自动电位滴定法测定甲醛含量

用自动电位滴定测定甲醇生产装置废水和季戊四醇生产副产品甲醇中的甲醛含量 ,采用预设终点模式和动态滴定模式互补来实现分析中的中和滴定和含量测定两步过程 ,用 pH =6 .8、pH =9.2两种缓冲溶液对电极进行两点校准。试验结果标准偏差 0 0 5 1,加标回收率 94.0 %～ 98.0 %。测定快速、准确     

自动电位滴定法测定微量氯化物

在硝酸,硝酸锌介质中,用硝酸银自动电位滴定法测定亚铁氰化钾,亚铁氰化钠中微量氯化物,其测定结果的准确度,精密度均符合国家标准要求。     

自动电位滴定法测定化肥中氯离子含量

介绍自动电位滴定法测定化肥中氯离子含量的方法 ,与硝酸银滴定法相比 ,具有快速、准确、精密度高的优点     

自动电位滴定法测定微量氯化物

在硝酸、硝酸锌介质中 ,用硝酸银自动电位滴定法测定亚铁氰化钾、亚铁氰化钠中微量氯化物 ;其测定结果的准确度、精密度均符合国家标准要求     

电位滴定法测定对羟基苯甲醛

本文介绍了电位滴定法测定对羟基苯甲醛的原理、测定步骤和滴定终点的选择依据。方法简便易行,准确度达到工业分析要求。     

铜电极电位滴定法测定氢氧化镁

以HG／T3607—2000为基础，研究了用Metrohm 798 MPT Titrino全自动电位滴定仪测定氢氧化镁中镁离子质量分数的方法，铜电极为指示电极，银／氯化银为参比电极。与人工滴定比较，具有操作简便、分析速度快、终点判断准确的特点，受环境及溶液温度的影响小。并用基准氧化镁对该方法进行了验证。     

电位滴定法测定二羧酸钠

采用间接电位滴定法,以丙酮为溶剂,在室温下测定了混合二羧酸钠的含量。本方法操作简单,快速,准确。     

自动电位滴定法测定水和废水中的氯化物

探讨自动电位滴定法测定氯化物的检出限、精密度与准确度以及适宜测定的pH值范围。实验结果:方法检出限0.2 mg/L;对浓度分别为50 mg/L和200 mg/L的样品测定的相对标准偏差分别为1.3%和0.4%;加标回收率分别在97.8%～102.5%、99.0%～100.5%之间;适宜测定的pH范围为3～12。     

自动电位滴定法测定脂肪酸甲酯磺酸钠中二钠盐的含量

介绍了一种用于测定脂肪酸甲酯磺酸钠（MES）中二钠含量的准确、便捷的方法（自动电位滴定法）。通过该方法测定二钠盐含量,可以有效避免因指示剂使用而带来的误差,能够简化操作步骤,提高测定准确度。试验结果显示,测试相对标准偏差为0．91％,回收率在95．70％～104．71％。该方法完全能够满足质量分析的需要。     

Determination of iodine value without chlorinated solvents

A modified determination of iodine value in fats, fatty acids, and fatty acid derivatives is reported. The described procedures, visual and potentiometric, have wide applicability and generate less solvent waste. These analytical procedures are based on a nonchlorinated solvent system. The performance of the new procedures was evaluated in a multiple-laboratory study.     

高酸原油酸值测定的探讨

介绍了国内外测定石油及石油产品酸值的主要标准方法,比较了它们的特点、差别。以环烷基的高酸原油绥中36-1和石蜡基的高酸原油达尔原油为测定对象,用GB/T263(颜色法)与GB/T7304(电位滴定法)进行了对比试验,得出电位滴定法更加适合测定原油、渣油和其它石油产品的酸值。并在GB/T263(颜色法)的基础上进行了改进,改进后的方法用来测定环烷基高酸原油,测得的酸值结果与电位滴定基本一致,改进后的方法具有快速、简便、易操作的特点,有利于在实验室应用。     

Anomalous high iodine value of squalene and the impact on iodine values of shark liver oils

Squalene has six ethylenic bonds, but the experimental iodine values in two different solvent systems—chloroform and cyclohexane/acetic acid—were 25% higher than the theoretical values. We propose that this results from an additional halogen adding at each of the two terminal ethylenic bonds carrying two methyl groups. In the solvent system of cyclohexane alone, the excess is only 3–4% greater than the theoretical. Mixtures of squalene in seal oil confirmed the additivity of the experimental squalene high iodine value and the seal oil fatty acid iodine value with reasonable accuracy but depended on the skill of the operator in obtaining the titration end point for cyclohexane/acetic acid. This observation has particular relevance for shark liver oils and olive oils.     

