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1.
Studies were conducted to determine the anaesthetic/sedative concentrations and durations that would maximise anaesthetic/sedative residue concentrations in rainbow trout (Oncorhynchus mykiss) skin-on fillet tissue. Rainbow trout (167–404 g) were exposed to 50 mg l?1 AQUI-S® 20E (10% active ingredient, eugenol) in 17°C freshwater for durations up to 1440 min, 100 and 250 mg l?1 AQUI-S® 20E for durations up to 240 min, and 500 and 1000 mg l?1 AQUI-S® 20E for durations up to 90 min. Fish exposed to 100 mg l?1 AQUI-S® 20E for durations of 30, 60, 120 and 240 min had the greatest eugenol concentrations in the fillet tissue, 50, 58, 54 and 62 µg g?1, respectively. All other exposure concentrations and durations resulted in significantly lower eugenol concentrations, i.e. all < 39 µg g?1.  相似文献   

2.
The Explorer® 2.0 tube test is a microbial inhibition test for the screening of antimicrobial residues in food samples. The new e-Reader® device coupled to Explorer® 2.0 operates by incubation at a selected temperature, determination of the endpoint of the assay and interpretation to generate results. This system was validated for muscle samples according to the European Commission Decision 2002/657/EC. Sensitivity towards 25 substances from several groups of antimicrobials was investigated in a first step. Detection capabilities for six substances representing the six major antimicrobial groups were also determined in bovine muscle. The detection capabilities for amoxicillin (10 µg l?1), cefalexin (200 µg l?1), doxycyclin (100 µg l?1), sulfamethazine (100 µg l?1), tylosin (100 µg l?1) and neomycin (200 µg l?1) were in all cases at or below the maximum residue limit (MRL). Specificity and applicability of the test were demonstrated with muscle samples from four animal species (bovine, porcine, ovine and poultry) and results were found to be satisfactory. Ruggedness was evaluated on negative and spiked samples with sulfamethazine as a representative antimicrobial. Neither false-positives nor false-negatives were detected when varying the sample volume, the time of pre-incubation, the temperature of incubation and the batch of the test. These results prove that Explorer® 2.0 coupled to e-Reader® is a valuable tool for the screening of a broad range of antimicrobials in muscle. This new methodology simplifies the analysis and increases the accuracy of interpretation of the test results since the endpoint of the assay is automatically determined and results are interpreted objectively.  相似文献   

3.
The reports on the volatile compounds of a dawadawa-type African food condiment produced from the alkaline fermentation of bambara groundnut (Vigna subterranea (L.) Verdc.) using Bacillus starter cultures are limited. Volatile compounds were isolated from dawadawa-type condiments using headspace solid phase microextraction and analysed by comprehensive gas chromatography coupled to time of flight mass spectrometry. Acids, aldehydes and alcohols accounted for over 70% of the volatile compounds produced in the Bacillus fermented samples. B. subtilis subsp. subtilis SFBA3 produced the highest content of acids (4969.60 µg kg?1), while the highest content of aldehydes (2811.90 µg kg?1) and alcohols (1247.60 µg kg?1) was detected with Bacillus cereus PALB7 and Bacillus licheniformis OALB2, respectively. Sulphur-containing compounds concentration (85.80 µg kg?1) was highest for Bacillus amyloliquefaciens SFBA2. Maximum 2-methyl butanoic acid and 3-methyl butanoic acid concentrations, indicative of typical dawadawa aroma, were produced by B. subtilis subsp. subtilis SFBA3.  相似文献   

