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1.
A liquid chromatographic (LC) method has been developed to determine narasin in feed premixes. Narasin is extracted from the premix with a methanol-water solvent, and the extracted solution is assayed by using LC. Recovery of narasin from a 12.5 g/lb premix is quantitative (100%), with a relative standard deviation of 1.44%. The results correlated well (coefficient 0.92) with a turbimetric bioassay method.  相似文献   

2.
A new approach is proposed for liquid/solid extraction of retinol and alpha-tocopherol from samples, using a disposable kieselguhr cartridge. The substitution of the mixture methanol-ethanol-n-butanol (4 + 3 + 1) for methanol in the alkaline hydrolysis solution makes it now possible to process fatty samples. Methanol is necessary to solubilize the antioxidant ascorbic acid, and a linear chain alcohol such as n-butanol is necessary to reduce the size of soap micelles so that they can penetrate into the kieselguhr pores. In comparisons of the proposed method with conventional methods on mineral premixes and fatty feedstuffs, recovery and accuracy are at least as good by the proposed method. Advantages are increased rate of determinations and the ability to hydrolyze and extract retinol and alpha-tocopherol together from the same sample.  相似文献   

3.
A liquid chromatographic (LC) method previously published for the determination of carbadox in finished feeds and premixes was slightly modified and tested in an interlaboratory study. The feed samples are extracted with methanol-acetonitrile (50 + 50) after wetting with water. The extracts are purified over a short alumina column. An aliquot of the eluate is analyzed with reverse phase liquid chromatography with ultraviolet detection. Before the actual interlaboratory study, a prestudy with 2 familiarization feed samples was performed. For the interlaboratory study, 2 series of meal and pelleted samples were prepared with carbadox from different suppliers. Eight collaborating laboratories received 6 feed samples previously milled and ground and 4 pelleted samples which had to be ground by the collaborator's in-house method. Collaborators also received 3 carbadox concentrates (about 10% w/w) and 4 premix samples derived from the concentrates (about 1% w/w). Coefficients of variation under reproducibility conditions were 8.3% for meal samples and 4.9% for pellets. A minor but significant effect was noted for the influence of pelleting temperature on the carbadox content. A minor and insignificant effect was observed for the influence of the milling and grinding procedure on the carbadox content. Alumina cleanup of 1% premixes was not essential, although the resulting chromatograms were cleaner. A slight difference in reproducibility was observed with concentrates (10%) when 0.2 or 0.5 g sample size was used, although the average carbadox concentration found was the same. For premixes and concentrates, coefficients of variation under reproducibility conditions were low, ranging from 2.9 to 7.5%.  相似文献   

4.
Corn, soybean meal, and isolated soybean protein samples were acid-hydrolyzed and analyzed for amino acid content by reverse phase liquid chromatography (LC) and by conventional ion-exchange chromatography (IEC) using an amino acid analyzer. The former method employed pre-column derivatization with orthophthalaldehyde (OPTA)/ethanethiol and fluorescence detection. In the LC procedure, glycine and threonine were not resolved, and proline and cyst(e)ine were not detected. In general, amino acid values obtained by LC and IEC compared closely within and across feedstuffs, and both agreed well with published amino acid composition data. The notable exceptions were aspartic acid, glutamic acid, and alanine. Results of this study suggest that reverse phase LC with pre-column OPTA derivatization can be applied to accurately measure primary amino acids in individual feedstuffs.  相似文献   

5.
A gas-liquid chromatographic method is presented for determining ethopabate in 0.8 and 8.0% premixes. A sample is extracted with tetrahydrofuran containing an internal standard, by sonication or overnight soaking. The extract is clarified by centrifugation, diluted if necessary, and injected into a gas chromatograph equipped with a flame ionization detector. Average per cent recoveries for spiked blank samples were 100.6 at the 0.8% level and 100.4 at the 8.0% level. Precision, as indicated by replicate analyses of several premixes, ranged from 0.5 to 1.7% relative standard deviation.  相似文献   

