Microwave-assisted headspace controlled temperature liquid-phase microextraction of chlorophenols from aqueous samples for gas chromatography-electron capture detection.

A modified headspace liquid-phase microextraction (HS-LPME) method was studied for the extraction of chlorophenols (CPs) from aqueous samples with complicated matrices, before gas chromatographic (GC) analysis with electron capture detection (ECD). Microwave heating was applied to accelerate the evaporation of CPs into the headspace, and an external-cooling system was used to control the sampling temperature. Conditions influencing extraction efficiency, such as the LPME-solvent, the sampling position of LPME, the sampling temperature, microwave power, and irradiation time (the same as sampling time), sample pH, and salt addition were thoroughly optimized. Experimental results indicated that the extraction of CPs from a 10mL aquatic sample (pH 1.0) was achieved with the best efficiency through the use of 1-octanol as solvent, microwave irradiation of 167W, and sampling at 45 degrees C for 10min. The detections were linear in the concentration of 5.0-100microg/L for 2,4-dichlorophenol (2,4-DCP), and 0.5-10microg/L for 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP) and pentachlorophenol (PCP). Detection limits were found to be 0.7, 0.04, 0.07, and 0.08microg/L for 2,4-DCP, 2,4,6-TCP, 2,3,4,6-TeCP, and PCP, respectively. A landfill leachate sample was analyzed with recovery between 83 and 102%. The present method was proven to serve as a simple, sensitive, and rapid procedure for CP analysis in an aqueous sample.

Airflow obstruction and left ventricular filling pressure in suspected chronic obstructive pulmonary disease.

Left ventricular (LV) filling impairment is present in patients with chronic obstructive pulmonary disease (COPD). Airflow obstruction is related to reduced LV end-diastolic volume, stroke volume, and cardiac output. The ratio of peak early diastolic filling velocity of the mitral inflow to peak early diastolic velocity of the mitral annulus (E/e'), an echocardiographic parameter, can be applied as a surrogate marker of LV filling pressures. Forty-seven individuals with suspected COPD underwent pulmonary function tests and echocardiography. The ratio of forced expiratory volume in 1s to forced vital capacity (FEV1/FVC) and the E/e' ratio were determined. Multivariate linear regression analysis showed that the FEV1/FVC ratio (ß=0.01; 95% confidence interval, 0.001-0.019; p=0.036) independently predicted the log transformed E/e' ratio. An increase of FEV1/FVC ratio (in percentage) by 1 unit was associated with an increase of the E/e' ratio multiplied by 1.01. Airflow obstruction inversely predicts LV filling pressure in suspected COPD cases.