4.
A method for determination of ochratoxin A (OTA) in wines using a new-solid phase extraction clean-up procedure followed with ultra performance liquid chromatography (UHPLC)-Orbitrap MS based on two scan events (full-scan Fourier transform mass spectrometer [FTMS] and higher energy-induced collision dissociation[HCD] data-dependent MS/MS) in positive ionization mode has been developed. The limit of detection (LOD) was estimated at 0.46 μg l?1 for white wine, 0.53 and 0.54 μg l?1 for rosé and red wines, respectively. The limit of quantification (LOQ) was estimated at 1.57 μg l?1 in white wine, 1.77 and 1.81 μg l?1 in rosé and red wines. Recovery experiments were carried out with spiked samples at three concentration levels (2, 5 and 10 μg l?1). The OTA recoveries in spiked white wine samples varied from 69.6 % to 99.8 %, while the recoveries for rosé and red wine samples were in the range of 63.0–110.2 % and 63.6–103.2 %, respectively. Finally, based on the results, it is concluded that the combination of C18 cartridge with conventional particle packed columns and UHPLC LTQ-Orbitrap XL is an appropriate procedure for OTA analysis in wines.  相似文献   

5.
A selective sorbent for solid phase extraction (SPE), based on a chemically modified mesoporous silica (SBA-15), followed by inductively coupled plasma-optical emission spectrometry was used for extraction, preconcentration, and determination of selenium in water and food samples. The main parameters of SPE including pH, amount of mesoporous (solid phase), concentration of the eluent (desorption solvent), and equilibrium time were optimized by using a fractional central composite design (f-CCD). The optimum conditions were found to be 3.2 for pH, 21 mg for amount of the mesoporous, 1 mol l?1 for eluent concentration, and 9 min for equilibrium time. Under the optimal conditions, the limit of detection (LOD) was 2.56 μg l?1. The linear dynamic range (LDR) was 5–1,000 μg l?1 with determination coefficient (R 2) of 0.999. Relative standard deviation (C?=?400 μg l?1, n?=?5) was 3.84 %. The enrichment factor was 20. The maximum sorption capacity of the modified SBA-15 was 15 mg g?1. The sorbent presented good stability, reusability, high adsorption capacity, and fast rate of equilibrium for sorption/desorption of selenium (IV) ions.  相似文献   

6.
In the present study, dispersive liquid–liquid micro-extraction has been applied for trace extraction and determination of mercury (Hg) ions in environmental samples. The mean centering of ratio spectra method was used to optimize the experimental parameters affecting the extraction of Hg. The factors influencing the extraction procedure such as type and volume of extracting and disperser solvent, concentration of chelating reagent, pH, salt effect, and centrifuge time were investigated and optimized. Under the optimized conditions, the limit of detection of the method was 0.15 μg l?1 and enrichment factor was 39. The calibration curve was linear in the range of 0.5–100 μg l?1 with a correlation of determination (R 2) of 0.998. The relative standard deviation for determination of 40 μg l?1 of Hg(II) was 2.6 % (n?=?5). The proposed method was applied for the determination of Hg in pine leaf, sea and river fish, sand, and water samples as indicators of environmental pollution and cigarette with satisfactory analytical results. In comparison with other methods, the proposed method is very simple, easy, rapid, and sensitive for determination of Hg at trace levels in complex matrices.  相似文献   

7.
One hundred and forty-six samples of animal feed (barley, n = 60; wheat bran, n = 22; wheat dry pulp, n = 29; and canola meal, n = 35) were collected in 2011 from Mashhad (Khorasan, Iran). Aflatoxins (AFs) were determined in these samples after immunoaffinity column clean-up by high-performance liquid chromatography (HPLC) with fluorescence detection. Aflatoxin B1 (AFB1) contamination was found in 28 samples: in five of the barley samples (8.3%) at a mean level of 0.48 µg·kg?1, in two wheat bran samples (9.0%) at a mean level of 0.88 µg·kg?1, in 10 wheat dry pulp samples (34.5%) at a mean level of 0.30 µg·kg?1 and in 11 canola meal samples (31.4%) at a mean level of 0.92 µg·kg?1. AFB1 levels were below the maximum levels of Iran regulations (5 µg·kg?1) and the EU maximum limit (5 µg·kg?1).  相似文献   

