Novel Method for the Extraction of Cocaine from Oral Fluid by Means of Disposable Pipette Modified with Restricted Access Material

Abstract

This study proposes a new, efficient, and selective method for the analysis of cocaine in oral fluid. For this purpose, an extractive phase with restricted access materials (RAM) capable of extract and pre-concentrate low molecular weight analytes and simultaneously exclude macromolecules was developed for disposable pipette extraction (DPX) followed by liquid chromatography coupled to mass spectrometry (LC-MS) analyses. The proposed method was optimized using a 24 factorial design which pointed higher extraction efficiency under the following conditions: pH 9, 10 cycles of extraction (aspirate/dispense), 3 cycles of desorption (aspirate/dispense) and acetonitrile as desorption solvent. The DPX-RAM/LC-MS method showed linearity range from 10 to 100 ng mL-1 with determination coefficient (R2) = 0.999, accuracy values ranged from -0.9 to 4.3%, precision values ranged from 1.7 to 9.1% and recovery values ranged from 97.9 to 101.1%. The benefits of this method are that it can be performed in few minutes and that the analytical performances, including the limit of detection (3.13 ng mL-1), limit of quantitation (10 ng mL-1) and linear range were found to be in agreement with other methods used for similar analysis.

Determinação de pesticidas em alimentos derivados da cana-de-açúcar por LC-MS/MS empregando DPX como técnica de preparo de amostra

“…A passagem de amostra pela ponteira é conhecida como ciclo, ou seja, cada aspiração/dispensa da amostra constitui um ciclo. Alguns trabalhos [88][89][90][91] indicam que realizar este processo várias vezes aumenta a sorção dos analitos à fase extratora, resultando em maiores recuperações.…”

Desenvolvimento de métodos espectrométricos (UHPLC-MS/MS e MS/MS) para a determinação de peptídeos β-amilóides em amostras de líquido cefalorraquidiano de pacientes com a doença de Alzheimer

“…A técnica DPX tem sido reportada em diversas áreas de aplicação, como por exemplo, análise forenses [143,144], ambientais [145][146][147][148][149][150] e alimentícias [151].…”