Molar absorptivity alcohols

The ultraviolet spectrum of brinzolamide in reagent alcohol exhibited a maximum at 252 nm, with a molar absorptivity of 9,400 liters/mole. The spectrum is shown in Figure 5. 

The Ni(tpp) prepared by this method is of analytical purity. It is slightly soluble in CHC13, CH2 Cl2, and ligating solvents, such as pyridine. It is insoluble in acetic acid, water, and alcohols. The material is indefinitely stable in the solid state and is stable in solution when protected from the light. The electronic absorption spectrum in dichloromethane shows maxima at 413 and 527 nm with molar absorptivities of 275,750 and 18,450, respectively. 

The X max. at 239 nm is typical of styrene chromophores which have undergone a wavelength shift and loss of intensity due to lack of coplanarity among the components of the chromophore. The solvent used was 95% alcohol, and a molar absorptivity value of 12,300 was obtained. The instrument used was a Cary 14-Spec trophotome ter. 

The best solvents for the extraction of arsenomolybdenum blue are butyl and amyl alcohols, ethers, and ethyl acetate. The molar absorptivity e of the As-Mo blue in butanol solution is 2.5-10 at Xmax=730 nm (a=0.33). Both the e and the Xmax values depend on the reducing agent and the extraction solvent used. 

The cobalt(ll) thiocyanate complex can be extracted with oxygen-containing solvents, such as a mixture of diethyl ether with isoamyl alcohol (1+1), MIBK, or acetylacetone [23,24], The molar absorptivity, e, of the complex in the ether-isoamyl aleohol mixture is about 30% smaller than in the aqueous acetone media. 

At Xmax 546 nm, the molar absorptivity of the copper(I)-cuproine complex in isoamyl alcohol is 6.4-10 (specific absorptivity 0.10). 

Neocuproine reacts with copper(I) within the pH range 3-10, to form an orange complex extractable with -amyl and isoamyl alcohols, -hexanol, and MIBK. Neocuproine is added to the sample as an ethanol solution, and the complex formed is extracted with CHCI3 [29]. The molar absorptivity of the complex in isoamyl alcohol at Xmax = 545 nm is 7.9-10 (a = 0.12). 

The bathocuproine method for the determination of copper(I) [30,31 ] is about twice as sensitive as those based on cuproine and neocuproine. The molar absorptivity of the copper-bathocuproine complex in isoamyl alcohol at max = 479 nm is 1.42-10 (a = 0.22). 

The molar absorptivity of the thiocyanate complex in isoamyl alcohol (absorption spectrum shown in Fig. 31.1) is EbTO" (specific absorptivity 0.17) at 470 nm. 

For measurement, the complex is extracted into organic solvents, usually isoamyl alcohol, DIPE, and MIBK a mixture of isoamyl alcohol and CHCI3 has also been used. The molar absorptivity of the complex in isoamyl alcohol is 1.56-1 O at A, ,ax = 403 nm (a = 0.09). The absorption spectrum of the complex is shown in Fig. 31.1. The existing procedures for the determination of W with thiocyanate have been discussed in detail [127]. 

The molar absorptivity of the rhenium-thiocyanate complex in isoamyl alcohol is 3.8T0" (a = 0.21) at 430 nm. The absorption spectrum is shown in Fig. 40.1. The following species interfere in the determination of rhenium by the thiocyanate method Mo, W, V, and Cr, as well as oxidizing and reducing agents. 

The following triphenylmethane dyes have been employed for determination of Sc similarly to Xylenol Orange Methylthymol Blue [33], Chrome Azurol S [34,35], Chromal Blue G [36], and Eriochrome Brilliant Violet B [37]. Much higher sensitivities have been obtained in the presence of some cationic surfactants [38 0]. In the method with Chrome Azurol S and Zephiramine, the e value is 1.5-10 at 610 nm, and in the method with Eriochrome Cyanine R and CP, e = 9.2-10" at 600 nm [40]. When o-hydroxy-quinonephthalein and CP are used, the molar absorptivity is 1.1-10 at 555 nm [41], Scandium has been determined with the use of Nile Blue in a poly(vinyl alcohol) medium [42]. 

Molybdosilicic acid can also be reduced after extraction into an oxygen-containing organic solvent e.g., amyl alcohol) [29,30]. Alternatively, silicomolybdenum blue may be formed in the aqueous phase and then extracted. The heteropoly blue exhibits similar molar absorptivities in both the organic phase and in the aqueous solution, but the absorption maximum is shifted slightly towards shorter wavelengths in organic solvents. 

Silicomolybdenum blue produced by extraction of molybdosilicic acid into amyl alcohol and reduction with SnCl2 has its A-max at 750 nm. The molar absorptivity is 1.7-10, sp. abs. 0.60. 

