Analytical methods offered by the Reston Stable Isotope Laboratory.
For a list of prices for these services, see our Analyical Services and Prices page.
δ2H replicate analysis of water by dual-inlet isotope-ratio mass spectrometry: Sample preparation by equilibration with gaseous hydrogen and automated analysis; requires 1 to 2 milliliters of water. Isotopic analysis by laser absorption spectrometry is avoided as a primary analytical technique for all USGS water samples because this method can produce anomalous results that will not hold up in court. The "gold standard" for δ2H determination on water is dual-inlet isotope-ratio mass spectrometry. For 2-mL samples, the estimated expanded uncertainty of replicate hydrogen-isotope measurements is 2 per mil. This means that if the same sample were resubmitted for isotopic analysis, the newly measured value would lie within the uncertainty bounds 95 percent of the time.
δ18O replicate analysis of water by dual-inlet isotope-ratio mass spectrometry: Sample preparation by equilibration with carbon dioxide and automated analysis; requires 0.2 to 2.0 milliliters of water. Isotopic analysis by laser absorption spectrometry is avoided as a primary analytical technique for all USGS water samples because this method can produce anomalous results that will not hold up in court. The "gold standard" for δ18O determination on water is dual-inlet isotope-ratio mass spectrometry. For 2-mL samples, the estimated expanded uncertainty of replicate oxygen-isotope measurements is 0.2 per mil. This means that if the same sample were resubmitted for isotopic analysis, the newly measured value would lie within the uncertainty bounds 95 percent of the time.
δ2H and δ18O replicate analysis of water extracted from soils and plants: Water is extracted from soils and plants by distillation with toluene; recommended sample size is that which will provide 1 to 5 milliliters of water per sample. Analysis is by dual-inlet isotope-ratio mass spectrometry. Isotopic analysis by laser absorption spectrometry is deprecated because the smallest remaining fraction of toluene in water will produce anomalous isotopic results.
δ15N and δ18O replicate analysis of dissolved nitrate in water: Dissolved nitrate in water is converted to nitrous oxide (N2O) by denitrifying bacteria, and the nitrous oxide is analyzed for nitrogen and oxygen isotopic abundance by continuous-flow isotope-ratio mass spectrometry. A minimum total amount of 0.002 milligrams of nitrate as nitrogen is required. The estimated expanded uncertainty of δ15N measurement results for samples with nitrate concentrations of at least 0.06 mg/L as nitrogen is ±0.5 per mil unless otherwise specified, and this value is conservative. The estimated expanded uncertainty of δ18O measurement results for samples with nitrate concentrations of at least 0.06 mg/L as nitrogen is ±0.5 per mil unless otherwise specified, and this value is conservative. If any given sample were resubmitted for nitrogen- and oxygen-isotope analysis, the measured values would fall within the uncertainty bounds of the previous results more than 95 percent of the time.
δ15N replicate analysis of dissolved ammonium in water: Dissolved ammonium in freshwater or saline water is converted to gaseous ammonia (NH3), converted quantitatively to ammonium sulfate, and combusted in an elemental analyzer to gaseous nitrogen and sulfur dioxide. The gaseous nitrogen is separated by gas chromatography and analyzed for nitrogen isotopic composition with continuous-flow isotope-ratio mass spectrometry. The concentration of ammonium in sample must be at least 0.2 milligrams per kilogram as nitrogen. A minimum amount of ammonium in sample must be 0.2 milligrams as nitrogen. The estimated expanded uncertainty of δ15N measurement results is ±0.8 per mil unless otherwise specified. If any given sample were resubmitted for nitrogen-isotope analysis, the measured values would fall within the uncertainty bounds of the previous results more than 95 percent of the time.
δ13C of dissolved inorganic carbon: The method is modified from the ThermoFisher Scientific GasBench II Operating Manual (January 2018). The carbon isotopic composition of CO2 released from dissolved carbon in a sample by reaction with H3PO4 is measured. The expanded uncertainty is ±0.4 per mil, unless otherwise indicated. This means that if the same sample were resubmitted for isotopic analysis, the newly measured value would lie within the uncertainty bounds 95 percent of the time.
δ34S replicate analysis of dissolved sulfate in water: Dissolved sulfate is precipitated to barium sulfate, combusted in an elemental analyzer to sulfur dioxide, and analyzed for sulfur isotopic composition with continuous-flow isotope-ratio mass spectrometry. The concentration of sulfate must be at least 20 milligrams per liter. The estimated expanded uncertainty of δ34S measurement results is ±0.4 per mil unless otherwise specified. If any given sample were resubmitted for sulfur-isotope analysis, the measured values would fall within the uncertainty bounds of the previous results more than 95 percent of the time.