8.
Bisphenol A (BPA) was determined in sugary carbonated, non-carbonated and milk-based beverages, through HLPC-fluorescence detection and confirmed by LC-MS/MS, in a selection of brands that are mostly consumed by Italian children. The daily intake was determined through the WHO budget method (BM). BPA was found at detectable levels in 57% of carbonated beverages, in 50% of non-carbonated and in 100% of milk-based beverages. The median concentrations were 1.24 µg l–1 (range = < LOD–4.98 µg l–1) in canned carbonated beverages and 0.18 µg l–1 (< LOD–1.78 µg l–1) in non-canned carbonated beverages. In non-carbonated beverages, median concentrations were 0.80 µg l–1 (< LOD–2.79 µg l–1) and 0.18 µg l–1 (< LOD–3.58 µg l–1), respectively, for canned and non-canned beverages; in milk-based products the BPA median concentration was 3.60 µg l–1 (1.00–17.65 µg l–1). BPA daily intake from sugary drink consumption in children ranged from 0.008 to 1.765 µg kg–1 bw day–1. The median exposure values for the ‘best’ and ‘worst’ cases were 0.16% and 0.47% respectively of the EFSA t-TDI for BPA (4 µg kg–1 bw day–1), and 10.59% and 35.30% of the t-TDI when the maximum levels were considered.  相似文献   

9.
This survey was carried out to evaluate the occurrence of total aflatoxins (AFs; B1+B2+G1+G2) in unpacked composite spices. A total of 75 samples of composite spices such as biryani, karhai, tikka, nihari and korma masalas were collected from local markets of Karachi, Pakistan, and analysed using HPLC technique. The results indicated that AFs were detected in 77% (n = 58) samples ranging from 0.68 to 25.74 µg kg?1 with a mean of 4.63 ± 0.95 µg kg?1. In 88% (n = 66) samples, AFs level was below the maximum limits (ML = 10 µg kg?1) as imposed by EU. Furthermore, 61% (n = 46) tested samples contained AFs level between 1 and 10 µg kg?1, 9% (n = 7) exhibited AFs contamination ranged 10?20 µg kg?1 and only 3% (n = 2) of the investigated samples contained AFs levels higher than the ML of 20 µg kg?1 for total aflatoxins as set by the USA. It was concluded that there is need to establish a strict and continuous national monitoring plan to improve safety and quality of spices in Pakistan.  相似文献   

10.
A total of 635 raw milk samples from 45 dairy farms, from three regions of São Paulo state – Brazil, were evaluated during 15 months for aflatoxin M1 (AFM1). AFM1 was determined by high performance liquid chromatograph with fluorescence detection. AFM1 was detected (>0.003 µg kg?1) in 72.9%, 56.3% and 27.5% of the samples from Bauru, Araçatuba and Vale do Paraíba regions, respectively. The mean AFM1 contamination considering all the samples was 0.021 µg kg?1. Furthermore, the concentration of AFM1 was quite different among Bauru (0.038 µg kg?1), Araçatuba (0.017 µg kg?1) and Vale do Paraíba (<0.01 µg kg?1) regions. Only three samples (0.5%) had higher contamination than the tolerated limit in Brazil (0.50 µg kg?1) and 64 samples (10.1%) had a higher contamination than the maximum limit as set by the European Union (0.050 µg kg?1). The estimated AFM1 daily intake was 0.358 and 0.120 ng kg?1 body weight per day for children and adults, respectively.  相似文献   

11.
A new procedure has been developed for the simultaneous analysis of malachite green (MG), leucomalachite green (LMG), crystal violet (CV), and brilliant green (BG) in seafood using a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure and subsequent determination by ultrahigh performance liquid chromatography coupled to tandem mass spectrometry in <5.5 min. The developed method was validated at 2, 10, 25, and 100 μg kg?1, obtaining recoveries in the range of 48–112 %, with repeatability and interday precision values (expressed as relative standard deviation) ≤17 and ≤24 %, respectively. Matrix effect was evaluated for different types of seafood (shrimp, salmon, and trout), indicating that shrimp can be chosen as representative matrix for the determination of the selected dyes, except for LMG. Limits of quantification (LOQs) were <0.5 μg kg?1, which were always below the minimum required performance limits established by the European Union. The decision limit (CCα) and detection capability (CCβ) values were also estimated in the three matrices evaluated, and CCβ ranged from 0.46 to 1.22 μg kg?1. Finally, several types of seafood were analyzed, and some dye residues (MG, CV and BG) were detected in a salmon sample.  相似文献   

