[Determination of vitamin A, D and E in dishes by two-dimensional liquid chromatography].

OBJECTIVE: To establish a method for the simultaneous determination of vitamins A, D and E in dishes by two-dimensional liquid chromatography. METHODS: The samples were saponified and extracted with a mixture of ethyl acetate and n-hexane(3∶2, V/V)under the protection of antioxidants, and determined by two-dimensional liquid chromatography. The baseline separation of retinol, α-tocopherol, ß-tocopherol, γ-tocopherol, δ-tocopherol, and α-tocotrienols was achieved by using Alphasil pentafluorophenyl column(PFP, 150 mm×4.6 mm, 5 µm) as the one-dimensional column, and using water and methanol as mobile phases for gradient elution under the fluorescence detector. The separation detection of ergocalciferol and cholecalciferol from other impurities was achieved on the UV detector by Alphasil VC-C_(18) column(150 mm×4.6 mm, 3.5 µm) as the two-dimensional column. RESULTS: The baseline separation detection of retinol, ergocalciferol, cholecalciferol and five tocopherols was achieved. The compounds were linearly correlated within the set range, and the correlation coefficients were >0.999. The recovery rate of the method was between 85.4% and 106.4%. The detection limit of all-trans retinol was 0.7 µg/100 g, and the limit of quantitation was 2.4 µg/100 g. The limits of detection and quantification of tocopherols ranged from 1.1 to 2.5 µg/100 g and 3.6 to 8.3 µg/100 g. The detection limit of ergocalciferol and cholecalciferol was 0.3 µg/100 g, and the limit of quantification was 1.0 µg/100 g. In the end, finished dishes such as dry fried hairtail, braised mushroom, steamed egg with soy sauce, sweet and sour ribs were repeatedly measured by this method for six times, and the relative standard deviation was less than 10%. CONCLUSION: The method has the characteristics of simple operation, good repeatability, high accuracy and friendly to operators and ecological environment. It can realize the simultaneous typing detection of vitamins A, D and E in finished dishes.

[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.

[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.

Simultaneous detection of multiple hydroxylated polychlorinated biphenyls from biological samples using ultra-high-performance liquid chromatography with isotope dilution tandem mass spectrometry.

We established a method for the separation and detection of nine hydroxylated polychlorinated biphenyls in whole blood and urine samples using ultra high performance liquid chromatography coupled with electrospray negative ionization tandem mass spectrometry. Clean-up procedures involved a filtration step, and optimization involved a pretreatment step consisting of a simple liquid-liquid extraction using hydrated silica-gel chromatography (5%). Nine hydroxylated polychlorinated biphenyls were separated on an ultra high performance liquid chromatography HSS T3 column using a gradient elution program of 2 mmol ammonium formate aqueous solution (A) and methanol (B). Recovery ranged from 84.0 to 105.4% for the nine different hydroxylated polychlorinated biphenyls in urine with three spiked levels of 0.1, 1, and 2 ng and from 73.5 to 98.6% for the blood with spiked levels of 0.2, 1, and 2 ng. The relative standard deviations were <8.7% (n = 6), and the limits of detection in urine and whole blood for the nine hydroxylated polychlorinated biphenyls were in the range of 1.5-4 and 20-100 pg/g, respectively. This analytical method may enable the simultaneous detection of various hydroxylated polychlorinated biphenyls from complex tissue matrices.

[Determination of vitamin K in animal foods].

