Determination of the triglyceride composition of grapes by HPLC

Summary The triglyceride composition of the Tempranillo grape (Vitis vinifera) has been examined by a combination of HPLC and GLC. To identify the triglycerides, equations were applied relating log k′ with the molecular variables: equivalent carbon number, chain length and number of double bonds in each of the fatty acids in the glycerides. Ten triglycerides were found, the principal ones being trilinolein (35.75%), dilinoleyl-olein (21.03%) and dilinoleyl-palmitin (17.02%).     

Determination of triacylglycerols of manketti oil by reversed-phase HPLC

Using reversed-phase HPLC with refractometric detection, we determined the composition of triacylglycerols (TAGs) of manketti oil and calculated its fatty acid composition. It was shown that the oil consists of octadecatrienoic (34.6 ± 0.8 mol %), linoleic (35.4 ± 0.8 mol %), oleic (14.6 ± 0.4 mol %), palmitic (7.2 ± 0.3 mol %), and stearic acids. Using spectrophotometric detection, for the oils of centrathus and jacaranda seeds, it was demonstrated that octadecatrienoic acid is presented mainly by α-eleostearic acid and small impurities of β-eleostearic (2.8 mol %) and jacarandic (0.3 mol %) acids. The results of the quantitative determination of TAGs, obtained by refractometric detection (with corrections of the peak areas to the calculated values of the refractive indices of TAGs), are consistent with the data obtained using spectrophotometric detection.     

Determination of the triglyceride composition of avocado oil by high-performance liquid chromatography using a light-scattering detector.

The triglyceride composition of avocado oil was determined by high-performance liquid chromatography using a light-scattering detector. Two avocado varieties, Fuerte and Hass, were analysed, and the qualitative composition of each was found to be similar, though quantitative differences were detected. The triglyceride composition was predicted using a system of equations based on the relationship between log k' and the molecular variables equivalent carbon number, chain length and number of double bonds for each of the fatty acids in the glycerides. A total of 24 molecular species of triglycerides were identified. The chromatographic system used successfully separated the critical pairs OOO-LOS, PaPaO-LnPP and PaOO-LOP (O = olein; L = linolein; S = stearin; Pa = palmitolein; Ln = linolenin; P = palmitin). Detector response was found to have a linear relationship with the amount of sample injected over the injection range 10-70 micrograms.     

Determination of the lipophilicity of quinolinesulfonamides by reversed-phase HPLC and theoretical calculations

Reversed-phase high-performance liquid chromatography analyses were used for the determination of the retention factor (log k) of a set of quinolinesulfonamides. The analyses utilized a mixture of acetonitrile/water as the mobile phase. The log k values were linearly dependent on the concentration of acetonitrile and extrapolated to 100% water and gave the lipophilicity parameter log k_w. The parameter log P_HPLC was determined from log k_w values using the calibration curve obtained for five standards. The log P_HPLC parameters are discussed in terms of structure–lipophilicity relationships. Furthermore, the theoretical lipophilic parameters (log P_calc) for all compounds were calculated using chemical programs (e.g., Advanced Chemistry Development (ACD/ logP), miLogP, AlogP, ClogP, and Pallas). The determined log P_HPLC and calculated log P_calc values were compared by linear regression analysis.     

Optimization of the separation of a mixture of unknown composition by reversed-phase HPLC

A method is presented for the computer-assisted optimization of mobile phaseselection for the separation of a synthetic intermediate of unknown composition by reversed-phase HPLC.The method is based on recognition of the order of the peaks by comparisonof peak area ratio and followed by the BSOS-L(Binary Solvent Optimization System forHPLC)method.Excellent agreement was obtained between predicted data and experimentalresults.     

Determination of the triglyceride composition of certain fats

Conclusions Enzymatic hydrolysis, together with Coleman's method of calculation, as modified by us has been used to determine the glyceride composition of oils. It has been established that almost all (93–96%) of the -positions of the glycerides of the coils studied are occupied by radicals of unsaturated acids.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 2, pp. 76–79, 1969     

Determination of phenolic compounds in medicinal herbs by reversed-phase HPLC

An HPLC procedure is proposed for the determination of 12 phenolic compounds in plant tissues by reversed-phase HPLC with gradient elution and UV detection. The influence of pH, composition of the mobile phase, concentration of the organic modifier, and temperature on the separation of gallic, protocatechuic, trans-ferulic, trans-caffeic acid, rutin, quercetin, dihydroquercetin, and (_)-epicatechin for 30 min is studied. The lower limit of quantification of phenolic compounds is 1–2.5 μg/L. The procedure was applied to the determination of phenolic compounds in aqueous extracts of Hypericum perforatum; its sample was found to contain protocatechuic acid, (_)-epicatechin, and also rutin.     

Optimization of the mobile phase composition in gradient elution reversed-phase HPLC by stochastic prediction

Summary Quantitative analysis of more than ten compounds in a sample generally requires complex mobile phases to optimize the separation of the analytes by gradient elution reversed-phase HPLC. For this purpose, CHEOPS, a software package has been developed from the fully stochastic Computer Chromatogram Simulation Method. Calculation principles and optimization criteria are described. Experimental validation is presented with amino acids and steroids.     

油茶籽油中角鲨烯含量的气相色谱法测定

建立了油茶籽油中角鲨烯含量测定的气相色谱检测方法.油茶籽油样品经氢氧化钾-乙醇溶液皂化,石油醚萃取净化,经HP -5色谱柱分离,气相色谱仪(GC-FID)检测,外标法定量.在5～ 200g/L线性范围内线性良好,在1.0～3.0g/kg添标水平,平均回收率在93.7％ ～ 101.3％,相对标准偏差在1.7％～6.8％...     

