Chloride-hydrochloric acid buffer

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. 

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). 

This is a crystalline product of insulin and an alkaline protein where the protein/insulin ratio is called the isophane ratio. This product gives a delayed and uniform insulin action with a reduction in the number of insulin doses necessary per day. Such a preparation may be made as follows 1.6 g of zinc-insulin crystals containing 0.4% of zinc are dissolved in 400 ml of water, with the aid of 25 ml of 0.1 N hydrochloric acid. To this are added aqueous solutions of 3 ml of tricresol, 7.6 g of sodium chloride, and sufficient sodium phosphate buffer that the final concentration is As molar and the pH is 6.9. 

Buffer solution. Add 55 mL of concentrated hydrochloric acid to 400 mL de-ionised water and mix thoroughly. Slowly pour 310 mL of redistilled monoethanolamine with stirring into the mixture and cool to room temperature (Note 2). Titrate 50.0 mL of the standard magnesium chloride solution with standard (0.01M) EDTA solution using 1 mL of the monoethanolamine-hydrochloric acid solution as the buffer and solochrome black as the indicator. Add 50.0 mL of the magnesium chloride solution to the volume of EDTA solution required to complex the magnesium exactly (as determined in the last titration), pour the mixture into the monoethanolamine-hydrochloric acid solution, and mix well. Dilute to 1 litre (Note 3). 

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. 

The mechanism of decarboxylation of acids containing an amino substituent is further complicated by the possibility of protonation of the substituent and the fact that the species NH2ArCOOH is kinetically equivalent to the zwitterion NHj ArCOO. Both of these species, as well as the anion NH2 ArCOO" and even NH3 ArCOOH must be considered. Willi and Stocker644 investigated by the spectroscopic method the kinetics of the acid-catalysed decarboxylation of 4-aminosalicyclic acid in dilute hydrochloric acid, (ionic strength 0.1, addition of potassium chloride) and also in acetate buffers at 20 °C. The ionisation constants K0 = [HA][H+][H2A+] 1 (for protonation of nitrogen) and Kx = [A"][H+] [HA]-1, were determined at /i = 0.1 and 20 °C. The kinetics followed equation (262)... 

Chloroform, sodium chloride, anhydrous sodium sulfate, sulfuric acid (97%), hydrochloric acid (36%), sodium bicarbonate, trifluoroacetic acid, tris(hydro-xymethyl)aminomethane (Tris), special grade Water, high-performance liquid chromatography grade 0.1 M Phosphate buffer solution (pH 7.0)... 

The membrane of the glass electrode is blown on the end of a glass tube. This tube is filled with a solution with a constant pH (acetate buffer, hydrochloric acid) and a reference electrode is placed in this solution (silver chloride or calomel electrodes). During the measurement, this whole system is immersed with another reference electrode into the test solution. The membrane potential of the glass electrode, when the internal and analysed... 

Vishwavidyalaya et al. [22] used a difference-spectrophotometric method for the estimation of primaquine phosphate in tablets. One portion of powdered tablets, equivalent to 7.5 mg of primaquine phosphate, was extracted with hydrochloric acid-potassium chloride buffer (pH 2) and a second portion was extracted with phosphate buffer (pH 10). Primaquine phosphate was determined from the difference in absorbance of the acid and alkaline extracts at 254.2 nm. The calibration graph was rectilinear from 2 to 14 pg/mL of primaquine phosphate. Recovery was 98.6% and no interference was observed from excipients. Results compared with those by the British Pharmacopoeial method. 

NH3 + 1 1 buffer may be produced by the partial neutralization of an ammonia solution with hydrochloric acid or by the addition of the appropriate quantity of ammonium chloride to an initial ammonia... 

The effects caused by the electrolyte nature of lignin sulfonates are eliminated by using a 0.5M sodium chloride solution as eluent. This eluent is made 0.1M with respect to Tris-HCl and buffered to pH 8 with hydrochloric acid in order to dissolve the proteins used as calibration standards (Fig. 5). 

The lithium carbonate concentration was measured by acidimetric titration with methyl orange indicator. The calcium sulfate and calcium hydroxide concentrations were determined by titration with disodium dihydrogen Versenate [the disodium salt of (ethylenedinitrilo) tetraacetic acid], with added magnesium chloride. A buffer of ammonium chloride in ammonium hydroxide was employed. The indicator was Erio-chrome Black T. A special high purity calcium carbonate in hydrochloric acid was used as a standard. Because of the high concentration of sodium sulfate it was con-... 

Method. The organothiophosphorus insecticides are separated on silica gel with hexane-acetone (2 1 or 3 1). The plate is dried in air and sprayed with a solution of calcein-palladium chloride (0.0005 M palladium chloride in 0.1 M hydrochloric acid mixed with an equal volume of 10-3 Af calcein, adjusted to pH 7.2 with phosphate buffer and diluted with water to obtain a 2.0 10 4Af solution of palladium equilibrated overnight) which is diluted 1 1 with a 50% solution of acetone—water. When the plate is translucent it is dried in air and stored for 18—24 h in a closed chromatographic tank containing a beaker of a saturated solution of calcium nitrate tetrahydrate. This procedure permits the full fluorescence to develop under controlled humidity. The plate is then observed under a UV light at 365 nm, or scanned quantitatively at 365 nm (excitation) and 518 nm (emission). 

Assay Accurately weigh about 500 mg of the residue obtained in the test for Loss on Ignition (below), dissolve it in a 1 50 mixture of hydrochloric acid water, dilute with water to 100.0 mL, and mix. Transfer 50.0 mL of this solution into a 250-mL Erlenmeyer flask, add 10 mL of ammonia-ammonium chloride buffer TS and 12 drops of eriochrome black TS, and titrate with 0.1 M disodium EDTA until the wine red color changes to pure blue. Each milliliter of 0.1 M disodium EDTA is equivalent to 12.04 mg of MgS04. 

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