Sensitive extraction-spectrophotometric methods are based on the extractable (into CHCI3, 1,2-diehloroethane, benzene, or toluene) ion-associates of basic dyes and anionic Ag complexes with cyanide [35,36], iodide [37,38], and bromide [39]. In these methods, use has been made of such dyes as Crystal Violet [35,39], Brilliant Green [38,39], Malachite Green [39], Methylene Blue [36], and Nile Blue A [37]. In some of these methods the molar absorptivities are elose to MO [36,39]. A flotation method has been proposed, based on the addition compound [R6G ][Ag(SCN )2] [R6G ][SCN ] which is formed by silver ions (at pH 2-5) in the presence of thiocyanate and Rhodamine 6G (flotation with DIPE, the precipitated compound is washed and dissolved in acetone, e = 1.5-10 ) [40]. The complex Ag(CN)2 , associated with Crystal Violet, has been utilized in another flotation-spectrophotometric method of determining silver [41]. Silver has been determined also in a system comprising thiocyanate and Rhodamine B, as an aqueous pseudo-solution, in the presence of poly(vinyl alcohol) [42]. 

Detection of the sorbate peak after elution from the adsorption column was accomplished using a variable wavelength detector. With the exception of 2,4-decadienal, many of the solutes utilized in this research had small molar absorptivities and could only be detected in the far ultraviolet region of the spectrum. Convenient wavelengths for monitoring purposes were 215-230 nm for the carbonyl-bearing compounds and 200 nm for the n-alcohols. 

Yeast alcohol dehydrogenase (ADH) has its highest activity at 30°, and this decreases sharply with increase of temperature above 50°. No activity is observed at 70°. This inactivation process can be monitored by measuring the remaining activity of the enzyme during the incubation at elevated temperatures. ADH from yeast is assayed by monitoring ethanol-dependent NAD reduction at 340 nm ADH activity is expressed as micromoles of NADH produced per minute with a molar absorption coefficient of 6.22 mA/ cm . The influence of molecular chaperonin on ADH inactivation can be examined as follows. 

Sanger s reagent, 2,4-dinitrofluorobenzene, can also be employed for the colormetric detection of amino acids. The reagent reacts with both primary and secondary amines and derivatives are detected at 420 nm. The molar absorptivity of the reagent is 10", allowing quantification of amino acids at the micromolar level. The reagent also reacts with thiols and alcohols, but these products are relatively unstable. 

L/min N2) for the characterization of alcohol (AE) and alkylphenolethoxylates (APE). The authors noted that for those APEs with a low number of ethylene oxide residues, the ELSD skews the molecular weight distribution to higher molecular weights. This is due in part to the volatility of those species (and therefore a lower than expected signal). Conversely, the UV absorptivity must be corrected for the decrease in molar absorptivity as the chain length increases. The latter fact is critical if one pure standard is used for quantitation of all components. Overall, peak shapes were excellent and the authors claimed excellent reproducibility. 

The detailed plan of the study was set out clearly in writing so that all subjects would follow the same protocol. This plan (Fig. 1) began with two control days during which the person took the normal unrestricted diet, including their usual alcohol. During this time, two consecutive 24 hour urine collections were examined for volume, urate concentration and creatinine concentration. Urate was measured by an automated uricase method based on that of Liddle et alii (1959) (2) which gave a molar absorption of urate within 15 of published values. Blood was collected for urate... 

Ultraviolet detection at 245-254 nm is not sensitive enough for naturally occurring levels of thiamine, TMP, TPP and TTP in foods, and therefore is more used for enriched foods. Although some methods enable the determination of thiamine directly by HPLC with UV detection, the low vitamin content, very low molar absorption of thiamine and the high quantity of interfering compounds in foodstuff s means that better thiamine analysis is obtained when it is preceded by oxidation to thiochrome by either pre- or post-column reaction with or without extraction into isobutyl alcohol with precise timings and when the final analysis is carried out using HPLC with FL detection. 

The first overtone of P-H stretching was found at 5288 cm (1891 nm) in a number of organo-phosphorus compounds. It is slightly more intense than the S-H absorption, having a molar absorptivity of about 0.24 1/mol-cm. It is described as being more diffuse and less sharp, however. The POH group is observed in phosphorothioic acids. The absorption is significantly shifted relative to the hydroxyl in alcohols, as it is in mid-infrared. The near-infrared (NIR) peak appears at about 5241 cm (1908 nm). 

Alcohol dehydrogenase is an enzyme that catalyzes the conversion of ethanol to acetaldehyde in yeast (Eq. 10.10). Its activity can be monitored by following the increase in absorbance at 340 nm due to the formation of NADH. NAD+ does not absorb at this wavelength. Given the absorbance data below, calculate the activity of the enzyme in units per mL. One unit of alcohol dehydrogenase is defined as the amount needed to reduce 1 pmole of NAD+ per minute. The molar absorption coefficient, e, is 6220/M/cm. 

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