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1.
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   

2.
Apple sour is a traditional product of Kastamonu, Turkey. It is consumed by spreading on bread or drinking after diluting with water. The aim of this study was to determine patulin (PAT) and 5-hydroxymethylfurfural (HMF) in apple sour. This study is the first to evaluate the occurrence of PAT and HMF in apple sour. The samples were extracted with ethyl acetate using liquid-liquid extraction technique. PAT and HMF were determined by HPLC with UV detection. PAT was detected in all samples, and the PAT level in 94.9% of samples was found to be equal or greater than the legal limit for juice concentrates. The mean value for PAT was found to be 284 ± 307 μg kg?1. PAT levels in 13 of 39 samples were in the range of 100 ≤ x < 200 μg kg?1, two samples were in the range of 0 ≤ x < 50 μg kg ?1 and two samples were in the range of 1000 ≤ x < 1500 μg kg1. HMF levels of all samples were above the legal limit for solid molasses. The mean value for HMF was found to be 16215 ± 13317 mg kg?1. HMF levels of 10 of 39 samples were determined to be in the range of 10000 ≤ x < 20000 mg kg?1, eight samples were in the range of 20000 ≤ x < 30000 mg kg?1 and only three samples were in the range of 100 ≤ x < 1000 mg kg?1. There was a significant and inverse relationship between HMF and pH of the samples. These results indicate that consumption of apple sour is a considerable risk in terms of HMF and PAT toxicity.  相似文献   

3.
A magnetic solid-phase extraction (MSPE) protocol prior to HPLC was developed for the extraction and determination of Allura Red in food samples. Magnetic nanoparticles were coated with tetraethylorthosilicate and 3-aminopropyltriethoxysilane and modified by graphene. Scanning electron microscopy, transmission electron microscopy and Fourier-transform infrared spectrometry were used to characterise the graphene-functionalised sorbents; and the main parameters affecting the extraction such as sample volume, temperature, pH and time were investigated and established. Under optimised conditions, the pre-concentration factor of Allura Red was 200, and the calibration curve was linear at a concentration range of 5–1500 μg kg?1. The LOD was 2 μg kg?1, the limit of quantification was 7 μg kg?1, and the relative standard deviation was 3.3%. The prepared MSPE procedure was simple and fast, and it was successfully applied for the determination of Allura Red in beverages, candy and jelly.  相似文献   

4.
In the present study, a sensitive and rapid method for separation and determination of hydroxymethylfurfural (HMF) in fruit puree and juices was proposed. Dispersive liquid–liquid microextraction (DLLME) coupled with high-performance liquid chromatography (HPLC) was used for extraction and quantitative determination of HMF in fruit puree and juices. The effective parameters such as the type and volume of extraction and dispersive solvents, pH and salt amount (NaCl) were studied and optimized with the aid of response surface methodology based on Box–Behnken design to obtain the best condition for HMF extraction. At the optimized conditions, parameter values were 60 µL extracting solvent, 600 µL dispersive solvent, 2 g NaCl and pH 5. Repeatability of the method, described as the relative standard deviation, was 3.1% (n?=?6) and the recovery was 98.4%. The limit of detection and limit of quantitation were 1.47 and 5.28 µg L?1, respectively. The merit figures of DLLME–HPLC–UV method showed that the proposed method can be noticed as a new, fast and good alternative method for investigation of HMF in various fruit puree and juice samples.  相似文献   

5.
A simple, fast, and efficient method consisted of optimized dispersive liquid–liquid microextraction (DLLME) followed by UV–vis spectrophotometry was developed for determination of β-carotene in fruits and vegetables. Chloroform and methanol were chosen as extraction and disperser solvents, respectively. The extraction process was optimized using a central composite design (CCD) with the optimum points of 115 μL for volume of extraction solvent and 6.5 % (w/v) for salt concentration. Under the optimal conditions, the relative standard deviation (RSD, C?=?500 μg L?1, n?=?5), limit of detection (LOD), linear dynamic range (LDR), and coefficient of determination (R2) were 1.08 %, 2 μg L?1, 50–1,500 μg L?1, and 0.991, respectively. The present method consisted of a simple and fast sample preparation procedure without any antioxidant addition, saponification, and purification was used.  相似文献   

