Application of a sensitive liquid chromatography-tandem mass spectrometric method to determination of octreotide in human plasma

Importance of the Topic

A reliable and sensitive quantitation of therapeutic peptides in biological fluids underpins drug development, pharmacokinetic profiling and therapeutic drug monitoring. Octreotide, a long-acting somatostatin analog used in oncology and endocrinology, requires accurate measurement at very low concentrations in human plasma to support dose optimization, safety assessments and regulatory compliance.

Objectives and Study Overview

This work presents the development and validation of a rapid ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS) assay for octreotide in human plasma. The primary aims were to achieve a lower limit of quantitation (LLOQ) of 5.0 pg/mL, minimize sample volume, simplify sample preparation and maintain high accuracy, precision and throughput.

Methodology and Instrumentation

The assay combined µElution mixed-mode weak cation exchange solid phase extraction (SPE) with UHPLC-MS/MS detection.

• Sample Preparation: 200 µL plasma spiked with internal standard (leuprolide, 1.0 ng/mL), acidified with 4% phosphoric acid. SPE plate conditioned with methanol and water, samples loaded, washed sequentially with 5% ammonium hydroxide and 20% acetonitrile, eluted with 1% TFA in 75:25 acetonitrile/water, diluted and vortexed prior to injection.
• UHPLC System: Shimadzu Nexera UHPLC, InertSustain Swift C18 column (2.1 × 100 mm, 1.9 µm), mobile phase A: 0.1% formic acid in water; B: acetonitrile; flow 0.4 mL/min; gradient elution; column at 40 °C.
• MS/MS Detection: Shimadzu LCMS-8050 triple quadrupole with ESI in positive mode, spray voltage +4.0 kV, nebulizing gas 3.0 L/min, drying gas 5.0 L/min, interface and block temperatures 400 °C, DL at 200 °C. MRM transitions: octreotide m/z 510.30→120.00, IS leuprolide m/z 605.40→249.05.

Main Results and Discussion

The method exhibited excellent performance across the calibration range 5–2000 pg/mL.

• Linearity: correlation coefficient (r) 0.9993 with regression equation Y = 2.89×10⁻³ X – 6.34×10⁻³.
• Sensitivity: LLOQ of 5 pg/mL with signal-to-noise >10.
• Precision and Accuracy: intra-day precision (RSD) 2.32–7.43%, inter-day precision 2.44–8.99%; accuracy within ±15% at 15, 150 and 1500 pg/mL.
• Recovery: mean recoveries 70.1–71.5% across three QC levels; matrix effect factors >80%, internal standard-normalized factors >90%.
• Carryover: no significant signal observed in blank injections after upper limit calibration samples.

Benefits and Practical Applications

This sensitive UHPLC-MS/MS assay requires only 200 µL plasma and employs a streamlined SPE protocol compatible with 96-well plates, enabling high-throughput sample processing. Its robust performance supports drug metabolism and pharmacokinetic (DMPK) studies, bioequivalence testing and clinical monitoring of octreotide therapy.

Future Trends and Potential Applications

Advances in peptide bioanalysis may leverage further miniaturized SB-SPE workflows, automated sample handling, and high-resolution mass spectrometry to improve sensitivity and selectivity. Integration with lab-on-a-chip platforms and multiplexed assays could expand monitoring to multiple peptide therapeutics and biomarkers in personalized medicine.

Conclusion

The described UHPLC-MS/MS method delivers a highly sensitive, precise and accurate tool for quantifying octreotide in human plasma, offering streamlined sample preparation and reliable performance suitable for research and regulatory applications.

Reference

• Song Y, Yao J, Hao H, Li Q, Huang T, Kawano S, Hashi Y. Application of a sensitive liquid chromatography-tandem mass spectrometric method to determination of octreotide in human plasma. Shimadzu Global COE, 2015.