Other Liquids

WARNING: We DO NOT ACCEPT samples with enriched 14C (often used as a tracer).  Any contamination of any amount of enriched 14C ("hot") material may cause thousands of dollars in clean-up and other costs. If you submit "hot" samples to this lab, you may be liable.

Quantitative - NCHS

Requirements:

  • Typically 0.1 mL of liquid is used (about 0.1 g). Please send at least 1 mL.
  • Liquids (other than water) must be clearly identified as to type in the submission form.
  • Vials should be air-tight, especially when %H is required in order to avoid water loss or absorption.

Methodology:

Elemental analysis is the determination of the elemental composition of organic or inorganic compounds.The Elementar Isotope Cube is used in the Lab to determine %N, %C, %H, and %S.

In general, 0.1mL of liquid is measured into special smooth wall tin capsules, flushed with Helium and a cold weld is created using our liquid sealing device. The closed capsules are re-weighed on the microbalance. Calibrated standards are prepared in a range of weights and run with the samples. A "blind" standard is also run as a check for the calibration.

The prepared capsules are loaded into the carousel of the autosampler. A sample falls down into the top of a column of solid chemicals at 1150°C, and is flash combusted at 1800°C with the addition of oxygen. Ultra-pure helium is used to carry the resulting gases through the column of chemicals to obtain N2 , CO2 , H2O, and SO2, then through a series of adsorption traps to separate the gases according to the "trap and purge" method. A thermoconductivity detector (TCD) measures the gases as they are released. Elementar's own software, which controls the EA in stand-alone mode, is used to process the results.

The analytical precision (2 sigma) is +/- 0.1%.

References:

  • Elementar Americas, Inc.
  • Instruction Manuals for the Isotope Cube and the VarioEL Cube.
Hydrogen Isotopes

Requirements:

  • Organic and inorganic material must be submitted in separate submission files; they have different media codes (one media code per file).
  • Purity or %H for each sample must be indicated in submission file. If the %H is unknown, an elemental analysis run (separate submission) must be done first.
  • About 0.1mg of H equivalent is required, please send more material though for repeats or duplicates.
  • Liquids (other than water) must be clearly identified as to type in the submission form.
  • Vials should be air-tight, especially when %H is required in order to avoid water loss or absorption.

Methodology:

In general, enough liquid to obtain 0.1 mg of H2 is measured into special smooth wall silver capsules, flushed with Helium and a cold weld is created using our liquid sealing device. The closed capsules are re-weighed on the microbalance.

The encapsulated samples are analyzed with a Thermo DeltaPlus XP continuous-flow isotope-ratio mass spectrometer coupled with a Thermo Scientific thermal conversion elemental analyzer (TC/EA) using a zero blank autosampler, via a Confo IV. The method of Qi and Coplen is used: He flow rate = 120 mL/min, reactor temperature = 1450°C, GC temperature = 85°C, and GC length = 1m, 5Å. Calibrated internal/international standards are prepared with every batch of samples for normalization of the data.

The analytical precision is +/- 3 permil.

References:

  • Coplen, Tyler B., and Qi, Haiping (2012) USGS42 and USGS43: Human-hair stable hydrogen and oxygen isotopic reference materials and analytical methods for forensic science and implications for published measurement results, Forensic Science International, Volume 214, Issues 1–3, 10 January 2012, Pages 135–141.
  • Instruction Manuals for the Thermo TC/EA and the Thermo Finnigan DeltaPlus XP.
Carbon Isotopes

Requirements:

  • Organic and inorganic material must be submitted in separate submission files; they have different media codes (one media code per file).
  • Purity or %C for each sample must be indicated in submission file. If the %C is unknown, an elemental analysis run (separate submission) must be done first.
  • About 0.4mg of C equivalent is required, please send more material though for repeats or duplicates.  We can also use less, down to 0.020mg of C
  • Liquids (other than water) must be clearly identified as to type in the submission form.
  • Vials should be air-tight in order to avoid water loss or absorption.

