Skip to main content
U.S. flag

An official website of the United States government

Instructions for Collecting RSIL Samples

Information about collecting samples for analysis by the Reston Stable Isotope Laboratory (RSIL).

Follow the sample collection instructions below for RSIL analysis. For pricing information, please take note of the lab code.

 

Lab Code:
600
Description: 
  • Low-level tritium (hydrogen-3) in water by helium-3 ingrowth (0.1 TU)
Bottle: Clean 500-mL HDPE plastic bottle. Collect in duplicate.
Treatment, Preservation, and Sample Amount: 
Collect in duplicate. We recommend HDPE plastic bottles to reduce the possibility of breakage in transit and to prevent evaporative losses.

 

Lab Code:
610
620

Description: 

  • Helium-3/helium-4 (δ3He) in helium dissolved in water (lab code 610)
  • Noble gas suite (helium, neon, argon, krypton, and xenon) dissolved in water (lab code 620)
Bottle:
Samples are collected in 15-inch long 3/8" copper tube and holder, and closed with two clamps via two 1/2" nuts available from the RSIL.
Treatment, Preservation, and Sample Amount: 
The copper tube can normally be flushed and filled within 5 minutes at a flow rate of 500 mL per minute. Take care not to scratch or bend or otherwise damage the ends of the copper tube. Damage to the ends of the copper tube may prevent proper attachment of the sample tube to the vacuum extraction line for sample preparation at the laboratory. The copper tube, which is fixed in an aluminum channel holding the stainless steel clamps, is connected to a closed path from the sample pump. The connection to the pump can be of almost any material, including plastic, rubber, Teflon, or metal tubing, providing that all connections are airtight and will not come loose when back pressure is applied during closing of the clamps. Clear plastic tubing (Tygon) is preferred because one can visually observe whether air bubbles are present in the water line. It is recommended that connections be secured with stainless steel hose clamps, again being careful not to damage the ends of the copper tube. The length of connection tubing from the pump reel or other connection point should be kept short to minimize the possibility of degassing in the water sample prior to sealing the copper tube.

Any trapped air or formation of gas bubbles in the copper tube water sample will cause erroneous results. Back pressure is normally applied to the discharge end of the copper tube during flushing to minimize degassing. The sample collector will need to obtain a small valve and suitable tubing to attach the valve to the discharge end of the copper tube. Both water flow and back pressure on the sample should be increased if gas bubble formation is observed. Back pressure of approximately 1 atmosphere, 15 psi, is normally sufficient to prevent gas bubble formation in a groundwater sample. However, in general, to prevent gas-bubble formation, the back-pressure applied must exceed the internal pressure of the dissolved gases in the water sample.

A socket wrench (1/2" or 12-point 13mm) typically is used to turn the bolts that close the clamps. Prior to turning the bolts, the entire line from the well through the copper sample tube should be tapped to dislodge any gas bubbles that may be in the line or copper tube. During the tapping process, the copper tube should be held at an approximate 45-degree angle with discharge pointing up, to assure that gas bubbles, if present, will be completely flushed. This tapping procedure normally requires about 1 minute to complete. Once satisfied that water flowing through the copper tube is free of any gas bubbles, the socket wrench is used to close the bolts on the clamps, beginning with the bolts at the discharge end. Before turning the bolts, be sure to position the copper tube in the approximate center of the clamp. There are two bolts on each clamp. Turn the bolts in successive order back and forth to tighten the clamp until firmly closed so that the blades of the clamp close approximately evenly. The clamps are machined to leave about a 1-mm space when the bolts are turned all the way down and the clamp is closed on the ends. After tightening the discharge end bolts, tighten the inlet end bolts in the same manner, again centering the copper tube in the clamp. When done, double check to be sure that all bolts are tight. The sample is then complete and the copper tube can be disconnected from pump. 

Remove the back-pressure valve from the discharge end of the copper tube. Precautions should be taken not to scratch or otherwise damage the ends of the copper tubes.

 

Lab Code:
489
1142
1172
1574

Description: 

  • Only O-18/O-16 isotope-ratio analysis of water (lab code 489)
  • Both H-2/H-1 and O-18/O-16 isotope-ratio analysis of water (lab code 1142)
  • Both H-2/H-1 and O-18/O-16 isotope-ratio analysis of water (quantity of 40 or more) (lab code 1172) 
  • Only H-2/H-1 isotope-ratio analysis of water (lab code 1574)
Bottle:
2oz (60ml) glass bottle with Polyseal cap available free from RSIL (internal USGS customers can order Q411FLD through the USGS Hydrologic Instrumentation Facility One Stop Shopping website).
For small samples, 11 mL glass vials with Polyseal caps are available for purchase from RSIL in boxes of 144 units.
Treatment, Preservation, and Sample Amount:
Do not field rinse bottle. Do not add chemical treatment. Fill bottle two-thirds full with either raw or filtered water so that if sample expands or freezes during shipping, bottle will not break. Cap bottle with Polyseal cap. Store at ambient temperature until shipped to laboratory.

