Sample preparation improvement in polycyclic aromatic hydrocarbons determination in olive oils by gel permeation chromatography and liquid chromatography with fluorescence detection.

The determination of 15 polycyclic aromatic hydrocarbons (PAHs) in olive oil samples has been improved in order to obtain a fast methodology with a low limit of detection through the combination of liquid-liquid extraction with acetonitrile and preparative gel permeation chromatography (GPC) prior to the injection of purified extracts into a C18 column. Acetonitrile-water was used as the mobile phase with a gradient from 50 to 95%, w/w, acetonitrile in 30 min. The oven temperature was maintained at 15 degrees C, and fluorometric detection was made at a fixed excitation wavelength of 264 nm and variable, optimal emission wavelength for each analyte ranging from 352 nm for 11-H-benzo(b)fluorene to 500 nm for indeno(1,2,3-cd)pyrene. Recovery for all the compounds studied varied from 75 to 111%, and limit of detection values from 0.05 ng/g for benzo(k)fluoranthene to 0.48 ng/g for indeno(1,2,3-cd)pyrene, corresponding to 0.09 ng/g benzo(a)pyrene. Results were compared with those obtained by liquid-liquid extraction followed by a cleanup on silica and a direct GPC treatment of oil samples diluted in dichloromethane, 2 other methodologies that are appropriate for quantifying PAHs in olive oils. However, the proposed method improves the determination limits, reduces the time of analysis, and provides a highly stable baseline for sample chromatograms.

[An exploratory approach on teaching for prevention of medical error]. / Estudio exploratorio sobre la enseñanza de la comunicación humana asociado a la práctica médica.

INTRODUCTION: Medical error is prevalent in the contemporary practice of medicine. Prevention and solution of the majority of medical errors can be focused upon from the early stages of physician formation by improving knowledge and abilities with regard to human communication. Despite its importance, information systematized with empirical bases on the teaching of human communication in Mexico is non-existent. PURPOSE: Our purpose was to highlight the experience of an exploratory nature on the educative intervention on human communication in medicine in medical residents of different medical specialties. METHODS: A study of educational intervention was presented 216 medical residents of the National Institutes of Health in Mexico City on the topic of human communication in medical practice. Chi square distribution was employed to find associations among variables. RESULTS: Eighty percent of students presented deficiencies in knowledge and thinking abilities for clinical communication. As a result of the educational intervention, 70 percent of medical resident students reached acceptable significant learning on the topic. There were no appreciable differences between the men and women in response patterns. Data indicated necessity of incorporating this topic pre-and postgraduate studies, to achieve improvement of quality of medical care and prevention of conflicts in medicine.