Potassium Citrate Tablets
DEFINITION
Potassium Citrate Tablets contain NLT 90.0% and NMT 110.0% of the labeled amount of potassium (K).
IDENTIFICATION
• A.
The Sample solution for Strength produces line emissions or absorptions at the characteristic wavelengths for potassium.
• B. Identification Tests—General, Citrate 
191
191
Analysis:
Grind a Tablet to a fine powder in a mortar. Transfer the powder to a centrifuge tube, add 2–5 mL of water, sonicate for 1 min, shake, and centrifuge.
Acceptance criteria:
The supernatant meets the requirements for the test.
STRENGTH
• Content of Potassium, Procedure 1
[Note—A standard stock solution is commercially available at different potassium concentrations, which may be used for preparation of the Standard stock solution. Necessary volumetric adjustment can be made in the Standard solution. Concentrations of the Standard solution and the Sample solution may be modified to fit the linear or working range of the instrument. ]
Standard stock solution:
Solution of potassium chloride, previously dried at 105
for 2 h, in water containing 1000 mg/L of potassium.
for 2 h, in water containing 1000 mg/L of potassium.
Standard solution:
To a 50-mL volumetric flask add 20 mL of water and 1 mL of nitric acid, and mix thoroughly. Pipet 10.0 mL of the Standard stock solution into a volumetric flask, and dilute with water to volume to obtain a solution having a known concentration of about 200 µg/mL of potassium.
Sample solution:
Weigh and finely powder NLT 20 Tablets. Transfer an accurately weighed portion of the powdered Tablets, equivalent to about 0.1 g of potassium, to a 50-mL flask. Add 10 mL of nitric acid, and heat the solution to a gentle boil, during which fuming evolves. Boil the solution for an additional 30 min with constant swirling, during which time no fuming should be observed. Cool the solution to room temperature. Quantitatively transfer all of the solution to a 500-mL volumetric flask, dilute with water to volume, mix, and filter.
Inductively coupled plasma system
(See Plasma Spectrochemistry 730.)
730.)
Mode:
Atomic emission spectroscopy
Analytical wavelength:
766.49 nm. [Note—The operating conditions may be developed and optimized based on the manufacturer's recommendation. A typical setting includes radio frequency (RF) power of about 1300 watts, argon torch flow of about 15 L/min, argon auxiliary flow of about 0.2 L/min, and a nebulizer flow rate of about 0.8 L/min. ]
Blank:
2% nitric acid solution
Analysis
Samples:
Standard solution, Sample solution, and Blank
Calculate the percentage of the labeled amount of potassium (K) in the portion of Tablets taken:
Result = (rU/rS) × (CS/CU) × 100
| rU | = | = response from the Sample solution |
| rS | = | = response from the Standard solution |
| CS | = | = concentration of potassium in the Standard solution (µg/mL) |
| CU | = | = nominal concentration of potassium in the Sample solution (µg/mL) |
Acceptance criteria:
90.0%–110.0% of the labeled amount of potassium
• Content of Potassium, Procedure 2
Standard stock solution A:
100 µg/mL of potassium chloride, previously dried at 105 for 2 h, in water
for 2 h, in water
Standard stock solution B:
10 µg/mL of potassium from Standard stock solution A in 0.125 N hydrochloric acid
Standard solutions:
Transfer 5.0, 10.0, 15.0, 20.0, and 25.0 mL of Standard stock solution B to separate 100-mL volumetric flasks. Dilute the contents of each flask with 0.125 N hydrochloric acid to volume to obtain solutions containing 0.5, 1.0, 1.5, 2.0, and 2.5 µg/mL of potassium.
