Determination Of Amphetamine In Urine Research Articles

Efficient determination of amphetamine and methylamphetamine in human urine using electro-enhanced single-drop microextraction with in-drop derivatization and gas chromatography

An efficient method for the determination of amphetamine (AM) and methylamphetamine (MA) using electro-enhanced single-drop microextraction (EE-SDME) and gas chromatography has been developed. One advantage of this method is that the extraction efficiency is greatly enhanced by the electric field acceleration of the mass transfer of target analytes from the sample solution to the organic solvent drop. In addition, the extracted analytes were in situ derivatized with isobutyl chloroformate (IBCF) in the droplet, which further improved the sensitivity of this method. Under the optimum conditions, the enrichment factors (EFs) for AM and MA were 247 and 782, respectively. The proposed method exhibited low limits of detection (0.27 μg/L for AM and 0.14 μg/L for MA) and good linearity over the concentration range between 1 and 2000 μg/L with regression coefficients (r2) of more than 0.99. The intra- and interday recoveries were from 89.6 to 96.2% and 82.7–90.5%, respectively, and the intra- and interday precisions (RSDs) were from 5.2 to 8.3% and 8.9–12.8%. The proposed method was applied to the determination of amphetamines in a urine sample.

Measurement uncertainty for the determination of amphetamines in urine by liquid-phase microextraction and gas chromatography-mass spectrometry

A gas chromatography-mass spectrometry method for the determination of amphetamines in urine samples by means of liquid-phase microextraction was validated, including calculation of measurement uncertainty. After extraction in the three-phase mode, acceptor phase was withdrawn from the fiber and the residue was derivatized with trifluoroacetic anhydride. The method showed to be very simple, rapid and it required a significantly low amount of organic solvent for extraction. The limits of detection were 10 and 20μg/L for amphetamine and methamphetamine, respectively. The calibration curves were linear over the specified range (20μg/L to 1400μg/L; r2>0.99). The method showed to be both precise and accurate and a relative combined uncertainty of 2% was calculated. In order of importance, the factors which were more determinant for the calculation of method uncertainty were: analyte concentration, sample volume, trueness and method precision.

A SPECIFIC METHOD FOR THE DETERMINATION OF AMPHETAMINE IN URINE.

Abstract A specific and sensitive method for the quantitative determination of amphetamine in urine, by gas chromatography, is described.

Solvent-enhanced microwave-assisted derivatization following solid-phase extraction combined with gas chromatography–mass spectrometry for determination of amphetamines in urine

An approach using microwave-assisted derivatization (MAD) following solid-phase extraction (SPE) combined with gas chromatography–mass spectrometry (GC–MS) was developed to determine amphetamines in urine samples. The parameters affecting the derivatization efficiency – including microwave power and irradiation time – were investigated. Besides, solvent is thought critically important to MAD. Derivatization performance was studied using various solvents and compared with the performance obtained without solvent. Derivatization efficiency was clearly found to be enhanced by the presence of solvent. The highest derivatization efficiencies were obtained in ethyl acetate (EA) under microwave power of 250 W for 1 min. Calibration curves for all amphetamines were linear over a range from 1 to 1000 ng/mL, with correlation coefficients above 0.9992. The intra-day and inter-day precision were less than 15%. The applicability of the method was tested by analyzing amphetamine-abusing subjects urine samples. Accordingly, the solvent-enhanced MAD-GC–MS method appears to be adequate for determining amphetamines in urine.

Miniaturized sample preparation method for determination of amphetamines in urine

A simple and miniaturized sample preparation method for determination of amphetamines in urine was developed using on-column derivatization and gas chromatography–mass spectrometry (GC–MS). Urine was directly applied to the extraction column that was pre-packed with Extrelut and sodium carbonate. Amphetamine (AP) and methamphetamine (MA) in urine were adsorbed on the surface of Extrelut. AP and MA were then converted to a free base and derivatized to N-propoxycarbonyl derivatives using propylchloroformate on the column. Pentadeuterated MA was used as an internal standard. The recoveries of AP and MA from urine were 100 and 102%, respectively. The calibration curves showed linearity in the range of 0.50–50 μg/mL for AP and MA in urine. When urine samples containing two different concentrations (0.50 and 5.0 μg/mL) of AP and MA were determined, the intra-day and inter-day coefficients of variation were 1.4–7.7%. This method was applied to 14 medico-legal cases of MA intoxication. The results were compared and a good agreement was obtained with a HPLC method.

Fluorimetric determination of amphetamine in urine by flow injection with on-line liquid–liquid extraction

Determination of amphetamine in urine was performed by batch and flow injection methodologies. The suitable experimental conditions for fluorimetric measurements were established. The liquid–liquid extraction was carried out at pH 13 using diethyl ether as extracting reagent. The measurement conditions were 260 nm and 277 nm for excitation and emission wavelengths, respectively. The method requires standard addition calibration and Youden blank correction. The influence of the main metabolites of amphetamine and metamphetamine were studied. The accuracy and precision of the proposed method was tested and the method is adapted to the flow injection procedure with on-line extraction.

