Chromatography compounds identified

Following i.p. injection of dZ-[l,6- C]lipoate, 56% of the radioactivity was recovered in urine within 24 hours, When acidified and extracted with benzene, 92% remained in the aqueous phase, which contained at least ten [ C]compounds when fractionated by anion-exchange chromatography (Fig. 3). Two of these, fractions 6 and 10, were identified as lipoate and e-hydroxybisnorlipoate, respectively. The 8% of urinary radioactivity extracted into benzene was fractionated by hydrophobic gel filtration (Fig. 4) followed by paper chromatography. Compounds identified were (1) lipoate, (2) bisnorlipo-ate, and (3) tetranorlipoate plus a keto compound. 

Procedures for the isolation and characterization of trace gases and odorants in the dust from pig houses are given by SCHAEFER et al. (29), HAMMOND et al.(30) and TRAVIS and ELLIOTT (31). Alcoholic solvents were found to be effective for the extraction of volatile fatty acids and phenols from the dust of hen (32) and pig houses (33), (34). Today, gas chromatography is usually used for the separation and identification of the trace gases. Table IV gives a literature review of compounds identified in the dust of pig houses. There are only very few reports on investigations on the dust from hen houses (32). 

This system was studied by Schwartz. Toluene at 10 ppm, nitric oxide at 1 ppm, and nitrogen dioxide at 1.2 ppm were irradiated with ultraviolet lamps in a 17-m batch reactor for 270 min. Collected aerosols were successively extracted with methylene chloride and then methanol. The methylene chloride extract was fractionated into water-soluble and water-insoluble material, and the latter fraction was further divided into acidic, neutral, and basic fractions. The acidic and neutral fractions were analyzed by gas chromatography and chemical-ionization mass spectrometry the compounds identified are shown in Figure 3-7. The two analyzed fractions represented only about 5.5% of the total aerosol mass. It is noteworthy that classical nitration of an aromatic ring appears to... 

Schoenmakers et al. [72] analyzed two representative commercial rubbers by gas chromatography-mass spectrometry (GC-MS) and detected more than 100 different compounds. The rubbers, mixtures of isobutylene and isoprene, were analyzed after being cryogenically grinded and submitted to two different extraction procedures a Sohxlet extraction with a series of solvents and a static-headspace extraction, which entailed placing the sample in a 20-mL sealed vial in an oven at 110°C for 5,20, or 50 min. Although these are not the conditions to which pharmaceutical products are submitted, the results may give an idea of which compounds could be expected from these materials. Residual monomers, isobutylene in the dimeric or tetrameric form, and compounds derived from the scission of the polymeric chain were found in the extracts. Table 32 presents an overview of the nature of the compounds identified in the headspace and Soxhlet extracts of the polymers. While the liquid-phase extraction was able to extract less volatile compounds, the headspace technique was able to show the presence of compounds with low molecular mass... 

A 40 mg sample of 1 2 placed between two disk glass filters was irradiated using a 400-W high-pressure Hg lamp in a thermostat. The products (3 and dimers of 1) and unreacted 1 were isolated by column chromatography. Compound 3 and the dimers of 1 were identified by comparison with authentic samples prepared by alternative methods. 

The presence of relatively high levels of strong organic chelators like EDTA in the water samples prompted a detailed chemical speciation study aimed at determining whether the organic compounds identified in the survey study are chelated or complexed to radionuclides. Water samples from waste trenches 19S and 27 and inert atmosphere wells WIN and W2NA were fractionated by steric exclusion chromatography and subsequently analyzed for their... 

All classes of organic compounds each compound identified by its mass spectrum Mass spectrometer Gas chromatography VOCs (EPA 8260) and SVOCs (EPA 8270) dioxins/furans (EPA 8280, EPA 8290) CLP SOW for organic analysis Liquid chromatography solvent-extratable nonvolatile compounds (EPA 8321, EPA 8325) Interferences from Oily matrices Trace level laboratory artifacts Interferences from Organic acids Phenols Trace level laboratory artifacts... 