6.
A simple and rapid binary solvents-based dispersive liquid–liquid microextraction (BS-DLLME) method has been developed for determination of patulin (PAT) in apple juice followed by high-performance liquid chromatography. This method involves the use of an appropriate mixture of miscible binary extraction solvents and disperser solvent to form fine droplets of extractant in a sample solution. Parameters affecting extraction efficiency such as the type and volume of high-density extraction solvent, the volume of ethyl acetate, the kind and volume of disperser solvent, and salt addition were investigated and optimized. The detection and quantification limits were 2.0 and 10.0 μg L?1, respectively. The relative standard deviation for five measurements of 25 μg L?1 of PAT was 3.8 %. The relative recoveries of PAT from apple juice samples at spiking levels of 25, 50, and 75 ng mL?1 were in the range of 91.3–95.2 %.  相似文献   

7.
Subcritical water extraction followed by solid-phase extraction and ultra-high performance liquid chromatography coupled with tandem mass spectrometry detection is reported for the first time for the determination of 6 trichothecenes (deoxynivalenol, deoxynivalenol-3-glucoside, 3-acetyl-deoxynivalenol, 15-acetyl-deoxynivalenol, HT-2 toxin, and T-2 toxin) from different cereals. Water with 1% formic acid was used as the extraction solvent followed by a solid-phase extraction clean-up, achieving good performance with acceptable extraction recoveries, method detection limits between 0.05 μg kg?1 and 4.0 μg kg?1, and method quantification limits between 0.4 μg kg?1 and 20 μg kg?1. The use of water as the extraction solvent allowed a selective extraction affording low matrix effect levels and the detection and quantification of natural target trichothecenes at very low concentration levels. This extraction method was applied to different cereals, a pseudocereal and an oilseed sample, of which maize, millet, and oat were contaminated by at least one trichothecene.  相似文献   

8.
This paper described an ionic liquid-based dispersive liquid–liquid microextraction (IL-DLLME) combined with high-performance liquid chromatography (HPLC) method to determine fungicides in fruit juices. In this method, 1-hexyl-3-methyli-midazolium hexafluorophosphate (HMIMPF6) was used as extraction solvent, which dispersed into the fruit juices under vigorously shaking with the vortex. The effects of experimental parameters, such as extraction solvent volume, disperser solvent and its volume, vortex time, centrifugation time, sample pH, on the extraction efficiency were investigated. Under the optimum conditions, the linear correlation coefficients ranged from 0.9902 to 0.9979 for concentration levels of 0.02–2 mg l?1, the extraction recoveries were ranged 66.2–92.9 % except pyrimethanil (39.5–44.6 %), The relative standard deviations (RSDs; n?=?6) ranged from 2.2 % to 11.6 %, and the limits of detection (LODs) for the fungicides were between 3.1 and 10.2 μg l?1. Two real samples including apple and grape juices, spiked at two concentration levels were analyzed and yielded recoveries ranging from 71.3–93.1 % and 65.4–87.7 %, respectively.  相似文献   

