Hydrochloric acid-potassium chloride buffer

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. 

Hilton [82] described a colorimetric method B for determining amine antioxidants (p-phenylenediamine derivatives) based on the reaction of an ethanol extract of the polymer with cupric acetate in an hydrochloric acid/potassium chloride buffered medium. Kabota [83] made coloured derivatives of amines with benzothiazoline-2-one hydrazone hydrochloride and ferric chloride, and evaluated the colours obtained, spectroscopically. 

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)... 

Subphase buffers at pH 9-11 and 0.1 to 0.2 ionic strength were prepared with sodium or potassium bicarbonate-carbonate mixtures (8, 26). Subphase buffers at pH 8-11 were prepared by adding 0.01M tris to 0.1M or 1.0M sodium chloride and adjusting the pH with concentrated hydrochloric acid or concentrated sodium hydroxide. Another alkaline subphase contained 0.1 N sodium hydroxide (pH 12.7). The acid subphase contained 0.01N hydrochloric acid and 0.1M sodium chloride (pH 2.1). All subphases contained 0.1mM EDTA. 

Substance/ ingredients per ml 20 mg methyl cellulosepropy) glyceroletheri sodium chloride potassium chloride, calcium chloride-2 HjO. lactic acid, hydrochloric add. sodium hydroxide methylhydroxy-propykeJlulose 18.0 to 22.0 mg, sodium chloride, potassium chloride, calcium chloride x lactic acid, hydrochloric acid, sodium hydroxide, water for injection 20 mg methyl-hydroxy propyl cellulose, 4.9 mg sodium chloride, 0.75 mg potassium chloride, 0.48 mg calciumchloride. 0.3 mg magnesium chloride, 3.9 mg sodium acetate, 1.7 mg sodium citrate, HCl/sodium hydroxid buffer solvent 20 mg methyl-hyd oxyp opyl-cellulose, 9 mg sodium chloride, 2.7 mg boric add, 0.2 mg sodium, aqua ad injectibila 20 mg methyl-hydroxy propyl-cellulose, 9 mg sodium chloride, 2.7 mg boric acid, 0.2 mg sodium, aqua ad injectibila 18 mg hydroxy-propy Im et hy Icell u 1 o se, 5.9 mg sodium chloride, 0.75 mg potassium chloride, 0.48 mg calcium chloride, 0.3 mg magnesium chloride, 3.9 mg sodium acetat, L7 mg sodium citrate... 

The effect of chloride ions on the rate of polymerization of acrylic acid needs further elucidation. Thus Katchalsky and Blauer [38] showed that chloride ions were strong inhibitors of the polymerization of methacrylic acid at a pH below 2.5, an effect not found with sulfate or nitrate ions. Yet their work was carried out in a buffer system consisting of sodium acetate and hydrochloric acid. A more recent patent, on the other hand, claims that the rate of polymerization of acrylic acid in the presence of potassium persulfate, 2-mercaptoethanol, the tetrasodium salt of EDTA, and a sulfonated castor oil was significantly increased when l-897o of an alkali metal chloride was present [40]. 

Pipette 4 ml of this solution into a 100-ml graduated flask and into another 100-ml graduated flask pipette 2 ml of an accurately prepared 0 05 per cent solution of procaine hydrochloride in water. To each flask add 50 ml of a buffer solution (prepared by mixing 11 90 ml of 0-2M hydrochloric acid and 88 10 ml of 0 2M potassium chloride) and then add 5 ml of a 1 per cent solution of p-dimethylaminobenzaldehyde in 95 per cent ethanol (prepared not more than three days before use and stored in an amber-coloured bottle), dilute to volume with water and mix. 

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