12.
Aflatoxin B1 (AFB1) levels were evaluated in betel nuts (Areca catechu L.) being imported to Pakistan during 2010–2011. In total, 278 betel nut samples (India = 21, Indonesia = 51, Sri-Lanka = 34 and Thailand = 172) were received from the Department of Customs and were analysed by thin layer chromatography (TLC). All Indian origin betel nuts showed AFB1 contamination ranging from 11.7–262.0 µg kg?1 with a mean of 92.5 µg kg?1. Among Indonesian and Sri Lankan shipments, 80.4% and 73.5% betel nuts were contaminated with AFB1 ranging between 3.3–39.2 and 6.5–103.4 µg kg?1 with a mean of 11.6 and 35.0 µg kg?1, respectively. However, only 30.2% of Thailand origin samples showed AFB1 contamination ranging 3.3–77.0 µg kg?1 with a mean of 6.6 µg kg?1. The widespread occurrence of AFB1 increases the hazard associated with betel nuts. Thus, strict control is a pre-requisite for the production and import/export of psychoactive substances as betel nuts.  相似文献   

13.
Over the past two years low levels of prednisolone have been reported in bovine urine by a number of laboratories in European Union member states. Concentrations vary, but are reported to be below approximately 3 µg l–1. Forty per cent of bovine urine samples from the Dutch national control plan had concentrations of prednisolone between 0.11 and 2.04 µg l–1. In this study the mechanism of formation of prednisolone was investigated. In vitro conversion of cortisol by bacteria from faeces and soil, bovine liver enzymes and stability at elevated temperatures were studied. In vitro bovine liver S9 incubation experiments showed a significant 20% decrease of cortisol within 6 h, and formation of prednisolone was observed from 0.2 g l–1 at t = 0 to 0.5 g l–1 at t = 6. Under the influence of faeces, the stability of cortisol in urine is reduced and cortisol breaks down within 50 h. Prednisolone is formed up to 4 µg l–1 at 70°C after 15 h. However, this decreases again to zero after 50 h. With soil bacteria, a slower decrease of cortisol was observed, but slightly higher overall formation of prednisolone, up to 7 µg l–1 at 20°C. As opposed to incurred urine, in fortified urine incubated with faeces or soil bacteria no prednisolone was detected. This difference may be explained by the presence of natural corticosteroids in the incurred sample. With UPLC-QToF-MS experiments, in urine and water samples incubated with faeces, metabolites known from the literature could be (tentatively) identified as 20β-hydroxy-prednisolone, cortisol-21-sulfate, oxydianiline, tetrahydrocortisone-3-glucuronide and cortexolone, but for all compounds except 20β-hydroxy-prednisolone no standards were available for confirmation. Based on the results of this study and literature data, for regulatory purposes a threshold of 5 µg l–1 for prednisolone in bovine urine is proposed. Findings of prednisolone in concentrations up to 5 µg l–1 in bovine urine can, most likely, originate from other sources than illegal treatment with growth promoters.  相似文献   