6.
Melengestrol acetate (MGA) is determined by liquid chromatography using a fraction from preparatory LC as a means of sample cleanup for feedstuffs, both dry and liquid. Dry ground feed is Soxhlet extracted with hexane and passed through a 2% deactivated alumina column for initial cleanup. The eluate is evaporated, redissolved in methanol, filtered, and injected onto a preparatory LC column. The fraction containing MGA is separated from the remaining matrix, evaporated to dryness, dissolved in methanol, and quantitated by LC analysis. Liquid supplements are extracted in methanol, and the extract is evaporated to near dryness. The residue is diluted with water, extracted with chloroform, passed through sodium sulfate, and evaporated to dryness. The remaining sample is dissolved in methanol prior to preparative LC and quantitative LC. Recoveries for 2 laboratory-fortified commercial feeds, one dry and one liquid, containing 0.39 and 0.40 mg/lb, were 98.3% +/- 4.4 and 95.8% +/- 4.3, respectively. Results compare favorably with existing methods. Up to a 4-fold time savings was realized by this method without automation.  相似文献   

7.
An AOAC modified method is described for the microbiological assay of neomycin, which has been adapted to include complete feeds, supplements, premixes, liquids, oil suspensions, boluses, and antibiotic-impregnated paper. The method features a more sensitive standard response line with a monolayer plating system. The use of a buffered plating medium in place of the water-prepared medium results in a curve with less degree of slope, which allows for more accurate interpretation of the standard response. The feed extract diluent used for standard response line dilution, which is prepared from exposure of the feed extract fluid to pH changes, heat, and sodium hypochlorite, has been eliminated. The constant salt concentration diluent used for the preparation of standards is the same as the salt concentration of the sample extract solution to be tested. Results for 50 commercial complete feeds and 50 commercial premixes received over the last 5 years produced an overall mean recovery of 101% with a mean percent recovery range of 80-112%. A statistical analysis of these 100 commercial, complete feeds and premixes, ranging in concentration from 47 g/ton to 70 g/lb, indicates the assay has little, if any, concentration-related bias. Precision and accuracy of the method was supported by laboratory studies of 20 assays that produced a mean recovery of 101% and standard deviation of 3.  相似文献   

8.
The normal phase liquid chromatographic (LC) method for determination of trans- and cis-isomers of vitamin K1 (phylloquinone) in infant formula described here uses an Apex silica column, isocratic elution, and UV absorption detection at 254 nm. Vitamin K1 is extracted quantitatively from the product matrix by pretreating the as-fed liquid with concentrated ammonium hydroxide and methanol, and then extracting it with a 2:1 mixture of dichloromethane and isooctane. The extract is cleaned up by silica open-column chromatography and concentrated for LC analysis. For trans-vitamin K1, the method precision is less than or equal to 3.3% RSD (relative standard deviation), and the spike recovery is 98 +/- 4%. For cis-vitamin K1, the precision is less than or equal to 12% RSD, determined at levels near the detection limit, and the spike recovery is 95 +/- 9%. The detection limit is 0.3 ng for both isomers at signal/noise = 3.  相似文献   

9.
利用奶粉的溶解性,通过水和0.5%次氯酸钠溶液洗涤混有乳源性成分和牛、羊肉骨粉的饲料样品,去除饲料中的乳粉成分后,再使用16S rDNA PCR方法进行动物源性检测。结果表明,实验所建立的方法能够完全区分饲料中的乳粉与肉骨粉。当乳粉含量分别为25%、50%和75%时,混合饲料中牛、羊肉骨粉的检出限分别为2%、0.5%和0.1%。此方法操作简单,容易掌握,可用于鉴别反刍动物饲料中非乳源性成分的牛、羊源性成分。  相似文献   

10.
A liquid chromatographic method for the assay of oxytetracycline in premixes and veterinary products is described. Premix samples are extracted with acidified methanol, diluted with mobile phase, and filtered before chromatography on a C-8, reverse phase column. The assay method separates oxytetracycline from epioxytetracycline, tetracycline, and chlortetracycline. Total elution time for oxytetracycline is less than 5 min at 1.5 mL/min. Five spiked premix samples each of 2 and 50 g/lb had a coefficient of variation of 3.5 and 4.5% and a mean recovery of 99 and 104%, respectively. The results of premixes and veterinary products assayed by this method compared closely with those of the same assayed by the official AOAC microbiological method.  相似文献   

11.
Seventeen laboratories evaluated the pyridine extraction method and neomycin-sensitized agar for the determination of zinc and MD bacitracin in swine and broiler rations at 10 and 100 g/ton. The method was also applied to the analysis of 2 premixes labeled 50 g/lb (MD bacitracin) and 40 g/lb (zinc bacitracin). Bacitracin activity was determined on each of 2 days with 2 dilutions on each day. No significant difference was found between dilutions within a day or between days for each sample. The type of bacitracin or type of feed did not significantly affect results. The difference in results between MD and zinc bacitracin in premixes approached significance. The large coefficients of variation for premixes (ca 13%) and complete feeds (ca 15--30%) indicate operational problems. The main difficulty was evaporation of pyridine. Some laboratories were not able to evaporate it completely, whereas others lost bacitracin activity, probably due to high temperature of drying. The pyridine extraction method as in 42.200 and 42.204 should be discontinued.  相似文献   

