常规火焰光度法测定复混肥中氧化钾的方法改进

火焰光度法测定复混肥中K2O含量,由于标准溶液与待测溶液基体不一致,使测定结果重现性差,与重量法测定结果相差较大.为此,对方法进行了改进,采用基体一致,用已知K2O含量的复混肥(其氧化钾含量以重量法测定结果为准)作为标准溶液对仪器进行校准.大量的对照实验表明,此法所测K2O结果与重量法测定结果较吻合,且方法简单,快速,...     

The determination of sodium,potassium and magnesium in surfactants by flame spectrophotometry

A method for determining sodium, potassium, and magnesium in soaps and detergents by means of flame spectrophotometry is described in detail. Sodium and/or potassium are normally present in high percentages; magnesium is usually found in relatively low concentrations as part of the antioxidant system of bar soaps. The spectrophotometric procedure has the following advantages over commonly used wet methods: 1) rapidity, 2) simplicity, and 3) the cations are determined directly and independently of each other. Soap additives, such as perfumes, colors, super-fatting agents or germicides do not interfere with this method. Possible interferences between sodium, potassium, and magnesium cations were evaluated and eliminated. Typical examples, including toilet soaps, combination soap-detergent bars, and sprayed detergents are described. Presented at the AOCS meeting in Toronto, Canada, 1962.     

Selective hydrogenation of soybean oil with sodium borohydride-reduced catalysts

The reaction of metallic salts in aqueous solution with sodium borohydride produces finely divided metals that are catalytically active for hydrogenation. Salts of nickel, cobalt, palladium and platinum give active catalysts for the selective hydrogenation of soybean oil. Iron and silver salts, when reduced with sodium borohydride, show no activity at 200C and atmospheric hydrogen pressure. The cobalt catalyst produces the least amount of stearate. Incorporation of palladium, platinum, copper or chromium up to 2% enhance the activity of the nickel catalyst. Copper and chromium salts, when reduced together, form catalysts that hydrogenate linolenyl groups in soybean oil seven times more rapidly than linoleyl groups. No stearate formation is observed with these binary catalysts. Presented at the AOCS Meeting, Houston, April 1965. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Nephelometric determination of phosphorus in soybean and corn oil processing

A procedure to measure phosphorus content of soybean and corn oil samples has been developed using nephelometry (turbidity). The method uses the relationship between phosphorus level due to phosphatides in vegetable oil and turbidity formed in phosphatide mixtures. The rapid 10-min determination of phosphorus in process samples is 30 times faster than colorimetric methods. Phosphorus vs turbidity data formed nearly linear relationships for crude, degummed, once-refined, bleached and deodorized soybean and corn oil process samples.     

连续流动火焰光度法快速测定有机肥料中氧化钾含量

采用连续流动火焰光度法测定有机肥料中的氧化钾含量。该方法测定快速准确,溶液标准曲线相关系数可达0.999 9,平均加标回收率达101.19%,平行测定的绝对误差小,且实现了自动进样和自动检测,能够满足生产控制过程及各种检测机构的检测要求。     

气相色谱-火焰光度法测定苯中微量环丁砜和噻吩

建立了气相色谱-火焰光度法测定苯中微量环丁砜和噻吩的方法,对色谱条件进行了优化,定量方法采用外标法。该方法的加标回收率为114%～136%;相对标准偏差（RSD）不大于7%。测定苯样品中微量环丁砜和噻吩具有灵敏度高、重现性好和可靠性高等优点。     

Ion chromatographic determination of phosphorus and tungsten in epoxidized soybean oil

Soybean oil has been epoxidized with hydrogen peroxide in the presence of catalytic amounts of trioctylmethyl-ammonium tetra(diperoxotungsto)phosphate. A fast ion-exchange chromatographic method with suppressed conductivity detection has been developed for determining residual contents of tungsten and phosphorus in the oil. Tungsten and phosphorus could be determined at concentrations of 66 and 11 ppm, respectively. At tungsten and phosphorus concentrations of 1000 and 50 ppm, measured repeatabilities were 1.3 and 1.5%, respectively.     

The determination of soap in refined vegetable oil using the flame photometer

Summary A method has been developed for the determination of sodium soap as sodium in refined vegetable oil. The oil is extracted with hydrochloric acid, and the sodium is determined in the aqueous extract by using the flame photometer.     

原子吸收光度法直接测定工业硫酸中镍

建立火焰原子吸收光谱法直接测定工业硫酸中重金属镍的方法。采用稀硫酸配制标准系列溶液,用火焰原子吸收光谱法直接测定工业硫酸中金属镍含量。在选定的仪器测定条件下,采用标准加入法考察方法的准确度和精密度。结果表明,加标回收率为97.4%,相对标准偏差(RSD)为0.45%,方法检出限为0.012μg/mL。结论:方法简单易操作、快速可靠,可用于工业硫酸中镍含量的直接测定。     

悬浮液进样-火焰原子吸收光谱法测定云冈石窟降尘中的锰

把降尘样品干燥磨碎并过200目筛后悬浮于0.15%琼脂胶体中制成悬浮液,用火焰原子吸收光谱法成功测定了云冈石窟降尘中锰元素的含量.对悬浮剂进行了选择,考察了共存离子的影响.在优化条件下测定锰的线性回归方程为A=2.936 6c(μg/mL)-0.007 5(r=0.998 2),精密度为3.56%,检出限为0.001 2 μg/mL,回收率在101.9%～103.5%之间,方法简便、快速、无污染、无被测元素损失.     