14.
A simple and efficient ultrasonic-assisted extraction (UAE) procedure has been proposed for the pre-concentration of (2S)-2-[(4-{[(2-amino-4-hydroxypteridin-yl)methyl]amino}phenyl)formamido]pentanedioic acid (folic acid) in vegetables, pharmaceuticals and foods prior to determination at 540 nm using UV-Vis spectrophotometry. The method is based on hydrophobic ternary complex formation of folic acid with silver ions in the presence of cetyltrimethylammonium bromide (CTAB) as a sensitivity enhancer counter ion at pH 7.0, and then extraction into a micellar phase of polyethylene glycol monoalkyl ether (Genapol X-080). The impacts on the extraction efficiency and complex formation of analytical parameters such as sample pH, concentration of silver, concentration of surfactants and extraction time, ultrasonic time and sample volume, were investigated and optimised in detail. The matrix effect on the pre-concentration and determination of folic acid was investigated, and it was observed that the proposed method was highly selective against possible matrix co-extractives. Under optimised conditions, a good linear relationship between the analytical signal and folic acid concentration was obtained in the range of 0.6–180 μg l?1 with a detection limit of 0.19 μg l?1 and quantification limit of 0.63 μg l?1. The applicability was evaluated using samples fortified at different concentration levels, and recoveries higher than 94.1% were obtained. The precision as the percent relative standard deviation (RSD%) was in range of 2.5–3.8% (10 and 40 μg l?1, n = 5). The proposed method was validated by analysis of two standard reference materials (SRMs) and various real samples, and satisfactory results were obtained.  相似文献   

15.
This study aims to detect aflatoxins (AFs) in dairy cow feed, milk and milk products using a high-performance liquid chromatography coupled with fluorescence detection (HPLC-FLD) method. All the validation parameters met the method performance criteria of the European Union. The samples comprised 76 dairy cow feeds and 205 milk and milk products (including yoghurt and yoghurt-based beverage, ayran). AFs were present in 26.3% of the feed samples. Two feed samples exceeded the maximum limit (ML) of 5 µg kg?1 for AFB1 as established by the EU. Nineteen milk samples (21.1%) contained aflatoxin M1 (AFM1) of which three exceeded the EU ML of 0.05 µg l?1. In addition, only two yoghurt samples and one ayran sample contained AFM1, but the levels were lower than the EU ML.  相似文献   

16.
A novel and sensitive method utilising high-performance liquid chromatography coupled to triple quadrupole-linear ion trap mass spectrometry (LC-QqQLIT-MS/MS) was developed in order to analyse the content of ochratoxin A (OTA) in coffee samples. The introduction of the triple-stage MS scanning mode (MS3) has been shown to increase greatly sensitivity and selectivity by eliminating the high chromatographic baseline caused by interference of complex coffee matrices. The analysis included the sample preparation procedure involving extraction of OTA using a methanol–water mixture and clean-up by immunoaffinity columns and detection using the MS3 scanning mode of LC-QqQLIT-MS/MS. The proposed method offered a good linear correlation (r2 > 0.998), excellent precision (RSD < 2.9%) and recovery (94%). The limit of quantification (LOQ) for coffee beans and espresso beverages was 0.010 and 0.003 µg kg?1, respectively. The developed procedure was compared with traditional methods employing liquid chromatography coupled to fluorescent and tandem quadrupole detectors in conjunction with QuEChERS and solid-phase extraction. The proposed method was successfully applied to the determination of OTA in 15 samples of coffee beans and in 15 samples of espresso coffee beverages obtained from the Latvian market. OTA was found in 10 samples of coffee beans and in two samples of espresso in the ranges of 0.018–1.80 µg kg?1 and 0.020–0.440 µg l?1, respectively. No samples exceeded the maximum permitted level of OTA in the European Union (5.0 µg kg?1).  相似文献   

17.
A new cloud-point extraction (CPE) method was developed for the pre-concentration and simultaneous determination of Sb(III) and B(III) by flame atomic absorption spectrometry (FAAS). The method was based on complexation of Sb(III) and B(III) with azomethine-H in the presence of cetylpyridinium chloride (CPC) as a signal-enhancing agent, and then extraction into the micellar phase of Triton X-114. Under optimised conditions, linear calibration was obtained for Sb(III) and B(III) in the concentration ranges of 0.5–180 and 2.5–600 μg l?1 with LODs of 0.15 and 0.75 μg l?1, respectively. Relative standard deviations (RSDs) (25 and 100 μg l?1 of Sb(III) and B(III), n = 6) were in a range of 2.1–3.8% and 1.9–2.3%, respectively. Recoveries of spiked samples of Sb(III) and B(III) were in the range of 98–103% and 99–102%, respectively. Measured values for Sb and B in three standard reference materials were within the 95% confidence limit of the certified values. Also, the method was used for the speciation of inorganic antimony. Sb(III), Sb(V) and total Sb were measured in the presence of excess boron before and after pre-reduction with an acidic mixture of KI-ascorbic acid. The method was successfully applied to the simultaneous determination of total Sb and B in selected beverage and dairy products.  相似文献   

