Ammonia N 13 Injection

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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1 DEFINITION

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Ammonia N 13 Injection is a sterile aqueous solution of [¹³N] Ammonia (¹³NH₃). It contains NLT 90% and NMT 110% of the labeled amount of [¹³N] Ammonia (¹³NH ) expressed in MBq(mCi)/mL at the time indicated in the labeling. It may contain buffering agents, preservatives, stabilizing agents, or sodium chloride. It does not contain any added carrier. 

2 IDENTIFICATION

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A. Radionuclidic Identity

(See Radioactivity 〈821〉, 5. Identification of Radionuclides, 5.1 Half-Life Determination.) The half-life of 13N is 9.5–10.5 min. 2S (USP41)

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B. Radiochemical Identity

Procedure: After completing the Analysis in the Radiochemical Purity test, spray or stain the TLC strip with iodoplatinate TS. Allow the TLC strip to develop for 10 min. Place the developed TLC strip in an iodine chamber. The spot due to ammonium ion on the strip for the Standard solution appears as an orange-brown spot against a light maroon background.

Acceptance criteria: The R value of 13NH in the Sample solution is 90%–110% of the R value of the ammonium ion as determined in the

Standard solution in the test for Radiochemical Purity.2S (USP41)

3 ASSAY

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Radioactive Concentration (Strength)

(See Radioactivity 〈821〉, 6. Assay of Radionuclides.)

Analysis: Determine the radioactivity, in MBq (or mCi)/mL, of the Injection, using a suitable calibrated system.

Acceptance criteria: 90%–110% at the time indicated on the label 2S (USP41)

4 PURITY

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Radionuclidic Purity

(See Radioactivity 〈821〉, 5. Identification of Radionuclides, 5.2 Gamma-Ray Spectrometry.)

[Note-This may be a periodic quality indicator test. The Injection may be distributed and dispensed prior to completion of this test.]

Analysis: Determine the purity of ammonia N 13 in the portion of Injection taken for the Radionuclidic Impurities test:

Result = [1 − (C_i/C_T)] × 100

C_i = sum of the concentrations of all longer-lived radionuclides, decay corrected to the expiration time from the Radionuclidic Impurities test (Bq/mL) or (μCi/mL)

C_T = sum of the concentrations of all long-lived radionuclides and ammonia N 13, all decay corrected to the expiration time from the Radionuclidic Impurities test (Bq/mL) or (μCi/mL)

Acceptance criteria: At the time of expiration, NLT 99.5% of radionuclides in the Injection correspond to ¹³N.

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4.1 Radiochemical Purity

Standard solution: 100 mg/mL of USP Ammonium Chloride RS in water

Sample solution: A volume of Injection, appropriately diluted if necessary, to a concentration of 5–30 MBq (0.135–0.81 mCi)/mL or to a concentration suitable for the detector to be used

4.2 Chromatographic system

Mode: TLC

Detection: Radio-TLC scanner

Adsorbent: Cellulose diethylaminoethyl strips; 1.5-cm × 8-cm

Application volume: 0.5 μL

Developing solvent: Methanol and water (75:25)

4.3 Analysis

Samples: Standard solution and Sample solution

Apply the Standard solution and Sample solution independently as two adjacent spots on the TLC strip. Allow the spots to dry. Place the TLC strip in the developing chamber with Developing solvent. When the solvent front reaches about 1 cm from the top of the strip, remove the strip from the chamber and allow it to dry. Determine the radioactivity distribution by scanning the chromatogram with a suitable radiation detector. After completing the test for Radiochemical Purity, use the TLC radiochromatogram for the Radiochemical Impurities test. After completing the test for Radiochemical Purity, use the TLC strip for the Radiochemical Identity test.

Calculate the percentage of the labeled amount of ¹³NH₃ in the portion of Injection taken from the chromatogram of the Sample solution:

Result= (r_U/r_T) × 100

r_U = response of 13NH from the Sample solution

r_T = sum of the responses of all peaks including 13NH from the Sample solution

Acceptance criteria: NLT 95% of the total radioactivity is due to ammonia N 13.

