Quantitative detection of trichloroacetic acid in human urine using isotope dilution high-performance liquid chromatography-electrospray ionization tandem mass spectrometry.
The chemical disinfection of drinking water to control microbial contaminants results in the formation of disinfection byproducts (DBPs). The volatile trihalomethanes and the nonvolatile haloacetic acids (HAAs) are the most prevalent DBPs. It is important to monitor human exposure to HAAs because of their potential adversehealth effects, such as cancer. Among the HAAs, urinary trichloroacetic acid (TCAA) is a potential valid biomarker for assessing chronic ingestion exposure to HAAs from drinking water. We have developed a rugged, high-throughput, sensitive, accurate, and precise assay for the measurement of trace levels of TCAA in human urine using a simple solid-phase extraction (SPE) cleanup followed by isotope dilution high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). TCAA is extracted from the urine using SPE, separated from other extract components by reversed-phase HPLC, and analyzed by negative ion electrospray ionization-isotope dilution-MS/MS using a multiple reaction monitoring experiment. The method is simple and fast and is not labor intensive (sample preparation and analysis can be performed in approximately 15 min) with a limit of detection of 0.5 ng/mL in 1 mL of urine.
A single automated instrument for monitoring total trihalomethane and total haloacetic acid concentrations in near real-time.
A single instrument is presented for selectively measuring the concentrations of total trihalomethanes (THM4) and total haloacetic acids (HAA9) directly from drinking water distribution systems. The method is based on the fluorescence reaction of THM4 or HAA5 species with nicotinamide. The method detection limit (MDL) for THM4 was 2.5 microg L(-1) with mean % recovery of 108% and % relative standard deviation (% R.S.D.) of 4%. For HAA5, the MDL was 3.3 microg L(-1) with mean % recovery and % R.S.D. of 102% and 3.5%, respectively. Side-by-side comparisons to United States Environmental Protection Agency methods (Methods 502.2 and 552.3) in chlorinated and chloraminated distribution systems exhibited reproducible biases that ranged from approximately 0.2 to 5 microg L(-1) for THM4 and from approximately -0.7 to -27 microg L(-1) for HAA5. The device provides for automated on-line sampling and analysis of THM4 and HAA9 with hourly sample analysis rates and is effectively a real-time system for drinking water monitoring.
Bodies Politic : Disease , Death and Doctors in Britain , 1650-1900
In spite of its intellectual, literary and comic brilliance, this book contains a dark and disturbing, but revealing, message. In some ways, my melancholy reading of Bodies Politic has inevitably been shaped by Roy's recent untimely death. Roy Porter was without doubt the finest social historian of medicine this country, or indeed the world, has produced. Expansive, humorous, intelligent, and incisive, his broad range of historical works has excited and educated several generations of students of history over the past thirty years. His death leaves an unfillable void within the global history of medicine. At the same time, however, this book itself, completed well before his death, is haunted by elements of despair and uncertainty that should make us carefully reconsider not only the purpose and direction of our professional inquiries but also our own mortality.