WATER QUALITY--Collecting Water Samples for Stable Isotope Analysis 

In Reply Refer To:                         October 27, 1981
EGS-Mail Stop 412



QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM NO. 82.01

Subject: WATER QUALITY--Collecting Water Samples for Stable 
                        Isotope Analysis

The attached instructions describe approved methods for the 
collection of water samples for analysis of the stable 
isotopes of hydrogen, oxygen, and carbon.

These instructions will be incorporated into a forthcoming 
TWRI on sampling methods.



                             R. J. Pickering 
                             Chief, Quality of Water Branch

Attachment 

WRD Distribution: A, B, S, FO, PO 

Key Words: water quality, sampling, stable isotope analysis 

This memorandum does not supersede any previous memorandum.











     Collection of Water Samples for Stable Hydrogen and
                   Oxygen Isotope Analysis

1. Application

   This method may be used to collect water samples for 
analysis of the ratios of hydrogen and oxygen isotopes. 

2. Interferences

   2.1 Samples containing extremely high sulfur 
concentrations produce S02 which interfers with the analysis 
unless special precautions are taken. Notify the Analytical 
Services Coordinator of samples with high sulfate 
concentrations.

   2.2 Organic carbon in samples with high organic contents 
may exchange with the carbon in the C02 used for sample 
equilibration, resulting in poor analyses. 

3. Apparatus

   3.1. Standard, approved sample collection devices are 
satisfactory for this procedure.

   3.2. Sample bottle, 2-ounce, glass with Polyseal cap (cap 
with plastic conical insert). van Waters and Rogers 
Scientific No. 16151-049 bottle; Van Waters and Rogers 
Scientific No. 16217-045 cap; or equivalent. 

4. Reagents

Mercuric chloride tablet containing 10 mg HgCl2 in a NaCl 
base. 

Procedures have been updated since this memorandum was issued;
See http://isotopes.usgs.gov/lab/instructions.html9
Use of mercury is no longer recommended.
5. Procedure 5.1. Collect sample by approved method (Guy and Norman, 1970; Wood, 1976). 5.2. A filtered sample is preferred but is not required. 5.3. Rinse the sample bottle and fill with sample to the shoulder leaving an air space. 5.4. Add 1 HgC12 tablet. 5.5. Cap tightly and ship. References Guy, H. P., and Norman, V. W., 1970, Field methods for measurement of fluvial sediment, Techniques of Water- Resources Investigations of the United States Geological Survey, Book 3, Chapter C2, p. 59. Wood, W. W., 1976, Guidelines for collection and field analysis of ground-water samples for selected unstable constituents, Techniques of Water-Resources Investigations of the United States Geological Survey, Book 1, Chapter D2, p. 24. Collection of Water Samples for Stable Carbon Isotope Analysis 1. Application 1.1. This method may be used to collect water samples for analysis of the ratios of the stable carbon isotopes. 1.2. Water may contain a number of dissolved inorganic carbon species including bicarbonate, carbonate, carbonic acid, carbon dioxide, and others. The analysis provides the stable isotopic composition of the sum of tnese species. 2. Interferences Sulfate concentrations exceeding 500 mg/L may interfere necessitating a correction to the data (A. Hassan, 1981, Northeastern Region, written communication). 3. Apparatus 3.1. Standard, approved sample collection devices are satisfactory for this procedure. 3.2. Sample bottle, 1 liter, glass with polyseal cap (cap with plastic conical insert). Van Waters and Rogers Scientific No. 16151-129 bottle; Van Waters and Rogers Scientifc No. 16217-125 cap, or equivalent. Teflon-coated screw caps provide a better seal and may be preferable in many cases. 3.3. Plastic syringe, 50-mL capacity, Van Waters and Rogers Scientific No. BD5663 or equivalent. Attach 15 cm of Tygon tubing to tip. 4. Reagents Ammoniacal strontium chloride hexahydrate solution: dissolve 1 pound (453 g) of reagent grade SrC12.6H20 in 4 pounds (1812 g) concentrated reagent grade NH40H. Allow the solution to remain undisturbed for 2 days. Decant the clear solution into glass field reagent bottles and seal tightly. Solution is stable for several years as long as it is tightly sealed to prevent contamination with atmospheric C02. 5. Procedure 5.1. Collect sample by approved method (Guy and Norman, 1970, Wood, 1976). 5.2A. Filter surface water samples containing carbonate sediments. 5.2B. Do not filter ground water samples . 5.3. Rinse a clean sample bottle with water to be sampled. 5.4. Fill sample bottle to about 90 percent of capacity with sample. 5.5. Rinse syringe and Tygon hose with about 10 mL of ammoniacal strontium chloride solution and discard rinse. 5.6. Add 50 mL of ammoniacal strontium chloride reagent (see NOTE 1), cap bottle tightly, wrap cap with plastic electrical tape to prevent loosening, and ship. NOTE 1. If the water contains over 600 mg/L alkalinity, 250 mL of sample and 15 mL ammoniacal strontium chloride is sufficient and preferable. References Guy, H. P., and Norman, V. W., 1970, Field methods for measurement of fluvial sediment, Techniques of Water- Resources Investigations of the United States Geological Survey, Book 3, Chapter C2, p. 59. Wood, W. W., 1976, Guidelines for collectin and field analysis of ground-water samples for selected unstable constituents, Techniques of Water-Resources Investigation of the United States Geological Survey, Book 1, Chapter D2, p. 24.