Quantitative determination of cisplatin in plasma and urine in clinical research by triple quadrupole LC/MS/MS

Importance of the Topic

Cisplatin is a platinum-based chemotherapeutic agent widely used against various cancers. Accurate quantification of cisplatin in plasma and urine is essential for dosing optimization, pharmacokinetic profiling, and monitoring nephrotoxicity in preclinical and clinical research.

Objectives and Study Overview

This work aimed to develop and validate a highly sensitive liquid chromatography–tandem mass spectrometry (LC/MS/MS) method for quantitative determination of cisplatin in rat plasma and urine following derivatization with diethyldithiocarbamate (DDTC). The assay covers a dynamic range of 3–3000 ng/mL and supports pharmacokinetic studies across dosing from 0.5 to 3.5 mg/kg.

Methodology and Instrumentation

Sample Preparation: Biological samples (45 µL) were spiked with cisplatin and palladium internal standard, derivatized with DDTC in alkaline medium at 40 °C for 30 minutes, precipitated with acetonitrile containing DPCPX internal standard, centrifuged, dried under nitrogen, and reconstituted in water:acetonitrile:formic acid (80:20:0.1).

Chromatography: Separation was achieved on an Agilent InfinityLab Poroshell 120 EC-C18 column (3 × 50 mm, 2.7 µm) using a binary gradient of 0.1% formic acid in water (A) and acetonitrile (B) at 0.35 mL/min, with a 7-minute run time and 10 µL injection volume.

Mass Spectrometry: Detection employed an Agilent 6460 triple quadrupole with electrospray ionization in positive MRM mode. Key transitions included m/z 492→116, 114, 88 for Pt-DDTC, m/z 403→339,254 for Pd-DDTC, and m/z 305→178 for DPCPX. Optimized gas temperatures, flows, voltages, and collision energies ensured high sensitivity.

Main Results and Discussion

The method demonstrated linearity (r2 >0.999) over 5–3000 ng/mL with 1/x2 weighting. The limit of detection was 1 ng/mL and the LLOQ was 3 ng/mL. No interfering peaks were observed in blank matrices. Intra- and inter-day accuracy and precision met acceptance criteria (±15% for QCs, ±20% at LLOQ). The assay was successfully applied to rat pharmacokinetic profiling.

Benefits and Practical Applications

This approach requires minimal sample volume (45 µL), offers superior sensitivity via DDTC derivatization, and provides robust, selective quantification. It is well suited for preclinical pharmacokinetic studies, toxicology assessments, and may support dose individualization.

Future Trends and Potential Uses

Future developments may extend this method to clinical therapeutic drug monitoring, high-throughput microsampling platforms, multiplexed analysis of platinum-based drugs, and integration into personalized oncology workflows.

Conclusion

The validated LC/MS/MS assay with DDTC derivatization delivers a precise, accurate, and sensitive tool for cisplatin measurement in biological matrices, facilitating pharmacokinetic and toxicological research with minimal sample requirements.