OBJECTIVE: To establish a high performance liquid chromatography method with fluorescence detection for a variety of vitamin K and to assess the content of vitamin K in animal foods. METHODS: Animal foods were hydrolyzed by 0.2 g lipase and 0.1 g protease in pH 8 for 4 hours, extracted with isooctane followed by rotary evaporation and reconstitution. The mobile phase was 900 mL methanol and 100 mL tetrahydrofuran which contained 5 mmol glacial acetic acid, 11 mmol zinc chloride and 6 mmol anhydrous sodium acetate. The content of vitamin K_1, menaquinone-4(MK-4), and menaquinone-7(MK-7)were separated on Atlantis T3 column(4.6 mm×250 mm, 5 µm)by high-performance liquid chromatography. The fluorescence detector was set at a wavelength of 320 nm for excitation and 410.3 nm for emission. RESULTS: The linear range of the method was 0.01-0.40 µg/mL, and coefficient of determination was > 0.999. The spiked recoveries were 84.4%-124.2% with relative standard deviation was <6%(n=6). MK-4 was the main form of vitamin K in pork and chicken. The highest content of vitamin K_1 was found in beef, and MK-7 could be detected in aquatic products. CONCLUSION: The proposed method is successfully applied for the determination of vitamin K in animal foods. A variety of vitamin K are distributed differently in distinct animals.

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.

A combined tryptic peptide and winged peptide internal standard approach for the determination of α-lactalbumin in dairy products by ultra high performance liquid chromatography with tandem mass spectrometry.

A robust ultra high performance liquid chromatography with tandem mass spectrometry method at peptide level was established for measuring α-lactalbumin in various dairy products. An isotope-labeled winged peptide (VKKILDKVG*INYW*LAHKALCSEKL) with extra amino acids of the sequence of signature peptide concatenated at each end as the internal standard was spiked in samples to participate in the whole tryptic digestion process. The peptide VG*INYW*LAHK that resulted from the isotope-labeled winged peptide was used as the final isotopically labeled internal standard of the α-lactalbumin signature peptide (VGINYWLAHK) during the quantitative analysis. The contents of α-lactalbumin in samples were calculated based on the equimolar relationship between the α-lactalbumin protein and signature peptide. The optimized molar ratio of trypsin to protein (1:60) and enzymatic digestion time (5 h) could not only improve the digestion efficiency and reduce the cost, but also minimize the period of sample pretreatment. Considering the robustness of the current method using the isotopically labeled internal standard and acceptable measurement cost, its application may promote the development of nutrient investigation and quality control of α-lactalbumin in dairy products. This protein analysis method might provide a new reference strategy for food analysis and quantitative protein analysis.

Study of the matrix effects of tetrodotoxin and its content in cooked seafood by liquid chromatography with triple quadrupole mass spectrometry.

Tetrodotoxin is a marine biotoxin with high acute toxicity. The levels in cooked seafood will help us to assess its intake in humans and may help assess the risk of toxicity. However, heavy matrices hinder the direct quantitation of tetrodotoxin. A quantitative method of measuring tetrodotoxin in cooked seafood using liquid chromatography with triple quadrupole mass spectrometry was established in this study. Tetrodotoxin was extracted from the sample matrix using 2% formic acid in methanol and cleaned using a cation exchange cartridge. The cleanup conditions were optimized. The matrix effects were determined using the postextraction spiking method and by comparing the slope of the linear regression equation in sample matrix to that in solvent. The limit of detection in the sample matrix was 5 µg/kg and the limit of quantification was 10 µg/kg. The mean recoveries at three spiking levels were 66.9-89.2% with relative standard deviations of 5.0-10.8% (n = 6) in five different matrices. Tetrodotoxin was found at concentrations of 26.1-2462 µg/kg in nine of 83 cooked seafoods tested in this study. Eight analogs of Tetrodotoxin were detected in the samples studied.

Determination of disialoganglioside GD3 and monosialoganglioside GM3 in infant formulas and whey protein concentrates by ultra-performance liquid chromatography/electrospray ionization tandem mass spectrometry.

A method of ultra-performance liquid chromatography combined with electrospray ionization triple quadrupole tandem mass spectrometry (UPLC-ESI-MS/MS) has been established for simultaneous determination of major disialoganglioside 3 (GD3) and monosialoganglioside 3 (GM3) in infant formulas and whey protein concentrates. Gangliosides were extracted by using the technique of Svennerholm and Fredman and then cleaned up with OASIS HLB solid-phase extraction (SPE) cartridges. The various molecular species of gangliosides were separated on an Acquity UPLC BEH C8 column and analyzed under the negative ion mode. GD3 and GM3 were rapidly quantified using internal standard (IS) method. The developed method was further validated by determining the linearity, average recovery, sensitivity (limit of quantification), and precision. The results presented high correlation coefficients (R(2) > 0.993) of the selected 16 gangliosides molecular species and provided the respective linear ranges. The limit of quantification was 0.325-0.734 mg/100 g for eight molecular species of GD3 and 0.008-0.312 mg/100 g for eight molecular species of GM3, respectively. The reasonable average recoveries (81-95%) and precision (relative standard deviation [RSD] ≤15%) were also demonstrated in three different spiked levels. This new method would be very useful in the quantitative determination of gangliosides in infant formulas and whey protein concentrates.

