Acetic Acid buffer

Another level of regulatory significance is the toxic characteristic leach procedure (TCLP) limit of a characteristic waste. A material which is a waste because of the TCLP is ha2ardous if a Hquor resulting from an 18-h leach in an acetic acid buffer exceeds 5 ppm (mg/L) lead in the leach Hquor. 

Reagents. In view of the sensitivity of the method, the reagents employed for preparing the ground solutions must be very pure, and the water used should be re-distilled in an all-glass, or better, an all-silica apparatus the traces of organic material sometimes encountered in demineralised water (Section 3.17) make such water unsuitable for this technique unless it is distilled. The common supporting electrolytes include potassium chloride, sodium acetate-acetic acid buffer solutions, ammonia-ammonium chloride buffer solutions, hydrochloric acid and potassium nitrate. 

Hydroxylammonium chloride. 10 per cent aqueous solution, or benzene-1,4-diol (quinol), 1 per cent solution in an acetic acid buffer of pH ca 4.5 (mix 65 mL of 0.1M acetic acid and 35 mL of 0.1M sodium acetate solution). Prepare when required. 

Both HMR and MR have strong absorption peaks in the visible portion of the spectrum the colour change interval from pH 4 to pH 6 can be conveniently obtained with a sodium acetate-acetic acid buffer system. 

Sodium acetate-acetic acid buffer. Prepare a solution which is 0.2 M in sodium acetate and 0.8 M in acetic acid. The pH is 4.0. 

Pal, B., Sen, P.K. and Sen Gupta, K.K. (2001) Reactivity of alkanols and aryl alcohols towards tetrachloroaurate(lll) in sodium acetate-acetic acid buffer medium. Journal of Physical Organic Chemistry, 14, 284. 

This reaction is found to be stable in sodium acetate and acetic acid buffer (pH 4.65), and so it has only been studied in this medium. The faradaic rectification theory becomes highly complicated when extended to three-electron charge transfer reactions due to the formation of the two intermediate species Al(II) and A1(I). In order to determine the three rate constants and the two unknown concentration terms, C°Rl and C°Ru, corresponding to the two intermediate species formed, it becomes necessary to carry out the experiment at five different concentrations of aluminum ion, each below 2.00 mM. 

Figure 7. V versus to 1/2 plots for Al3+ in sodium acetate-acetic acid buffer...

Palfray and Sabetay246 added an emulsifying agent, Gardinal, to aid in the oxidation of the water-insoluble 1-0-benzylglyceritol. Aqueous solutions of methanol,247 248 ethanol,13 - 249-261 dioxane,74 - 262 266 acetic acid,230 - 266 and acetic acid buffered with lithium acetate164 have been used. The use of lithium periodate or triethylammonium periodate in aqueous alcohol solution has been suggested,267 because of the solubility of these salts in this medium. 

J(P1)720>. These cyclizations were mediated with sodium acetate-acetic acid buffers affording moderate to good yields (52-86%) and low to moderate yields (10-60%) of 7-acyl-substituted 1H- and (mesoionic) 2//-pyrrolote-trazole derivatives 67a-g, and 70a-d and 70f-h, respectively. In most cases, deacylation of pyrrolotetrazoles 67 and 70 could be effected easily by heating with HC1 affording moderate to excellent yields of 68a-e and 71a-e. 

Acidic compounds Carboxylic Phosphate buffer, 1% acetic acid (buffered to pH 3.0)... 

What is the molar ratio of salt/acid needed to prepare an acetic acid buffer having a pH of 5. 

Reverse phase HPLC describes methods that utilize a polar mobile phase in combination with a nonpolar stationary phase. As stated above, the nonpolar stationary phase structure is a bonded phase—a structure that is chemically bonded to the silica particles. Here, typical column names often have the carbon number designation indicating the length of a carbon chain to which the nonpolar nature is attributed. Typical designations are C8, C18 (or ODS, meaning octadecyl silane), etc. Common mobile phase liquids are water, methanol, acetonitrile (CH3CN), and acetic acid buffered solutions. 

Electrochemical reduction of benzylic nitro compounds (27) in an ethanolic aqueous acetic acid buffer (35 65) affords a mixture of the corresponding oxime and hydroxylamine (equation 6)48. The hydroxylamine can subsequently be oxidized back to the oxime (28) (via the intermediate nitroso compound) conversions as high as 90% can be obtained. 

