N, C, and S Isotopes

δ¹⁵N and δ¹³C ANALYSIS

Solids including soils and sediments, vegetation, biological tissues, and materials trapped on glass fiber filters* are analyzed for δ¹⁵N and δ¹³C using either a Costech ECS 4010 interfaced with a ConFlo IV and Thermo Finnigan DELTA^plus XP IRMS, or a Thermo EA IsoLink CN interfaced with ConFlo IV and a Thermo MAT 253 IRMS.

Method

Dried, homogenized^† samples are weighed into tin capsules^‡. Samples are dropped sequentially by autosampler into an oxidation reactor and flash-combusted with research grade (99.999% pure) oxygen at ~ 1700 °C. Halogens and sulfur in the sample are trapped using silvered cobaltous oxide in the bottom of the reactor. Sample gases are swept on a stream of ultra high purity (99.999% pure) helium to a reduction column, where excess oxygen is trapped out and nitrogen oxides are reduced to N₂. Waters of combustion are removed using a magnesium perchlorate trap. Remaining N₂ and CO₂ are separated inside a 3-meter packed gas-chromatographic column, then introduced separately into the IRMS via ConFlo IV for measurement against reference gases.

Approximately ten percent of the CO₂ introduced into the IRMS cracks to CO. In samples with atomic C:N ratios at or above ~ 80, the amount of CO is sufficiently large to interfere with δ¹⁵N measurements. For such samples, or where only δ¹⁵N is desired, a CO₂ trap is attached between the reduction column and the water trap on the EA.

QA/QC

Final δ¹⁵N and δ¹³C values are expressed in permil relative to the atmospheric nitrogen (AIR) and Vienna Pee Dee Belemnite (VPDB) scales, respectively.

Long-term standard deviation of δ¹⁵N and δ¹³C measurements, as assessed by repeated analyses of blind standards, is better than 0.2 permil.

Sample Size

Minimum amount: 0.06 mg of nitrogen

Ideal amount: ~ 0.10 mg of nitrogen

Minimum amount: 0.05 mg of carbon

Ideal amount: ~ 0.10 mg of carbon

Customers are encouraged to contact the KSIGL lab manager prior to sample submission to determine optimal and minimum sample weights required for analysis. We strongly recommend a 10% duplication of samples for accurate precision determination. 

 

*Samples on glass fiber filters may incur additional costs.

^†Samples should be homogenized prior to encapsulation and shipment. If this is not possible, unweighed samples can be homogenized and encapsulated at KSIGL. Please see the pricing tab for current rates.

^‡Unweighed samples can be shipped in individual containers and weighed into tin capsules at KSIGL by trained technician. Please see the pricing tab for current rates.

 

 

δ³⁴S ANALYSIS

Organic and inorganic materials are analyzed for δ³⁴S using a Thermo EA IsoLink CN with ramped-temperature GC column interfaced with a ConFlo IV and Thermo MAT 253 IRMS. The ramped GC column produces shorter, sharper sulfur peaks than traditional EA setups, which improves precision, accuracy, and sample throughput while lowering sample weight requirements. Currently, as little as 0.080 mg of Ag₂S or BaSO₄ is required to obtain reliable δ³⁴S values.

Method

Same in principal as for δ¹⁵N and δ¹³C except 1-2 mg of powdered tungsten oxide is added to each sample to improve combustion. A single combination-oxidation/reduction reactor without sulfur-trapping chemicals and the ramped-temperature GC column are used.

Customers planning to weigh samples into tin capsules prior to submission must add 1-2 mg of powdered tungsten oxide (click here for an example) to each tin capsule. Tungsten oxide powder promotes the full combustion of each sample, improving peak shape and ensuring no carryover (i.e. memory effect) between samples.

QA/QC

Final δ³⁴S are expressed in permil relative to the Vienna Canyon Diablo Troilite (VCDT) scale. Long-term standard deviation of δ³⁴S measurements, as assessed by repeated analyses of blind standards, is better than 0.2 permil.

