Alcohols sample preparation

Name Stearyl alcohol Sample preparation Potassium bromide dispersion 1.5 mg / 300 mg... 

Name CocoHut, fatty alcohols Sample preparation Film, sodium chloride cell... 

Acetaldehyde [75-07-0] (ethanal), CH CHO, was first prepared by Scheele ia 1774, by the action of manganese dioxide [1313-13-9] and sulfuric acid [7664-93-9] on ethanol [64-17-5]. The stmcture of acetaldehyde was estabhshed in 1835 by Liebig from a pure sample prepared by oxidising ethyl alcohol with chromic acid. Liebig named the compound "aldehyde" from the Latin words translated as al(cohol) dehyd(rogenated). The formation of acetaldehyde by the addition of water [7732-18-5] to acetylene [74-86-2] was observed by Kutscherow] in 1881. 

For the higher alkoxy groups, standard carbon and hydrogen analysis may be used, although careful sample preparation is required because of the ease of hydrolysis. Quantitative vapor-phase chromatography of alcohol Hberated during hydrolysis may also be used, but care must be taken in this case to ensure that hydrolysis is complete before the estimation is carried out. 

Theoretical and applied aspects of microwave heating, as well as the advantages of its application are discussed for the individual analytical processes and also for the sample preparation procedures. Special attention is paid to the various preconcentration techniques, in part, sorption and extraction. Improvement of microwave-assisted solution preconcentration is shown on the example of separation of noble metals from matrix components by complexing sorbents. Advantages of microwave-assisted extraction and principles of choice of appropriate solvent are considered for the extraction of organic contaminants from solutions and solid samples by alcohols and room-temperature ionic liquids (RTILs). 

Reduction of 17a-EthynyI to 17a-Ethyl °° A solution of 5 g of 17a-ethynyl-androst-5-ene-3j9,17j5-diol in 170 ml of absolute alcohol is hydrogenated at atmospheric pressure and room temperature using 0.5 g of 5 % palladium-on-charcoal catalyst. Hydrogen absorption is complete in about 8 min with the absorption of 2 moles. After removal of the catalyst by filtration, the solvent is evaporated under reduced pressure and the residue is crystallized from ethyl acetate. Three crops of 17a-ethylandrost-5-ene-3) ,17j9-diol are obtained 3.05 g, mp 197-200° 1.59 g, mp 198.6-200.6° and 0.34 g, mp 196-199° (total yield 5.02 g, 90%). A sample prepared for analysis by recrystallization from ethyl acetate melts at 200.6-202.4° [aj, —70° (diox.). 

Colorless phosphate ester surfactants were also prepared by treating P4O,0 with an organic OH-containing compound in the presence of a phosphinic acid color inhibitor, e.g., bis(hydroxymethyl)phosphinic acid color inhibitor. Thus, 558 parts dodecanol containing 2.4 parts of phosphinic acid color inhibitor was treated with 142 parts P4O10 at 100-135°C. The phosphate ester surfactant had a VCS color value of 1, whereas a sample prepared without the color inhibitor had a VCS color value of 5. Twenty-eight similar surfactants were prepared using various alcohols and alcohol-alkylene oxide condensates [22]. 

In this case, three particles are shown, a 40 u, 20 p and a 10 p particle. The most important step is sample preparation on the microscope slide, since only a pinch of materied is used, one must be sure that the sample is uniform and representative of the material. Also, since most materials tend to agglomerate due to accumulated surface charge in a dry state, one adds a few drops of alcohol and works it with a spatula, spreading it out into a thin layer which dries. Too much working breaks down the original peirticles. 

Sample preparation for the common desorption/ionisation (DI) methods varies greatly. Films of solid inorganic or organic samples may be analysed with DI mass spectrometry, but sample preparation as a solution for LSIMS and FAB is far more common. The sample molecules are dissolved in a low-vapour-pressure liquid solvent - usually glycerol or nitrobenzyl alcohol. Other solvents have also been used for more specialised applications. Key requirements for the solvent matrix are sample solubility, low solvent volatility and muted acid - base or redox reactivity. In FAB and LSIMS, the special art of sample preparation in the selection of a solvent matrix, and then manipulation of the mass spectral data afterwards to minimise its contribution, still predominates. Incident particles in FAB and LSIMS are generated in filament ionisation sources or plasma discharge sources. 

The urine of people who are heavy smokers contains mutagenic chemicals, chemicals that cause mutations in biological cells. Bioanalytical laboratories can analyze urine samples for these chemicals, but the samples must be cleaned up first prior to extraction with methylene chloride. The procedure for this cleanup utilizes an open column chromatography. Columns several inches tall and about an inch wide are prepared by packing them with an adsorbing resin that has been treated with methyl alcohol. The urine samples are passed through these columns as part of the sample preparation scheme. 

From a sample prepare the dimethiodide thus Dissolve the base in a little methyl alcohol and warm the solution with about three parts of methyl iodide. Recrystallise from a little methyl alcohol. 

In Figure 3, the active steroid (triamcinolone acetonide) and preservative (benzyl alcohol) are determined from a steroid cream. The higher molecular weight components of the cream base are well separated from the analytes. The ability to elute all the components of a cream or ointment in a SMGPC analysis gives an important sample preparation advantage over competing separation techniques. 

Aldehydes (Preparation of Sample). Transfer 120ml of alcohol sample to a 250ml Erlenmeyer flask, add about 20m 1 of distd w and a few grains of carborundum. Distill slowly into a 100ml volumetric flask to the mark, and mix... 

DL-Dihydrostreptose and its ribo isomer were similarly obtained. Birch reduction of 2-methyl-3-furoic acid, followed by addition of methanol, bromination, and dehydrobromination, gave 402 as a mixture of the isomers. Hydroxylation of 402 with osmium tetraoxide-so-dium chlorate, and subsequent treatment with acetone-sulfuric acid afforded three isomeric acetals (403-405). The structures of these compounds were assigned on the basis of their H-n.m.r. spectra. In addition, the relationship between 403 and 404 was established by hydrolysis and reglycosidation. The methyl esters 403-405 were quantitatively reduced to the corresponding alcohols. The mixture of alcohols obtained from 403 and 404 was converted into crystalline 5-deoxy-3-C-(hydroxymethyl)-l,2-0-isopropylidene-a-DL-ribofuran-ose (406), which was compared directly with a sample prepared from D-xylose. Methyl 5-deox y-3-C-(hydroxy methyl)-2,3-O-isopropy lidene-/3-DL-lyxofuranoside (407), obtained by reduction of 405 with lithium aluminum hydride, was hydrolyzed with dilute hydrochloric acid, to give a,/3-DL-dihydrostreptose.2,ifi... 

A similar though considerably less well-ordered lamellar product is obtained when ethanol or methanol are used instead of water under solvothermal conditions Figure lb shows the powder XRD diagram of a sample prepared in ethanol at 90 °C dm = 3.50 nm). Considerably different products, however, are obtained when alcohols are used at lower temperatures, i.e. under non-solvothermal conditions. Figures lc and Id show the diffraction patterns of two example products from syntheses in methanol at 25 °C and in ethanol at 10 °C, respectively. In both cases the XRD reflections can be attributed to two distinct phases. One of these has a hexagonal symmetry with a dm value of 1.88 nm this mesophase will be discussed in detail below. An additional broad reflection is found at a Bragg angle comparable to that of the 001... 

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