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.

Health risk assessment of heavy metals in marine fish to the population in Zhejiang, China.

Environmental pollution with toxic metals can lead to the possible contamination of the marine fish. We investigated the levels of As, Cd, Cr, Hg and Pb in 652 marine fish samples (15 species) collected from coastal areas of Zhejiang, China and estimated their health risk. Mean concentrations of As, Cd, Cr, Hg and Pb were 0.783, 0.009, 0.114, 0.031, 0.043 mg/kg wet weight. The average estimated daily intakes (EDIs) for As, Cd, Cr, Hg and Pb were 1.214, 0.014, 0.177, 0.048 and 0.067 µg/kg bw/day. The risk assessment at mean exposure level showed that there was no health risk associated with these elements through consumption of marine fish. However, potential health risk may exist for high exposure consumers considering the possible contamination of As and Hg. Given that the different levels of certain elements in marine fish in China, this study provides a scientific basis for food safety assessment and suggestions for risk management.

[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.

Determination of ibotenic acid and muscimol in plasma by liquid chromatography-triple quadrupole mass spectrometry with bimolecular dansylation.

Ibotenic acid (IBA) is an amino acid and muscimol (MUS) is the decarboxyl derivative of IBA. They are mushroom neurotoxins with high polarity and low molecular weight. Only one transition (159->113 for IBA and 115->98 for MUS) can be found when directly measured by high performance liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS). Therefore, the identification and quantification of trace amount of the toxins in biomaterial are difficult. A highly sensitive and accurate analytical method for IBA and MUS in plasma was developed by LC-MS/MS with the application of bimolecular dansylation and internal standard calibration. Acetonitrile was used for protein precipitation and for toxin extraction from plasma. The toxins and internal standards (L-tyrosine-13C9,15N for IBA and tyramine-d4 for MUS) were derivatized with dansyl chloride (DNSCl). The reaction conditions of the bimolecular dansylation were optimized and the fragmentation pathways of the derivatives in MS/MS were studied. Method validation was carried out according to the Bioanalytical Method Validation Guidance for Industry (FDA, USA, 2018). The limits of detection for IBA and MUS in plasma were 0.3 ng mL-1 and 0.1 ng mL-1, respectively. The linear ranges in plasma were 1-500 ng mL-1 and 1-200 ng mL-1 with the correlation coefficients of 0.998 and 0.999 for IBA and MUS, respectively. The recoveries at three spiked levels were 90.7-111.4% with relative standard deviations (RSDs) of 6.4-10.3% for IBA and the results were 85.1-94.2% with RSDs of 5.0-8.9% for MUS. The toxin levels in patients' plasma samples under different poisoning degree were presented.

[Study on the pollution status of PCDD/Fs and PCBs in sludge and crucian from typical polluted areas of Zhejiang Province].

OBJECTIVE: To reveal the pollution status of PCDD/Fs and PCBs in sludge and crucian from typical polluted areas of Zhejiang Province. METHODS: After having been spiked the 13C-labeled surrogate internal standards, the extracts were purified by a series of columns like GPC, multiple silica columns and alumina columns, and then analyzed hy HRGC-HRMS. RESULTS: Concentration ranges of dioxins and PCBs in sludge and Crusians from five areas were 379.6-9811.6 pg/g dry weight, 10,000-762,433 pg/g dry weight and 0.084-12.l68 pg/g wet weight, 149.03-57,304 pg/g wet weight, respectively. Ranges of total WHO-TEQ in sludge and crucians are 11.2-2162 pg/g dry weight and 0.234-39.251 pg/g wet weight. CONCLUSION: A wide variety of concentrations of dioxins and PCBs in sludge and crusians from five areas were detected, especially for that of Luqiao. For the pollution status of Luqiao, effluents of E--waste recycling industries maybe are the main sources of PCB exposure. The environment is now heavily threatened by such pollutants.