δ34S replicate analysis of low-concentration sulfate in water: Dissolved sulfate having a concentration of less than 20 milligrams per liter is collected on an anion-exchange resin in the field, eluted in the laboratory with potassium chloride, precipitated with barium chloride to barium sulfate, combusted in an elemental analyzer to sulfur dioxide, and analyzed for sulfur isotopic composition with continuous-flow isotope-ratio mass spectrometry. The estimated expanded uncertainty of δ34S measurement results is ±0.4 per mil unless otherwise specified. If any given sample were resubmitted for sulfur-isotope analysis, the measured values would fall within the uncertainty bounds of the previous results more than 95 percent of the time.
δ34S replicate analysis of total sulfur in solids: A homogeneous powder is combusted with an elemental analyzer. Combusted gases are separated by gas chromatography and the sulfur dioxide is analyzed for sulfur isotopic abundance by continuous-flow isotope-ratio mass spectrometry. The estimated expanded uncertainty of δ34S measurement results is ±0.4 per mil unless otherwise specified. If any given sample were resubmitted for sulfur-isotope analysis, the measured values would fall within the uncertainty bounds of the previous results more than 95 percent of the time.
δ15N and δ13C replicate analysis of total nitrogen and carbon in solids: A homogeneous powder is combusted to gaseous nitrogen and carbon dioxide with an elemental analyzer. These gases are separated by gas chromatography and are analyzed for nitrogen and carbon isotopic abundance by continuous-flow isotope-ratio mass spectrometry. A minimum required amount of nitrogen and carbon in a sample is 0.15 milligrams and 0.15 milligrams. The estimated expanded uncertainty of δ15N measurement results is ±0.5 per mil unless otherwise specified. The estimated expanded uncertainty of δ13C measurement results is ±0.5 per mil unless otherwise specified. If any given sample were resubmitted for nitrogen- and carbon-isotope analysis, the measured values would fall within the uncertainty bounds of the previous results more than 95 percent of the time.
δ15N replicate analysis of total nitrogen in solids: A homogeneous powder is combusted to gaseous nitrogen and carbon dioxide with an elemental analyzer. These gases are separated by gas chromatography and the gaseous nitrogen is analyzed for nitrogen isotopic abundance by continuous-flow isotope-ratio mass spectrometry. A minimum required amount of nitrogen in a sample is 0.15 milligrams. The estimated expanded uncertainty of δ15N measurement results is ±0.5 per mil unless otherwise specified. If any given sample were resubmitted for nitrogen-isotope analysis, the measured values would fall within the uncertainty bounds of the previous results more than 95 percent of the time.
Related Content
Determination of the δ2H and δ18O of soil water and water in plant matter; RSIL lab code 1700
Determination of the δ13C of dissolved inorganic carbon in water; RSIL lab code 1710
Determination of the delta(2H/1H)of Water: RSIL Lab Code 1574
Determination of the delta(18O/16O)of Water: RSIL Lab Code 489
Determination of the delta(15N/14N)of Ammonium (NH4+) in Water: RSIL Lab Code 2898
Determination of the δ15N of total nitrogen in solids; RSIL lab code 2893
Determination of the δ15N of nitrate in water; RSIL lab code 2899
Determination of the δ15N and δ18O of nitrate in water; RSIL lab code 2900
Determination of the δ15N and δ13C of total nitrogen and carbon in solids; RSIL lab code 1832
Determination of the δ34S of sulfate in water; RSIL lab code 1951
Determination of the δ34S of low-concentration sulfate in water; RSIL lab code 1949
Determination of the δ34S of Total Sulfur in Solids: RSIL Lab Code 1800
Related Content
- Publications
Determination of the δ2H and δ18O of soil water and water in plant matter; RSIL lab code 1700
The purpose of the Reston Stable Isotope Laboratory lab code 1700 is to determine the δ2H/1H), abbreviated as δ2H, and the δ18O/16O), abbreviated as δ18O, of soil water and water in plant matter. This method is based on the observation that water and toluene form an azeotropic mixture at 84.1 °C. This temperature is substantially lower than the boiling points of water (100 °C) and toluene (110 °C)AuthorsKinga M. Revesz, Bryan Buck, Tyler B. CoplenDetermination of the δ13C of dissolved inorganic carbon in water; RSIL lab code 1710
The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 1710 is to present a method to determine the δ13C of dissolved inorganic carbon (DIC) of water. The DIC of water is precipitated using ammoniacal strontium chloride (SrCl2) solution to form strontium carbonate (SrCO3). The δ13C is analyzed by reacting SrCO3 with 100-percent phosphoric acid (H3PO4) to liberate carbon quantitativelyAuthorsGlenda L. Singleton, Kinga Revesz, Tyler B. CoplenDetermination of the delta(2H/1H)of Water: RSIL Lab Code 1574
