[汇总]usp中缓冲溶液和标准溶液的详细配制方法

[汇总]usp中缓冲溶液和 标准 excel标准偏差excel标准偏差函数exl标准差函数国标检验抽样标准表免费下载红头文件格式标准下载 溶液的详细配制方法 BUFFER SOLUTIONS The successful completion of many Pharmacopeial tests and assays requires adjustment to or maintenance of a specified pH by the addition of buffer solutions. In pH measurements, standard buffer solutions are required for reference purposes. For convenience, the preparation of these solutions is in some instances described in the sections in which their use is specified; i.e., five separate phosphate buffers are described under Antibiotics -- Microbial Assays <81>, and several miscellaneous single-purpose solutions are described in the individual monographs. A solution is said to be buffered if it resists changes in the activity of an ion on the addition of substances that are expected to change the activity of that ion. Buffers are substances or combinations of substances that impart this resistance to a solution. Buffered solutions are systems in which the ion is in equilibrium with substances capable of removing or releasing the ion. Buffer capacity refers to the amount of material that may be added to a solution without causing a significant change in ion activity. It is defined as the ratio of acid or base added (in gram-equivalents per liter) to the change in pH (in pH units). The capacity of a buffered solution is adjusted to the conditions of use, usually by adjustment of the concentrations of buffer substances. Buffers are used to establish and maintain an ion activity within narrow limits. The most common systems are used to establish hydrogen-ion activity for the calibration of pH meters, in the preparation of dosage forms that approach isotonicity, in analytical The required reagents are described in the section, Reagents. Buffers used in physiological systems are carefully chosen so as not to procedures, and to maintain stability of various dosage forms. . Previously dry the crystalline reagents, except the boric acid, at 110 interfere with pharmacological activity of the medicament or normal degrees to 120 degrees for 1 hour. function of the organism. It is essential that buffers used in chemical NOTE -- Where water is specified for solution or dilution of test analysis be compatible with the substance determined and the reagents substances in pH determinations, use carbon dioxide-free water. used. STANDARD BUFFER SOLUTIONS -- Standard solutions of definite pH are Store the prepared solutions in chemically resistant, tight containers readily available in buffer solutions prepared from the appropriate such as Type I glass bottles. Use the solutions within 3 months. reagents. In addition, buffer solutions, buffer tablets, and buffer Standard buffer solutions for various ranges between pH 1.2 and 10.0 solids may be obtained from commercial sources in convenient prepackaged may be prepared by appropriate combinations of 0.2 M solutions described form. Such preparations are available for the entire working range in herein, used in the proportions shown in the accompanying table. The pharmaceutical analysis, but are not recommended for pH meter volumes shown in the table are for 200 mL of buffer solution. standardization (see pH <791>1. Hydrochloric Acid, 0.2 M, and Sodium Hydroxide, 0.2 M -- Prepare and standardize as directed under Volumetric Solutions. 2. Potassium Biphthalate, 0.2 M -- Dissolve 40.85 g of potassium biphthalate [KHC[6]H[4](COO)[2]] in water, and dilute with water to 1000 mL. 3. Potassium Phosphate, Monobasic 0.2 M -- Dissolve 27.22 g of monobasic potassium phosphate (KH[2]PO[4]) in water, and dilute with water to 1000 mL. 4. Boric Acid and Potassium Chloride, 0.2 M -- Dissolve 12.37 g of boric acid (H[3]BO[3]) and 14.91 g of potassium chloride (KCl) in water, and dilute with water to 1000 mL. 5. Potassium Chloride, 0.2 M -- Dissolve 14.91 g of potassium chloride (KCl) in water, and dilute with water to 1000 mL. 6. Acetic Acid, 2 N -- Prepare and standardize as directed under Volumetric Solutions. Composition of Standard Buffer Solutions See Graphic G-1097 ------------------------------------------------------------------------ Hydrochloric Acid Buffer Place 50 mL of the potassium chloride solution in a 200-mL volumetric flask, add the specified volume of the hydrochloric acid solution, then add water to volume. pH 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 HCl, mL 85.0 67.2 53.2 41.4 32.4 26.0 20.4 16.2 13.0 10.2 7.8 Acid Phthalate Buffer Place 50 mL of the potassium biphthalate solution in a 200-mL volumetric flask, add the specified volume of the hydrochloric acid solution, then add water to volume. pH 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 HCl, mL 49.5 42.2 35.4 28.9 22.3 15.7 10.4 6.3 2.9 0.1 Neutralized Phthalate Buffer Place 50 mL of the potassium biphthalate solution in a 200-mL volumetric flask, add the specified volume of the sodium hydroxide solution, then add water to volume. pH 4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 5.8 NaOH, mL 3.0 6.6 11.1 16.5 22.6 28.8 34.1 38.8 42.3 Phosphate Buffer Place 50 mL of the monobasic potassium phosphate solution in a 200-mL volumetric flask, add the specified volume of the sodium hydroxide solution, then add water to volume. pH 5.8 6.0 6.2 6.4 6.6 6.8 7.0 7.2 7.4 7.6 7.8 8.0 NaOH, mL 3.6 5.6 8.1 11.6 16.4 22.4 29.1 34.7 39.1 42.4 44.5 46.1 Alkaline Borate Buffer Place 50 mL of the boric acid and potassium chloride solution in a 200-mL volumetric flask, add the specified volume of the sodium hydroxide solution, then add water to volume. pH 8.0 8.2 8.4 8.6 8.8 9.0 9.2 9.4 9.6 9.8 10.0 NaOH, mL 3.9 6.0 8.6 11.8 15.8 20.8 26.4 32.1 36.9 40.6 43.7 Acetate Buffer Place the specified amount of sodium acetate (NaC[2]H[3]O[2].3H[2]O) in a 1000-mL volumetric flask, add the specified volume of the acetic acid solution, then add water to volume, and mix. pH 4.1 4.3 4.5 4.7 4.9 5.1 5.2 5.3 5.4 5.5 pH (measured) 4.10 4.29 4.51 4.70 4.90 5.11 5.18 5.30 5.40 5.48 NaC[2]H[3]O[2]. 1.50 1.99 2.99 3.59 4.34 5.08 5.23 5.61 5.76 5.98 3H[2]O, g CH[3]COOH, mL 19.5 17.7 14.0 11.8 9.1 6.3 5.8 4.4 3.8 3.0