Screening of multi-class antibiotics in pork meat by LC-Orbitrap-MS with modified QuEChERS extraction.

The quantification capability of high resolution mass spectrometry is of great interest to analysts. We described a method for analysis of multi-class antibiotics in pork meat by UPLC-quadrupole (Q)-Orbitrap-MS. The QuEChERS approach with a clean-up step using a sorbent of primary-secondary amine (PSA) and C18 was adopted for sample preparation, and 37 antibiotics including beta-lactams, tetracyclines, sulfonamides, fluoroquinolones and macrolides were analyzed. The Q-Orbitrap method showed high sensitivity with limits of detection (LODs) ranging from 0.8 µg kg-1 to 2.9 µg kg-1. The method was further validated by intra and inter-day tests with fortified samples. Recovery (85-105.6%) and precision values (RSDs < 15%) for all analytes were obtained. The result indicates that UPLC-Q-Orbitrap-MS coupled with QuEChERS preparation can serve as a routine method for multi-class antibiotic analysis in pork meat.

Simultaneous determination of four water-soluble vitamins in fortified infant foods by ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry.

A novel ultra-performance liquid chromatography electrospray ionization tandem triple quadrupole mass spectrometry method for the simultaneous determination of four water-soluble vitamins, including vitamin B5 (VB5), vitamin B8 (VB8), vitamin B9 (VB9), and vitamin B12 (VB12) in fortified infant foods is developed and validated. A reverse phase UPLC separation system consisting of a Waters ACQUITY UPLC BEH C-18 column (2.1 mm x 100 mm i.d., 1.7 microm) and a binary gradient acetonitrile-water mobile phase is applied for the separation of the four water-soluble vitamins. Formic acid is spiked into the mobile phase to enhance the ionization efficiency. Tandem MS-MS analysis is performed in multi-reaction monitoring mode (MRM). Product-ion traces at m/z 220.1 --> 89.9 for VB5, 245.1 --> 227.1 for VB8, 442.3 --> 295.2 for VB9, and 678.9 --> 147.0 for VB12 are used for quantitation of the corresponding vitamins, and traces at m/z 455.5 --> 308.0 are used for methotrexate (internal standard). Limits of quantitation (LOQs) are 0.016, 0.090, 0.020, and 0.019 microg/L for VB5, VB8, VB9, and VB12, respectively. Intra- and inter-day precisions for the determination of the four vitamins are better than 6.84% and 12.26% in relative standard deviations, and recoveries for the four vitamins are in the range of 86.0~101.5%. The developed approach is applied for the determination of the trace amounts of the vitamins in fortified milk powers and fortified rice powers.

Distribution of metals and metalloids in dried seaweeds and health risk to population in southeastern China.

Concern about metals and metalloids, especially heavy metals in seaweeds has risen due to potential health risk. This study investigated the distribution of 10 metals and metalloids in 295 dried seaweeds (brown and red) and estimated the possible health risk via hazard index (HI). Elements in seaweeds can be sequenced in descending order by mean values: Al > Mn > As > Cu > Cr > Ni > Cd > Se > Pb > Hg. The levels of Cd, Cu, Mn and Ni in red seaweeds were significantly higher than those in brown seaweeds (P < 0.01). Correlation analysis showed contents of Ni-Cr (r = 0.59, P < 0.01) in seaweeds had moderate positive correlations. Seaweeds from different geographical origins had diverse element distribution. Risk assessment showed that HI at mean level was less than the threshold of 1. It indicates that for the general people there is low health risk to these elements by the intake of seaweeds. Furthermore, in terms of the confirmative toxicity of some metals, such as Cd, Pb and Hg, surveillance of metals in seaweeds should be performed continuously.