Gas chromatography/ammonia

Gas Chromatography/Ammonia Chemical Ionisation Mass Spectroscopic Analysis Of The Small Per-Deuterated Dimethylsiioxane Cyclics. The Cl spectra were also recorded of the small perdeuterated dimethylsiioxane cyclics using foe same instrument as previously with ammonia Three competing processes are known to occur with ammonia in foe case of PDMS [70]. Quasimolecular ions are formed either by hydrogen or ammonium ion addition as well as subsequent trideuteriomefoyl loss. Ions can be observed at M +18, M + 2(18 - 19), M + 1, and M -18. Each of these processes are observed for foe cyclics upto foe decamer and spectra were obtained for foe pentamer up to foe decamer inclusive (Figures 33 and 34 show those of the hexamer and foe nonamer respectively). 

Tenberken, O., Worek, F., Thiermann, H., et al., 2010. Development and validation of a sensitive gas chromatography-ammonia chemical ionization mass spectrometry method for the determination of tabun enantiomers in hemo-lysed blood and plasma of different species. J. Chromatogr. B 878,1290-1296. 

ThioglycoHc acid can be identified by its in spectmm or by gas chromatography. Most of the by-products and self-esterification products are also detected by liquid chromatography, eg, thiodiglycolic acid, dithiodiglycolic acid, linear dimers, and polymers. Iron content can be assayed by the red sensitive complex of 1,10-phenanthroline [66-71-7] and ferrous ion of a mineralised sample. Ferric ion turns an aqueous ammonia solution deep red-violet. 

When 2,7-dimethyloxepin is treated with potassium in liquid ammonia at — 70 C, a mixture of oct-4-en-2-one (1) and octa-4,6-dien-2-one (2) in a ratio of 75 20 is obtained.203 The major product can be separated by preparative gas chromatography in 23% yield. The analogous reaction of 3-benzoxepin gives, in 30% yield, a mixture of (2-cthylphenyl)acetaldehyde (3) and (2-ethynylphenyl)acetaldehyde (4) that resists separation.203 The Latter product can be formed exclusively in 17% yield when 3-benzoxepin is treated with sodium amide in tetra-hydrofuran at 33 C for 210 minutes.203... 

A portion of the product was heated to reflux with methanolic sodium methoxide to convert it into the thermodynamic mixture of trans- (ca. 65%) and cis- (ca. 35%) isomers. Small amounts of the isomers were collected by preparative gas chromatography using an 8 mm. by 1.7 m. column containing 15% Carbowax 20M on Chromosorb W, and each isomer exhibited the expected spectral and analytical properties. The same thermodynamic mixture of isomers was prepared independently by lithium-ammonia reduction5 of 2-allyl-3-methyl-cyclohex-2-enone [2-Cyclohexen-l-one, 3-methyl-2-(2-propcnyl)-],6 followed by equilibration with methanolic sodium methoxide. 

Most supercritical fluid chromatographs use carbon dioxide as the supercritical eluent, as it has a convenient critical point of 31.3°C and 72.5 atmospheres. Nitrous oxide, ammonia and n-pentane have also been used. This allows easy control of density between 0.2g ml-1 and 0.8g ml-1 and the utilization of almost any detector from liquid chromatography or gas chromatography. 

Elemental composition H 11.83%, N 41.11%, S 47.05%. It may be analyzed by measuring its decomposition gaseous products, ammonia and hydrogen sulfide, either by gas chromatography using an FID or a TCD or by selective ion electrode or colorimetric techniques. 

A new gas chromatography (GC) method was developed to characterize artemether 28a and its metabolites in body fluids. The extracts were derivatized and then separated on an optimized capillary GC system and identified by chemical ionization MS using ammonia as the reagent gas <1998JCH(B)101>. A sensitive, selective, and reproducible GC-MS-SIM method has also been developed for the determination of artemether 28a and dihydroartemisinin 29a in plasma, using artemisinin 9a as an internal standard <1999JCH(B)251>. 

The water and ammonia content of anhydrous N2Hj are determined by a gas chromatography (Refs 37 38) method, and the analysis of the aniline in the mixture by ultraviolet spectroscopy. The total N2Hj content can be then determined by difference. Other methods are given at the end of section on Hydrazine Chemistry... 

Ammonia is readily detectable in air in the range of a few parts per million by its characteristic odor and alkaline reaction. Specific indicators, such as Nessler s reagent (Hgk in KOH), can detect ammonia in a concentration of 1 ppm. For the quantitative determination of ammonia in air, synthesis gas and aqueous solutions, these methods can be used74 Acidimetry and Volumetric Analysis By Absorption, Gas Chromatography, Infrared Absorption, Thermal Conductivity Measurement, Electrical Conductivity Measurement, Measurement of Heat of Neutralization, and Density Measurement (for aqueous ammonia). 

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