9.
A green, simple and sensitive method was developed for the analysis of volatile carboxylic acids (VFAs) and perfluorocarboxylic acids (PFCAs) in food packaging materials. The acidic compounds in food packaging materials were first extracted by gas purge microsyringe extraction (GP–MSE) with 1.0 mL 0.1 mol·L?1 NaOH solution, then the analytes were dispersive liquid-liquid microextracted (DLLME) by 50 μL chloroform as extraction solvent and 200 μL acetonitrile as dispersive solvent. The 2-(5-Benzoacridine) ethyl-p-toluenesulfonate (BAETS) with excellent fluorescence property was applied to enhance the high performance liquid chromatography (HPLC) sensitivity. The obtained recoveries for the VFAs ranged from 92.0 to 101 %. The method LODs calculated at a signal-to-noise ratio (S/N) of 3 were in the range of 0.80–3.40 μg·kg?1, while the LOQs calculated at S/N of 10 were in the range of 2.5–10.2 μg·kg?1. All compounds were in good linearity with concentration coefficients of higher than 0.997. Perfluorooctanoic acid (PFOA) was found in all of the 15 kinds of samples analyzed with concentrations ranging from 4.86–7.56 μg·kg?1. Acetic acid, butyric acid, and caprylic acid were found in half of the samples analyzed. The other analytes were also found in more than 30 % samples with concentrations varied between 3.96 and 293 μg·kg?1.  相似文献   

10.
Selectivity of solid-phase extraction (SPE) was combined with the concentration power of dispersive liquid–liquid microextraction (DLLME) to obtain a sensitive, low solvent consumption method for high-performance liquid chromatography determination of diazinon and chlorpyrifos in rice. In this method, rice samples were extracted by ultrasound-assisted extraction followed by SPE. Then, the SPE eluent was used as a disperser solvent in the next dispersive liquid-liquid microextraction step for further purification and enrichment of diazinon and chlorpyrifos. Under the optimal conditions, the linear range was from 5.0 to 250 μg kg?1 for diazinon and from 2.5 to 250 μg kg?1 for chlorpyrifos. Limits of detection of diazinon and chlorpyrifos were 1.5 and 0.7 μg kg?1, respectively. Limits of quantitation of diazinon and chlorpyrifos were 5.5 and 3.0 μg kg?1, respectively. The precisions and recoveries also were investigated by spiking 10 μg kg?1 concentration in rice. The recoveries obtained were over 90 % with relative standard deviation (RSD%) below 9.0 %. The new approach was utilized to successfully detect trace amounts of diazinon and chlorpyrifos in different Iranian rice samples.  相似文献   

11.
A novel method based on ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) has been developed for the preconcentration of cobalt prior to its determination by graphite furnace atomic absorption spectrometry. In the UASEME technique, chloroform was used as the extraction solvent, sodium dodecyl sulfate was adopted as emulsifier, and ultrasound was applied to assist emulsification. There is no need of using organic dispersive solvent which is typically required in conventional dispersive liquid–liquid microextraction method. Several parameters that affect the extraction efficiency, such as the kind and volume of the extraction solvent, the type and concentration of the surfactant, pH of sample solution, concentration of the chelating agent, and extraction time and temperature were investigated and optimized. Under the optimal conditions, the linearity of calibration curve was in the range of 0.1–5 ng mL?1 with a correlation coefficient (R 2) of 0.9992. An enrichment factor of 58 was achieved with a sample volume of 5.0 mL. The detection limit of this method for Co was 15.6 ng L?1, and the relative standard deviation (RSD) was 4.3 % at 1.0 ng mL?1 concentration level of Co. The accuracy of the developed method was evaluated by analysis of the certified reference materials GBW07605 tea leaf and GBW10015 spinach. The method was successfully applied to determine trace cobalt in food and water samples with satisfactory results.  相似文献   

12.
A simple and sensitive method was developed for the determination of four sulfonylurea herbicides (metsulfuron-methyl, chlorsulfuron, chlorotoluron, and bensulfuron-methyl) using matrix solid-phase dispersion (MSPD) extraction followed by high-performance liquid chromatography. The experimental conditions for the MSPD extraction, such as type and amount of dispersant, the ratio of dispersant to sample, type and volume of washing and elution solvent were evaluated and optimized. Under the optimal conditions, the calibration curves for the sulfonylurea herbicides had good linear relationships (r?>?0.997) in the concentration range of 0.2–10 μg g?1, and the limits of detection were in the range of 0.02–0.07 μg g?1. The recoveries of the sulfonylurea herbicides at two fortification levels were between 62.0 and 102.6 % with the relative standard deviations less than 6.92 %. The methodology was successfully applied to the analysis of four sulfonylurea herbicides in food crops.  相似文献   

