Isolation, identification and quantitation of urinary organic acids

An application of the HISLIB program for the comparison of gas chromatographic-mass spectrometric profiles of urinary organic acids isolated by extraction and ion-exchange methods is described. Ion-exchange methods are clearly superior to solvent extraction in terms of the variety of compounds isolated. However, the former method has practical difficulties which make solvent extraction more attractive for rapid analyses. For the compounds isolated by both methods, the precision of analysis is similar, with standard deviations of relative concentration in the range 10--30% for most compounds.     

Isolation and identification of individual oxyethyl esters of n-aliphatic acids using critical nanoemulsions

Russian Journal of General Chemistry - The use of critical nanoemulsions based on toluene, acetone, and water for isolation and identification of individual esters has been demonstrated. Analytical...     

12,14-二羟基紫韧革烯的分离和结构测定

由紫韧革菌(Stereum purpureum)代谢产物中分离出一个新的三环倍半萜烯醇(sterpurenol), 12,14-二羟基紫韧革烯。用二维核磁共振确定了它具有紫韧革烯(sterpurene,1)的骨架及它的整个分子结构。     

Isolation and identification of the thermophilic alkaline desulphuricant strain

A desulfurization strain that belongs to the thermophilic alkaline desulphuricant is designated as strain GDJ-3 and isolated from Inner Mongolia, China. The colony of the strain shows tiny, yellow, or white-yellow, and it becomes henna with the protracting of cultivated time. The cells are bacilliform (0.3 -0.6 × 1.0-1.2 μm), motive, and Gram negative. The strain GDJ-3 is able to utilize respectively the thiosulphate, sulfate, sulfite, or sulfide as sulfur source, utilize the carbon dioxide as the carbon source, and utilize the ammonium or nitrate as the nitrogen source. According to GenBank data, 16s RNA results of GDJ-3 are in good agreement with Alpha proteobacterrium sp. (97%) and Ochrobactrum sp. (98%). For GDJ-3, the optimum growth temperature is at 45℃, the optimum pH is at 8.5-8.8, and the optimum rocking speed of sorting table is at 150 r/min. Under the optimum culture condition, the cells of the strain can live for about 18 h. In the desulfurization solution, which is prepared according to the composition of DDS solution, the objectionable constituents of sodium thiosulphate and sodium sulfide were added factitiously, and the bacterial cell concentration was set at 107/mL. After the regeneration of the above desulfurization solution by the strain cells, the concentration of sodium thiosulphate was decreased by 14.75 g/L (percentage loss of content 13.21%), the concentration of sodium sulfide was decreased by 0.76 g/L (percentage loss of content 87.36%) in the desulfurization solution in 9.5 hours, and sulfur appeared. Maybe, this kind of strain can be used as the regeneration's bacterial source of DDS solution.     

Isolation and identification of sialylcompounds from hemofiltrate

Summary Hemofiltrate of patients with end stage renal disease is a source of sialyl compounds of unusual composition which accumulate in uremia. The large volumes involved (20–30l), are concentrated and desalted by modified reverse osmosis using membranes with a nominal cut-off of 500 D. The transport of the individual solutes during this process is monitored by reversed-phase HPLC of the permeates and retentates, respectively. By a combination of size-exclusion and ion-exchange chromatography 11 sialyl compounds are isolated preparatively. All structures have been determined using one and two dimensional NMR spectroscopy, enzymatic degradation and FAB mass spectrometry.Supported by the Deutsche Forschungsgemeinschaft     

Isolation and identification of metabolites from dihydromyricetin

Dihydromyricetin (DHM) is the major bioactive constituent of Rattan Tea, which is the tender stems and leaves of Ampelopsis grossendentata. Seven metabolites (2-8) of DHM (1) were obtained by the chromatographic method. The metabolites 2-5 were obtained from the urine of rats administered orally with DHM; and metabolites 6-8 were detected in the fecal specimens of rats, which were also produced by human intestinal bacteria (HIB) in vitro, and were separated from the cultured media of HIB containing DHM. Their structures were elucidated as 5,7,3',5'-tetrahydroxyflavanonol (2); 5,7,3',5'-tetrahydroxy-4'-methoxyflavanonol (3); 5,7,4',5'-tetrahydroxy-3'-methoxyflavanonol (4); and dihydromyricetin-O-5-beta-D-glucuronide (5); (2R,3S)-5,7,3',4',5'-pentahydroxyflavanonol (6); 3,4,5,7,3',4',5'-hepthydroxyflavan (7) and 5,7,3',4',5'-pentahydroxyflavanone (8) on the basis of UV, NMR and LC-MS/MS data. These seven metabolites were formed through familiar metabolic reactions. Dihydromyricetin-O-5-beta-D-glucuronide (5) is a new compound. The (13)C-NMR data of (2) and (4) are reported for the first time.     