Methodology:

Organic liquids are weighed into smooth-walled tin capsules. These capsules are cold-weld sealed using our liquid sealing device. Calibrated internal standards are prepared with every batch of samples for normalization of the data. In general, 300µg of C are required for analysis, although 20µg can also be easily done. Elemental analysis must be performed first if the quantities of carbon and/or nitrogen in a sample are unknown.

The isotopic composition of organic carbon is determined by the analysis of CO2 produced by combustion on an Elementar Isotope Cube Elemental Analyser followed by "trap and purge" separation and on-line analysis by continuous-flow with a DeltaPlus Advantage isotope ratio mass spectrometer coupled with a ConFlo III.

The routine precision of the analyses is 0.20‰.

References:

  • Pella, E., (1990) Elemental organic analysis, parts 1-2. American Laboratory, Feb. & Aug.
  • Instruction Manuals for the elementar Vario Isotope Cube
  • Instruction manual Thermo Finnigan DeltaPlus Advantage.
  • Instruction manual Thermo Finnigan Conflo III.
Nitrogen Isotopes

Requirements:

  • Organic and inorganic material must be submitted in separate submission files; they have different media codes (one media code per file).
  • Purity or %N for each sample must be indicated in submission file. If the %N is unknown, an elemental analysis run (separate submission) must be done first.
  • About 0.1mg of N equivalent is required, please send more material though for repeats or duplicates.
  • Liquids (other than water) must be clearly identified as to type in the submission form.
  • Vials should be air-tight in order to avoid water loss or absorption.

Methodology:

The liquids are weighed into smooth-walled tin capsules. These capsules are cold-weld sealed using our liquid sealing device. Calibrated internal standards are prepared with every batch of samples for normalization of the data. In general, 100µg of N are required for analysis. Elemental analysis must be performed first if the quantities of carbon and/or nitrogen in a sample are unknown.

The isotopic composition is determined by the analysis of N2 produced by combustion on an Elementar Isotope Cube Elemental Analyser followed by "trap and purge" separation and on-line analysis by continuous-flow with a DeltaPlus Advantage isotope ratio mass spectrometer coupled with a ConFlo III.

The routine precision of the analyses is 0.20‰.

References:

  • Pella, E., (1990) Elemental organic analysis, parts 1-2. American Laboratory, Feb. & Aug.
  • Instruction Manuals for the elementar Vario Isotope Cube
  • Manual for Thermo Finnigan DeltaPlus Advantage.
Oxygen Isotopes

Requirements:

  • Organic and inorganic material must be submitted in separate submission files; they have different media codes (one media code per file).
  • Purity or %O for each sample must be indicated in submission file. If the %O is unknown, an elemental analysis run (separate submission) must be done first.
  • About 0.1mg of O equivalent is required, please send more material though for repeats or duplicates.
  • Liquids (other than water) must be clearly identified as to type in the submission form.
  • Vials should be air-tight, especially when %O is required in order to avoid water loss or absorption.

Methodology:

In general, enough liquid to obtain 0.1 mg of O2 is measured into special smooth wall silver capsules, flushed with Helium and a cold weld is created using our liquid sealing device. The closed capsules are re-weighed on the microbalance.

The encapsulated samples are analyzed with a Thermo DeltaPlus XP continuous-flow isotope-ratio mass spectrometer coupled with a Thermo Scientific thermal conversion elemental analyzer (TC/EA) using a zero blank autosampler, via a Confo IV. The method of Qi and Coplen is used: He flow rate = 120 mL/min, reactor temperature = 1450°C, GC temperature = 85°C, and GC length = 1m, 5Å. Calibrated internal/international standards are prepared with every batch of samples for normalization of the data.

The analytical precision is +/- 0.4 permil.

References:

  • Coplen, Tyler B., and Qi, Haiping (2012) USGS42 and USGS43: Human-hair stable hydrogen and oxygen isotopic reference materials and analytical methods for forensic science and implications for published measurement results, Forensic Science International, Volume 214, Issues 1–3, 10 January 2012, Pages 135–141.
  • Instruction Manuals for the Thermo TC/EA and the Thermo Finnigan DeltaPlus XP.
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