Fast Ephedrine Quantification by Gas Chromatography Mass Spectrometry

Abstract

Ephedrines are widely used in therapy. Because of their stimulant properties, these substances are relevant in different forensic fields. At present, the state of the art for ephedrines quantification relay based on a liquid chromatography mass spectrometry, mainly because of the dilute-andshoot approach. Notwithstanding, several gas chromatography based methods have already been described, all of them include cleanup steps, with the potential disadvantage of incurring errors and increasing the workload. In this paper, a straightforward method for ephedrine quantification based on gas chromatographic mass spectrometry, without cleanup and based on Doehlert matrix optimization is presented. Only 10 µL of a urine sample is necessary and for N-methyl-N-(trimethylsilyl)trifluoroacetamide/N-methyl-bis-trifluoracetamide derivatives, the intermediate precision was 2.77% for ephedrine, 9.20% for cathine, 8.29% for norephedrine and 4.27% for pseudoephedrine. The limit of detection was 20 ng mL -1 for ephedrine, 30 ng mL -1 for cathine and 40 ng mL -1 for norephedrine and pseudoephedrine.

Zebrafish (Danio rerio) water tank model for the investigation of drug metabolism: Progress, outlook, and challenges

“…The injector, column and mass spectrometry conditions were the same as described by Carneiro et al 21 The GC temperature programming was set as follows: initial column oven temperature 130°C (held 1 minute), then programmed to increase to 210°C at 10°C/min, then to 250°C at 10°C/min and to 300°C at 30°C/min. The injector, column and mass spectrometry conditions were the same as described by Carneiro et al 21 The GC temperature programming was set as follows: initial column oven temperature 130°C (held 1 minute), then programmed to increase to 210°C at 10°C/min, then to 250°C at 10°C/min and to 300°C at 30°C/min.…”

“…21 The number of fish was the principal variable for investigation because it is directly related to the kinetics of the process, and the concentration of the drug in the ZWT was evaluated because it is a relevant variable for other in vivo models. 21 The number of fish was the principal variable for investigation because it is directly related to the kinetics of the process, and the concentration of the drug in the ZWT was evaluated because it is a relevant variable for other in vivo models.…”

“…For diastereomeric derivatives analysis, the GC-MS analysis was performed with a quadrupole mass spectrophotometry ISQ (Thermo Scientific, San Jose, CA, USA) equipped with a TriPlus RSH autosampler. The injector, column and mass spectrometry conditions were the same as described by Carneiro et al 21 The GC temperature programming was set as follows: initial column oven temperature 130°C (held 1 minute), then programmed to increase to 210°C at 10°C/min, then to 250°C at 10°C/min and to 300°C at 30°C/min. Figure S1).…”

“…Multivariate optimization is considered to be more efficient than univariate processes because it allows the evaluation of the influences of several parameters within a procedure simultaneously using a smaller number of experiments. 21 This division in groups was performed to analyze the different phases of metabolism and the kinetics of the formation of metabolites, as those belonging to group 1 were the precursors of the other SIB metabolites and those belonging group 2 are the inactive and more water-soluble metabolites, according to previous studies. 22 The optimization of the ZWT conditions was performed by employing a Response Surface Methodology based on a Doehlert matrix.…”

“…Multivariate optimization is considered to be more efficient than univariate processes because it allows the evaluation of the influences of several parameters within a procedure simultaneously using a smaller number of experiments 21. (Figure S1).…”