Protocols for Cleaning a Teflon Cone Splitter to Produce Contaminant-Free Subsamples for Subsequent Determinations of Trace Elements In Reply Refer To: February 7, 1997 Mail Stop 412 OFFICE OF WATER QUALITY TECHNICAL MEMORANDUM 97.03 Subject: Protocols for Cleaning a Teflon Cone Splitter to Produce Contaminant-Free Subsamples for Subsequent Determinations of Trace Elements SYNOPSIS This memorandum describes laboratory and field protocols for cleaning a Teflon cone splitter to collect a contaminant-free subsample for subsequent determination of trace elements. Also described is the testing that was done to determine if these protocols allow production of contaminant-free (at the microgram-per-liter level) trace-element data from filtered surface-water samples. The laboratory-cleaning ("laboratory") protocol is adapted from methods developed and tested by the Office of Water Quality (OWQ) and the National Water Quality Assessment (NAWQA) Program. The field-cleaning ("field") protocol is supported by data from tests performed by the Upper Colorado River Basin Study Unit (UCOL) of the NAWQA. Results of tests for the field protocol, and an evaluation of information available for the laboratory protocol, show that these protocols can be used to clean a Teflon cone splitter to produce contaminant-free subsamples for analysis of trace elements. These protocols do not address the use of methanol and the additional cleaning steps that may be required when splitting samples to be analyzed for organic constituents. Because the possibility of unpredictable and erratic contamination always exists, adequate quality-control measures are required (Horowitz and others, 1994). BACKGROUND The Water Resources Division Instrument Committee (ICOM) funded a series of tests to develop nationally consistent guidelines for selecting, cleaning, and using the cone splitter and the U.S. Geological Survey (USGS) churn splitter. One component of these tests focuses on cleaning a Teflon cone splitter to produce contaminant-free subsamples for subsequent analysis of trace elements. To this end, the Office of Water Quality, in cooperation with the NAWQA, developed two protocols: a laboratory-cleaning protocol adapted from a procedure described by Shelton (1994, p.13) and Horowitz and others (1994, pp. 41-44) and a field-cleaning protocol based on a procedure for cleaning a USGS churn splitter described by Horowitz and others (1994, pp. 52-56). The efficacy of the laboratory protocol is supported by unpublished data collected under the NAWQA program. The field protocol was tested by the NAWQA UCOL under the guidance of Bob Boulger (Grand Junction, Colorado) at six surface-water sites affected by acid-mine drainage. Principal differences between the laboratory and field protocols are: 1. The laboratory protocol entails complete disassembly of the cone splitter, whereas the field protocol does not require complete disassembly except after obtaining subsamples of water that is very turbid or is suspected of being highly contaminated. If that condition exists, the laboratory protocol is required. 2. The laboratory protocol includes a detergent soak-and-scrubbing step, whereas no detergent is used to clean the cone splitter in the field protocol. 3. The laboratory protocol includes a 30-minute acid soak, whereas a single acid rinse is used in the field protocol. PROTOCOLS FOR CLEANING A TEFLON CONE SPLITTER FOR TRACE ELEMENTS A. LABORATORY CLEANING PROTOCOL The laboratory cleaning is required for new or previously used equipment. It may be done in a laboratory or another suitable location, such as a motel room. This procedure also should be followed when the splitter has been used at a site with known or suspected high concentrations of trace elements. (NOTE: this procedure can only be done outside of the laboratory if the 5-percent hydrochloric acid (HCl) used is initially prepared in a laboratory): 1. Fully disassemble the cone splitter, carefully safeguarding all of the small parts. 2. Soak the splitter parts and Teflon tubing for 30 minutes in a 2-percent or less solution of phosphate-free detergent. The amount of detergent used depends on the hardness of the tap water. Wearing disposable gloves, scrub with a nonmetallic brush. A metal-free swab such as those designed for cleaning video cassette recorders can be used to clean the small splitter parts. 3. Change gloves and rinse thoroughly with warm tap water to remove all soap residue. 