Sample Size

Minimum amount: 0.005 mg of sulfur

Ideal amount: 0.01 mg of sulfur

Customers are encouraged to contact the KSIGL lab manager prior to sample submission to determine optimal and minimum sample weights required for analysis. We strongly recommend a 10% duplication of samples for accurate precision determination. 

 

 

SIMULTANEOUS δ¹⁵N, δ¹³C, and δ³⁴S ANALYSIS

Simultaneous measurement of δ¹⁵N, δ¹³C, and δ³⁴S in solids is possible using a Thermo EA IsoLink CN with ramped-temperature GC column interfaced with a ConFlo IV and Thermo MAT 253 IRMS.

The range of materials with atomic N:C:S ratios appropriate for simultaneous δ¹⁵N/δ¹³C/δ³⁴S measurement is limited. Consultation with KSIGL is required prior to sample submission.

 

H and O Isotopes

δ²H ANALYSIS

δ²H is measured in solids including vegetation, biological tissues, and hydrated silicas using a Thermo TC/EA interfaced with a ConFlo III and Thermo Finnigan DELTA^plus XP IRMS.

Method

Dried, homogenized* samples are weighed into furnace- or oven-baked silver capsules^†. Samples are dropped sequentially by a zero-blank (helium-flushed) autosampler into a glassy carbon reactor and thermally converted at 1450 °C. Sample gases are swept on a stream of ultra high purity (99.999% pure) helium to a 0.6 meter packed gas-chromatographic column to separate sample H₂, N₂, and CO, then introduced into the IRMS via ConFlo III for measurement against an H₂ reference gas.

QA/QC

Final δ²H values are expressed in permil relative to the Vienna Standard Mean Ocean Water (VSMOW) scale. Long-term standard deviation of δ²H measurements, as assessed by repeated analyses of blind standards, is better than 0.2 permil.

Typical sample size: 0.1 to 0.4 mg

Further Reading

Chesson LA, Podlesak DW, Cerling TE, Ehleringer JR. 2009. Evaluating uncertainty in the calculation of non-exchangeable hydrogen fractions within organic materials. Rapid Communications in Mass Spectrometry 23: 1275-1280.

Martin E, Bindeman I, Balan E, Palandri J, Seligman A, Villemant B. 2017. Hydrogen isotope determination by TC/EA technique in application to volcanic glass as a window into secondary hydration. Journal of Volcanology and Geothermal Research 348: 49-61.

Seligman AN, Bindeman IN, Watkins JM, Ross AM. 2016. Water in volcanic glass: from volcanic degassing to secondary hydration. Geochimica et Cosmochimica Acta 191: 216-238.

Wassenaar LI, Hobson KA. 2003. Comparative equilibration and online technique for determination of non-exchangeable hydrogen of keratins for use in animal migration studies. Isotopes in Environmental and Health Studies 39(3): 211-217.

 

 

δ¹⁸O ANALYSIS

δ¹⁸O is measured in solids including vegetation, biological tissues, nitrates, sulfates, and phosphates using a Thermo TC/EA interfaced with a ConFlo III and Thermo Finnigan DELTA^plus XP IRMS. Measurement of δ¹⁸O in silicates is also possible using a fluorinating agent to release oxygen from the sample.

Method

Same as the δ²H method described above. Because residual phosphate interferes with the measurement of sulfate oxygen, we use separate reactors for each material.

QA/QC

Final δ¹⁸O values are expressed in permil relative to Vienna Standard Mean Ocean Water (VSMOW). Long-term standard deviation of δ¹⁸O measurements, as assessed by repeated analyses of blind standards, is better than 0.2 permil.

Typical sample size: 0.2 to >2 mg

Further Reading

Bӧhlke JK, Mroczkowski SJ, Coplen TB. 2003. Oxygen isotopes in nitrate: new reference materials for ¹⁸O:¹⁷O:¹⁶O measurements and observations on nitrate-water equilibration. Rapid Communications in Mass Spectrometry 17: 1835-1846.

Boschetti T, Iacumin P. 2005. Continuous-flow δ¹⁸O measurements: new approach to standardization, high-temperature thermodynamic and sulfate analysis. Rapid Communications in Mass Spectrometry 19: 3007-3014.

