Analysis of fluorescein isothiocyanate derivatized amphetamine and analogs in human urine by capillary electrophoresis in chip‐based and fused‐silica capillary instrumentation

Abstract

Amines can easily be derivatized with fluorescein isothiocyanate isomer I (FITC) and analyzed by capillary electrophoresis (CE) using alkaline buffers with or without dodecyl sulfate micelles. This paper reports the CE analysis of FITC-derivatized amphetamine, methamphetamine, 3,4-methylenedioxymethamphetamine and beta-phenylethylamine in human urine using chip-based and fused-silica capillary instrumentation with laser-induced fluorescence detection. Data obtained via direct labeling of fortified urine are compared to those generated after FITC labeling of urinary extracts that were prepared by solid-phase extraction using a copolymer phase. For a urine volume of 5 mL with a "spiked amine": FITC ratio of 1:250, the latter approach was found to provide a sensitivity that is relevant for toxicological drug screening and confirmation (about 200 ng/mL urine). With direct labeling of 10 microL urine that was alkalinized and diluted for derivatization, the limit of identification was determined to be about 10 microg/mL, a value that is too high for practical purposes. Compared to fused-silica capillaries, electrophoresis in microstructures is shown to provide faster separations and higher efficiencies without loss of accuracy and precision.

A rapid method for the in-field analysis of amphetamines employing the Agilent Bioanalyzer

“…28,36 Experiments were performed to simplify the FITC derivatisation procedure using a dry heating block. Initially, experiments were conducted using a water-bath as performed by Zhou et al, 31 however a dry heating block was chosen due to its reduced complexity.…”

“…27 The reaction of FITC with proteins and amino acids was first reported in 1969 by Maeda et al 27 and has been used to label amphetamines and other amine-containing compounds. 28,29 Typical derivatisation times with FITC have been up to 12 hours, with recent attempts to shorten the reaction time. Dominguez-Vega et al 30 described an accelerated FITC derivatisation of the amino acid ornithine.…”

“…The signal intensity associated with the microwave procedure was improved in comparison to the procedures at room temperature and 100 C in a water-bath. 31 Ramseier et al 28 reported the separation and detection of amphetamine analogues in human urine. The separation run time was 10 minutes, involving a 24 hour labelling process with FITC.…”

Cation‐selective exhaustive injection and sweeping MEKC for direct analysis of methamphetamine and its metabolites in urine

“…Many methods have been used for analyzing methamphetamine and its metabolites, including GC [3][4][5], HPLC [6,7], and CE [8][9][10][11][12][13][14][15][16][17], but they need tedious derivatizations and/or pretreatments. CE has the advantages of high efficiency, rapid separation, and little solvent consumption, but its sensitivity is not favored due to the short path length of detection and the small sample volume.…”

“…Fluorescent derivatizations have been developed for LIF detection [8,9,16] with a sensitivity more than required to detect 20 ng/mL [8]. Additionally, the combination of CE with MS has been attractive for monitoring abused drugs, but it still requires sample pretreatment and expensive equipments [11,13].…”