Fig. 9.1.2. Compounds identified in the phenolic fraction of a bleach plant E effluent by gas chromatography-mass spectrometric (GC-MS) analysis...

The halocyclization of a homoallylic carbamate 718, containing (S)-l-phenylethylamine as chiral source, similarly affords a 50 50 diastereomeric mixture of tetrahydro-2//-l,3-oxazin-2-ones 8, which can be easily separated by chromatography and identified by 1 H-NMR spectroscopy. In compounds 8, the substituent at C-6 displays a strong tendency to occupy the equatorial position in both isomers. 

The composition of reaction mixtures obtained under classical Fischer-Zach conditions was determined by capillary gas chromatography [53] of per-O-silylated and per-O-acetylated components of the crude reaction mixtures, and some progress was made in explaining the mechanism behind typical side-product formation. The compounds identified included products of solvolytic displacement of an anomeric bromine by acetic acid and water as well as 2,3-unsaturated derivatives. Interestingly, there was a difference in the reaction outcome of pentopyranosyl versus hexopyranosyl substrates. In the former case, glycals were accompanied by acetylated 1,5-anhydropentitols in the latter, hex-l-enitols contained admixtures of peracetylated 2-deoxyhexopyranosides. 

Numerous reviews are in the literature on the fermentation-derived components of distilled spirits. Over 280 components have been identified in whiskies(25) and over 400 components have been found in rum(26). The conditions of fermentation and distillation determine the concentration of volatiles. For example the concentration and composition of trace sulfur compounds in grain spirits reflects the manner in which the distillation was carried out. No attempt will be made to compile the complete list of compounds identified to date. Rather, several newly identified components made possible by the recent advances in gas chromatography/mass spectrometry will be reported. 

Gas chromatography (GC) with an infrared (IR) detector was introduced as a method to detect volatile radiolytic products, some of which were hypothesized to be responsible for the bad smells emanating from irradiated drugs. Thiocyanic acid was held responsible, for example, for the sulfurous smell in irradiated ampicillin. The head-space (HS) injection technique for GC and the on-line MS detection allowed new approaches to detect radiosterilization [12]. Many volatile radiolytic products were identified from the mass spectral libraries. Some ofthe compounds identified such as aldehydes, esters and sulfides were quite malodorous. A few of the volatile radiolytic products came from the degradation of drug molecules by the ionizing radiation, whereas residual solvents played a key role in the formation of other volatile radiolytic products. 

Gas chromatography-mass spectrometry (GC-MS) was carried out on selected samples either to confirm compounds Identified by retention times or to Investigate the Identities of other peaks of Interest. Samples were run on a Finnigan Model 9610 GC coupled to a Finnigan Model 4021 quadrupole MS. Mass spectrometrlc data were acquired and processed with a Flnnlgan-INCOS 2300 Data System. The MS was operated In electron Impact mode with 70 eV electron energy. Gas chromatographic conditions were comparable to those used for GC-FID. 

Gas chromatography-mass spectrometry analysis was performed on an HP 5890 series II chromatograph (Hewlett-Packard) coupled to an HP 5973 mass spectrometer (Hewlett-Packard) and equipped with an HP-5 capillary column (50 m X 0.32 mm i.d., film thickness = 1.05 mm, Hewlett-Packard). The injector was maintained at 270 C. After injection, oven conditions were as follows 35 C for 10 min, 7 C min-1 to 150 C, 15 C/min to 250 C, 250 C for 10 min. The transfer line to the mass spectrometer was maintained at 280 C. Mass spectra were generated by electronic impact. A solution of n-alkanes (C5-C18) was analyzed under the same conditions to calculate lineal retention indices (LRI). Compounds were identified by comparing mass spectra and LRI with those of reference compounds analyzed under the same conditions. Only the compounds identified that were previously described as dry-cured ham odorants (6, 7) were taken into account. 

G6. Gallice, P., Monti, J. P., Crevat, A., et al., A compound from uremic plasma and from normal urine isolated by liquid chromatography and identified by nuclear magnetic resonance. Clin. Chem. (Winston-Salem, N.C.) 31, 30-34 (1985). 

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