Isolation and identification of nondestructive desulfurization bacterium

A nondestructive desulfurization microorganism has been isolated. The metabolism product analyses show that the strain can be a kind of biocatalyst to oxidize dibenzothiophene (DBT) into 2-hydroxydiphenyl (HBP), therefore the sulfur in DBT is removed selectively. The 16SrRNA information, cell wall analysis, physical, biochemical properties and morphological properties suggest that the isolated strain is Rhodococcus erythropolis. The strain can grow in the basal salts medium (BSM) that DBT concentration is no more than 10 mmol/L, and the optimal DBT concentration for growth is 1 mmol/L, however, the optimal DBT concentration for desulfurization is 0.5 mmol/L. The further research shows that the strain can also desulfur some other or-ganosulfur-containing compounds such as thianaphthene, phenyl sulfide and 4,6-dimethyldiben-zothiophene (4,6-DMDBT).     

天然维生素E制品中杂质的分离与鉴定

利用高效液相色谱、气相色谱-质谱联用与高分辨质谱对天然维生素E制品中的杂质进行了分离分析与结构鉴定。采用正相高效液相色谱法分离天然维生素E的4种异构体及2种杂质,并对杂质馏分进行富集纯化。将气相色谱-质谱联用与高分辨质谱检测相结合,用于获得杂质的结构信息。通过比较杂质精确相对分子质量和解析质谱碎片离子,推断杂质为芝麻素及其同分异构体表芝麻素。经与芝麻素对照品保留时间及碎片离子数据比对,确证了对杂质结构的推断。所建立的杂质鉴定方法快捷、有效,可应用于天然维生素E制品的食品安全控制。     

Mass spectrometric identification of oleanolic and ursolic acids

p-Toluidides of 3-acetoxy ursolic and 3-acetoxy oleanolic acids were prepared. On the basis of different intensities of the m/e 452 and 453 peaks the identification of oleanolic and ursolic acids is possible.     

Separation and identification of lichen acids of the pulvinic acid series

Lichen acids, pulvinic acid, vulpinic acid, pinastric acid, leprapinic acid, lsoplnastric acid and pulvinic acid dilactone, which occur in certain yellow varieties of lichens and are difficult to separate, have been successfully separated and identified by TLC on chlorobenzene-impregnated silica gel plates.     

Isolation and identification of mutagenic nitro-pah in diesel-exhaust particulates

More than 50 nitro-PAH have been tentatively identified in an extract of diesel-exhaust particulates. Identifications are based on high-resolution mass spectrometry of directly mutagenic fractions derived from sequential fractionation of the extract by both low- and high-resolution liquid chromatography. The diversity of nitro-PAH tentatively identified suggests that large numbers of such compounds are formed during or following the combustion process.     

Isolation and identification of inulooligosaccharides resulting from inulin hydrolysis

In this study, inulooligosaccharides (F_n-type inulin) resulting from the endo-inulinase hydrolysis of globe artichoke inulin were purified and characterized. The aim was to produce F_n oligomer standards with the intention of identifying them in the complex inulin chromatogram. Inulin was extracted from globe artichoke and presented a high average degree of polymerization (DP) of about 80 as determined by high-performance anion exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD). This inulin was hydrolyzed by a commercial endo-inulinase yielding a product with a very high F_n/GF_n molecule ratio, thus limiting the interference of GF_n during the purification process. High-performance size exclusion chromatography was used to individually isolate and collect each retention peak corresponding to a specific oligomer. The purity of these fractions was checked by HPAEC-PAD and showed that relatively pure molecules were produced. Electrospray ionization mass spectrometry allowed the molecular weight determination of these purified oligomers and ascertained their DP as F₂, F₃ and F₄. These F_2-4 standards were used with glucose, fructose, sucrose and GF_2-4 (commercially available) to spike commercial oligofructose products in order to determine the elution profile in the HPAEC-PAD chromatogram.