Reston Stable Isotope Laboratory (RSIL) lab code 1574 describes a method used to determine the relative hydrogen isotope-ratio delta(2H,1H), abbreviated hereafter as d2H of water. The d2H measurement of water also is a component of the National Water Quality Laboratory (NWQL) schedules 1142 and 1172. The water is collected unfiltered in a 60-mL glass bottle and capped with a Polyseal cap. In the lAuthorsKinga Revesz, Tyler B. CoplenDetermination of the delta(18O/16O)of Water: RSIL Lab Code 489
The purpose of the technique described by the Reston Stable Isotope Laboratory (RSIL) lab code 489 is to present a method to determine the delta(180/160), abbreviated as delta-180, of water. This delta-18O measurement of water also is a component of National Water Quality Laboratory (NWQL in USGS) schedules 1142 and 1172. Water samples are loaded into glass sample containers on a vacuum manifold tAuthorsKinga Revesz, Tyler CoplenDetermination of the delta(15N/14N)of Ammonium (NH4+) in Water: RSIL Lab Code 2898
The purpose of the technique described by Reston Stable Isotope Laboratory (RSIL) lab code 2898 is to determine the N isotopic composition, delta(15N/14N), abbreviated as d15N, of ammonium (NH4+) in water (freshwater and saline water). The procedure involves converting dissolved NH4+ into NH3 gas by raising the pH of the sample to above 9 with MgO and subsequently trapping the gas quantitatively aAuthorsJanet E. Hannon, John Karl BöhlkeDetermination of the δ15N of total nitrogen in solids; RSIL lab code 2893
The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2893 is to determine the δ(15N/14N), abbreviated as δ15N , of total nitrogen in solid samples. A Carlo Erba NC 2500 elemental analyzer (EA) is used to convert total nitrogen in a solid sample into N2 gas. The EA is connected to a continuous flow isotope-ratio mass spectrometer (CF-IRMS), which determines relative difference in theAuthorsKinga Revesz, Haiping Qi, Tyler B. CoplenDetermination of the δ15N of nitrate in water; RSIL lab code 2899
The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2899 is to determine the δ15N of nitrate (NO3-) in water. The δ15N of the dissolved NO3- is analyzed by conversion of the NO3- to nitrous oxide (N2O), which serves as the analyte for mass spectrometry. A culture of denitrifying bacteria is used in the enzymatic conversion of the NO3- to N2O, which follows the pathway shown in equaAuthorsTyler B. Coplen, Haiping Qi, Kinga Revesz, Karen Casciotti, Janet E. HannonDetermination of the δ15N and δ18O of nitrate in water; RSIL lab code 2900
The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 2900 is to determine the δ15N and δ18O of nitrate (NO3-) in water. The δ15N and δ18O of the dissolved NO3- are analyzed by converting the NO3- to nitrous oxide (N2O), which serves as the analyte for mass spectrometry. A culture of denitrifying bacteria is used in the enzymatic conversion of the NO3- to N2O, which follows the pathwAuthorsTyler B. Coplen, Haiping Qi, Kinga Revesz, Karen Casciotti, Janet E. HannonDetermination of the δ15N and δ13C of total nitrogen and carbon in solids; RSIL lab code 1832
The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 1832 is to determine the δ(15N/14N), abbreviated as δ15N, and the δ(13C/12C), abbreviated as δ13C, of total nitrogen and carbon in a solid sample. A Carlo Erba NC 2500 elemental analyzer (EA) is used to convert total nitrogen and carbon in a solid sample into N2 and CO2 gas. The EA is connected to a continuous flow isotope-ratAuthorsKinga Revesz, Haiping Qi, Tyler B. CoplanDetermination of the δ34S of sulfate in water; RSIL lab code 1951
The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 1951 is to determine the δ(34S/32S), abbreviated as δ34S, of dissolved sulfate. Dissolved sulfate is collected in the field and precipitated with BaCl2 at pH 3 to 4 as BaSO4 in the laboratory. However, the dissolved organic sulfur (DOS) is oxidized to SO2, and the carbonate is acidified to CO2. Both are degassed from the water samAuthorsKinga Revesz, Haiping Qi, Tyler B. CoplenDetermination of the δ34S of low-concentration sulfate in water; RSIL lab code 1949
The purpose of the Reston Stable Isotope Laboratory (RSIL) lab code 1949 is to determine the δ(34S/32S), abbreviated as δ34S, of dissolved sulfate having a concentration less than 20 milligrams per liter. Dissolved sulfate is collected on an anion-exchange resin in the field, eluted in the laboratory with 3 M KCl, and precipitated with BaCl2 at pH 3 to 4 as BaSO4. The precipitated BaSO4 is filtereAuthorsKinga Revesz, Haiping Qi, Tyler B. CoplenDetermination of the δ34S of Total Sulfur in Solids: RSIL Lab Code 1800
The purpose of Reston Stable Isotope Laboratory Lab (RSIL) Code 1800 is to determine the δ(34S/32S), abbreviated as δ34S, of total sulfur in a solid sample. A Carlo Erba NC 2500 elemental analyzer (EA) is used to convert total sulfur in a solid sample into SO2 gas. The EA is connected to a continuous flow isotope-ratio mass spectrometer (CF-IRMS), which determines the relative difference in stableAuthorsKinga Revesz, Tyler B. Coplen