Improved microbiological procedure for determining bacitracin in premixes and mixed feeds

An improved microbiological procedure is presented for determining bacitracin in premixes and mixed feeds. Premixes are extracted with acidic 50% aqueous methanol, and mixed feeds are extracted with 50% dimethylformamide after washing with acetone to remove fats and pigments. Extracts are diluted with pH 6.0 phosphate buffer and assayed by using a 2-point assay system with Micrococcus flavus as the test organism. The simpler extraction coupled with the 2-point assay system measured bacitracin levels as low as 10 g/ton. Accuracy and repeatability of the 2-point system were at least equivalent to those for official AOAC methods.     

Rapid colorimetric method for carbadox in animal feeds

The colorimetric method for carbadox in animal feeds was modified to be simpler and faster. Carbadox is extracted with dimethyl-formamide and separated from interferences on an alumina column in the absence of water by controlling the amount of sample extract on the column and the flow rate. The isolated carbadox is eluted into sodium hydroxide and the resultant yellow chromophor is measured spectrophotometrically at 420 nm.     

Modification of mckay-perring method for the calculation of mean activity coefficients of solutes in mixed solutions

formerly Graduate Student, Department of Metallurgy, Kyoto University, Japan     

Recommended method for the analysis of amino acids in biological materials

Methods are presented for the preparation of large monodomain phospholipid bilayer arrays containing variable amounts of water approaching the two-phase limit. The optical birefringence of these lamellar phases of dipalmitoyl phosphatidylcholine (DDPC) is measured over a range of temperature and water content, and phase transitions are observed. The techniques employed for pure DPPC and water are extended in order to produce macroscopically aligned samples containing varying concentrations of cholesterol, inorganic salts, antibiotics, and chlorophyll a. Polarization studies of the 670-nm band of chlorophyll a indicate macroscopic orientational order in the chromophore under the same conditions.     

Gas-liquid chromatographic determination of T-2 toxin and diacetoxyscirpenol in corn and mixed feeds

A gas-liquid chromatographic method has been developed for the simultaneous determination of the T-2 toxin and diacetoxyscirpenol (DAS) in corn and mixed feeds. The analytes are extracted with aqueous methanol. Ammonium sulfate is used to denature and precipitate proteinaceous compounds and to salt out low polar compounds. The analytes are selectively concentrated into chloroform, which is washed with aqueous potassium hydroxide to remove acidic compounds. Residual interferences are removed by silica gel column chromatography. Heptafluorobutrylimidazole (HFBI) is added to form esters of the analytes. The HFB-esters are separated on an SE-30 glass column and measured witha 63Ni electron capture detector, using methoxychlor as an internal standard. The method has been applied to corn, livestock feeds, and pet food. The limit of detection is 100 ng T-2 toxin and 25 ng DAS/G. Average recoveries of 105 and 97% and coefficients of variation of 17 and 10% were obtained for T-2 toxin and DAS, respectively.     

光谱法测定贵金属湿法冶炼物料中的金

将等离子体光谱法和X荧光光谱法应用于贵金属湿法冶炼物料中金的测定。通过对多种不同组成物料的测定及与经典火试金法进行的大量对照试验,拟定了测定金的新方法。光谱法具有测定快速、线性范围宽、准确度好、精密度高等优点,完全能满足生产控制及科研的需要。     

Thin-layer chromatographic determination of monensin in feeds: screening method

Monensin is extracted from feed with methanol and purified by solvent-partitioning solid-phase extraction. After solvent reduction, monensin is separated by thin-layer chromatography on silica gel and visualized by color development with vanillin. No false-positive results were obtained in validation studies by submitting or peer laboratories when blank samples were analyzed. Three of 20 samples spiked with 5 ppm monensin were reported as containing no monensin. All samples spiked with 10 ppm monensin were reported positive for monensin.     

Culture method for detection of Salmonella in dried active yeast: collaborative study

A method for detecting Salmonella in dried active yeast was subjected to collaborative study. This method employs trypticase soy broth as the pre-enrichment medium, a sample-to-broth ratio of 1:10, and subsequent transfers to lauryl sulfate tryptose broth and tetrathionate before streaking onto selective agars. Each collaborating analyst received ten 25 g samples of dried active yeast. Duplicate 25 g samples were each inoculated with Salmonella oranienburg at a low level (28 cells) and a high level (107 cells). Similarly, duplicate 25 g samples were each inoculated with S. senftenberg at a low level (30 cells) and a high level (114 cells). The remaining 2 of 10 samples were not inoculated. Results from 12 of 13 collaborators were evaluated. Only 2 (8.2%) of the 24 low level S. oranienburg samples were reported incorrectly as negative. Twelve of the analysts detected S. senftenberg at both levels and S. oranienburg at the high level in the inoculated samples. Results from 12 collaborators used in the final evaluation show that 117 of 119 (98.3%) collaborative determinations are in agreement. The official final action method for the detection and identification of Salmonella, 46.013-46.026, has been revised official first action to include applicability to dried active yeast.     

