The estimation of lactic acid in lactylated monoglycerides and shortenings containing lactylated monoglycerides

A titrimetric method has been presented for the determination of lactic acid in lactylated monoglycerides and shortenings containing these products, when the only water soluble acid present is lactic acid. Analyses by this method: of knowns, samples from a material balance test, and commercial products, indicate that it is applicable to these types of product. Comparison of analyses of the material balance samples and commercial products by the titrimetric method and the colorimetric p-phenylphenol method indicated that the latter gave lower and more variable results.     

The determination of lactic acid in shortening containing lactylated glycerides,by liquid-liquid partition chromatography

Shortenings containing ca. 1% lactic acid added as lactylated glycerides are analyzed for total or water insoluble combined lactic acid (WICLA) by a liquid-liquid partition Chromatographie pro-cedure. The sample is saponified, acidified with H₂SO₄, dispersed on silicic acid, slurried with chloroform and transferred to the top of a chro-matographic column composed of a 0.5 N sulfuric acid stationary phase supported on silicic acid. After elution of the fatty acids by chloroform, 15% m-butanol removes the excess H₂SO₄ fol-lowed by a well resolved lactic acid fraction. Titration of the latter fraction with standard methanolic sodium hydroxide has shown the lactic acid recovery to be 94%. The WICLA determina-tion requires 7 hr and has a standard deviation of ±0.020%. Presented in part at the AOCS Meeting, New Orleans, 1962.     

A chromatographic method for the analysis of propylene glycol fatty acid esters in shortenings containing mono- and diglycerides

A procedure is described for the separation, identification, and quantitative estimation of propylene glycol mono- and diesters of lauric, myristic, palmitic, stearic, and oleic acids in shortenings and lard containing mono- and diglycerides. Lipid classes are separated on a silicic acid column, and individual esters are estimated by gas chromatography. Analyses of several control mixtures and commercial samples are reported. Recoveries for individual components range from 92 to 105%, and total recoveries range from 96 to 100%.     

Blending of poly(lactic acid) and starches containing varying amylose content

Four dry corn starches with different amylose content were blended at 185°C with poly(lactic acid) (PLA) at various starch:PLA ratios using a lab‐scale twin‐screw extruder. Starch with 30% moisture content also was blended with PLA at a 1:1 ratio. Each extrudate was ground and dried. The powder was mixed with about 7.5% plasticizer, and injection molded (175°C) into test tensile bars. These were characterized for morphology, mechanical properties, and water absorption. Starch performed as a filler in the PLA continuous matrix phase, but the PLA phase became discontinuous as starch content increased beyond 60%. Tensile strength and elongation of the blends decreased as starch content increased, but no significant difference was observed among the four starches at the same ratio of starch:PLA. The rate and extent of water absorption of starch/PLA blends increased with increasing starch. Blends made with high‐amylose starches had lower water absorption than the blends with normal and waxy corn starches. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3639–3646, 2003     

一种测定湿法磷酸中氧化铝含量的化学方法

采用EDTA容量法测定湿法磷酸中氧化铝含量。该方法利用氢氧化铝的两性性质,在湿法磷酸中加入过量的氢氧化钠,使其中的金属杂质离子与强碱反应生成沉淀而分离,氧化铝则与强碱生成可溶性的偏铝酸盐,从而测定其含量。结果表明,此方法Al_2O_3的平均回收率可达101.62%,具有快速准确的特点。     

一种测定邻苯二甲醛含量的新方法

建立了邻苯二甲醛含量的化学分析测定方法,并采用t检验法进行显著性检验。结果表明,样品平均回收率(n=5)为99.82%,RSD为1.29%,t值均小于t表值(2.776),方法准确、可靠、重现性好,与气相色谱法无显著性差异,适用于芳醛的常量分析,能够满足邻苯二甲醛生产中监控分析的需要。     

A method for the determination of linoleic acid and conjugated dienoic acids in materials containing eleostearic acids

Summary A procedure has been described which extends the scope of the spectrophotometric method for polyun-saturated acids to the determination of linoleic and conjugated acids in the presence of large quantities of conjugated trienoic acids. Basis for the proposed method rests on equations which are offered to correct the “end” or “back-ground” absorption of the highly absorbing triene conjugated acids at 233 mμ, the position of maximum absorption of conjugated dienoic acids and alkali isomerized linoleic acids. The method is limited to samples which do not contain nonconjugated trienoic acids (linolenic acids). The method has been tested by the analysis of several mixtures of cottonseed and dehydrated castor oils of known composition, to which varying amounts of alpha, beta, and mixtures of alpha- and beta-eleostearic acids have been added. These samples have been used to demonstrate the application of the proposed method for the determination of dienoic conjugated acids, alpha-eleostearic acid, beta-eleostearic acid linoleic acid, oleic acid, and total saturated fatty acids. Comparisons of the results obtained with similar values, calculated from the known composition of the mixtures, prove that the proposed method gives reasonable results. Standard deviations between determined and calculated results vary from 0.36 for diene conjugated acids to 1.40 for oleic acid. The method has been applied to the analysis of foreign and domestic tung oils. Presented before the American Oil Chemists' Society, Cincinnati, O., Oct. 20–22, 1952. One of the laboratories of the Bureau of Agricultural and Industrial Chemistry, Agricultural Research Administration, U. S. Department of Agriculture.     

