Detection of Cocaine in Seized Drug Samples by Capillary Electrophoresis Tandem Mass Spectrometry
A methodology using capillary electrophoresis with tandem mass spectrometry detection (CE-MS/MS) was developed, and applied to determine the cocaine content of seized drugs. The cocaine separation among other concomitants by capillary electrophoresis was achieved in just 4.0 minutes using 30 mM ammonium formate, pH 6.5, as a background electrolyte (BGE). The correlation coefficient of the calibration curve in the range of 0.02 to 1 μg/mL was upper 0.999, and the limits of detection (LOD) and limits of quantification (LOQ) were 0.003 μg/mL and 0.01 μg/mL, respectively. The relative standard deviation repeatability (intraday and interday) was less than 6.5% (peak area). The analysis of seized suspected illegal drugs revealed the presence of cocaine in 93% of samples (n = 11), in amounts ranging from 0.04 to 429 mg/g, showing a high variability of concentrations of cocaine. The user can change the provider and, due to the large variability of concentration, be lead to an accidental overdose.
A simple approach to compensate the suction caused by the electrospray ionization source in capillary electrophoresis‐mass spectrometry systems
ESI sources continuously consume the liquid at the tip of the capillary, which causes the dragging of the BGE. The laminar nature of this flow causes the broadening of the peaks and loss of separation efficiency. The usual solution for this problem is to compensate this phenomenon by reducing the pressure at the inlet vial by either leveling of this vial or pumping off the air that is over it. However, one must know the pressure to be applied in order to prevent under‐ or over‐compensation. The procedure herein introduced allows the easy calculation of this pressure by obtaining two electropherograms at two different values of separation voltage. The migration times of the peaks allow the calculation of the apparent mobilities even in the presence of the laminar flow. Therefore, one can calculate the contributions from both electrophoresis and hydrodynamic flow, and finally the pressure associated with the undesirable flow. This pressure is then applied as a negative pressure at the inlet vial in the following experiments. Increase of up to 192% in the number of plates was obtained in a simple experiment. In addition, the bubble forming caused by the ESI suction during injection was prevented by turning off the nebulizer gas during the changes of inlet vials.
Genetics of the phenotypic evolution in sheep: a molecular look at diversity-driving genes
Background After domestication, the evolution of phenotypically-varied sheep breeds has generated rich biodiversity. This wide phenotypic variation arises as a result of hidden genomic changes that range from a single nucleotide to several thousands of nucleotides. Thus, it is of interest and significance to reveal and understand the genomic changes underlying the phenotypic variation of sheep breeds in order to drive selection towards economically important traits. Review Various traits contribute to the emergence of variation in sheep phenotypic characteristics, including coat color, horns, tail, wool, ears, udder, vertebrae, among others. The genes that determine most of these phenotypic traits have been investigated, which has generated knowledge regarding the genetic determinism of several agriculturally-relevant traits in sheep. In this review, we discuss the genomic knowledge that has emerged in the past few decades regarding the phenotypic traits in sheep, and our ultimate aim is to encourage its practical application in sheep breeding. In addition, in order to expand the current understanding of the sheep genome, we shed light on research gaps that require further investigation. Conclusions Although significant research efforts have been conducted in the past few decades, several aspects of the sheep genome remain unexplored. For the full utilization of the current knowledge of the sheep genome, a wide practical application is still required in order to boost sheep productive performance and contribute to the generation of improved sheep breeds. The accumulated knowledge on the sheep genome will help advance and strengthen sheep breeding programs to face future challenges in the sector, such as climate change, global human population growth, and the increasing demand for products of animal origin.