12.
A liquid chromatographic (LC) method for determining furazolidone in finished feeds and premixes was collaboratively studied. Finished feed sample is extracted with acetone-water (93 + 7) on a Goldfisch apparatus, extracting solvent is removed, and the residual material is dissolved in warm DMF. A solution of tetraethylammonium bromide is added, the fat layer is removed, and the sample is clarified by filtration and injected onto a reverse phase LC system with detection at 365 nm. Premixes, extracted by shaking with DMF and diluted so that the final furazolidone concentration is about 55 micrograms/mL, are chromatographed and detected the same as finished feed samples, using a mobile phase of acetonitrile-2% acetic acid (20 + 80). Ten commercial feed samples were preweighed and supplied to 14 collaborators. The 5 matched pairs were chosen to represent the following allowed levels: 0.0055, 0.022, 0.033, 2.2, and 22%. Two familiarization samples at the 0.0055 and 11% levels were also supplied. Instructions called for a single analysis of each sample. Two results were eliminated by the Dixon test. The coefficients of variation, following treatment by the ranking test, ranged from 2.0 at the 22% level to 6.5 at the 0.0055% level. Calculated F-values are not significant (P greater than 0.01) except for the 0.0055% level samples extracted overnight. This method has been adopted official first action.  相似文献   

13.
A liquid chromatographic (LC) method was developed for the determination of aflatoxins in feedstuffs containing citrus pulp. The feed-stuff sample is extracted with chloroform, followed by Sep-Pak Florisil cartridge cleanup and Sep-Pak C18 cartridge cleanup. The final eluate (water-acetone, 85 + 15, v/v) is submitted to reverse-phase liquid chromatography with water-methanol-acetonitrile (130 + 70 + 40, v/v/v) as mobile phase and postcolumn derivatization with iodine. Citrus components are removed from the extract efficiently. The limit of detection for aflatoxin B1 is less than 1 microgram/kg. Other aflatoxins can also be detected and measured. Recoveries of aflatoxins B1, B2, G1, and G2 for dairy rations spiked at 13, 5, 10, and 4 micrograms/kg were 87, 86, 81, and 82%, respectively. Corresponding coefficients of variation were 3.1, 3.6, 5.2, and 3.8%, respectively.  相似文献   

14.
A sensitive, rapid, reproducible, and reliable liquid chromatographic (LC) method is described for determination of ergosterol in feedstuffs. The sample is saponified directly and the saponified mixture is extracted with n-hexane. Ergosterol is determined without further purification or cleanup steps by using a liquid chromatograph with a 250 X 4.6 mm column packed with LiChrosorb Si 60, 5 microns, and a high pressure column prefilter. The ultraviolet detector is set at 282 nm. The limit of detection was 0.1 ppm; recovery ranged between 96.7 and 102.2%. Diode array technology is used for identification and peak purity control. Under strong UV irradiation (254 nm) and oxygen or nitrogen atmosphere ergosterol was converted almost quantitatively to ergocalciferol. Under the described conditions of the method, ergosterol proved to be stable. Ergosterol was determined in cereals, mixed feeds (e.g., for swine and poultry), and their components of plant and animal origin. It was not found in carcass meal, meat-and-bone meal, citrus pulps, or molasses; only traces were detected in fish meal.  相似文献   

15.
Numerous methods to analyze biogenic amines in biological materials have been described. A versatile and rapid methodology to analyze these compounds in feedstuffs, complete feeds, and animal tissues, however, has not been reported. The current method was developed to address this need. Biogenic amines in feedstuffs, complete animal feeds, and animal tissues were extracted with 10% trichloroacetic acid, reacted with O-phthaladehyde using high-performance liquid chromatographic employing a cation exchange column. Detection limits were 50 pmol/mL for tyramine, histamine, putrescine, and spermine; 40 pmol/mL for cadaverine; and 25 pmol/mL for spermidine. Extraction efficiency of biogenic amines in feedstuffs, duodenum, liver, ileum + jejunum, and whole shrimp and shrimp hepatopancreas ranged between 99-105, 93-135, 80-85, 65-102, 88-98, and 88-97%, respectively. It can be concluded that the current method can be applied to individual feedstuffs, complete feeds, and animal tissues for the rapid and accurate determination of concentration of biogenic amines.  相似文献   