4. Soak non-metal parts for 30 minutes in a 5-percent, by volume, solution of HCl. Carefully swirl the acid solution several times during the 30-minutes soak to enhance desorption of trace elements not removed during the detergent washing process. The used acid/water solution should be placed in a neutralization container for proper disposal (Horowitz and others, 1994, p. 12). 5. Change gloves and rinse three times with 1-liter aliquots of deionized water. Reassemble the cone splitter. NOTE: This cleaning protocol is approved only for trace-element samples. If organic samples are collected, a methanol rinse is needed (see Shelton, 1994). 6. Place the cone splitter in a new plastic bag and seal; store in a plastic storage container or a second plastic bag for transport. Validation of Laboratory Protocol: The laboratory protocol, adapted from a procedure developed by the OWQ and the NAWQA (Shelton, 1994, p. 13), is supported by data collected operationally by the NAWQA. Although very little data was collected to validate the laboratory protocol, its efficacy can be inferred from that fact that its requirements (disassembly, detergent rinse, and a 30-minute acid soak) are more stringent than those for the field cleaning protocol, which provided acceptable results. In combination, this information has led to the laboratory protocol's Division-wide acceptance. B. FIELD CLEANING PROTOCOL The field-cleaning protocol is used if the splitter is to be used at another site during the same sampling trip. (The laboratory protocol is required if the splitter has been allowed to dry before being cleaned or if the splitter was used at a site with known or suspected high concentrations of trace elements.) After processing an environmental sample and before leaving a field site, clean the Teflon cone splitter as follows: 1. Inspect the cone splitter. If it appears dirty, is suspected of being contaminated, or has been allowed to dry, then it should be fully disassembled and cleaned using the laboratory cleaning protocol described above. Otherwise, proceed as outlined below. 2. Discard any used plastic bags from storing cone splitter. 3. Rinse the splitter thoroughly with deionized water. 4. Wearing disposable gloves, rinse by passing one liter of 5-percent by volume HCL through the cone splitter. The used acid/water solution should be placed in a neutralization container for proper disposal (Horowitz and others, 1994, p. 12). NOTE: This cleaning protocol is approved only for trace-element samples. If organic samples are collected, a methanol rinse is needed (see Shelton, 1994). 5. Change gloves and rinse the cone splitter with at least three 1-liter aliquots of deionized water. 6. Pack the cone splitter in a new plastic bag and seal; store in a plastic storage container or a second plastic bag for transport to the next site. Field Protocol Test Procedure: Two Teflon cone splitters of standard design manufactured by Geotech Environmental Equipment, Inc., were used in the tests. Although Teflon screens in the cylindrical reservoir normally are used to prevent larger detritus from passing through the cone splitter and into subsamples, no screens were available for use in these tests. The tests were performed with the cone splitter enclosed in a plastic bag chamber to minimize the potential for introducing air-borne contaminants. At each of six sites during a regularly scheduled field trip, environmental samples of water affected by acid mine drainage were processed through the cone splitter. After the environmental sample was processed at the first site, the wet cone splitter was placed in double plastic bags, returned to a motel room, cleaned using the laboratory protocol, and reassembled, placed in a clean set of plastic bags, and transported to the second site. At the second, and each of four subsequent sites, an environmental sample was processed through the cone splitter and the splitter was cleaned using the field protocol. After each field cleaning, field-blank subsamples were obtained, and the splitter was placed in clean, double plastic bags and then in the field vehicle for transport to the next site. Blank samples were analyzed for trace elements and other ions (schedule 172) at the National Water-Quality Laboratory (NWQL). Environmental samples were analyzed at the NWQL using NAWQA schedule 2703. The constituents analyzed were aluminum, antimony, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, silver, uranium, and zinc (table 1). Detailed information on the