5 IMPURITIES

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5.1 Radionuclidic Impurities

[Note-This may be a periodic quality indicator test. The Injection may be distributed or dispensed prior to completion of the test.]

Sample: A suitable volume of Injection, decayed for a suitable length of time to eliminate interference due to 13N emissions

Analysis: Using a suitable gamma-ray spectrometer, count an appropriate aliquot of the sample solution for a period of time sufficient to collect a gamma spectrum. The resultant gamma spectrum should be analyzed for the presence of identifiable photopeaks which are characteristic of radionuclidic impurities.

Determine the concentration of radionuclidic impurities in Bq (or μCi)/mL, decay corrected to the expiration time of the Injection:

Result = (C_i/C_T) × 100

C_i = sum of the concentrations of all longer-lived radionuclides decay, corrected to the expiration time (Bq/mL) or (μCi/mL)

C_T = sum of the concentrations of all long-lived radionuclides and ammonia N 13, all decay corrected to the expiration time (Bq/mL) or (μCi/mL)

Acceptance criteria: Total radionuclidic impurities are NMT 0.5% of the radioactivity of the Injection (see the Assay), decay corrected to the time of expiration.

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5.2 Radiochemical Impurities

Analysis: Calculate the percentage of radiochemical impurities in the portion of Injection taken from the TLC radiochromatogram of the

Sample solution, as obtained in the Radiochemical Purity test.

Result= (r_i/r_T) × 100

r_i = sum of the responses all peaks excluding the response of ¹³NH from the Sample solution

r_T = sum of the responses of all peaks including ¹³NH from the Sample solution

Acceptance criteria: NMT 5% 2S (USP41)

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5.3 Chemical Purity

[Note-This article may be synthesized by different methods and processes and, therefore, contains different impurities. The presence of unlabeled ingredients, reagents, and by-products specific to the process must be controlled, and their potential for physiological or pharmacological effects must be considered.]

ALUMINUM (to be determined if Devarda's alloy is used to reduce ¹³N nitrate/nitrite)

Standard solution: 2 μg/mL of aluminum prepared by dissolving 35.2 mg of aluminum potassium sulfate dodecahydrate in 1L of water

Blank standard solution Transfer 10mL of Standard solution to a 50mL volumetric flask. Add 3 drops of methyl orange TS and 2 drops of 6N ammonium hydroxide. Add 0.5N hydrochloric acid dropwise until the solution turns red. Add 1mL of edetate disodium TS. Add 5mL of eriochrome cyanine TS and 5mL of acetate buffer TS. Dilute with water to volume.

Analytical standard solution Transfer 10mL of Standard solution to a 50mL volumetric flask. Add 3 drops of methyl orange TS and 2 drops of 6N ammonium hydroxide. Add 0.5N hydrochloric acid dropwise until the solution turns red. Add 25mL of sodium thioglycolate TS. Add 5mL of eriochrome cyanine TS and 5mL of acetate buffer TS. Dilute with water to volume.

Sample solution: Use the Injection

Blank sample solution: Transfer 1mL of Injection to a 50mL volumetric flask. Add 3 drops of methyl orange TS and 2 drops of 6N ammonium hydroxide. Add 0.5N hydrochloric acid dropwise until the solution turns red. Add 1mL of edetate disodium TS. Add 5mL of eriochrome cyanine TS and 5mL of acetate buffer TS. Dilute with water to volume.

Analytical sample solution: Transfer 1mL of Injection to a 50mL volumetric flask. Add 3 drops of methyl orange TS and 2 drops of 6N ammonium hydroxide. Add 0.5N hydrochloric acid dropwise until the solution turns red. Add 25mL of sodium thioglycolate TS. Add 5mL of eriochrome cyanine TS and 5mL of acetate buffer TS. Dilute with water to volume.

