*Methods@#The 21 calcium based toothpaste samples from supermarkets and shops in the urban areas of Hangzhou were digested by 6 mL HNO3 and 1 mL H2O2 in microwave digestion system. Then He-SQ mode and O2-MS/MS mode of ICP-MS/MS were respectively used for the determination of Ni and V, Cr, Se, As. Indium ( In ) was used as internal standard for calibration. @*Results@# Good linear relationships were obtained for these five elements from 1.0 to 32.0 μg/L, with the correlation coefficients ranged from 0.999 3 to 1.000 0. The detection limits of the method ranged from 0.000 25 to 0.006 08 mg/kg. The recovery rates of standard spiking were 80.7%-105.7% when set at 0.4, 0.8 and 1.6 mg/kg, the recovery of standard reference material was 102.2%, and the relative standard deviations were 2.6%-4.8%. The concentrations of V, Cr, Ni, Se and As in 21 calcium based toothpaste samples were 0.024-1.935 mg/kg, 0.085-5.759 mg/kg, 0.090-3.673 mg/kg, <0.002 72-0.016 mg/kg and <0.006 08-0.321 mg/kg.@*Conclusion@#Microwave digestion-ICP-MS/MS can effectively reduce the interferences of polyatomic ions and doubly charged ions from the matrix, which is suitable for the determination of V, Cr, Ni, Se and As in calcium based toothpaste.

Detection of 20 phthalate esters in breast milk by GC-MS/MS using QuEChERS extraction method.

A detection method for 20 different phthalate esters (PAEs) in breast milk analyzed by quick, easy, cheap, effective, rugged, and safe (QuEChERS) clean-up with five internal standards and quantitative GC-MS/MS was established. This method can effectively remove interfering substances such as lipids and fatty acids from breast milk using acetonitrile as the extraction solvent and PSA/C18 as clean-up materials. The 20 PAEs had a linear range of 5.0-500.0 µg/L and recoveries of 83.3-123.3% with RSDs of 0.2-7.6% (n = 6). The method detection limits (LODs) were 0.004-1.3 µg/kg. Dimethyl phthalate (DMP), Diethyl phthalate (DEP), Diisobutyl phthalate (DIBP), Di-n-butyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP) were detected in the 35 breast milk samples, with median levels of 1.2, 6.8, 7.3, 32.9 and 13.6 µg/kg, respectively, and the concentrations of 20 PAEs ranged between 0.5 and 137.3 µg/kg. This is a fast, simple, sensitive and accurate method for the detection of 20 PAEs in breast milk or dairy products.

Detection of 20 Phthalate Esters in Different Kinds of Food Packaging Materials by GC-MS/MS with Five Internal Standards.

>Background: Phthalate esters (PAEs) are a group of chemical compounds widely used as plasticizers to increase the flexibility of plastics that are used in the manufacturing of kitchen utensils and food containers. Objective: In this study, a simple, rapid, and sensitive method for the determination of 20 PAEs in different kinds of food packaging materials has been developed. Methods: Samples injected with five internal standards were extracted with acetonitrile saturated with n-hexane and then detected by GC-MS/MS without a purification step. Results: The standard calibration curves were linear for all analytes over the concentration range of 5-500 µg/L, and the correlation coefficients ranged from 0.9913 to 0.9999. The LODs and LOQs were in the ranges of 1.7-62.5 and 5.5-208.3 µg/kg, respectively. The accuracy of this method was evaluated by measuring the recovery from spiked samples. The recoveries of all 20 phthalates from samples spiked at three different concentrations were measured, and the recovery was in the range of 82.1-110.8% and the relative standard deviation range of recovery result (n = 6) was 0.3-9.7%. Conclusions: The method presented here is simple, rapid, and sensitive and can be applied to large-scale detection of PAEs in plastic materials. Highlights: Instead of only one solvent, acetonitrile saturated with n-hexane was used as the extraction solvent. Samples were pretreated without a purification step. Five internal standards were used for quantitative determination.

Simultaneous determination of 3-monochloropropane-1,2-diol and acrylamide in food by gas chromatography-triple quadrupole mass spectrometry with coupled column separation.

Both 3-monochloropropane-1,2-diol (3-MCPD) and acrylamide are contaminants found in heat-processed foods and their related products. A quantitative method was developed for the simultaneous determination of both contaminants in food by gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS). The analytes were purified and extracted by the matrix solid-phase dispersion extraction (MSPDE) technique with Extrelut NT. A coupled column (a 3 m Innowax combined with a 30 m DB-5 ms) was developed to separate both compounds efficiently without derivatization. Triple quadrupole mass spectrometry in multiple reaction monitoring mode (MRM) was applied to suppress matrix interference and obtain good sensitivity in the determination of both analytes. The limit of detection (LOD) in the sample matrix was 5 µg kg(-1) for 3-MCPD or acrylamide. The average recoveries for 3-MCPD and acrylamide in different food matrices were 90.5-107% and 81.9-95.7%, respectively, with the intraday relative standard deviations (RSDs) of 5.6-13.5% and 5.3-13.4%, respectively. The interday RSDs were 6.1-12.6% for 3-MCPD and were 5.0-12.8% for acrylamide. Both contaminants were found in samples of bread, fried chips, fried instant noodles, soy sauce, and instant noodle flavoring. Neither 3-MCPD nor acrylamide was detected in the samples of dairy products (solid or liquid samples) and non-fried instant noodles.