LaPorte DF, Holmden C, Patterson WP, Prokopiuk T, Eglington BM. 2009. Oxygen isotope analysis of phosphate: improved precision using TC/EA CP-IRMS. Journal of Mass Spectrometry 44: 879-890.

Lécuyer C, Fourel F, Martineau F, Amiot R, Bernard A, Daux V, Escarguel G, Morrison J. 2007. High-precision determination of 18O/16O ratios of silver phosphate by EA-pyrolysis-IRMS continuous flow technique. Journal of Mass Spectrometry 42: 36-41.

Menicucci AJ, Spero HJ, Matthews J, Parikh SJ. 2017. Influence of exchangeable oxygen on biogenic silica oxygen isotope data. Chemical Geology 466: 710-721.

Webb EA, Longstaffe FJ. 2002. Climatic influences on the oxygen isotopic composition of biogenic silica in prairie grass. Geochimica et Cosmochimica Acta 66(11): 1891-1904.

 

^†Samples should be homogenized prior to shipment. If this is not possible, samples can be homogenized at KSIGL. Please see the pricing tab for current rates.

^‡Samples can be shipped in individual containers and weighed into tin capsules at KSIGL by trained technician. Please see the pricing tab for current rates.

 

 

Carbonate Isotopes

The δ¹³C and δ¹⁸O of headspace CO₂ evolved from carbonate-bearing samples is measured using a Thermo GasBench II interfaced with a Thermo Finnigan DELTA^plus XP IRMS.

Method

Carbonate-bearing materials are weighed into 12 mL round-bottom Labco Exetainers and dried at ~65 °C, flushed with ultra high purity (99.999% pure) helium, and then reacted at 25 °C with '100%' H₃PO₄. Seven individual injections of headspace CO₂ are then transferred on a stream of UHP helium to the IRMS for measurement.

QA/QC

Raw data are currently normalized using NBS18 and NBS19. Additional reference materials with low (~ -40 permil) carbon isotope values are under evaluation. During normalization, the first two injections are ignored while the last 5 injections are averaged to produce a raw isotope value. Long-term standard deviation of δ¹³C and δ¹⁸O measurements, as assessed by repeated analyses of blind standards (NIST SRM 915b, NIST SRM 88b) is 0.2 permil or better.

Sample Size

Minimum sample amount: 0.009 mg of carbon

Ideal sample amount: 0.03 mg of carbon

We strongly recommend a 10% duplication of samples for accurate precision determination. 

 

Further Reading

Duhr A, Hilkert AW. 2008. δ¹³C and δ¹⁸O determination of carbonates using Thermo Scientific GasBench II. Thermo Application Note 30050. 4 pages.

Breitenbach SFM, Bernasconi SM. 2011. Carbon and oxygen isotope analysis of small carbonate samples (20 to 100 μg) with a GasBench II preparation device. Rapid Communications in Mass Spectrometry 25: 1910-1914.

Skrzypek G, Paul D. 2006. δ¹³C analyses of calcium carbonate: comparison between the GasBench and elemental analyzer techniques. Rapid Communications in Mass Spectrometry 20: 2915-2920.

Spӧtl C. 2011. Long-term performance of the Gasbench isotope ratio mass spectrometry system for the stable isotope analysis of carbonate microsamples. Rapid Communications in Mass Spectrometry 25: 1683-1685.

 

%NCHOS

%N and %C ANALYSIS

Solids including soils and sediments, vegetation, biological tissues, and materials trapped on glass fiber filters* are analyzed for %N and %C using either a Costech ECS 4010 or a Thermo EA IsoLink CN elemental analyzer.

