Methanol gas chromatography

The crude reaction was filtered, and the filtrate [containing triphenyl-phosphine (75 mg, 0.28 mmol)] was concentrated in vacuo. Acetone (1.5 ml), sodium iodide (84 mg, 0.56 mmol), and high loading Merrifield resin (140 mg, 4.38 mmol of Cl/g) were added, and the slurry was allowed to stir at room temperature. After 18 h, the mixture was filtered and washed with tetrahydrofuran (3x3 ml), water (3x3 ml), acetone (3x3 ml), and methanol. Gas chromatography (GC) analysis of combined filtrates and weight gain of the resin indicated complete removal of triphenylphosine from the reaction mixture. 

Atrazine, simazine, terbuthylazine, molinate Solid-phase microwave-assisted extraction using methanol Gas chromatography-mass spectrometry. Limit of detection 1-10 ng/g [382]... 

Atrazine, simazine, linuron, metribuzin, triallate, phorate Methanol Gas chromatography with ECD [385,386]... 

MEASUREMENT METHODS Charcoal tube benzene methanol gas chromatography with electron capture detection. 

MEASUREMENT METHODS 2-Ethoxy ethanol charcoal tube methylene chlo-ride/methanol gas chromatography with flame ionization detection 2-methoxyethanol charcoal tube carbon disulfide gas chromatography with flame ionization detection. 

MEASUREMENT METHODS Silica gel methanol gas chromatography with flame... 

Instmmental methods of analysis provide information about the specific composition and purity of the amines. QuaUtative information about the identity of the product (functional groups present) and quantitative analysis (amount of various components such as nitrile, amide, acid, and deterruination of unsaturation) can be obtained by infrared analysis. Gas chromatography (gc), with a Hquid phase of either Apiezon grease or Carbowax, and high performance Hquid chromatography (hplc), using siHca columns and solvent systems such as isooctane, methyl tert-huty ether, tetrahydrofuran, and methanol, are used for quantitative analysis of fatty amine mixtures. Nuclear magnetic resonance spectroscopy (nmr), both proton ( H) and carbon-13 ( C), which can be used for quaHtative and quantitative analysis, is an important method used to analyze fatty amines (8,81). 

The separation and analysis of 1-propanol are straightforward. Gas chromatography is the principal method employed. Other iastmmental techniques, eg, nmr, ir, and classical organic quaHtative analysis, are useful. Molecular sieves (qv) have been used to separate 1-propanol from ethanol and methanol. Commercial purification is accompHshed by distillation (qv). 

Several properties of the filler are important to the compounder (279). Properties that are frequentiy reported by fumed sihca manufacturers include the acidity of the filler, nitrogen adsorption, oil absorption, and particle size distribution (280,281). The adsorption techniques provide a measure of the surface area of the filler, whereas oil absorption is an indication of the stmcture of the filler (282). Measurement of the sdanol concentration is critical, and some techniques that are commonly used in the industry to estimate this parameter are the methyl red absorption and methanol wettabihty (273,274,277) tests. Other techniques include various spectroscopies, such as diffuse reflectance infrared spectroscopy (drift), inverse gas chromatography (igc), photoacoustic ir, nmr, Raman, and surface forces apparatus (277,283—290). 

There is no specific color or other reaction by which methyl chloride can be detected or identified. QuaUty testing of methyl chloride for appearance, water content, acidity, nonvolatile residue, residual odor, methanol, and acetone is routinely done by production laboratories. Water content is determined with Kad Fischer reagent using the apparatus by Kieselbach (55). Acidity is determined by titration with alcohoHc sodium hydroxide solution. The nonvolatile residue, consisting of oil or waxy material, is determined by evaporating a sample of the methyl chloride at room temperature. The residue is examined after evaporation for the presence of odor. Methanol and acetone content are determined by gas chromatography. 

One of the first examples of the application of reverse-phase liquid chromatography-gas chromatography for this type of analysis was applied to atrazine (98). This method used a loop-type interface. The mobile phase was the most important parameter because retention in the LC column must be sufficient (there must be a high percentage of water), although a low percentage of water is only possible when the loop-type interface is used to transfer the LC fraction. The authors solved this problem by using methanol/water (60 40) with 5% 1-propanol and a precolumn. The experimental conditions employed are shown in Table 13.2. 

Hydrogenation of exocyclic, pyranoid vinyl ethers could afford a mixture of both possible 6-deoxy-D and L-hexoses. Our observations show that the proportion of each isomer is dependent upon the catalyst and the substituents on the vinyl ether. Thus, treatment of a methanol solution of l,2,3,4-tetra-0-acetyl-6-deoxy-/ -D-xylo-hex-5-eno-pyranose (12) with hydrogen in the presence of a palladium catalyst afforded a mixture which was shown by gas chromatography to contain 96% of the 6-deoxy-D-gluco isomer (11) and 4% of the 6-deoxy-L-ido isomer (13). In this... 

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. 

Fig. 6 shows the evolution of the CO concentration after the introduction of the methanol/water mixture to the reformer, indicating a CO spike at the initial stage of operation. CO concentration of up to 2% (dry basis) was observed at the reformer outlet by gas chromatography, but it was reduced to 0.6% in 20 min as shown in Fig. 6. CO concentration at the outlet of the PROX reactor operating at an 02 CO ratio of 1, increased rapidly to 1 lOOppm...

The same samples, after a pretreatment in flowing oxygen (10%) at 625 K, were used as catalysts for the oxidative dehydrogenation of ethanol and methanol in the same reactor. The reaction mixture consisted of O2 (3 or 5%), methanol vapor (3%) or ethanol vapor (5%) and He (balance), all delivered by Tylan mass flow controllers or vaporizer flow controllers. Products were analyzed by gas chromatography. The catalysts exhibited no induction period and their activities were stable over many days and over repeated temperature cycles. 

Plant samples are homogenized with sodium hydrogencarbonate aqueous solution to prevent decomposition of the analytes during homogenization. Imibenconazole and its primary metabolite, imibenconazole-debenzyl, are extracted from plan materials and soil with methanol. After evaporation of methanol from the extracts, the residues are extracted with dichloromethane from the residual aqueous solution. The dichloromethane phase is cleaned up on Florisil and Cig columns. Imibenconazole and imibenconazole-debenzyl are determined by gas chromatography/nitrogen-phosphorus detection (GC/NPD). 

Plant materials are homogenized with methanol. Acetamiprid residue is extracted with dichloromethane by liquid-liquid partitioning. Dichloromethane is removed by rotary evaporation, and the residue is subjected to a clean-up procedure using Florisil PR column chromatography. The concentrated eluate is analyzed by gas chromatography (GC). 

The experimental results are presented for the esterification of dodecanoic acid (C12H24O2) with 2-ethylhexanol (CgHigO) and methanol (CH4O), in presence of solid acid catalysts (SAC). Reactions were performed using a system of six parallel reactors (Omni-Reacto Station 6100). In a typical reaction 1 eq of dodecanoic acid and 1 eq of 2-ethylhexanol were reacted at 160°C in the presence of 1 wt% SAC. Reaction progress was monitored by gas chromatography (GC). GC analysis was performed using an InterScience GC-8000 with a DB-1 capillary colunm (30 m x 0.21 mm). GC conditions isotherm at 40°C (2 ntin), ramp at 20°C min to 200°C, isotherm at 200°C (4 min). Injector and detector temperatures were set at 240°C. 

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