High performance liquid chromatographic method fo pyrantel tartrate in swine feeds and supplements

A new method for the determination of pyrantel tartrate in swine feed an supplements has been developed because the current official AOAC method is not applicable to feeds co-medicated with tylosin. The new method involves: (a) leaching of drug from feed with methanolic NaCl solution, (b) removal of interfering substances by ion pair liquid-liquid extraction and high performance liquid chromatography, and (c) quantitation of pyrantel tartrate by monitoring the ultraviolet absorption of the effluent stream at 313nm. The method of standard addition is used to compensate for the effect of the feed matrix on drug recovery. No interference is encountered from tylosin, carbadox, lincomycin, non-drug components of feeds and supplements, or potential degradation products of pyrantel tartrate, i.e., cis isomer of pyrantel tartrate and (E)-N-(3-methylaminopropyl)-2-thiopheneacrylamide. Results for the assay of 3 lots each of feeds and supplements containing 0.0106 and 0.106% pyrantel tartrate, respectively, were within +/-4% of label claim. Coefficients of variation ranged from 1.6 to 1.8% for feeds and from 1.9 to 3.9% for supplements.     

惰气熔融-红外吸收/热导法在无机固态材料气体分析中的应用

综述了近十年来惰气熔融-红外吸收/热导法在金属合金、稀土材料、冶金添加剂、耐火陶瓷等无机固态材料气体元素分析中的应用现状, 侧重汇总了称样量、助熔剂、分析功率、标准样品等主要分析条件, 介绍了氢、氧、氮元素分量测定的最新进展。讨论了该法存在的问题, 并提出相关建议, 展望了无机固态材料中气体分析的应用前景和发展方向。     

Microbiological method for determining macrolides in animal feeds in the presence of other drugs by thin-layer chromatography detection

A method was developed to separate, detect, and quantitate erythromycin (ERY) and tylosin (TYL) in animal feeds in the presence of 11 other drugs: 3 nitrofurans, 2 tetracycline antibiotics, 3 sulfonamides, 2 coccidiostats, and 1 antibacterial growth promoter. ERY and TYL were separated from coexisting drugs, detected by thin-layer chromatography, and quantitated microbiologically by an agar diffusion method. Analysis of 125 experimental animal feed samples fortified at 5 levels (7.5-400 ppm) with ERY and TYL and at 1 level (50 ppm) with the rest of the drugs gave limits of quantitation of 2 and 5 ppm, recoveries of 90.3 and 92.4%, and relative standard deviations of 4.3-7.3% and 3.6-6.1%, respectively.     

韶关冶炼厂烧结机供风系统改造及其效果

介绍了韶关冶炼厂两个烧结系列供风系统的改造情况及改造后的效果。     

Guidance method to use mixed coal in blending for coking

Based on the principle that the adaptation can be reflected by the overlap of reflectance distribution peaks,the effect of various types mixed coal for coking is analyzed.Based on the action of the vitrinite of different reflectance range and the adaptation,a new method for guidance blending coal is established.Through simulation,blending coal using the software of HD automatic microscope photometer,makes the synthetic blending coal reflectance distribution map to nothing notch wide single peak flat-shap...     

Calculation method for percolation thresholds in modeling porous and composite materials

A method is suggested for calculating percolation thresholds in two- and three-dimensional materials allowing for remote interaction and elongation of particles forming these materials. Calculated results are compared with known data. It is shown that it is possible to use the method when simulating elastic and plastic properties of porous materials.     

Modification of method for determination of medium-molecular peptides and its application in pediatric surgery

Taking into account clinical significance of determination of medium-molecular peptides' concentration in various surgical diseases and limitation of blood sampling in children, modification of the method for determination of medium-molecular peptides in blood serum is proposed, which requires 0.1 ml of serum and is based on deproteinization of cooled ethanol followed by spectrophotometry of peptide solution at 210 nm. Comparison study of the results of examination by this method and routine one was carried out. Specificity and advantages of the suggested modification are discussed.     

New method for the production of composite materials

A new method is proposed for the production of articles consisting of several metals or alloys by joint plastic deformation of their workpieces using rolling or compression. To perform joint plastic deformation, grooves are made on a contact surface at various angles of inclination to it.     

Determination of carbon and silicon in sintered nickel-base sealing materials by the method of spectral analysis

Summary The results of this investigation demonstrate, in the first place, the need for the analysis of chemical composition changes and the importance of employing the spectral analysis of surface layers.In view of the observed substantial changes in chemical composition, the operating conditions leading to these changes must be taken into account in the manufacturing technique with a view to selecting the most suitable composition of sintered sealing materials.By using spectral analysis, it is possible to choose materials with higher stability of chemical composition and, consequently, wear-resistance characteristics. The existing materials should be employed more effectively by allowing for the changes taking place during operation.