For sample amounts as small as 0.5 mL, please contact RSIL.

 

Lab Code:
1700
Description: 
  • H-2/H-1 and O-18/O-16 of pore water in sediments or biological material such as branches and plants (toluene extraction method)
Bottle:
Container that prevents evaporation of water.
Treatment, Preservation, and Sample Amount: 
Ship sediments so that they do not freeze. Freeze biological material after collection and ship frozen.

Sufficient sample should be shipped to provide at least 5 g water.

 

Lab Code:
1135
1137
Description: 
  • Both C-13/C-12 and O-18/O-16 of powdered calcite (lab code 1135)
  • Only O-18/O-16 of powdered calcite (lab code 1137)
Bottle:
HDPE 20-mL scintillation vial with Polyseal cap, Wheaton 986706.

Treatment, Preservation, and Sample Amount: 
Sample should be dried and powdered to between 100 and 200 micrometer to ensure isotopic homogeneity.

Maximum sample amount of calcite is 0.5 g. For sample amounts as small as 0.02 g, contact RSIL.

 

Lab Code:
1832
1833
1834
1835
2896
2893
3401
3501

Description: 
  • C-13/C-12, N-15/N-14, C conc, & N conc of plants, invertebrates, and sediments (lab code 1832)
  • C-13/C-12 & C conc of plants, invertebrates, and sediments (lab code 2896)
  • N-15/N-14 & N conc of plants, invertebrates, and sediments (lab code 2893)
  • C-13/C-12; N-15/N-14, C conc, & N conc of suspended particles or sediments on filters (lab code 1833)
  • C-13/C-12 & C conc of suspended particles or sediments on filters (lab code 1834)
  • N-15/N-14 & N conc of suspended particles or sediments on filters (lab code 1835)
  • For  lab code 3401 and lab code 3501: H-2/H-1, O-18/O-16, and S-34/S-32 and H, O, and S conc. are included
  • For lab code 3501: ICP-MS analysis is included

Bottle:
HDPE 20-mL scintillation vial with Polyseal cap, Wheaton 986706.

Treatment, Preservation, and Sample Amount: 
Sample should be dried and powdered to 100 to 200 micrometer to ensure isotopic homogeneity. No treatment, preservation, or special shipping requirements.

Concentration of N in sample must be at least 1 mg/g; concentration of C in sample must be at least 1 mg/g. Total amount of N in sample must be at least 0.15 mg; total amount of C in sample must be at least 0.15 mg. Maximum sample amount is 1 g.

For LC1833, LC1834, and LC1835, the sample collection on the filter is dependent on the method performed by the customer.

For LC3401: The total amount of sample must be at least 500 mg.

For LC3501: The total amount of sample must be at least 2 g. The submission of 5 g of sample is preferred. The ICP-MS instructions for LC3501 is equivalent to EPA 200.8, with the subtraction of Hg and Th, and the addition of Li, B, Fe, Rb, Sr, La, and Ce. The best TMR reference is TM5-B1.

 

Lab Code:
1948
Description: 
  • S-34/S-32 of dissolved sulfide, pure Ag2S
Bottle:
Contact RSIL
Treatment, Preservation, and Sample Amount: 
Contact RSIL

 

Lab Code:
1949
2949
Description:
  • S-34/S-32 (with or without O-18/O-16) of dissolved SO4 < 20 mg/L
Bottle:
Collected on anion exchange resin (Amberlite IRA-400 (RN(CH3)3 + Cl-) ordered from RSIL ($35 each). Rinse with 50 mL DI water before use.
Treatment, Preservation, and Sample Amount: 
Sulfate and sulfide concentration should be determined in the field before sample collection. Each sample that contains < 20 mg/L sulfate should be collected on anion exchange resin, chilled, and maintained at 4 deg C until shipped. Fill a 10-L bucket with sample and acidify with 1M HCl to pH of 3 to 4. With a rate of 0.4 liter/minute, pump with a peristaltic pump sufficient sample through resin to collect 20 to 40 mg of sulfate. Resin capacity is such that it can easily accommodate 4 L water having a sulfate concentration of 10 mg/L, or 8 L of 5 mg/L, or 20 L of 1 mg/L. If the water contains sulfide, the collection should be fast to avoid possible oxidation by oxygen in air of the sulfide to sulfate.

