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Archive for February, 2004

Ultra-Low Analysis of Pesticides and PCB Aroclors in Ground Water

Wednesday, February 4th, 2004

Ultra-Low-Analysis-of-Pesticides-and-PCB-Aroclors-in-Ground-WaterThe toxicity and environmental impact of organochlorine pesticides and polychlorinated biphenyls (PCBs) is well documented. Routine environmental analysis of these compounds has remained largely unchanged since the advent of EPA method 8081 and EPA method 8082. However, recent instrumental advances and implementation of ultra-trace extraction techniques have allowed for significant improvements in detection limits.

The CAS Kelso laboratory has developed procedures that produce detection limits low enough to meet the requirements of the majority of studies. The extraction and analysis procedures include modifications to increase sensitivity, but still meet the requirements of the traditional EPA SW846 methods. Samples are prepared according to EPA Method 3520C with modifications, including a 2L continuous liquid-liquid extractor. Special glassware handling techniques are incorporated to minimize potential background contamination.

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Measurement of Trace Level Mercury by EPA Method 1631

Wednesday, February 4th, 2004

Measurement-of-Trace-Leve--Mercury-by-EPA-Method-1631Mercury is responsible for over three-quarters of all contaminant-related advisories for threats to human health. During the 1990’s, the number of mercury related fish consumption advisories more than doubled, despite significant decreases in the total mercury emissions over the last 20 years. The increase in advisories is probably the result of more testing rather than more contamination.

While the contamination is showing up in lakes and fish, most mercury does not come from effluent, rather is derived from atmospheric deposition. Atmospheric transport and subsequent bioaccumulation of mercury can affect aquatic ecosystems far from mercury sources. According to EPA estimates, emissions from coal-fired utilities account for 13 to 26 percent of the total (natural plus anthropogenic) airborne emissions of mercury in the United States. Thus, the EPA has begun to regulate emissions from power plant boilers and process heaters.

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Sampling and Analysis of the Atmosphere Surrounding an Egyptian Mummy

Tuesday, February 3rd, 2004

The Department of Antiquities Conservation of the J. Paul Getty Museum recently requested assistance from CAS’ Simi Valley Air Quality Laboratory to sample and analyze the atmosphere surrounding a second century Egyptian mummy. About six years ago, the mummy was sealed in a case containing ambient air. The museum wished to determine the volatile and semivolatile organic compounds off-gassing from the mummy. One purpose of the study was to determine the impact of off-gassing on other artifacts that were to be displayed with it.

Compounds of interest included low molecular weight organic acids, volatile organic chemicals, and the semivolatile compound, guaiacol. Guaiacol is a component of cedar oil and one of the embalming fluids used by the Egyptians.The other chemicals were associated with previous restoration activities with the mummy.

In order to collect the samples, two holes were drilled in the case housing the mummy. Sampling ports consisting of Teflon tubing (1/4” OD) and a ferrule and female Swagelok fitting were installed in the holes. The ports were sealed off at the time of installation and only opened during sampling periods.

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