A method for the determination of maleic anhydride content in copolymers

Summary A simple and reliable non-aqueous direct titration method for the determination of anhydride content in maleic anhydride-vinyl acetate copolymers is described. The procedure involves reaction of the anhydride with a large excess of aniline followed by direct titration of the resulting monoacid with ethanolic NaOH using potentiometric or thymol blue end point detection. The method overcomes many of the disadvantages of previously published methods, and its application to other copolymers is considered.     

一种快速准确测定磷酸中硫酸根含量的方法

传统的玫瑰红酸钠比色法测定磷酸中SO3含量时,只能测量出SO3的质量浓度范围,不能满足对磷酸料浆中硫酸根含量范围要求较窄的工艺要求。通过对传统的玫瑰红酸钠比色法进行改进,同时改进计算方法,便可以快速准确测定磷酸中的硫酸根含量。改进后该分析方法精密度高,加标回收率高,能满足实际生产的需要。     

A rapid oxygen bomb method for evaluating the stability of fats and shortenings

A modification of the A.S.T.M. oxygen bomb method for evaluating the stability of any fat within a period of six hours or less has been developed. It is based upon the addition of selected levels of a copper, catalyst, operating under the conditions previously used without catalyst. The precision of this bomb method has been characterized and the contributions of several factors to the overall variation have been estimated. The research indicates that it will not be possible to express bomb data in terms of AOM values by employing a factor. On the basis of precision obtained by this procedure, it is concluded that it should be readily adaptable to industrial control applications.     

A new method for cement content determination of fresh concrete

A new method for the rapid determination of the cement content of fresh concrete based on flotation principles is presented. Results may be obtained within a time of 20 minutes and are independent of type of cement, grain-size of aggregate, age of the mix and the testing temperature. The method is specially suited for site application.     

A proposed method for the polarographic determination of Mo(IV) in the presence of glycolic,lactic or malic acid

It was found that the polarographic reduction of molybdate(VI) was possible in the presence of glycolic, lactic and malic acids in neutral borate-phosphate solution. The polarographic wave was precisely proportional to the concentration (<10^?2M) of molybdate, and hence the straight line was useful as a calibration curve in quantitative analysis of molybdate. It was suggested that a reducible species on a mercury electrode was molybdate complex produced through hydrogen (glycolic, lactic or malic acid)-oxygen (molybdate) bond.     

精己二酸中硝酸含量测定方法的改进

对“精己二酸中硝酸含量的测定SH／T1499．7—1997”石化行业标准中的结晶、溶液颜色异常现象进行了研究试验。结果表明,减小溶液中精己二酸浓度、增大氢氧化钠浓度可以消除结晶及溶液颜色异常现象。新方法的相关系数为0．9995,回收率为95．1％-107．3％,标准偏差为0．03-0．23,完全满足产品分析检验方法的需要。     

氢氟酸重量法测定硅质耐火材料中二氧化硅含量的改进

提出了用水润湿试样,延长氢氟酸低温浸泡试样的时间,低温加热一次氢氟酸挥散硅重量法测定硅质耐火材料中二氧化硅含量的方法。与现有的方法相比,改进后的方法氢氟酸用量减少了40%,硝酸用量减少了70%,试验时间缩短,能耗大幅减少。方法更安全可靠,更节能环保。用标准物质对方法进行了考察,表明测定结果准确。     

A rapid sensitive colorimetric method for the determination of ascorbic acid

A new colorimetric procedure based on the interaction of ascorbic acid with 4,4′-dimethoxydiquinone (I) in an aqueous dioxane solution was developed. In this procedure the diquinone reagent (I) is reduced to a blue-violet product (II)¹ which absorbs maximally at 490–500 nm. The colour development takes place within 6 min at 25°C and absorbance vs concentration was linear up to a sample size of 600 μg. Reducing substances likely to be present in biological fluids or in natural extracts of the vitamin do not interfere with colour development and average recoveries of 99.8 ± 0.4% were obtained for solutions containing these substances.     

酯化气相色谱法与化学分析法测定氯乙酸含量的比较

介绍采用酯化气相色谱法测定工业氯乙酸及其杂质的含量,对方法的重复性和准确度进行了试验,并与化学分析法进行了比较,探讨了产生差异的原因.     

土壤中总铬测定方法的探讨

采用盐酸-硝酸-氢氟酸-高氯酸消解预处理土壤样品,结合工作曲线法和标准加入法测定土壤中总铬的含量。结果表明,该法与国标方法比较,提高了测定样品的准确度和精密度,完全能满足环境土壤中总铬测定的要求。     

A comparison of nuclear magnetic resonance and dilatometry for estimating solids content of fats and shortenings

The percent solids values of fats and shortenings using nuclear magnetic resonance (NMR) and solid fat index (SFI) have been compared. The samples used were: blends of hard fat and safflower oil, safflower oil hydrogenated to varying degrees, and different types of shortenings. This investigation demonstrated the empirical nature of the SFI technique and shows the nature of the deviations from the solids content determined by the NMR method. The magnitude of the deviation of SFI from the NMR solids content increased with the level of the solids. The SFI values and the NMR solids content were similar at the lower levels (SFI values of 10) but at the upper limit for the SFI method (SFI values of 50) the solids content by the NMR method can be 80% or more, a difference of 30 units. Although the determination of solids content by NMR is reliable, the relationship between SFI values and NMR values for different types of samples is so variable that the calculation of the SFI value from percent solids by NMR, or percent solids from SFI values from prediction equations is not very reliable. Since NMR measures the solids content more accurately than SFI and is applicable over the entire range of solids, 0 to 100%, it will be very useful in fat and oil research and control.