13.
A dispersive liquid–liquid microextraction (DLLME) method coupled to high-performance liquid chromatography was developed for the analysis of α-tocopherol in grain samples. The DLLME parameters including the type and volume of extractants, the volume of disperser and the addition of salt were examined. The optimized DLLME procedure consisted in the formation of a cloudy solution promoted by the fast addition to the sample (5 mL of saponified sample solution diluted with 5 mL of water) of a mixture of carbon tetrachloride (extraction solvent, 80 μL) and ethanol (dispersive solvent, 200 μL) without the addition of salt, followed by shaking for 5 min and centrifuging for 3 min at 5,000 rpm. Intra- and inter-day repeatability expressed as % RSD were 3.5 and 7.6 %, respectively. The limit of detection and the limit of quantification were 1.9 and 6.3 μg?L?1. The comparison of this method with the national standardized extraction method, supercritical carbon dioxide extraction, accelerated solvent extraction, and conventional heat-reflux extraction indicates that the DLLME was accurate (no significant differences at the 0.05 % probability level), high efficient, low organic solvent-consuming, and low cost. This procedure was successfully applied to 42 samples of 14 types of purple wheat, for which the content of α-tocopherol exhibited a significantly negative correlation with the pigment content measured by a spectrophotometer. The recovery rates ranged from 90.5 to 103.7 %.  相似文献   

14.
A novel sorbent for simultaneous separation of cadmium, copper, nickel, and lead was prepared by functionalizing SBA-15 nanoporous silica with dithizone. A solid-phase extraction method using the above sorbent was developed to separate and preconcentrate trace amounts of cadmium, copper, nickel, and lead ions from food and agricultural products by flame atomic absorption spectrometry measurements. The optimum experimental conditions such as pH; flow rates; type, concentration, and volume of the eluent; breakthrough volume; and effect of coexisting ions on the separation and determination of these heavy metals were evaluated. The extraction efficiencies for the mentioned heavy metals were greater than 97 %, and the limits of detection were 0.09, 0.16, 0.21, and 0.45 μg?L?1 for cadmium, copper, nickel, and lead, respectively. The preconcentration factor for simultaneous analysis of the four heavy metals was found to be 100 approximately. The relative standard deviations of the method were <5 % for 10 separate column experiments for the determination of 5.0 μg of cadmium, copper, nickel, and lead ions. The adsorption capacity of the dithizone-SBA-15 was 189 mg?g?1 for cadmium, 102 mg?g?1 for copper, 91 mg?g?1 for nickel, and 208 mg?g?1 for lead.  相似文献   

15.
The present paper describes the validation of ultrasound-assisted emulsification-microextraction method followed by ion mobility spectrometry (IMS) detection for simultaneous determination of two organophosphorus pesticides, diazinon and chlorpyrifos. Ultrasound radiation was applied for accelerating the emulsification of microliter organic solvent in aqueous solutions and enhancing the microextraction efficiency. This preconcentration step combined with IMS detection provided a precise and accurate method for determination of trace amounts of diazinon and chlorpyrifos pesticides. The effect of parameters influencing the extraction efficiency such as sonication time, type of extraction solvent, extraction solvent volume, and salt concentration were investigated and discussed. The enrichment factors found, under optimum conditions, were 230 and 300 for diazinon and chlorpyrifos, respectively, with corresponding LOD of 2.1 and 3.2 μg L?1. The presented method can be applied for the determination of diazinon and chlorpyrifos in the range 6.0–700 and 8.9–750 μg L?1, respectively, with correlation coefficients (R 2)?>?0.99. The applicability of the proposed method was evaluated by determination of the residues of the investigated pesticides in rice paddy water gathered from four stations during 60 days after spraying (June 2014), and in storage rice samples in Mazandaran province, Iran.  相似文献   

