Measurement methods acetone

A value for the equivalent conductance at infinite dilution for lithium bromide in acetone was first calculated in 1905 by Dutoit and Levier (13) for 18°C 166 12 1 cm2 eq-1. A graphical method involving Ostwald s dilution law (A-1 = Ao-1 + cA/KdAq2), applied to their data in 1913 by Kraus and Bray (14), produced values of 5.7 X 10 4 for Kd and 165 12 1 cm2 eq-1 for Aq. Deviations from the mass action law (nonlinearity in the graph) become appreciable at concentrations of ca. 10 3N. Both groups pointed out that measurements in acetone are liable to error from several sources, including the presence of solvent impurities and exposure to light. A solvent correction of 21% was applied to their most dilute solution. 

Spectrophotometric assessment of chlorophyll content is based on the strong electronic absorption spectra of these pigments. Arnon (1949) developed an early method measuring 80% acetone/20% water plant extracts based on the electronic absorption spectra of chlorophylls a and b. Absorbance of the extract was measured at different wavelengths, and simultaneous equations were constructed based on extinction coefficients for each derivative s unique electronic absorption maxima. Over the... 

MEASUREMENT METHODS Charcoal tube acetone/carbon disulfide gas chromatograph with flame ionization detection. 

MEASUREMENT METHODS Particulate filter acetone/triacetin phase contrast microscopy. 

MEASUREMENT METHODS Silicon dioxide acetone gas chromatography. 

MEASUREMENT METHODS Petroleum-based charcoal tube acetone/cyclohexane gas chromatography with electron capture detection. 

It is worth to note that the solid state X-ray structure determination of (H)(p.-H)Os3(CO),o(HN=CPh2) (syn-isomer) yields an Os-H —H-N distance of only 1.79(6) A.[46] This finding provides support to the view that the corresponding distances determined in solution by the relaxometric method represent averaged values, as the imine ligand appears to be involved in lai e oscillations over the metallic cluster. Clearly the competition for the formation of intermolecular hydrogen bonds with the dipolar solvent molecules further increases the space swept by the imine ligand as testified by the increased value of the Os-H —H-N distance measured in acetone. 

Chlorophyll was measured by acetone extraction method and total algae density was measured by new method of detecting and counting—algae floating microscopic method. 

The alkalinity of acetone is determined by a titration with 0.05 N H2SO4 in the presence of methyl red indicator. The test method provides a measure of acetone alkalinity calculated as ammonia. 

The evaluation method according to this technique is as follows the pigment extract is taken to a known volume with a solvent appropriate for spectrophotometric measurement (ethanol, acetone, etc.). The absorbance at the wavelength of measurement must be between 0.2 and 0.8, and quantification is performed adapting the formula of the Beer-Lambert law ... 

When there is significant random error in all the variables, as in this example, the maximum-likelihood method can lead to better parameter estimates than those obtained by other methods. When Barker s method was used to estimate the van Laar parameters for the acetone-methanol system from these data, it was estimated that = 0.960 and A j = 0.633, compared with A 2 0.857 and A2- = 0.681 using the method of maximum likelihood. Barker s method uses only the P-T-x data and assumes that the T and x measurements are error free. 

Yields of excited states from 1,2-dioxetane decomposition have been determined by two methods. Using a photochemical method (17,18) excited acetone from TMD is trapped with /n j -l,2-dicyanoethylene (DCE). Triplet acetone gives i7j -l,2-dicyanoethylene with DCE, whereas singlet acetone gives 2,2-dimethyl-3,4-dicyanooxetane. By measuring the yields of these two products the yields of the two acetone excited states could be determined. The yields of triplet ketone (6) from dioxetanes are determined with a similar technique. 

A number of methods have been proposed for the detection of rancidity. The determination of active oxygen consists of dissolving the fat in a suitable medium such as chloroform and acetic acid, adding potassium iodide, and titrating the liberated iodine with a standard thiosulfate solution (16, 20). This is perhaps the most widely used method at the present time. Another procedure which has been proposed for the detection of peroxides employs ferrous ammonium sulfate and ammonium thiocyanate in acetone. The resulting red color of ferric thiocyanate is measured spectrophotometrically, and is said by the authors to yield more reproducible results than do the usual titration methods (21). 

Other detection methods are based on optical transmittance [228-231], Alcohol sulfates have been determined by spectrophotometric titration with barium chloride in aqueous acetone at pH 3 and an indicator [232] or by titration with Septonex (carbethoxypentadecyltrimethylammonium bromide) and neutral red as indicator at pH 8.2-8.4 and 540 nm [233]. In a modified two-phase back-titration method, the anionic surfactant solution is treated with hyamine solution, methylene blue, and chloroform and then titrated with standard sodium dodecyl sulfate. The chloroform passing through a porous PTFE membrane is circulated through a spectrometer and the surfactant is analyzed by determining the absorbance at 655 nm [234]. The use of a stirred titration vessel combined with spectrophotometric measurement has also been suggested [235]. Alternative endpoint detections are based on physical methods, such as stalag-mometry [236] and nonfaradaic potentiometry [237]. 

It is poorly soluble in acetone, 2-butanone, ethyl acetate, acetonitrile, and DMF, and insoluble in alcohols, petroleum ether, and diethyl ether. The partition coefficients of a number of solutes between PCL and water have been measured and correlated with octanol-water partition coefficients (Fig. 9) (58,59). The linear correlation (Eq. 2) when combined with the water solubility of the solutes serves as a method of estimating the solubility of drugs in PCL from first principles. ... 

The isotopic method has been used in conjunction with a flow apparatus by Stranks, to measure the exchange between the cyclopentadienyl complexes of iron (III) and iron (II) in methanol. Separation was based on the insolubility of Fe(C5H5) in petroleum ether at —80 °C. Using Fe(II) and Fe(III) 10 M and short reaction times ( msec), a rate coefficient 8.7 x 10 l.mole .sec at — 75 °C was obtained. The rate of exchange in the presence of chloride ions and inert electrolytes was found to be more rapid. Calculations using Marcus Theory showed reasonable agreement with the experimental observations. In deuterated acetone, line broadening measurements have led to an estimate of this rate coefficient of > 10 l.mole . sec at 26 °C. 

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