Determination of NDSRI in Chlorpromazine Tablets by LCMS-8050

Importance of the Topic

Chlorpromazine is a key phenothiazine antipsychotic whose tertiary amine core can form carcinogenic nitrosamine impurities during manufacturing. Regulatory agencies such as the FDA classify N-nitroso-desmethyl-chlorpromazine as a high-risk nitrosamine with strict intake limits. Reliable detection of these impurities at trace levels is critical for patient safety, product quality, and regulatory compliance.

Objectives and Overview of the Study

The study aimed to develop and validate a rapid, sensitive LC-MS/MS method using the Shimadzu LCMS-8050 system to quantify N-nitroso-desmethyl-chlorpromazine in chlorpromazine tablets. Key goals included minimizing analysis time, achieving a low quantification limit, and demonstrating robustness for routine quality control.

Methodology and Instrumentation

Sample Preparation:

• Weighed two 25 mg tablets, extracted with 5 mL 50% acetonitrile–water via 30 min ultrasonication.
• Centrifuged at 5000 rpm for 5 min, filtered supernatant through 0.22 µm nylon membrane.
• Prepared calibration standards at 0.1–80 ng/mL in acetonitrile.

Chromatography and Mass Spectrometry Conditions:

• System: Shimadzu Nexera XS UHPLC with Shim-pack GISS HP-C18 column (100 × 2.1 mm, 3 µm) at 30 °C.
• Mobile phase: A = 0.05% formic acid in water, B = acetonitrile; gradient 55%–100% B in 5.5 min; flow 0.3 mL/min; injection 2 µL.
• MS: LCMS-8050, ESI positive; nebulizing gas 3 L/min, drying and heating gases 10 L/min; interface 350 °C; DL 200 °C; heat block 400 °C; IF voltage 1 kV; ESI position +1 mm.
• MRM transitions optimized for precursor/product ions with collision energies and biases tailored for both analyte and internal standards.

Main Results and Discussion

Analysis Speed and Sensitivity:

• Total run time: 5.5 min per injection.
• Lower limit of quantification: 0.1 ng/mL.

Linearity and Precision:

• Calibration curve linear from 0.1 to 80 ng/mL (R² = 0.9992) with accuracy between 94.3% and 109.9%.
• Repeatability (n=6) RSD for retention time <0.11% and for peak area <5.8% at 0.5 ng/mL, improving at higher concentrations.

Recovery and Specificity:

• Recovery rates for spiked samples (0.4 and 4 ng) ranged from 81.8% to 91.8% (RSD <3%).
• No interfering peaks observed in blank injections, confirming method specificity.

Benefits and Practical Applications

The validated method offers:

• Rapid throughput enabling high sample turnover in quality control labs.
• High sensitivity to meet stringent nitrosamine limits in pharmaceuticals.
• Robust performance with minimal matrix interference, suitable for routine monitoring of chlorpromazine products.

Future Trends and Possibilities

Advances may include:

• Integration of online sample cleanup techniques for automation and reduced hands-on time.
• High-resolution mass spectrometry to screen unknown nitrosamines concurrently.
• Miniaturized flow systems and microfluidic interfaces to decrease solvent use and enhance sensitivity.
• Machine learning for predictive optimization of chromatographic and MS parameters.

Conclusion

The presented LC-MS/MS method using Shimadzu LCMS-8050 achieves fast, precise quantification of N-nitroso-desmethyl-chlorpromazine in tablet formulations. It meets regulatory sensitivity requirements and demonstrates excellent linearity, precision, recovery, and specificity, making it a reliable tool for pharmaceutical quality control.