Acetic acid refractive index

For acrylate polymers with higher levels of carboxylic acids, THF can be modified by the addition of acids such as acetic, phosphoric, or trifluoroacetic. Levels as high as 10% acetic acid are considered acceptable by most manufacturers for their styrene/DVB columns. If such a modified mobile phase is used, it may need to be premixed rather than generated using a dynamic mixing HPLC pump because on-line mixing often leads to much noisier baselines, particularly when using a refractive index detector. 

If myrcene be heated with glacial acetic acid to 40° for three to four hours, with the addition of a little sulphuric acid, hydration takes place, and an alcohol, which is termed myrcenol is formed. This body is an oil, of specific gravity 0 9032, refractive index 1 4806 at 15°, and boiling-point 99° at 10 mm. pressure. It yields a phenylurethane melting at 68°. 

On oxidation with chromic acid in acetic acid solution, dihydrocarveol yields dihydrocarvone, which has a specific gravity 0 928 at 19°, and refractive index 1-47174. The dihydrocarvone from Zae o-dihydro-carveol is dextro-rotatory, and -vice versa. Its oxime melts at 88° to 89° for the optically active variety, and at 115° to 116° for the optically inactive form. 

Figure 21 Analytical scale separation of oligomers of a-(l,4)-linked galacturonic acid. Column 25 x 0.46 cm Dynamax NH2. (A) Gradient separation, pH 5.9, 0.1-0.4 M phosphate in 25 min. UV detection at 220 nm. (B) 0.8 M acetate, pH 5. Refractive index detection. (Reproduced with permission from Elsevier Science from Hotchkiss, Jr., A. T., Hicks, K. B., Doner, L. W., and Irwin, R L., Carb. Res., 215, 81, 1991.)...

Separation and quantitation of carbohydrate mixtures may be achieved using HPLC, a method that does not necessitate the formation of a volatile derivative as in GLC. Both partition and ion-exchange techniques have been used with either ultraviolet or refractive index detectors. Partition chromatography is usually performed in the reverse phase mode using a chemically bonded stationary phase and acetonitrile (80 20) in 0.1 mol U1 acetic acid as the mobile phase. Anion- and cation-exchange resins have both been used. Carbohydrates... 

When acetic acid is diffusing from a 1.9 iV solution in water into benzene, spontaneous emulsion forms on the aqueous side of the interface, accompanied by a little interfacial turbulence. Results can be obtained with this system, however, if in analysing the refractive index gradient near the surface a correction is made for the spontaneous emulsion the rate of transfer is then in excellent agreement (57) with Eq. (20) (Fig. 6). Consequently there is no appreciable energy barrier due to re-solvation of the acetic acid molecules at the interface, nor does the spontaneous emulsion affect the transfer. With a monolayer of sodium lauryl... 

Yellow monoclinic crystals refractive index 2.31 density 6.12 g/cm melts at 844°C decomposes on further heating insoluble in water also insoluble in ammonia and acetic acid soluble in acids and alkalies. 

Colorless, mobde hquid turns yellow on standing very pungent odor refractive index 1.4437 at 20°C density 1.667 g/mL at 20°C vapors heavier than air, vapor density 4.7 (air=l) melts at -51°C bods at 69.4°C sparingly soluble in water, decomposing slowly to sulfuric and hydrochloric acids forms a hydrate S02C12 I5H2O with ice-cold water miscible with benzene, toluene, chloroform, carbon tetrachloride, and glacial acetic acid decomposed by alkalies (violent reaction occurs)... 

Clarification by removal of casein with such agents as calcium chloride, acetic acid, cooper sulfate, or rennin has often been employed to obtain a serum more suitable for refractometric measurements. Obviously the composition, and hence the refractive index, of such sera will depend on the method of preparation. Furthermore, some of the serum proteins may be precipitated with the casein by some of the agents used, particularly if the milk has been heated. Refractive index measurements of such sera are not generally considered as satisfactory as freezing point measurements for detection of added water (David and MacDonald 1953 Munchberg and Narbutas 1937 Schuler 1938 Tell-mann 1933 Vleeschauwer and Waeyenberge 1941). Menefee and Overman (1939) reported a close relation between total solids in evaporated and condensed products and the refractive index of serum prepared therefrom by the copper sulfate method. Of course, a different proportionality constant would hold for each type of product. 

FIGURE 23. Tracing of ultraviolet (UV), refractive index RI and graphite furnace atomic absorption (GF-AA) recordings using 95/5/6 HjO/ acetonitrile/acetic acid and 0.005 M heptanesulphonic acid as solvent A = 1 arsenate/arsenite mixture B = 1 /rg arsenobetaine C = 1 /tg arsenocholine. 

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