scholarly journals High‐precision stable isotope analysis of <5 μg CaCO 3 samples by continuous‐flow mass spectrometry

2020 ◽  
Vol 34 (19) ◽  
Author(s):  
Hubert B. Vonhof ◽  
Stefan Graaf ◽  
Howard J. Spero ◽  
Ralf Schiebel ◽  
Suzan J.A. Verdegaal ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Stable Isotope ◽  
High Precision ◽  
Stable Isotope Analysis ◽  
Continuous Flow ◽  
Isotope Analysis

scholarly journals High-precision stable isotope analysis of less than 5 microgram carbonate samples by continuous-flow mass spectrometry

2020 ◽  
Author(s):  
Hubert Vonhof ◽  
Stefan de Graaf ◽  
Howard Spero ◽  
Ralf Schiebel ◽  
Suzan Verdegaal-Warmerdam ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Stable Isotope ◽  
Sample Size ◽  
Stable Isotope Analysis ◽  
Continuous Flow ◽  
Isotope Analysis ◽  
System Stability ◽  
Cold Trap ◽  
Good Precision ◽  
Flow Conditions

&lt;p&gt;Stable isotope analysis of biogenic carbonates has remained one of the most important tools in paleoceanography since Emiliani (1955) first described the fluctuation of oxygen isotopes in planktic foraminifers over the Pleistocene. Many laboratories now possess equipment with the capability to analyse foraminifer specimens singularly, at least for larger planktic forms.&lt;/p&gt;&lt;p&gt;Being able to run single specimens of planktic foraminifers is significant, because it yields entirely different information than when one would analyse multiple specimens from the same species. Planktic foraminifers have an average life span of about one month, so analysing single specimens, makes paleoceanographic data at seasonal resolution available (e.g. Ganssen et al., 2011; Metcalfe et al 2019, and references therein).&lt;/p&gt;&lt;p&gt;Most modern equipment for stable isotope analysis of CaCO&lt;sub&gt;3&lt;/sub&gt; samples yields good precision down to 10 microgram sample size. The smallest samples are generally measured with a dual inlet technique, because that quantitatively collects the CO&lt;sub&gt;2 &lt;/sub&gt;gas sample in a cold trap before analysis, leading to a more efficient use of the sample gas. Modern dual inlet equipment has a sample size limit somewhere between 10 and 6 microgram CaCO&lt;sub&gt;3&lt;/sub&gt; sample weight, and in that range usually operates at increased analytical uncertainty when compared to larger samples (e.g. Ganssen et al., 2011). Smaller samples are problematic, because at small amounts of sample gas, the dual inlet system is not able to maintain viscous flow conditions required for precise isotope analysis. To circumvent that barrier, one can use continuous-flow (CF) mass spectrometry because in CF systems the carrier gas ensures proper flow conditions even if there is (virtually) no sample gas produced. Doing so has previously allowed for the&amp;#160; isotope analysis of CaCO&lt;sub&gt;3 &lt;/sub&gt;samples in the 10 &amp;#8211; 6 microgram range at an external precision (1SD) of ~0.12&amp;#8240;&amp;#160; for both &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O and &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C (e.g. Metcalfe et al 2019).&lt;/p&gt;&lt;p&gt;To further improve the performance of CF mass spectrometry for small CaCO&lt;sub&gt;3&lt;/sub&gt; samples, we ran experiments on a Thermo GASBENCH system, equipped with a cold trap (cf. Fiebig et al 2005) and interfaced with a Delta-V mass spectrometer. The experiments consisted of replicate analysis of CaCO&lt;sub&gt;3&lt;/sub&gt; standards between 10 and 3 micrograms in weight, which is the weight range of many of the smaller specimens of planktic foraminifers.&lt;/p&gt;&lt;p&gt;Several hardware modifications were implemented to improve system stability and remove observed effects of contribution of blank CO&lt;sub&gt;2&lt;/sub&gt; building up in the sample vials. With these modifications, external reproducibility of the set-up for carbonate standard aliquots between 10 and 4 microgram reached a precision of ~0.10 &amp;#8240; for both &amp;#948;&lt;sup&gt;18&lt;/sup&gt;O and &amp;#948;&lt;sup&gt;13&lt;/sup&gt;C (1SD). This is similar to precisions typically attained for routine analysis of much larger samples in standard operation on the same equipment, and demonstrates that precise stable isotope analysis of smaller single-specimen planktic foraminifers than we could achieve so far is within reach of CF mass spectrometry.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;References:&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;em&gt;Emiliani, C. 1955, DOI: 10.1086/626295&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&lt;em&gt;Fiebig, J., et al. 2005, DOI: 10.1002/rcm.2060&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&lt;em&gt;Ganssen, G.M., et al., 2011, DOI:10.5194/cp-7-1337-2011&lt;/em&gt;&lt;/p&gt;&lt;p&gt;&lt;em&gt;Metcalfe, B., et al., 2019, DOI: 10.1029/2018PA003475&lt;/em&gt;&lt;/p&gt;

scholarly journals Integrating Continuous-Flow Mass Spectrometry and Automatic CO2 Collection for AMS

Radiocarbon ◽  
2007 ◽  
Vol 49 (2) ◽  
pp. 233-244 ◽  
Author(s):  
Jesper Olsen ◽  
Jan Heinemeier ◽  
Klaus Bahner ◽  
Barry Graney ◽  
Andy Phillips
Keyword(s):  
Mass Spectrometry ◽  
Stable Isotope ◽  
High Precision ◽  
Mass Spectrometer ◽  
Stable Isotope Analysis ◽  
Computer Control ◽  
Isotope Analysis ◽  
Carbon And Nitrogen ◽  
Cryogenic Trapping ◽  
Inlet Manifold

Accelerator mass spectrometry (AMS) radiocarbon measurements of organic samples require combustion to obtain CO2 for graphitization. Furthermore, determination of δ13C values is required in order to correct the 14C age due to carbon isotope fractionation effects. δ13C analysis is commonly carried out by stable isotope mass spectrometry because most applications demand high-precision δ13C values in addition to the requirements of 14C dating. A simplifying step is therefore to combine the combustion for stable isotope analysis with cryogenic trapping of CO2 for AMS graphite targets. Presented here is a simple CO2 trapping device based on a modified Gilson 220XL sampling (manifold) robot coupled to the inlet manifold system of a GV Instruments IsoPrime stable isotope mass spectrometer. The system is capable of batch combustion and analysis of up to 40 samples and is under full computer control by the mass spectrometer software. All trapping parameters such as flush time prior to trapping and total trap time are adjustable through the standard software user interface. A low 14C activity of background materials and high precision and accuracy of stable isotope analysis of carbon and nitrogen are demonstrated.

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