Development of a reference material for routine performance monitoring of methods measuring polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and dioxin-like polychlorinated biphenyls.

Matrix-matched environmental certified reference materials (CRMs) are one of the most useful tools to validate analytical methods, assess analytical laboratory performance and to assist in the resolution of data conflicts between laboratories. This paper describes the development of a lake sediment as a CRM for polychorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (DLPCBs). The presence of DLPCBs in the environment is of increased concern and analytical methods are being developed internationally for monitoring DLPCBs in the environment. This paper also reports the results of an international interlaboratory study involving thirty-five laboratories from seventeen countries, conducted to characterize and validate levels of a sediment reference material for PCDDs, PCDFs and DLPCBs.

Changes in the treatment of wheezing children in the emergency department.

This study prospectively examined the pharmacologic treatment of all wheezing children presenting to a pediatric emergency department from December 1987 to September 1991 (10,091 cases). There were increasing trends in rate of hospitalization, use of oxygen saturation measurements, use of corticosteroids and beta agents at discharge, and use of aerosolized bronchodilators administered in the emergency department. This cohort shows decreasing trends in use of theophylline and the use of subcutaneous bronchodilators administered in the emergency department. Increasing patient severity could not be confirmed in this cohort. The increase in use of corticosteroids in wheezing children is well supported in the literature. The use of theophylline appears to have significantly declined while there is still some controversy over its recommendations in the literature.

Oxygen saturation changes during the pediatric emergency department treatment of wheezing.

This study examined the oxygen saturation (OSAT) changes measured by pulse oximetry during emergency department (ED) bronchodilator treatment of wheezing patients. Data were collected prospectively on two cohorts (November 1987 to November 1988, 2,468 patients; and December 1988 to October 1990, 4,913 patients) presenting to a pediatric ED with wheezing-associated respiratory illnesses. Initial, posttreatment, and discharge OSAT was recorded in many of these patients. Improvement in OSAT following ED bronchodilator administration was noted in most patient groups. Initial OSAT was indicative of severity as measured by the need for hospitalization and the number of bronchodilator treatments administered in the ED. Subcutaneous epinephrine and aerosolized albuterol were compared in OSAT improvement and side effects. Aerosolized albuterol was not shown to be superior to epinephrine. Improvements in OSAT following bronchodilator administration documents the presence of relative preexisting hypoxemia which is reversed to some degree with bronchodilators. Pulse oximetry is an objective means of assessing asthma severity.

Dual-column high-performance liquid chromatographic cleanup procedure for the determination of polychlorinated dibenzo-p-dioxins and dibenzofurans in fish tissue.

A high-performance liquid chromatographic cleanup procedure employing normal-phase alumina and carbon--silica separations was developed for isolating polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) from other polychlorinated pollutants present in fish tissue. The method utilizes a column-switching step where the dioxins and furans are trace enriched onto a carbon-silica column as they are eluted from the alumina column. Interfering components such as polychlorinated biphenyls and chlorinated diphenyl ethers elute through the carbon--silica column. The PCDDs and PCDFs are subsequently recovered by backflushing the carbon--silica column using toluene.