Deacidification of soybean oil by membrane technology

After extracting free fatty acids (FFA) from a model crude vegetable oil with methanol, FFA were separated from methanol by nanofiltration. Of the several commercially available membranes that were evaluated, the best resulted in FFA rejection of >90% and flux of >25 Lm⁻²h⁻¹. A combination of high-rejection and low-rejection membranes resulted in a retentate stream of 35% FFA and a permeate stream with less than 0.04% FFA, which can be recycled to the extractor. No alkali is required, no soapstock is formed, and almost all streams within the membrane process are recycled with little discharged as effluent.     

A crystallization method for the determination of saturated fatty acids in soybean oil

Summary A crystallization method has been developed for the determination of saturated fatty acids in soybean oil. The method is simple and rapid. The results obtained by this method agree quite well with those obtained by the use of the Bertram oxidation method and are about 2 percent higher than those obtained by the use of the modified Twitchell method. The procedure recommended seems to give satisfactory results on soybean and cottonseed oils, but it will probably have to be modified for use with highly unsaturated oils such as perilla, or with oils such as olive which contain large amounts of oleic acid. A cooperative organization participated in by the Bureaus of Agricultural Chemistry and Engineering and Plant Industry of the U. S. Department of Agriculture, and the Agricultural Experiment Stations of the North Central States of Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin.     

The determination of tocopherol content during the commercial processing of soybean oil

Summary A method for the analysis of the total tocopherols in soybean oil has been presented, and judged by distillation and other procedures is estimated to be accurate to within 10%. A discussion is made of the tocopherol to within 10%. A discussion is made of the tocopherol losses in various steps of soybean oil refining. Communication No. 115 from the Research Laboratories of Distillation Products, Inc., Rochester, New York. (Presented at The American Oil Chemists Society meeting in New Orleans, May 20–22, 1947.)     

Metals in soybean oil

Certain metals often produce deleterious effects when present in soybean oil. Trace quantities of copper, iron and manganese dramatically reduce the oxidative stability of edible oils. The presence of calcium and magnesium in crude oils reduces the efficiency of degumming and refining operations. Sodium soaps reduce bleaching efficiency by inactivating adsorption sites on bleaching earth. Phosphatides or phosphorous containing lipids exert a poisoning effect on hydrogenation catalysts. Nickel, an artifact of hydrogenation, must be removed from the oil for health, stability and safety considerations. This paper provides an overview of the various effects of metals on processing and stability, describes how to inhibit or diminish their activity, and discusses various analytical techniques for identification and quantitation of the metals present in soybean oil.     

Detection of chlorophyll derivatives in soybean oil by HPLC

Chlorophyll derivatives have been isolated from a degummed soybean oil by cellulose column chromatography and resolved by reversed phase HPLC. The HPLC separation was performed on a Zorbax ODS column using acetone-methanol (75:25) as the mobile phase. Seven major components were detected by visible (650 nm) light absorption. Pheophytin A is the predominant component of the mixture (40–45% of the total). Pheophytin A’, pyropheophytin A, and three unidentified pigments having spectral features resembling pheophytin A comprise the other major pigments. No evidence was found for the presence of chlorophylls A and B in this oil.     

Oil stability index correlated with sensory determination of oxidative stability in light-exposed soybean oil

Validity of the oil stability index (OSI) as an accelerated test of oxidative stability has been questioned because of its high holding temperature, 110°C, which may cause reactions that would not occur at lower temperatures. The purpose of this study was to characterize the usefulness of OSI as an accelerated oxidative stability test for oil of varying metal catalyst content by correlating OSI with the sensory induction period of light-exposed soybean oil. Five 400-g aliquots of soybean oil were placed in Erlenmeyer flasks and treated with increasing levels of a metal pro-oxidant, Cu²⁺ 2-ethylhexanoate. Pro-oxidant concentration ranged from 0 to 3.13×10⁻⁵ M. Five-gram aliquots were taken from duplicate flasks and immediately tested using the Oxidative Stability Instrument. Heating block temperature was 110°C. Sample flasks were then exposed to 800 footcandles of light and held at ambient temperature for 3 wk. One-gram aliquots were regularly withdrawn and evaluated for rancidity by 10 trained panelists to determine the sensory induction period of each sample. Aliquots were also taken to determine OSI of light-exposed oil samples. Sensory induction periods were correlated with OSI, resulting in a squared partial correlation coefficient (r ²) of 0.920. The r ² for OSI of light-exposed oil samples ranged from 0.897 to 0.979. OSI appears to be an acceptable accelerated method for measuring the oxidative stability of light-exposed soybean oil that varies in metal catalyst content.