The use of surface-enhanced resonance Raman spectroscopy (SERRS) as an identification tool in TLC and HPLC has been investigated in detail. The chemical structures and common names of anionic dyes employed as model compounds are depicted in Fig. 3.88. RP-HPLC separations were performed in an ODS column (100 X 3 mm i.d. particla size 5 pm). The flow rate was 0.7 ml/min and dyes were detected at 500 nm. A heated nitrogen flow (200°C, 3 bar) was employed for spraying the effluent and for evaporating the solvent. Silica and alumina TLC plates were applied as deposition substrates they were moved at a speed of 2 mm/min. Solvents A and B were ammonium acetate-acetic acid buffer (pH = 4.7) containing 25 mM tributylammonium nitrate (TBAN03) and methanol, respectively. The baseline separation of anionic dyes is illustrated in Fig. 3.89. It was established that the limits of identification of the deposited dyes were 10 - 20 ng corresponding to the injected concentrations of 5 - 10 /ig/ml. It was further stated that the combined HPLC-(TLC)-SERRS technique makes possible the safe identification of anionic dyes [150],... 

Figure 27. Plots of the permeation current density vs. the square root of the Tafel reaction current density [Eq. (33)], recorded in ace-tate/acetic acid buffers at pH = 6 and 30°C, using carbon steel membranes of 1.0 and 0.5 mm thickness. ...

The leading electrolyte was 2.8 pM ammonium acetate - acetic acid buffer (pH 4.9) containing 0.3% Triton X 100. 5 pM acetic acid served as the terminator. 

The preparations proved to be 98 to 99% chromatographically pure, the contaminant always being the other isomer. The various absorption maxima are reported in Table I. All solutions were 0.01 M in complex. Those designated as HC or HT were measured either in water at pH 5-6, or in O.lM sodium acetate-acetic acid buffer at pH 5.5 (no spectral differences resulted) and those designated C or T were adjusted to pH 10.5 with ethylenediamine. 

Solochrome Violet R [2092-55-9] M 367.3. Converted to the monosodium salt by pptn with sodium acetate/acetic acid buffer of pH 4, then purified as described for Chlorazole Sky Blue FF. Dried at 110°. It is hygroscopic. [Coates and Rigg TFS 57 1088 1961],... 

Perfetti et al. (131) described a method for the determination of ethoxyquin in milk. Milk solids were precipitated by adding acetonitrile, and the water-acetonitrile supernatant was washed with hexane to remove fat. The addition of NaCl caused the water-acetonitrile solution to separate into an aqueous phase and an acetonitrile phase, thus separating ethoxyquin from most water-soluble impurities. A large volume of water was then added to the acetonitrile layer, and ethoxyquin was partitioned into hexane and removed at reduced pressure. The residue was dissolved in the mobile phase and analyzed on a 250-mm X 4.6-mm-ID. Ultrasphere ODS column using fluorescence detection with excitation of 230 nm, and emission of 418 nm, respectively. A mixture of water and acetonitrile with a diethylamine-acetic acid buffer was the mobile phase. Recoveries from milk samples fortified at 1, 5, and 10 ng/g averaged 78%, with a coefficient of variation of 5.0%. Low concentrations (less than 1 ng/g) of apparent ethoxyquin were detected in commercial milk samples analyzed by this method. 

Mobile phase EtOH, ACN, TRIS, acetic acid buffer (pH = 8). 

V-Formylkynurenine is one of the 16 autoxidation products of tryptophan (51) (Fig. 8). The dye-sensitized photo-oxygenation of tryptophan in sodium carbonate - acetic acid buffer (pH 7) gave TV-for my Iky n urenine as the major product (52). This is also the oxidation product of tryptophan with hydrogen peroxide (53) and with ozone (54). This is an interesting case the same degradation impurity can be obtained in different ways, probably... 

The desired relationship between pretazettine (242) and haeman-thidine (248) was achieved when 248 was oxidized to 250, converted, in turn, with sodium acetate-acetic acid buffer at reflux to 244, thus establishing a structural and stereochemical link between 242 and 248. At C-ll haemanthidine bears a hydroxy group directed toward the C-l-C-2 unsaturation, and since it seemed mechanistically... 

Samples of freeze-dried fish tissues are extracted with 25% tetramethy-lammonium hydroxide using a microwave digester. After extraction, the pH is adjusted to 4 with acetic acid buffer. A 1% solution of NaBEt4 is added, with some hexane. The solution is shaken for 5 minutes. A fresh portion of NaBEt4 is added, the shaking is repeated, and finally, a third portion is added and allowed to react. The sample is centrifuged and an aliquot of the supernatant hexane is taken for injection into the GC [132],... 

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