Determination of pamidronate in human whole blood and urine by reversed-phase HPLC with fluorescence detection

Pamidronate is a bisphosphonate that is effective in treating bone disease including osteopenia and osteoporosis in adults. A sensitive and reliable method for the analysis of pamidronate in whole blood and urine is key to the development of this drug for use in children. A previously described method for pamidronate analysis serum and urine did not consistently detect the drug at satisfactory levels in whole blood. The procedure involves co-precipitation of the bisphosphonates with calcium phosphate, pre-column derivitization with fluorescamine, HPLC utilizing a Nucleosil C(18) column, and fluorescence detection with excitation at 395 nm and emission at 480 nm.Changes to the original protocol included the use of a new internal standard (alendronate), the optimization of the concentration of ethylenediaminetetraacetic acid (EDTA) for dissolving the precipitate, and the elimination of the acidification step prior to deproteinization. The optimum EDTA concentration, which had a significant effect on the labeling capability of fluorescamine, was determined to be 20 mm.A good separation between pamidronate and alendronate was achieved using a heated (40 degrees C ) Nucleosil C(18), 10 micro m particle size column. The mobile phase was an aqueous solution of 1 mm Na(2)EDTA-methanol (97:3, v/v) adjusted to pH 6.5 using a fl ow-rate of 1 mL/min. Fluorescence detection was set at 395 nm for excitation and at 480 nm for emission. The limit of quantitation for pamidronate was 0.5 micro g/mL in whole blood and 0.1 micro g/mL in urine. The method was applied to both whole blood and urine samples from pediatric patients.     

聚乙二醇萃取-铬天青S光度法测定润滑油中的铁和铝

在石油加工过程中铁、铝会使催化剂中毒而促进石油馏分深度分解 ,造成气体及焦化率大大增加 ,影响产品产量和质量。润滑油中的铁、铝除来自添加剂及原油外[1 ] ,还有一部分来自机器部件。故检测铁、铝对研究添加剂的含量及机器部件的磨损情况有着十分重要的意义。根据石油产品中铁、铝含量的变化可以判断机器部件故障的部位。文献 [2 ,3]分别用铬天青Ｓ 溴化十六烷基三甲基胺显色体系测定了硅酸盐及岩石中的铁、铝 ,由于大量的干扰离子的存在需加几种掩蔽剂进行掩蔽或分离。对于润滑油中的干扰离子采用聚乙二醇 硫酸铵 铝试剂体系非有机溶剂…     

Determination of the uronic acid composition of seaweed dietary fibre by HPLC

A high-performance liquid chromatographic (HPLC) method is described for determination of the ratio of beta-d-mannuronic acid to alpha-l-guluronic acid (M/G ratio) in dietary fibre of edible seaweeds. Total dietary fibre (TDF) content was determined gravimetrically. The TDF fraction was hydrolysed with 12 m and 1 m H(2)SO(4), then neutralized with AG 4 x 4 resin. The uronic acids were separated in a Tracer Extrasil SAX 5 micro m column (25 cm x 4 mm) at 35 degrees C, with 2 mm KH(2)PO(4) containing 5% methanol as mobile phase at a fl ow rate of 1.5 mL/min. The detection wavelength was UV 210 nm. The chromatographic identifications of beta-d-mannuronic acid and alpha-l-guluronic acid were confirmed by liquid chromatography-mass spectrometry (LC-MS). The method precision was 1.4% for beta-d-mannuronic acid and 3.5% for alpha-l-guluronic acid. The method was used to determine M/G ratio in canned seaweeds (Saccorhiza polyschides and Himanthalia elongata) and in dried seaweeds (H. elongata, Laminaria ochroleuca, Undaria pinnatifida, Palmaria sp. and Porphyra sp.).     

分光光度法测定薯蓣皂苷元

采用高氯酸反应使薯蓣皂苷元显色 ,对影响显色反应的主要因素进行了考察 ,于 41 0nm波长处对穿山龙中薯蓣皂苷元的含量进行测定 ,测定结果与高效液相色谱法相近。方法的线性范围为 3.1 2～2 1 .84μg mL ,适用于薯蓣皂苷元提取过程中的常规检测     

HPLC-APCI-MS法分析测定白刺籽油中游离脂肪酸

利用荧光衍生试剂1,2-苯并-3,4-二氢咔唑-9-乙基对甲苯磺酸酯(BDETS)作为脂肪酸柱前衍生化试剂,采用梯度洗脱在Eclipse XDB-C8色谱柱上对游离脂肪酸(FFA)(油酸、亚油酸、软脂酸和硬脂酸)衍生物进行分离.利用柱后在线的串联质谱以大气压化学电离源(APCI)正离子模式实现了各组分的质谱定性.荧光检测的激发和发射波长分别为λex=333 nm,λem=390 nm.脂肪酸的线性回归系数大于0.9990,检出限为3.38～6.59 nmol/L.建立的方法具有良好的重现性.利用此方法对超临界CO2提取的唐古特白刺籽油中几种游离脂肪酸进行了分析.结果表明白刺籽油中含有大量的游离不饱和脂肪酸.     

Facile discrimination of aldose enantiomers by reversed-phase HPLC

One-pot reactions of aldoses with L-cysteine methyl ester and o-tolyl isothiocyanate yielded methyl 2-(polyhydroxyalkyl)-3-(o-tolylthiocarbamoyl)-thiazolidine-4(R)-carboxylates. Direct HPLC analysis of the reaction mixture and UV detection at 250 nm discriminated D- and L-enantiomers of aldoses. The reaction was applied to the determination of absolute configuration the sugar residues of an aroma precursor.