Hydrochloric Acid Buffer

Fig. 2.12 Potential-time curves on mild steel in sodium borate/hydrochloric acid buffer solutions, pH 7-60, oxygen-saturated solution (after Ashworth )...

The monoethanolamine-hydrochloric acid buffer has a buffering capacity equal to the ammonia-ammonium chloride buffer commonly employed for the titration of calcium and magnesium with EDTA and solochrome black (compare Section 10.54). The buffer has excellent keeping qualities, sharp end points are obtainable, and the strong ammonia solution is completely eliminated. 

Sodium acetate-hydrochloric acid buffer. Add 1M hydrochloric acid to 350mL of 1M sodium acetate until the pH of the mixture is 2.2 (pH meter). 

For tissue analysis, the sample is extracted with ethyl acetate in the presence of sodium chloride and piperonyl butoxide. After centrifugation, the supernatant is evaporated to dryness, and the residue is dissolved with dichloromethane/ hexane (1 1) to be applied onto a Bond-Elut silica cartridge. Following successive cartridge washing with petroleum ether and ethyl acetate/hexane (4 6), chloramphenicol is eluted with ethyl acetate/hexane (7 3) and the eluate is evaporated to dryness. The residue is dissolved in 0.05 M Tris/hydrochloric acid buffer pH 10.4, extracted with diethyl ether, and the extract is evaporated to dryness. Tlie... 

The homogenization of liver, kidney, and muscle tissues with glycine-hydrochloric acid buffer was presented for the determination of OTC, TC, and CTC. The supernatant was purified on a cyclohexyl SPE cartridge previously activated with MeOH and water. The TCs were eluted with MeOH, which was evaporated at 65°C, and the residue was dissolved in mobile phase. Recoveries were achieved greater than 70% in muscle at the MRL concentrations and higher than 60% for kidney with RSD <11%. Gradient elution was employed to improve the separation of OTC and TC from interference found in kidney samples. The eluate from HPLC was mixed with aluminium chloride solution in a low-volume T-piece and delivered into the PTFE tubing 13.7 m X 0.3 mm immersed in an oil bath at 60°C followed by fluorescent detection (22). 

Method for catecholamines by HPLC. A few microlitres of a 10 3-Af solution of dopamine, norepinephrine or similar compounds are transferred to a small test-tube and diluted to 20 jul with 0.05 M sodium phosphate (pH 8) at 4 °C [ 102]. 10 jul of a 0.2% solution of fluorescamine in acetone are then added with vigorous shaking. An aliquot portion of this mixture is applied directly to the HPLC column. The derivatives are separated on Hitachi 3011 or 3010-OH gels (column, 50 cm X 3 mm) with methanol-0.05 M Tris-hydrochloric acid buffer of pH 8 (7 3) at room temperature at a flow-rate of 0.72 ml/min. The separation of fluorescamine derivatives of dopamine and norepinephrine with this system is shown in Fig.4.52. 

The assay method of Dalziel is convenient. In a recording ultraviolet spectrophotometer set at 340 nm is placed a 3-mL quartz cuvette containing 2.4 mL of 0.10 M glycine-sodium hydroxide buffer solution, pH 9, 500 pL of a 54 mM solution of ethanol 1n the same buffer, and 100 pL of a 15 nM solution of NAD, also in the same pH 9 buffer. The volume is made up to 3.0 mL, and the assay initiated by the addition of 10 pL of a 1 mg per mL solution of HLADH in 0.10 M "Tris-hydrochloric acid buffer", pH 7.4. The change in optical density at 340 nm 1s monitored at 25°C and the activity calculated from the following equation ... 

Glycine-Hydrochloric Acid Buffer (0.05 M) Dissolve 3.75 g of glycine in about 800 mL of water. Add 1 N hydrochloric acid until the solution is pH 3.0, determined with a pH meter. Quantitatively transfer the solution to a 1000-mL volumetric flask, dilute to volume with water, and mix. 

Sample Preparation Using Glycine-Hydrochloric Acid Buffer, prepare a solution of the sample enzyme preparation so that 2 mL of the final dilution will give a corrected absorbance of enzyme incubation filtrate at 275 nm (AA, as defined in the Procedure) between 0.200 and 0.500. Weigh the enzyme preparation, quantitatively transfer it to a glass mortar, and triturate with Glycine-Hydrochloric Acid Buffer. Quantitatively transfer the mixture to an appropriately sized volumetric flask, dilute to volume with Glycine-Hydrochloric Acid Buffer, and mix. 

