Determination of cotinine by LC-MS-MS with automated solid-phase extraction

Area of Science:

• Biochemistry
• Analytical Chemistry
• Toxicology

Background:

• Cotinine is the primary nicotine metabolite and a crucial biomarker for assessing cigarette smoke exposure.
• Existing liquid chromatography-tandem mass spectrometry (LC-MS-MS) methods for cotinine quantification often involve time-consuming manual sample preparation.
• There is a need for efficient and automated methods for high-throughput cotinine analysis.

Purpose of the Study:

• To develop and validate a novel, automated LC-MS-MS method for the precise quantification of cotinine in human plasma.
• To establish a sensitive, specific, and rapid assay suitable for large-scale epidemiological studies.
• To streamline the sample preparation process for cotinine analysis.

Main Methods:

• Development of a liquid chromatography-tandem mass spectrometry (LC-MS-MS) method utilizing electrospray ionization and multiple reaction monitoring.
• Incorporation of an automated solid-phase extraction (SPE) procedure for sample preparation.
• Validation of the assay using cotinine-d3 as the internal standard.

Main Results:

• The assay demonstrated linearity over a wide analytical range (0.5-1,000 ng/mL).
• Low limits of detection (0.13 ng/mL) and quantification (0.20 ng/mL) were achieved.
• High precision (<5% intra-assay, <10% inter-assay CV) and excellent analytical recovery (>95-100%) were observed.
• Minimal matrix effects (<10%) in serum and plasma were noted.
• The method proved effective for analyzing over 500 samples in an epidemiological study.

Conclusions:

• A rapid, sensitive, and specific automated LC-MS-MS method for cotinine determination in human plasma has been successfully developed and validated.
• The straightforward automated SPE protocol significantly enhances efficiency for batch analyses.
• This method is well-suited for epidemiological studies requiring high-throughput analysis of cotinine levels.