Simultaneous supercritical fluid extraction and chemical derivatization for the gas chromatographic–isotope dilution mass spectrometric determination of amphetamine and methamphetamine in urine

An in-situ supercritical fluid extraction (SFE) and chemical derivatization (ChD) procedure followed by gas chromatography–isotope dilution mass spectrometry (GC–MS) for the determination of amphetamines in urine is described and evaluated. While using celite as the SFE wet-support, the one-pot sample pretreatment procedure also employs ammonium water to alkalize the urine matrix that contains protonated amphetamine (AP) and methamphetamine (MA). The mean recoveries achieved by simultaneous SFE–ChD, i.e., 95% (RSD=3.8%) for AP and 89% (RSD=4.0%) for MA, are significantly better than the corresponding overall recoveries obtained upon stepwise SFE–ChD, suggesting the unreacted trifluoroacetic anhydride (TFA) in the former procedure has strengthened the extracting power of CO 2 fluid as has been evidenced by a control test. As to GC–MS analysis, the optimal qualitative ions and quantitative ions of the respective analytes were determined via a rigorous evaluation process. Thus, the regression calibration curves for AP and MA in urine are linear within 100∼50 000 ng/ml, with correlation coefficients typically exceeding 0.999. The limits of detection determined by two methods for AP and MA vary from 19 to 50 ng/ml, and limits of quantitation from 21 to 100 ng/ml. Precisions calculated for the triplicate analyses of AP and MA in a 500-ng/ml spiked control, two real-case samples and two quasi real-case samples, respectively, using regression calibration are typically below 10%. The method is simple and reliable. It may serve as an alternative to the existing confirmatory protocol for forensic urine drug testing.

Aqueous alkylchloroformate derivatisation and solid-phase microextraction: determination of amphetamines in urine by capillary gas chromatography

The alkylchloroformate derivatisation and solid-phase microextraction of amphetamine and methamphetamine directly in urine samples prior to capillary gas chromatographic analysis is described. The alkylchloroformate reagent was added to the urine sample, which was adjusted to pH 10.8, and an internal standard was added. The resulting products were water-stable carbamates that were extracted without organic solvent. The polydimethylsiloxane coated fibre was inserted into the modified sample and agitated for 14 min. The fibre with the extracted derivatisation products was injected into the capillary gas chromatograph. The extracted carbamates were evaporated at 300°C in the split-splitless injection port of the gas chromatograph, separated on a methylsilicone capillary column and detected by either a nitrogen-phosphorus detector or by mass spectrometry. The method was shown to be reproducible with a detection limit of 50 ng/ml of amphetamine and methamphetamine in urine.

Determination of amphetamine in human urine by dansyl derivatization and high-performance liquid chromatography with fluorescence detection.

A simple procedure for the determination of amphetamine in urine with minimal sample preparation is described. This method involves direct addition of human urine to an acetone-dansyl chloride solution for simultaneous deproteinization and fluorescence derivatization. The derivatized amphetamine is then measured by HPLC with fluorescence detection. It eliminates the extraction procedures often required by other HPLC or GC methods. The effects of pH, temperature and reaction time on the derivatization reaction were investigated. The stability of amphetamine-dansyl chloride in different storage conditions was examined. The detection limit and linearity associated with this assay are discussed.

On-line derivatization into precolumns for the determination of drugs by liquid chromatography and column switching: determination of amphetamines in urine.

A chromatographic system for the on-line derivatization of drugs using column switching is described. The system uses a 20 mm x 2.1 mm i.d. precolumn packed with a unmodified ODS stationary phase. This column is used for sample cleanup and enrichment of the analytes. Next, the trapped analytes are derivatized by injection of the derivatization reagent into the precolumn. Finally, the derivatives are transferred to the analytical column for their separation under reversed-phase conditions. The influence of several parameters such as the reaction time, the amount of derivatization reagents, or the system design has been studied some amphetamines as model compounds and three derivatization reagents: sodium 1, 2-naphthoquinone-4-sulfonate, o-phthaldialdehyde, and 9-fluorenylmethyl chloroformate. The potential of the described approach is illustrated by determining amphetamine and methamphetamine in untreated urine at ambient temperature.

Automated Fluorometric Determination of Amphetaminein Urine

Abstract A completely automated fluorometric determination of amphetamine in urine is described and evaluated. The dihydrolutidine derivative produced by reaction of amphetamine with formaldehyde and acetylacetone is excited at 410 nm and the resulting intensity of fluorescence measured at 476 nm. The working limit of detection of amphetamine in fresh urine (1.5-ml samples) is 0.15 mg/liter. A result is produced for the first sample in about 20 min; subsequent results are obtained at 2-min intervals. Falsely positive reactions are given by 2-phenylethylamine and tuaminoheptane.

Determination of Amphetamine in Urine and Blood

The determination of amphetamine in body fluids is of interest in veterinary toxicology because of the possible use of amphetamine in the doping of race horses. Many types of methods for its detection and determination have been developed. In the newest methods gas chromatography and mass spectrometry have been applied, making it possible to detect and identify 1 µg amphetamine in blood samples (Bonnichsen et al. 1970).

Gas chromatography of biologically important amines

A gas chromatographic method is described employing a column containing 4% SE-30 siloxane polymer as the liquid phase which permits the separation of the following compounds: benzylamine, N-methylbenzylamine, β-phenylethylamine, amphetamine, β-phenylethanolamine, norephedrine, ephedrine, histamine, tyramine, octopamine, synephrine, normetanephrine, metanephrine, tryptamine, dimethyltryptamine, 5-methoxytryptamine, serotonin, N-acetyltryptamine, and melatonin. Various factors influencing the separations are given as well as a simple application of the technique to the determination of amphetamine in urine.