Identification of ethylsuccinylcarnitine present in some human urines.

Ethylsuccinylcarnitine, a previously undescribed acylcarnitine, was identified in urines obtained from 81% of adult volunteers. Its chemical structure was obtained by 1H nuclear magnetic resonance spectroscopy of the urinary purified compound and confirmed by its chemical synthesis. Its urinary excretion followed a circadian rhythm with a maximum occurring between 8 p.

Multiresidue determination of pesticides in drinking and related waters by solid-phase extraction and liquid chromatography with ultraviolet detection: interlaboratory study.

As part of a project funded by the European Commission (EC) for the development and evaluation of multiresidue methods for analysis of drinking and related waters, 17 European laboratories evaluated a method using styrene-divinylbenzene copolymer solid-phase extraction followed by liquid chromatography with diode array detection. The main aim of the study was to evaluate whether the method meets the requirements of EC Drinking Water Directive 98/83 in terms of accuracy, precision, and detection limit for 21 pesticides according to the following requirements: limit of detection, < or =0.025 microg/L; accuracy expressed as recovery, between 75 and 125%; and precision expressed as repeatability relative standard deviation of the method, <12.