Add 2 mL of Glycine-Hydrochloric Acid Buffer (instead of the Sample Preparation) to the substrate blank. After exactly 30 min, add 10 mL of TCA Solution to each enzyme incubation and to the substrate blank to stop the reaction. In the following order, prepare an enzyme blank containing 10 mL of Substrate Solution, 10 mL of TCA Solution, and 2 mL of the Sample Preparation. Heat all tubes in the water bath for 30 min, allowing the precipitated protein to coagulate completely. 

The reactions were carried out in a borate-hydrochloric acid buffer at pH 8.0, the pH being readjusted, if necessary, by addition of 1M sodium hydroxide solution after the addition of procyanidin. The above pH was chosen to obtain a convenient reaction rate while minimizing catechinic acid formation (36). It was found that, if water rather than buffer was used for the reaction, and the pH was simply adjusted to pH 8.0 as described by Kiatgrajai et al. (55), the observed pH was unstable and subject to drift. 

Dilute hydrochloric acid Buffering agent, pH adjustment, solubilizer, stabilizer iv, im, sc... 

The mixtures of Clark and Lubs are very easy to prepare. The starting materials are readily obtained in the pure state, and the arrangement of solutions at pH intervals of 0.2 unit is very convenient. The biphthalate-hydrochloric acid buffers, however, have two disadvantages which detract somewhat from its usefulness. 

The leading electrolyte was 0.01 H hydrochloric acid buffered to pH 8.2 with tris(hydroxymethyl)aminomethane (Kodak Laboratory and Research Products, Rochester, NT). The terminating electrolyte was... 

Fig. 4.7.2. Affinity chromatography of a-chymotrypsin on inhibitor Sepharose columns. The columns (50x5 mm) were equilibrated and run with O.OS M Tris-hydrochloric acid buffer (pH 8.0). Each sample (2.5 mg) was applied in 0.5 ml of the same buffer. The columns were run at room temperature with a flow-rate about 40 ml/h and fractions containing 1 ml were collected. The arrows indicate a change of elution buffer (0.1 M acetic acid, pH 3.0). (A) Sepharose coupled with e-aminocaproyl-D-tryptophan methyl ester (B) Sepharose coupled with D-tryptophan methyl ester (C) unsubstituted Sepharose. The first peaks in A and B were devoid of enzyme activity. Reproduced with permission from Ref. 46.

Using a pipette transfer 2, 3, 10, 20 and 25 ml of cyanide reference solution into five 230 ml measuring flasks and top each one up to the 230 ml mark with 0.4 m sodium hydroxide. Transfer 10 ml from each flask to five 23 ml measuring flasks. To each of these add 1 m hydrochloric acid, buffer solution, chloramine T solution and barbituric acid-pyridine reagent, as described under "Measurement". Then carry out photometric analysis, in which the measured values must lie on a straight line. Check the calibration curve from time to time. 

The preparation of silica gel plates for the cultivation of certain types of bacteria has been described by Muller and Holm (391). A silicic acid sol is made by adding a solution of sodium silicate to hydrochloric acid buffered at about pH 4.5. The gel is permitted to set in Petri dishes, washed, soaked in nutrient solution, and then autoclaved. For a purer medium, the intermediate sol may be dialyzed before it is permitted to set to gel (392). An improved procedure for incorporating nutrients directly into the acid, forming the gel under sterile conditions and eliminating dialysis, was developed by Sterges (393). A simplified method (394) is described as follows. Seven hundred milliliters of 0.5 N HCl is mixed with 300 ml of the mineral nutrient solution to be employed. To I volume of 0.5 N sodium silicate is added 1 volume of lime water, and to this 1 volume of the acid nutrient is added. The mixture is poured into Petri dishes, aged 2 hr, and placed in an oven at lOO C for 1 hr. The use of tetramethyl ester of orthosilicic acid is advocated by Ingelman and co-... 

Tris-acetic acid buffers have been proposed instead of Tris-hydrochloric acid buffers for preparative starch gel electrophoresis because the anodic solution does not drop to such low pH values (Pilz and Johann, 1966). Examples for use at 20°C are pH 7.3, four litres of 0.4m Tris plus 750 ml 2m acetic acid pH 8.6, 4.5 litres 0.4m Tris plus 280 ml 2m acetic acid. A recent paper describes buffers for the electrophoresis of enzymes on polyacrylamide gel (Orr et al., 1972). 

Fig. 16 Local property of the circular dichroism of CMADK (S-carboxymethyl-alanyl disulfide keratin) in tris-hydrochloric acid buffer solution (pH 7).

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