16.
A method is described for rapid cleanup followed by reverse-phase liquid chromatographic (LC) quantitation of aflatoxins in raw peanuts. A modified minicolumn cleanup is used for sample preparation, and a preliminary estimation of aflatoxin content by minicolumn can be made so that highly contaminated samples can be diluted before LC analysis. The use of the simple, quick minicolumn cleanup eliminates the need for further column or cartridge cleanup, thus greatly reducing sample preparation time. Sensitive quantitation is achieved using a phenyl column, a mobile phase of water-tetrahydrofuran (80 + 20, v/v), and postcolumn derivatization with water-saturated iodine followed by fluorescence detection. The recoveries of aflatoxins B1, B2, G1, and G2 from peanut meal spiked at 3 levels ranged from 71.7 to 88.3% (average 80%) with coefficients of variation from 2.7 to 10.4%.  相似文献   

17.
入仓原料种类识别是饲料生产过程中的关键环节之一。目前,入仓原料主要通过人工取样的方式,依靠工人感官经验识别原料种类,以确保原料正确入仓。为了实现饲料原料种类在线自动取样和识别,提高饲料加工的自动化水平,该研究设计了一种多通道饲料原料自动取样装置,应用机器视觉技术,搭建了原料种类在线识别系统。该系统主要由取样单元、样品输送单元、图像采集单元等组成;采用Arduino Uno为系统控制核心,设计了控制流程和控制线路;在Arduino IDE开发环境下编写了控制程序;运用卷积神经网络的方法构建了饲料原料种类识别模型CAM-ResNet18;基于PyQt5环境开发了饲料原料种类在线识别系统软件,包括上位机人机交互软件系统和下位机自控控制系统。上位机系统软件通过串口与下位机控制器通讯,实现对饲料原料种类在线取样识别装置的自动控制。通过模型嵌入和系统集成,对系统的基本功能、识别准确率和识别时间进行测试。饲料原料种类在线识别系统运行正常可靠,实现了饲料原料入仓过程中的自动取样、图像采集、种类识别、结果反馈、一键报警的全环节智能操作。系统性能测试中,饲料原料种类识别准确率为98%,取样识别周期为10.13 s。研究结果表明开发的饲料原料种类在线识别系统可以实现入仓饲料原料在线取样和种类识别功能,为饲料加工中饲料原料种类的自动识别提供了新的方法和技术支撑。  相似文献   

18.
Vitamin D2 or vitamin D3 is determined by liquid chromatography (LC) in milk and infant formula. Vitamin D is extracted from the saponified sample, passed through an amino-cyano LC cleanup column to remove major interferences, and quantitated using normal phase LC. Within-day precision is 4.5% relative standard deviation (RSD); the overall method RSD (reflecting technician-to-technician, day-to-day, and within-day variability) is 7.7%. Overspike recoveries averaged 97% for milk, 98% for milk-based infant formula, and 93% for soy-based infant formula. The performance of the method is compared with that of the official AOAC vitamin D method (rat bioassay). The method is applicable to the determination of vitamin D in milk and in the major milk- and soy-based infant formulas available in the United States. The method can quantitate (but not distinguish) either vitamin D2 or vitamin D3. The method is applicable to milk and infant formula samples containing between 100 and 1500 IU vitamin D/L. Sample throughput is between 4 and 8 replicates per day.  相似文献   

19.
An atomic absorption spectrophotometric method, using the vapor generation technique for the determination of selenium in animal feed premixes containing 0.4-0.002% selenium, is described. After the sample was digested in perchloric acid and hydrogen peroxide and reduced with 6M HCl, 3 aliquots of sample, each containing about 0.4 mug Se, were taken for analysis by the standard addition method. Sodium borohydride pellets were used for the generation of selenium hydride. The relative standard deviation of a single determination averaged +/- 19%.  相似文献   

20.
The official final action method, 42.028--42.032, for determining amprolium in feeds was modified by a change in the preparation of aluminum oxide for chromatography. A premix containing 0.5% amprolium was collaboratively studied by the modified and the official methods. Compared with the modified method, 87.7% of the drug was recovered from the premix by using the official method. The modification makes possible the assay of premixes as well as finished feeds. The official final action method has been modified to incorporate this change.  相似文献   

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