EQUIPMENT AND SUPPLIES: Sample Splitter for Water-Sediment Samples

                                             December 13, 1976

QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM NO. 77.01

Subject: EQUIPMENT AND SUPPLIES: Sample Splitter for Water-
         Sediment Samples

Recently, new USGS Churn Splitters were distributed to WRD 
field offices on the basis of one splitter to each office 
that operates NASQAN stations. Unfortunately, we 
underestimated the count and were about six short; the 
shorted offices will be supplied as soon as more splitters 
are received. Districts requiring additional splitters should 
contact the Branch.

INSTRUCTIONS FOR USE OF SPLITTERS

A set of "Procedures" was included with each splitter. These 
are the same instructions that were distributed to all field 
offices with QW Branch Memo 76.24-T on August 16, 1976. Also, 
please see QW Branch Memo 76.17 (May 12, 1976) for general 
instructions on sampling mixtures of water and suspended 
sediment. The QW Branch can provide additional copies of both 
memos if they are needed.

CLEANING

The Churn Splitter should be washed with a quality laboratory 
detergent and thoroughly rinsed with tap water followed by 
distilled water prior to taking it into the field. In 
addition, churns used for the splitting of trace metal 
samples should be acid washed--let soak for four hours in a 
5% solution of hydrochloric acid, then rinse with tap water 
and distilled water. Cleaning between station visits can be 
accomplished by rinsing with distilled water after sampling. 
Then, rinse with sample water before use.

WHEN TO USE CHURN SPLITTERS

Use of the Churn Splitter is not limited to samples collected 
at NASQAN sites.  All samples to be used for analysis of 
"total" constituents are to be collected from multiple 
verticals to ensure representativeness of the flow in the 
cross section (QW Branch Memo 76.17). Also, samples for 
'dissolved" analyses should be collected by the same means 
unless cross sectional uniformity is documented (QW 
Branch Memo 76.17, p. 4). The Churn Splitter is designed 
and tested especially for use in streams transporting sand-size 
sediments.  Other compositing containers such as jugs can be used 
satisfactorily for waters containing only fine materials; however, 
it is recommended that only the Churn Splitters be used because 
they can be cleaned much more easily than can jugs or other 
similarly shaped containers.  Samples may be taken from the Churn 
Splitter for analysis of all dissolved and suspended inorganic 
constituents, including trace metals, and phytoplankton analysis.

EXCEPTIONS

A statement on pages 4 and 5 of QW Branch Memo 76.17 deals 
with the choice of container materials. The following 
point is emphasized in the instructions for use of the 
Churn Splitter. THE CHURN SPLITTERS ARE MADE OF PLASTIC, AND 
THEREFORE, SHOULD NOT BE USED IN COMPOSITING SAMPLES FOR ANALYSES 
OF ORGANIC SUBSTANCES.  Bacteria samples are not to be taken from 
the Churn Splitter because it cannot be sterilized 
adequately.

SUMMARY

The new USGS Churn Splitter, designed and carefully tested for 
use in the field, is particularly well suited for splitting 
large composite samples of water-sediment mixture into 
subsamples of any desired volume. We believe that they are 
the best splitters available for these mixtures, and they are 
the only acceptable means of splitting samples containing 
sand-size materials in the field. The Jones Ore Splitter is 
still the most accurate, of course, for use in the laboratory 
to split a sample or subsample into equal volumes.



                           R. J. Pickering
                           Chief, Quality of Water Branch

WRD Distribution: A, B, F0, PO