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.


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|                                                                          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     |
--------------------------------------------------------------------------------------------------------------------------------------------



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| 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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