test procedure and results can be found in Bob Boulger's unpublished report, "Test of Field Cleaning of Teflon Cone Splitter for Trace metals Sample Processing." Instructions for obtaining an electronic copy of this document are provided at the end of this memorandum. Validation of Field Protocol: Table 1 shows analytical results from blank and environmental samples collected by the UCOL at six sites in October 1995. Of the five trace elements detected in the field blanks, only two -- copper and zinc -- were detected in blanks obtained after cleaning equipment at each of two or more sites. Detectable trace-element concentrations in the blanks were less than about twice the environmental-sample (schedule 2703) method detection limit. In two cases, zinc was detected in field blanks (0.7 & 0.6 micrograms/liter) taken after cleaning a cone splitter exposed to a high environmental concentration (3,100 & 1,400 micrograms/Liter, respectively). Also, the iron concentration in one field blank (6 micrograms/Liter) was found to exceed that of the environmental sample (4 micrograms/Liter). The type, frequency, and low concentrations detected in blank samples were considered typical of random detections characteristic of such quality-control testing. Furthermore, when cross-contamination does occur, it is insignificant with respect to the associated concentrations in the previously processed environmental sample, and (or) is random in nature. Overall, the results support the conclusion that the field protocol can be used to clean a Teflon cone splitter sufficiently to minimize cross-contamination of trace-element samples. EQUIPMENT AND FIELD BLANKS Equipment and field blanks should be processed in accordance with the procedures described in Horowitz and others (1994) and Shelton (1994). Equipment blanks are to be processed at least once a year for each set of sampling equipment. The number of field blanks required depends on individual project's data-quality objectives. CONCLUSIONS The tests described in this memo show that Teflon cone splitter can be cleaned sufficiently using the previously described protocols to produce contaminant-free subsamples for subsequent analysis of trace elements. These protocols do not address the additional cleaning steps that are required when splitting samples to be analyzed for organic constituents. Because the possibility of unpredictable, erratic contamination always exists, adequate quality-control measures are required (Horowitz and others, 1994). REFERENCES Horowitz, A.J., Demas, C.R., Fitzgerald, K.K., Miller, T.L., and Rickert, D.R., 1994, U.S. Geological Survey protocol of the collection and processing of surface-water samples for the subsequent determination of inorganic constituents in filtered water: Open-File Report 94-539, 57 p. Shelton, L.R., 1994, Field guide for collecting and processing stream-water samples of the National Water Quality Assessment Program: Open-File Report 94-455, 42 p. INSTRUCTIONS FOR OBTAINING FIELD PROTOCOL TEST INFORMATION Bob Boulger's unpublished report, "Test of Field Cleaning of Teflon Cone Splitter for Trace metals Sample Processing." Instructions for obtaining an electronic copy of this document in FrameMaker4 format via the file transfer protocol follow: type: ftp 136.177.10.10 at login prompt, type: anonymous at id prompt, type: anonymous type: cd pub/conesplitter/ type: binary type: get tcs.experiment.report/ David A. Rickert /S/ Chief, Office of Water Quality Attachment This memorandum does not supercede any existing memoranda. Distribution: A, B, S, FO, PO District Water-Quality Specialists Regional Water-Quality Specialists NR, SR, CR, WR Attachment ---------- Constituent concentrations in environmental1 and blank subsamples from a Teflon cone splitter for six surface-water sites, October 1995. -------------------------------------------------------------------------------------------------------------------------------------------- | Constituent Concentrations -------------------------------------------------------------------------------------------------------------------------------------------- | | Site 1 | Site 2 | Site 3 | Site 4 | Site 5 | Site 6 | -------------------------------------------------------------------------------------------------------------------------------------------- | Constituent| Method | Envirom | Equip- | Envirom | Field | Envirom | Field | Envirom | Field | Environ | Field | Envirom | Field | | in ug/L | Detection| ental | ment | ental | Blank | ental | Blank | ental | Blank | mental | Blank | ental | Blank | | | Level | Sample | Blank2 | Sample | | Sample | | Sample | | Sample | | Sample | | -------------------------------------------------------------------------------------------------------------------------------------------- -------------------------------------------------------------------------------------------------------------------------------------------- | Aluminum | 0.3 | 4 | <0.3 | 21,0003 | <0.3 | 600 | <0.3 | 30 | 0.4 | 10 | <0.3 | 5.0 | <0.3 | -------------------------------------------------------------------------------------------------------------------------------------------- | Antimony | 0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | -------------------------------------------------------------------------------------------------------------------------------------------- | Barium | 0.2 | 443 | <0.2 | 19 | <0.2 | 43 | <0.2 | 43 | <0.2 | 24 | <0.2 | 39 | <0.2 | -------------------------------------------------------------------------------------------------------------------------------------------- | Beryllium | 0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | -------------------------------------------------------------------------------------------------------------------------------------------- | Cadmium | 0.3 | <1 | <0.3 | 5 | <0.3 | 2 | <0.3 | <1 | <0.3 | 73 | <0.3 | 4 | <0.3 | -------------------------------------------------------------------------------------------------------------------------------------------- | Chromium | 0.2 | <1 | <0.02 | 43 | <0.02 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | <1 | 0.3 | -------------------------------------------------------------------------------------------------------------------------------------------- | Cobalt | 0.2 | <1 | <0.2 | 3603 | <0.2 | 11 | <0.2 | 7 | <0.2 | <1 | <0.2 | <1 | <0.2 | -------------------------------------------------------------------------------------------------------------------------------------------- | Copper | 0.2 | 2 | <0.2 | 8703 | 0.2 | 170 | <0.2 | 5 | <0.2 | 1 | 0.4 | <1 | 0.3 | -------------------------------------------------------------------------------------------------------------------------------------------- | Iron | 3.0 | <3 | <3 | 12,0003 | <3 | 190 | <3 | 4 | 6 | 13 | <3 | 8 | <3 | -------------------------------------------------------------------------------------------------------------------------------------------- | Lead | 0.3 | <1 | <0.3 | 393 | <0.3 | 1 | <0.3 | <1 | <0.3 | 7 | <0.3 | 2 | <0.3 | -------------------------------------------------------------------------------------------------------------------------------------------- | Manganese | 0.1 | 36 | <0.1 | 1,7003 | <0.1 | 480 | <0.1 | 370 | <0.1 | 26 | <0.1 | 15 | <0.1 | -------------------------------------------------------------------------------------------------------------------------------------------- | Molybdenum | 0.2 | 43 | <0.2 | <1 | <0.2 | <1 | <0.2 | 2 | <0.2 | <1 | <0.2 | <1 | <0.2 | -------------------------------------------------------------------------------------------------------------------------------------------- | Nickel | 0.5 | 2 | <0.5 | 293 | <0.5 | 10 | <0.5 | 8 | <0.5 | 2 | <0.5 | 1 | <0.5 | -------------------------------------------------------------------------------------------------------------------------------------------- | Silver | 0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | -------------------------------------------------------------------------------------------------------------------------------------------- | Uranium | 0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | <1 | <0.2 | -------------------------------------------------------------------------------------------------------------------------------------------- | Zinc | 0.5 | 170 | <0.5 | 1,300 | <0.5 | 430 | <0.5 | 120 | <0.5 | 3,1003 | 0.7 | 1,400 | 0.6 | -------------------------------------------------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------------------------------------- | 1Minimum reporting level for all environmental samples is 1.0 micrograms/Liter. | | | | 2The acid-rinse cleaning step for the equipment blank was preceded by soaking a disassembled cone splitter in phosphate-free | | detergent for 30 minutes, followed by 3 DIW rinses before reassembly. | | | | 3Maximum constituent concentration in the six environmental sample. | 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