Instrumental Conditions:

Mode: Vis

Analytical wavelength: 535 nm

Analysis:

Samples: Blank Standard solution,Analytical standard solution, Blank sample solution and Analytical sample solution

Procedure: Measure the absorbance of the Samples immediately. Calculate the amount of aluminum in μg/mL in the portion of the

Injection taken:

Result= [(A_u−A_ub)/A_s−A_sb)]×C_s× (V_s/V_u)]

A_u = absorbance of Analytical sample solution

A_ub = absorbance of Blank sample solution

A_s = absorbance of Analytical standard solution

A_sb = absorbance of Blank standard solution

C_s = concentration of aluminum in Standard solution, μg/mL

V_s = volume of Standard solution in Analytical standard solution

V_u = volume of Injection in Analytical sample solution

Acceptance criteria: NMT 10 μg/mL 2S (USP41)

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5.4 Limit of Ethanol

[Note-Perform this test if Ethanol is known to be present in the article. This may be a periodic quality indicator test. The Injection may be distributed and dispensed prior to completion of this test.]

Standard solution: 3.1 mg/mL of ethanol prepared as follows. Transfer 2 mL of USP Alcohol Determination±Alcohol RS to a 10 mL volumetric flask. Dilute with water to volume.

Sample solution: Use the Injection.

Chromatographic system

Mode: GC

Detector: Flame ionization

Column: 0.25-mm × 30-m fused-silica; coated with a 0.5-μm film of phase G16

Temperatures

Injection port: 250°

Detector: 300°

Column: See Table 1.

[Note-Depending on the syringe wash solvent, an additional ramp at 10°/min to bring the column to 240° with no hold time may be used before returning the column oven to initial conditions.]

Table 1

Carrier gas: Hydrogen

Flow rate: 1.3 mL/min

Injection volume: 1 μL

Injection type: Split ratio, 15:1

System suitability

Sample: Standard solution

Suitability requirements

Relative standard deviation: NMT 5.0%

Analysis

Samples: Standard solution and Sample solution

Acceptance criteria: The response for ethanol in the Sample solution is NMT the response of ethanol in the Standard solution (3.1 mg/mL of ethanol). 2S (USP41)

6 SPECIFIC TESTS

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pH

Analysis: Apply a suitable volume of the Injection on a suitable pH indicator paper, short-range.

Acceptance criteria: 4.5–7.5

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Bacterial Endotoxins Test

Meets the requirements

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Sterility Tests

[Note-The Injection may be distributed or dispensed prior to completion of the test, the latter test being started within 36 h of final manufacture.]

Sample: Use 0.1–0.3 mL of Injection

Acceptance criteria: Meets the requirements

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Appearance

Clear, colorless solution, free of foreign particulates

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Specific Activity: No carrier added 2S (USP41)

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Other Requirements: It meets the requirements under Injections 〈1〉, except that the Injection may be distributed or dispensed before completion of the test for Sterility Tests 〈71〉, the latter test being started within 24 h of final manufacture, and except that it is not subject to the recommendation in Volume in Container. 

7 ADDITIONAL REQUIREMENTS

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Packaging and Storage: Preserve in single-dose or multiple-dose containers that are adequately shielded. Store at controlled room temperature.2S (USP41)

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Labeling: The label indicates the time and date of calibration; the concentration of 13N as ammonia expressed in MBq (mCi)/mL, at the time of calibration; the expiration time and date; and the name and quantity of any added preservative or stabilizer. Calculate the correct dosage from date and time of calibration. The labeling indicates that in making dosage calculations, correction is to be made for radioactive decay. The radioactive half-life of 13N is 9.96 min. The label also indicates the following: [Caution-Radioactive Material. Do not use if cloudy or if it contains visible particulate matter.] 2S (USP41)

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USP Reference Standards 〈11〉

USP Alcohol Determination±Alcohol RS

USP Ammonium Chloride RS