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Little Extraction Detail, Big Impact on Performance – A Case Study
Oral Presentation
Prepared by S. Zeiner, R. Vitale, G. Yakub
Environmental Standards, Inc., 1140 Valley Forge Road, P.O. Box 810, Valley Forge, PA, 19460, United States
Contact Information: szeiner@envstd.com; 610-935-5577
ABSTRACT
There are a number of things to consider when submitting whole-volume, double-blind performance evaluation (PE) samples to commercial laboratories. During a long term project, the preparation and analysis of aqueous, whole-volume, double-blind PE samples for polyaromatic hydrocarbons (PAHs) yielded consistently poor recoveries for select PAHs at two separate commercial laboratory facilities, across multiple analytical events.
The investigation revealed that one laboratory was extracting the sample by separatory funnel and by continuous liquid/liquid procedures interchangeably. The other laboratory was only performing separatory funnel extraction. Each laboratory's Quality Assurance Officer investigated the issue, but the review of batch quality control, such as laboratory control samples and surrogate recoveries, did not identify any issues.
What aspect of the analysis would a PE sample test that the normal quality control elements do not? One overriding factor that was suspected by the authors and confirmed during interviews with the extraction personnel was related to inconsistent and ineffective sample bottle rinsing with the first aliquot of extraction solvent.
Specifically, what was suspected as the cause of the PE failures was quantitative transfer of the sample from the container to the extraction glassware. The standard operating procedure (SOP) for one laboratory described a brief rinse of the sample bottle with the first aliquot of extraction solvent and the other laboratory SOP was totally silent about rinsing the sample bottle. Confounding this bottle rinsing situation was the manner in which the PE provider described their manufacturing process for the whole volume PE samples.
This presentation will recount the authors’ investigation process including the PE manufacturing process, sample extraction process, and analytical determination, and the process correction needed which improved the performance for PAHs. On a separate, but related note, is a commentary on how manufactured whole-volume PE samples may not necessary reflect the behavior of real world environmental samples.
Oral Presentation
Prepared by S. Zeiner, R. Vitale, G. Yakub
Environmental Standards, Inc., 1140 Valley Forge Road, P.O. Box 810, Valley Forge, PA, 19460, United States
Contact Information: szeiner@envstd.com; 610-935-5577
ABSTRACT
There are a number of things to consider when submitting whole-volume, double-blind performance evaluation (PE) samples to commercial laboratories. During a long term project, the preparation and analysis of aqueous, whole-volume, double-blind PE samples for polyaromatic hydrocarbons (PAHs) yielded consistently poor recoveries for select PAHs at two separate commercial laboratory facilities, across multiple analytical events.
The investigation revealed that one laboratory was extracting the sample by separatory funnel and by continuous liquid/liquid procedures interchangeably. The other laboratory was only performing separatory funnel extraction. Each laboratory's Quality Assurance Officer investigated the issue, but the review of batch quality control, such as laboratory control samples and surrogate recoveries, did not identify any issues.
What aspect of the analysis would a PE sample test that the normal quality control elements do not? One overriding factor that was suspected by the authors and confirmed during interviews with the extraction personnel was related to inconsistent and ineffective sample bottle rinsing with the first aliquot of extraction solvent.
Specifically, what was suspected as the cause of the PE failures was quantitative transfer of the sample from the container to the extraction glassware. The standard operating procedure (SOP) for one laboratory described a brief rinse of the sample bottle with the first aliquot of extraction solvent and the other laboratory SOP was totally silent about rinsing the sample bottle. Confounding this bottle rinsing situation was the manner in which the PE provider described their manufacturing process for the whole volume PE samples.
This presentation will recount the authors’ investigation process including the PE manufacturing process, sample extraction process, and analytical determination, and the process correction needed which improved the performance for PAHs. On a separate, but related note, is a commentary on how manufactured whole-volume PE samples may not necessary reflect the behavior of real world environmental samples.