Anomalous high iodine value of squalene and the impact on iodine values of shark liver oils

Squalene has six ethylenic bonds, but the experimental iodine values in two different solvent systems—chloroform and cyclohexane/acetic acid—were 25% higher than the theoretical values. We propose that this results from an additional halogen adding at each of the two terminal ethylenic bonds carrying two methyl groups. In the solvent system of cyclohexane alone, the excess is only 3–4% greater than the theoretical. Mixtures of squalene in seal oil confirmed the additivity of the experimental squalene high iodine value and the seal oil fatty acid iodine value with reasonable accuracy but depended on the skill of the operator in obtaining the titration end point for cyclohexane/acetic acid. This observation has particular relevance for shark liver oils and olive oils.     

非水滴定法定量测定己二胺盐酸盐

建立了测定己二胺盐酸盐含量的非水滴定法。以高纯度冰醋酸为溶剂,0.2%结晶紫为指示剂,用0.1 mol/L高氯酸标准溶液滴定至己二胺盐酸盐溶液由紫色变为蓝色。分别采用电位滴定与指示剂两种指示终点的方法。结果表明:2种指示终点的方法无显著差异,相对平均偏差为0.047%～0.070%。该方法操作简单、准确可靠、滴定终点突跃明显,重现性好。     

汞量法测定五氯化磷含量

证明汞量法测定氯化物含量时,对PO3-4的限量范围为小于500mg/L。采用汞量法对五氯化磷水溶液中氯化物含量进行测定,方法准确性高,操作简便快速,同时,本计算方法可校正因杂质存在而造成的较大偏差,使结果比较接近于真实值。     

两种测定碘盐中碘含量的方法比较

本实验采用常量、微型滴定法对市售碘盐中碘的含量进行测定。结果表明：两种方法对同一样品的测定结果无显著差异,同样准确可靠。但因微型滴定法耗时短、成本低、仪器携带方便,所以推荐基层食品检验、经营等单位使用微型滴定法进行碘盐中碘含量的测定。     

Determination of iodine value of palm oil by differential scanning calorimetry

Iodine value (IV) is used as a parameter in process control as well as a quality parameter in traded palm oil products. IV measures the number of double bonds in the molecular structure of an oil. To form a double bond, carbon requires more energy (615 kJ/mol) than to form a single bond (350 kJ/mol). Therefore, the thermal behavior of an oil could reflect its iodine value. This study was conducted to demonstrate the use of a differential scanning calorimeter (DSC) to determine the IV of palm oil and its products as an attempt to reduce the use of chemicals in the analysis. The DSC thermograms of palm oil showed a clear separation of the substances that have low melting points (low-T), consisting of triunsaturated, monosaturated and disaturated triglycerides, from the high ones (high-T), consisting of trisaturated triglycerides. Regression analysis showed that the peak characteristics, namely, area and height of the low-T group and height of the high-T group in the heating thermogram and also the height of the high-T group in the cooling thermogram, can predict the IV of palm oil with R ² higher than 0.99. This study concludes that DSC can be used to determine the IV of palm oil and its products.     

Discrimination of edible oil products and quantitative determination of their iodine value by Fourier transform near-infrared spectroscopy

This work demonstrates the application of partial least squares (PLS) analysis as a discriminant as well as a quantitative tool in the analysis of edible fats and oils by Fourier transform near-infrared (FT-NIR) spectroscopy. Edible fats and oils provided by a processor were used to calibrate a FT-NIR spectrometer to discriminate between four oil formulations and to determine iodine value (IV). Samples were premelted and analyzed in gass vials maintained at 75°C to ensure that the samples remained liquid. PLS calibrations for the prediction of IV were derived for each oil type by using a subset of the samples provided as the PLS training set. For each oil formulation (type), discrimination criteria were established based on the IV range, spectral residual, and PLS factor scores output from the PLS calibration model. It was found that all four oil types could be clearly differentiated from each other, and all the validation samples, including a set of blind validation samples provided by the processor, were correctly classified. The PLS-predicted IV for the validation samples were in good agreement with the gas chromatography IV values provided by the processor. Comparable predictive accuracy was obtained from a calibration derived by combining samples of all four oil types in the training set as well as a global IV calibration supplied by the instrument manufacturer. The results of this study demonstrate that by combining the rapid and convenient analytical capabilties of FT-NIR spectroscopy with the discriminant and predictive power of PLS, one can both identify oil type, as well as predict IV with a high degree of confidence. These combined capabilities provide processors with better control over their process.