EQUIPMENT--Sample Splitting Devices In Reply Refer To: April 16, 1993 Mail Stop 412 OFFICE OF WATER QUALITY TECHNICAL MEMORANDUM 93.09 Subject: EQUIPMENT--Sample Splitting Devices Within the Water Resources Division (WRD), composited water samples traditionally have been subsampled for field and laboratory analyses by means of a churn splitter or, less frequently, a cone splitter. Historically, the splitting devices have been constructed of plastic, which has proved adequate for many water-quality parameters including field measurements, major ions, and nutrients. There are two concerns with using plastic devices for water samples that are to be analyzed for trace elements and semi- volatile trace organic chemicals (pesticides and base/neutral compounds). The first concern is contamination of the water sample by material inherent in the plastic. The second is analyte loss from the water sample due to sorption onto the plastic surfaces. To avoid these two potential problems, an all-Teflon cone splitter has been created, and plans are in progress for fabricating an all-Teflon churn splitter. The probability is that chemicals will have less of a tendency to sorb to a Teflon surface and, if cleaned properly before use, such containers should not contaminate water samples. However, experiments need to be run to test: (a) assumptions concerning contamination and analyte loss for all constituents, and (b) the splitting characteristics of the churn and cone splitters. Accordingly, the Office of Water Quality (OWQ) is beginning a series of studies aimed at evaluating the usefulness and limitations of splitting devices for water samples. Areas of investigation will include: 1. Contamination potential and proper cleaning procedures-- for both polyethylene and Teflon splitters--for the various splitting devices for a wide variety of analytes; 2. Potential for analyte loss for polyethylene and Teflon splitters; 3. Precision and accuracy of solids splitting; 4. Precision and accuracy of dissolved chemical splitting; 5. Reproducibility between different splitting devices; 6. Reproducibility between splitters of the exact same type; 7. Effects of different operators on the reproducibility of splitting. Paul Capel will coordinate the studies. Suggestions/concerns should be communicated to Paul by telephone (612/471/0438) or FAX (612/471/9070). The all-Teflon cone splitter has been used successfully within the WRD since 1991 for processing water samples for pesticides. A recent study (Attachment 1) evaluated the precision of the all- Teflon cone splitter for splitting water and solids over a range of particle sizes, sample volumes, and sample introduction techniques. The overall conclusion was that the all-Teflon cone splitter is comparable to the traditional plastic cone splitter. Results of the additional studies will be forthcoming from OWQ over the next several years. David A. Rickert Chief, Office of Water Quality Attachment This memorandum does not supersede any Office of Water Quality Technical Memorandum. Key Words: Equipment Distribution: A, B. S, FO, PO