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Posts Tagged ‘Method Detection Limits’

Polycyclic Aromatic Hydrocarbons (PAH) in Shellfish

Friday, May 28th, 2010

Polycyclic Aromatic Hydrocarbons (PAH) in Shellfish


Columbia Analytical Services, Inc. has extensive experience testing for low levels of Polycyclic Aromatic Hydrocarbons (PAH) in shellfish. Sensitive and selective techniques were developed over ten years ago and have been refined and improved on a continuing basis. In addition to the analysis for the common parent compounds, levels of the associated alkylated homologs can also be determined.

This analysis is typically performed using Gas Chromatography/Mass Spectrometry (GC/MS) operated in the Selective Ion Monitoring (SIM) mode. Key to the analytical procedure is proper sample preparation, which begins with shucking, compositing (as appropriate to the project plan), and homogenization via mechanical mixing. The preliminary preparation must be performed under clean laboratory conditions to prevent common PAH contamination. Decontamination of sample preparation equipment is performed and monitored closely to assure clean conditions. The sample homogenate is a homogenous slurry when prepared correctly. The homogenization techniques performed by Columbia Analytical have been inspected and approved by various organizations (e.g. US EPA, other federal government and state regulatory agencies, private industries, consultants, etc.) The data results for these projects were subjected to thorough government, public and private scrutiny.

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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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