16.
A vortex-assisted surfactant-enhanced emulsification–solidification liquid microextraction (VASEME-SFO) has been proposed for the determination of triazine and phenylurea herbicides in milk. 1-Dodecanol was used as the extraction solvent and dispersed into the aqueous samples by the assistance of a vortex mixer. Meanwhile, the addition of a surfactant, which was used as an emulsifier, could enhance the speed of the mass transfer from aqueous samples to the extract solvent. Acetic acid and Na2SO4 were applied and used to eliminate interference by proteins and fats. The influence of various parameters in the VASEME-SFO such as the type and volume of the extraction solvent, the type and concentration of the surfactant, and the vortex time, salt addition, and sample solution pH were investigated and optimized. Under optimal conditions, the limits of detection (LODs) and quantification (LOQs) reached ranges of 0.005–0.09 and 0.015–0.30 μg L?1, respectively. Dynamic linear ranges (DLRs) of 0.2–200 and 2–400 μg L?1 were obtained for triazine and phenylurea herbicides, respectively. The performance of the method was evaluated for extraction and determination of these herbicides in milk in micrograms per liter, and satisfactory results were obtained (RSD?<?10.6 %).  相似文献   

17.
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   

18.
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   

19.
An ultrasound-assisted emulsification microextraction with solidification of organic droplet method followed by high-performance liquid chromatography with diode array detection for six triazole fungicide determination (diniconazole, fluquinconazole, flusilazole, myclobutanil, tebuconazole, and tetraconazole) was developed. After some preliminary experiments, undecanol was chosen as extracting solvent using 50 μL for 10 mL of liquid sample. A central composite design was performed to obtain the best experimental conditions for the following variables NaCl concentration (250 g L?1), extraction time (18 min), and temperature (30 °C) in ultrasonic bath. After the ultrasound-assisted extraction, two steps considering centrifugation (4,200 rpm, 10 min) and solidification (5 min, 3 °C) were done. Following these conditions, the method showed linearity higher than 0.9930 with the concentration ranged from 20 to 890 μg L?1. The limits of detection obtained using calibration curves were from 10.9 to 17.2 μg L?1 and the intra- and inter-day repeatability at two levels showed RSD values between 1.9 and 10.6 %. The enrichment factors for the studied triazoles were between 226 (flusilazole) and 255 (tebuconazole). Recovery studies at two spiked levels in apple and grape juices gave values from 64 to 112 %.  相似文献   

20.
Polycyclic aromatic hydrocarbons (PAH4) (benzo[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene) are evaluated in a traditional and widely consumed staple in Lebanon “Lebanese Grilled Chicken.” Forty samples with different local additives grilled by charcoal were purchased from different restaurants located in different regions in Lebanon. For this purpose, a simple and a reliable analytical method based on sonication technique and gas chromatography coupled to mass spectrometer (GC-MS) has been developed and validated. Several parameters affecting the extraction efficiency, such as the nature and the volume of the extract solvent, as well as other factors were investigated and optimized. The developed method is environmentally and economically friendly with a minimized consuming time, consisting of a single sonication step for 15 min using 12 mL of non-carcinogenic solvent acetonitrile (ACN) and without any further concentration prior to analysis. Following extraction, the cleanup step was based on freezing and d-SPE by C18 addition. Under optimized conditions, the method performances were evaluated; the limits of quantification (LOQs) achieved were lower than 0.689 μg kg?1, and these values fit the performance criteria for the method given by the EC that defined the LOQ values of PAH lower than 0.9 μg kg?1. In addition, the recovery values of the analyzed PAHs ranged from 88.9 to 119.3% with relative standard deviations (RSDs) less than 8% (n = 15). The levels of PAH4 were in the range from 1.52 to 49.9 μg kg?1, where about 40% of the Lebanese grilled chicken exceeded the EU commission MRLs of 12 μg kg?1.  相似文献   

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