18.
The aim of this study was to determine the level of organochlorine (OC) pesticides in 57 samples of canned tuna and 31 samples of canned sardines in vegetable oil, collected from supermarkets in Serbia. OC pesticides α-HCH, β-HCH, δ-HCH, dichlorodiphenyltrichloroethane (DDT), DDE, DDD, dielderin, endosulfane I, endosulfane II, endosulan sulfate, endrin, endrin ketone, heptachlor, heptachlor epoxide, lindane, aldrin, metoxichlor, cis-chlordane and trans-chlordane were determined using a GS-MS method. The highest concentrations (µg kg?1, arithmetic means) in canned tuna were for δ-HCH (60.6 ± 97.0) and p, p´-DDT (55.0 ± 25.1), while the corresponding values in canned sardines were for δ-HCH (90.7 ± 102.7) and endosulfane II (78.0 ± 145.9). Mean level for the sum of endosulfans was above the maximum limit in canned sardines (85.0 µg kg?1). Also, dieldrin (39.7 µg kg?1) was measured above the ML.  相似文献   

19.
The development and validation of an extraction procedure for quantification of free amino acids in coated products by MTBSTFA derivatization and GC–MS detection is described. The extraction method entailed the sample homogenization with hydrochloric acid (HCl) by stirring at 40 °C followed by two centrifugation steps. The optimum combination of the extraction variables was achieved by response surface methodology. HCl concentration and volume and stirring time influenced free amino acid extraction yield. The selected optimal extraction conditions were 5 g of sample mixed to 7.5 ml of 0.1 N HCl and stirred during 90 min. Consistency between predicted and experimental values as well as in the quality parameters was observed. The calibration curves were linear within the range 5–100 μg ml?1 with correlation coefficient values (R 2 ) higher than 0.99. Detection and quantification limits of the analytical procedure ranged from 2.10?5 to 18.10?2 μg μl?1 and from 8.10?5 to 60.10?2 μg μl?1, respectively. Precision was 0.20–12.59 % for run-to-run and 3.38–17.60 % for day-to-day. The accuracy is between 82.99 and 115.77 %. Nineteen amino acids were analyzed in frozen-thawed and deep-fried coated products from different origin, with cysteine being the most relevant.  相似文献   

20.
Tintilia is an autochthonous grapevine of the Italian Molise region which risked to disappear. However, recently, the production of Tintilia red wines is resuming and in the year 2011 the protected designation origin ‘Tintilia del Molise’ was officially registered. In this work, an analytical characterization of representative red wines from Tintilia grape is reported. A total of 36 different physicochemical variables were determined and discussed, considering those with an estimated coefficient of variation <25 % as more characterizing. These were found to be (mean): density (0.9949); dry extract (34.4 g L?1) and ashes (3.8 g L?1); ethyl alcohol (14.2 mL 100 mL?1), glycerol (9.2 g L?1) and total higher alcohols (1.7 g L?1); pH (3.65); the titratable (5.9 g L?1), fixed (5.4 g L?1), and salified (2.5 g L?1) acidity; buffering capacity (52.6 mM/L/pH); total phenols (2,341 mg mL?1); total flavonols (223 mg mL?1) and epicathechin (75.0 mg mL?1); %Red (49.1 %) and %Yellow (43.6 %). Sensory analysis was also performed by professional wine tasters. Finally, the Tintilia results were compared with those of Montepulciano wines. Findings of this analytical study describe the Tintilia red wine as a full-bodied wine; alcoholic; with feeble, but stable acidic profile; rich of phenols, especially flavonols; and finally, with a color balanced between red and yellow pigments.  相似文献   

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