Sample solution:
Finely powder NLT 20 Tablets. Transfer an equivalent to 5 Tablets to a porcelain crucible. Heat the crucible in a muffle furnace maintained at 550 for 6–12 h, and cool. Add 60 mL of hydrochloric acid, and boil gently on a hot plate or steam bath for 30 min, intermittently rinsing the inner surface of the crucible with 6 N hydrochloric acid. Cool, and quantitatively transfer the contents of the crucible to a 100-mL volumetric flask. Rinse the crucible with small portions of 6 N hydrochloric acid, and add the rinsings to the flask. Dilute with water to volume, and filter, discarding the first 5 mL of the filtrate. Dilute this solution quantitatively with 0.125 N hydrochloric acid to obtain a nominal concentration of 2 µg/mL of potassium.
for 6–12 h, and cool. Add 60 mL of hydrochloric acid, and boil gently on a hot plate or steam bath for 30 min, intermittently rinsing the inner surface of the crucible with 6 N hydrochloric acid. Cool, and quantitatively transfer the contents of the crucible to a 100-mL volumetric flask. Rinse the crucible with small portions of 6 N hydrochloric acid, and add the rinsings to the flask. Dilute with water to volume, and filter, discarding the first 5 mL of the filtrate. Dilute this solution quantitatively with 0.125 N hydrochloric acid to obtain a nominal concentration of 2 µg/mL of potassium.
Instrumental conditions
Mode:
Atomic absorption spectrophotometry
Analytical wavelength:
766.5 nm
Lamp:
Potassium hollow-catode
Flame:
Air–acetylene
Blank:
0.125 N hydrochloric acid
Analysis
Samples:
Standard solutions and Sample solution
Determine the absorbances of the solutions, using the Blank. Plot the absorbances of the Standard solutions versus concentration, in µg/mL, and draw the straight line best fitting the five plotted points. From the graph so obtained, determine the concentration, C, in µg/mL of potassium in the Sample solution.
Calculate the percentage of the labeled amount of potassium (K) in the portion of Tablets taken:
Result = (C/CU) × 100
| C | = | = determined concentration of potassium in the Sample solution interpolated from the graph (µg/mL) |
| CU | = | = nominal concentration of potassium in the Sample solution (µg/mL) |
Acceptance criteria:
90.0%–110.0% of the label claim
SPECIFIC TESTS
• Microbial Enumeration Tests 2021:
The total aerobic microbial count does not exceed 103 cfu/g, and the total combined yeast and mold count does not exceed 102 cfu/g.
2021:
The total aerobic microbial count does not exceed 103 cfu/g, and the total combined yeast and mold count does not exceed 102 cfu/g.
• Absence of Specified Microorganisms 2022:
Meet the requirement of the test for absence of Escherichia coli
2022:
Meet the requirement of the test for absence of Escherichia coli
PERFORMANCE TESTS
• Disintegration and Dissolution 2040
2040
Medium:
Water; 900 mL
Apparatus 2:
75 rpm
Time:
30 min
Analysis:
Proceed as directed in Content of Potassium, Procedure 1 or Procedure 2, for Strength, making any necessary volumetric adjustments.
Sample solution:
If Content of Potassium, Procedure 1 is used, pipet 10.0 mL of the filtered pooled solution under test to a 50-mL volumetric flask, and dilute with 2% nitric acid solution to 50 mL. If Content of Potassium, Procedure 2 is used, dilute the filtered pooled solution under test with 0.125 N hydrochloric acid to a concentration falling within the range of the Standard solutions.
Calculate the percentage of the labeled amount of potassium (K) dissolved:
Result = (C × D × V/L) × 100
| C | = | = measured concentration of potassium in the Sample solution (mg/mL) |
| D | = | = dilution factor for the Sample solution |
| V | = | = volume of Medium, 900 mL |
| L | = | = label claim (mg/Tablet) |
Tolerances:
NLT 75% of the labeled amount of K is dissolved.
• Weight Variation 2091:
Meet the requirements
2091:
Meet the requirements
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in well-closed containers.
• Labeling:
The label states the quantity of potassium in terms of mg/Tablet.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Natalia Davydova
Scientific Liaison 1-301-816-8328 |
(DS2010) Monographs - Dietary Supplements |
| 2021 |
Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison 1-301-816-8339 |
(GCM2010) General Chapters - Microbiology |
| 2022 |
Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison 1-301-816-8339 |
(GCM2010) General Chapters - Microbiology |
USP35–NF30 Page 1413
Pharmacopeial Forum: Volume No. 34(2) Page 313