1M HCl can be prepared by adding 40.4 mL of 38% commercial HCl solution to 500 mL of DI water.

 

Lab Code:
1950
Description:
  • S-34/S-32 of sulfate in rock or sediment
Bottle:
Contact RSIL
Treatment, Preservation, and Sample Amount: 
Contact RSIL

 

Lab Code:
1951
2951
Description:
  • S-34/S-32 (with or without O-18/O-16) of dissolved SO4 > 20 mg/L
Bottle:
32 oz (1 L) polyethylene bottle (Q35FLD at One-Stop Shopping)
Treatment, Preservation, and Sample Amount: 
Sulfate and sulfide concentration should be determined in the field. Each sample should be filtered by a 0.4 µm polycarbonate membrane filter. Sample should be collected in a maximum of 1-L glass or plastic bottle. For sulfate concentration less than 20 mg/L, use 1949. A sample that contains > 0.01 mg/L sulfide or has a sulfate/sulfide ratio < 40 should be stripped of its sulfide in the field (please see USGS Open File Report 97-234).

 

Lab Code: 
1800
Description:
  • S-34/S-32 of biological material, sediment, and other solids
Bottle:
Contact RSIL
Treatment, Preservation, and Sample Amount:
Contact RSIL

 

Lab Code:
1853
Description:
  • C-13/C-12 of DIC
Bottle:
Brown or clear 40-mL glass bottle with black rubber septum. Collect in duplicate.
Treatment, Preservation, and Sample Amount: 
Collect in duplicate. Overfill bottle so that there is no headspace of air. Samples should be stored and shipped chilled. Do not freeze.

 

Lab Code:
2894
2897
Description:
  • N-15/N-14 of nitrate in soil (lab code 2894)
  • N-15/N-14 and O-18/O-16 of nitrate in soil (lab code 2897)
Bottle:
HDPE 20-mL scintillation vial with Polyseal cap, Wheaton 986706.
Treatment, Preservation, and Sample Amount: 
Sample should be dried (or frozen) to prevent biological reaction of nitrogen-bearing species during storage or transport to laboratory. No special shipping is required.

Concentration of nitrate in sample must be at least 1 mg/kg as N. Total amount of nitrate in sample must be at least 0.02 mg as N. Maximum sample amount is 30 g. For samples containing atmospheric nitrate, the bacterial method may overestimate the delta N-15 values by as much as 1 to 2 per mill. For samples that may contain more than about 20 percent atmospheric nitrate, users should collect samples with a minimum of 0.4 mg of N and contact RSIL about methods to avoid this problem.

For samples containing nitrite, the bacterial method will determine the N isotopic composition of the nitrate + nitrite, but the O isotopic composition may be incorrect. If nitrite concentrations are known to be significant, they should be provided to RSIL.

If nitrate concentration is too low or insufficient nitrate is provided, the RSIL will attempt an isotopic analysis, but may not be successful. The sample submitter will be charged for the full cost of the analysis. Sample submitters with laboratory capabilities may want to dissolve nitrate from sediments themselves and confirm that the nitrate concentration is sufficient prior to submitting the dissolved nitrate sample for isotopic analysis. The following procedure is suggested. Approximately 30 mg of solid sample is placed in a 150-mL beaker and 80 mL of DIW (deionized water) is added; the sample and water are stirred well and allowed to sit overnight covered. The sample is then filtered and rinsed several times with 10-mL aliquots of DIW, not to exceed more than 300 mL of water in total. An aliquot is submitted for determination of nitrate concentration--LC 1979 is recommended. The remaining sample is frozen. If LC 1979 indicates that the concentration is greater than 0.03 mg/L as N, the frozen sample is submitted on ice to the RSIL for isotopic analysis.

 

Lab Code:
2895
Description:
  • N-15/N-14 of ammonium in soil
Bottle:
16 oz (500 mL) polypropylene bottle, 89 mm cap (internal USGS customers can order Q413FLD (bottle) and Q422FLD (cap) through the USGS Hydrologic Instrumentation Facility One Stop Shopping website)
Treatment, Preservation, and Sample Amount: 
Sample should be dried (or frozen) to prevent biological reaction of nitrogen-bearing species during storage or transport to laboratory. No special shipping is required.

