Developing a rapid semi-automated sample preparation with alkaline hydrolysis in a 96-well plate for quantification of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid in urine samples by UHPLC-MS/MS

Publication date: Available online 23 August 2018Source: Journal of Pharmaceutical and Biomedical AnalysisAuthor(s): Lill Dannevig Müller, Mimi Stokke OpdalAbstractA simple, sensitive, rapid and robust manual (in glass tubes) and semi-automatic method (in a 96-well plate format) for quantification of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid (THCA) in urine using a UHPLC-MS/MS have been developed. The methods involved hydrolysis with potassium hydroxide in a 96-well plate, followed by neutralization and dilution of the sample in one step with a stable solution of formic acid-methanol-acetonitrile-water (2.2%/35/35/30) before centrifugation. The total chromatographic run time was 4.9 minutes, with retention times of 1.6 minutes for THCA. The linear calibration range (5–4000 ng/ml) prepared in urine matrix was wide to avoid reanalyzing. The methods take especially precautions to totally eliminate the carry over after run of the highest standard and to eliminate adsorption of THCA on lab-ware during sample preparation. High content of organic solvent in the neutralization and dilution solution and in the initial composition of the mobile phase gradient are therefore necessary. Standards and quality controls was pH adjusted to 8.4 to increase the solubility of the hydrophobic THCA in urine and prevent adsorption during storage. A preliminary study revealed that adsorption of THCA during semi- automatic sample preparation in a 96-well plate (plastic) was less comp...
Source: Journal of Pharmaceutical and Biomedical Analysis - Category: Drugs & Pharmacology Source Type: research