Method

Dried, homogenized^† samples are weighed into tin capsules^‡. Samples are dropped sequentially by autosampler into an oxidation reactor and flash-combusted with research grade (99.999% pure) oxygen at ~ 1700 °C. Halogens and sulfur in the sample are trapped using silvered cobaltous oxide in the bottom of the reactor. Sample gases are swept on a stream of ultra high purity (99.999% pure) helium to a reduction column, where excess oxygen is trapped out and nitrogen oxides are reduced to N₂. Waters of combustion are removed using a magnesium perchlorate trap. Remaining N₂ and CO₂ are separated inside a 3-meter packed gas-chromatographic column, then introduced separately into the onboard thermal conductivity detector (TCD) for measurement against repeated measurements of a reference standard with known %N and %C (e.g. acetanilide).

QA/QC

Long-term standard deviation of %N and %C measurements, as assessed by repeated analyses of blind standards, is better than 0.2 percent.

Sample Size

Minimum amount: 0.02 mg of nitrogen

Ideal amount: ~ 0.05 mg of nitrogen

Minimum amount: 0.05 mg of carbon

Ideal amount: ~ 0.2 mg of carbon

Customers are encouraged to contact the KSIGL lab manager prior to sample submission to determine optimal and minimum sample weights required for analysis. We strongly recommend a 10% duplication of samples for accurate precision determination. 

 

*Samples on glass fiber filters may incur additional costs.

^†Samples should be homogenized prior to shipment. If this is not possible, samples can be homogenized at KSIGL. Please see the pricing tab for current rates.

^‡Samples can be shipped in individual containers and weighed into tin capsules at KSIGL by trained technician. Please see the pricing tab for current rates.

 

%S ANALYSIS

Organic and inorganic materials are analyzed for δ³⁴S using a Thermo EA IsoLink CN with ramped-temperature GC column. The ramped GC column produces shorter, sharper sulfur peaks than traditional EA setups, which improves precision, accuracy, and sample throughput while lowering sample weight requirements.

Method

Same in principal as for %N and %C except 1-2 mg of powdered tungsten oxide is added to each sample to improve combustion. A single combination-oxidation/reduction reactor without sulfur-trapping chemicals, and the ramped-temperature GC column are also used.

QA/QC

Long-term standard deviation of %S measurements, as assessed by repeated analyses of blind standards, is better than 0.2 percent.

Sample Size

Minimum amount: 0.005 mg of sulfur

Ideal amount: 0.01 mg of sulfur

Customers are encouraged to contact the KSIGL lab manager prior to sample submission to determine optimal and minimum sample weights required for analysis. We strongly recommend a 10% duplication of samples for accurate precision determination. 

 

 

SIMULTANEOUS %N, %C, and %H ANALYSIS

Simultaneous measurement of %NCH in solids is possible using a Costech ECS 4010 EA outfitted with a 2-meter GC column. The magnesium perchlorate trap is also removed.

Sample Size

Contact KSIGL staff for optimal sample weight ranges.

 

 

SIMULTANEOUS %N, %C, and %S ANALYSIS

Simultaneous measurement of %NCS in solids is possible using a Thermo EA IsoLink CN with ramped-temperature GC column.

Sample Size

Contact KSIGL staff for optimal sample weight ranges.

 

 

%O ANALYSIS

Solids are analyzed for %O using a Thermo TC/EA interfaced with a ConFlo III and Thermo Finnigan DELTA^plus XP IRMS.

Method

Dried, homogenized* samples are weighed into silver capsules^†. Samples are dropped sequentially by a zero-blank (helium-flushed) autosampler into a glassy carbon reactor and pyrolyzed at 1450 °C. Sample gases are swept on a stream of ultra high purity (99.999% pure) helium to a 0.6 meter packed gas-chromatographic column to separate sample H₂, N₂, and CO, then introduced into the IRMS via ConFlo III for measurement. %O values are calculated using sample CO peak areas measured by the IRMS, and calibrated against a reference material with known %O.

QA/QC

Long-term standard deviation of %O measurements, as assessed by repeated analyses of blind standards, is better than 0.3 percent.

Sample Size: 1-2 mg

 

^†Samples should be homogenized prior to shipment. If this is not possible, samples can be homogenized at KSIGL. Please see pricing tab for current rates.

^‡Samples can be shipped in individual containers and weighed into tin capsules at KSIGL by trained technician. Please see pricing tab for current rates.