Implementing a superhydrophobic substrate in immersed solvent-supported microextraction as a novel strategy for determination of organic pollutants in water samples.

In this research, a new approach for extraction and determination of polycyclic aromatic hydrocarbons from sea and rain water samples was developed by implementing a superhydrophobic substrate and consuming the least amount of solvent. This version of solvent-supported microextraction enabled us to perform the procedure in the immersion mode with the slightest troubles arising from water leakage into the gas chromatography. The superhydrophobic property leads to the fixation of extracting solvent on the substrate surface during water sampling. To prepare a superhydrophobic substrate, a piece of melamine foam was coated by tannic acid and silica nanoparticles using methyltrimethoxysilane and tetramethyl orthosilicate. The morphology of the prepared foams was studied by scanning electron microscopy. The developed solvent-supported microextraction method in combination with gas chromatography-mass spectrometry was applied to the isolation and determination of some typical polycyclic aromatic hydrocarbons from aquatic media. Influential parameters such as substrate nature, extractive solvent, eluting solvent and its quantity and extraction time were investigated. The limits of detection and quantification of the method under the optimized conditions were 0.01-0.11 µg L-1 and 0.03-1.01 µg L-1, respectively. The relative standard deviations at the concentration level of 20 µg L-1 were between 3% and 14% (n = 3). The linearity of calibration curves ranged from 0.03 to 60 µg L-1. The implementation of the solvent-supported method to the analysis of real water samples was quite successful and the relative recoveries were between 88% and 107%.

Persistent isolated right atrial standstill associated with left atrial tachycardia.

INTRODUCTION: Atrial standstill is a rare condition, characterized by absence of atrial electrical and mechanical activity evident in surface electrocardiography echocardiography, or fluoroscopy, which is associated with unresponsiveness of atria to maximal output electrical stimulation. This condition can be present with thromboembolic complication, low cardiac output, and sometimes palpitation. CASE PRESENTATION: Here we presented a woman with right atrial stand still and left atrial tachycardia. It was confirmed by electrocardiogram, echocardiography, and intracardiac electrogram in basal state and during maximal output electrical stimulation. We treated her by implanting pacemaker to control bradycardia, oral calcium channel blocker to control palpitation episodes, and anticoagulation. CONCLUSIONS: Atrial standstill can be present partially that can be localized in one atrium and is associated with tachycardia in the other atrium.