Concentration of ammonium in sample must be at least 0.2 mg/kg as N. Total amount ammonium in sample must be at least 0.2 mg as N. Maximum sample amount is 1 kg.

 

Lab Code:
2898
Description:
  • N-15/N-14 of ammonium dissolved in water
Bottle:
32 oz (1 L) polyethylene bottle (internal USGS customers can order Q35FLD through the USGS Hydrologic Instrumentation Facility One Stop Shopping website).
Treatment, Preservation, and Sample Amount: 
Field rinse bottle. Filter sample thru 0.45 micron filter. Collect filtered water in polyethylene bottle with a Polyseal cap, leaving enough headspace to add preservative. Preserve the sample by adding concentrated (1:1 or 18N) H2SO4 to achieve a pH between 1.8 and 2.2. Usually 1 mL of 1:1 H2SO4 or 4 mL of 1:7 H2SO4 will be sufficient. Label the bottles to indicate how much H2SO4 has been added. Samples can be stored and shipped chilled or at room temperature. Submitter must provide concentration of ammonium in sample before sample can be analyzed.

Concentration of ammonium in sample must be at least 0.2 mg/kg as N. Total amount of ammonium in sample must be at least 0.2 mg as N. Maximum sample amount is 1 L.

 

Lab Code:
2900
Description:
  • N-15/N-14 and O-18/O-16 of nitrate dissolved in water
Bottle: 
4 oz (125 mL) amber polyethylene bottle, untreated (internal USGS customers can order Q33FLD or Q405FLD through the USGS Hydrologic Instrumentation Facility One Stop Shopping website). It is recommended that conical insert Polyseal caps be used with these bottles. Secure the caps with Parafilm or electrical tape to prevent leakage.
Treatment, Preservation, and Sample Amount: 
Field rinse bottle. Normally, there are two steps needed to filter the samples. The first filtration step is performed in the field with a 0.45 μM filter. The second filtration step is carried out with a 60 mL syringe and a 0.2 μM syringe filter either on site or in the laboratory. If the sample submitter is unable to perform the second filtration step, please contact RSIL.

Fill the bottle only ¾ full. Secure the caps with electrical tape to prevent leakage. Freeze sample to prevent biological reaction of nitrogen-bearing species during storage or transport to laboratory. Alternatively, samples can be preserved by adding reagent-grade NaOH or KOH to achieve a pH greater than 10, but not higher than 11.95 (typically 1 “pellet” per 125-mL bottle). Label the bottles to indicate if hydroxide has been added. Submitter must provide concentration of nitrate in sample with an accuracy of ± 10 percent or better before sample can be analyzed. If concentration provided is not accurate to within ±10 percent, the normal accuracy of the technique cannot be achieved and the submitter will be charged for any additional isotopic measurements needed. A "‹" value is not acceptable. Concentration of nitrate in a sample must be at least 0.06 mg/L as N. If the concentration of nitrate in a sample is less than 0.06 mg/L as N, the uncertainties for nitrogen and oxygen isotope analyses will be twice that of the samples with higher concentrations. LC 1975 can be used for samples with concentrations above 0.06 mg/L as N. LC 1979 can be used for samples with concentrations less than 0.06 mg/L. Samples should be held until nitrate concentration is available. Ship on ice or at 4 deg C if not preserved.

The minimum sample amount is 30 mL. Maximum sample amount is 125 mL. For samples containing atmospheric nitrate, the bacterial method may overestimate delta N-15 values by as much as 1 to 2 per mill.

For samples that may contain more than about 20 percent atmospheric nitrate, users should contact the RSIL. For samples containing nitrite, the bacterial method will determine the N isotopic composition of the nitrate + nitrite, but the O isotopic composition may be incorrect. If nitrite concentrations are known to be significant, they should be provided to RSIL.

 

Lab Code:
832
896
893
Description:
  • C-13/C-12 and/or N-15/N-14; C concentration and/or N concentration of vertebrates
Bottle:
HDPE 20-mL scintillation vial with Polyseal cap, Wheaton 986706.
Treatment, Preservation, and Sample Amount: 
​​​​​​​
Sample should be dried and powdered to 100 to 200 micrometer to ensure isotopic homogeneity. No treatment, preservation, or special shipping requirements.

Concentration of C in sample must be at least 1 mg/g and/or concentration of N in sample must be at least 1 mg/g. Total amount of C in sample must be at least 0.15 mg and/or total amount of N in sample must be at least 0.15 mg. Maximum sample amount is 1 g.