The CAIS uses state-of-the-art instrumentation and processing to enable individual compound classification with applications ranging from food, flavor and beverage authentication, archaeological specificity and marine processes in the near-shore and coastal environments. The refinement of isotopic analysis from bulk samples to chemical class analysis such as total alkanes or lipids, to ramped pyrolysis methods or those compounds released at increasing temperature ranges, has lead to even greater refinement in individual compound analysis.
For many years the technique of gas chromatography has been married to an isotope ratio mass spectrometer for the compound specific measurement of their δ13C and δD values. In addition, though much less frequently, δ15N and δ18O values on individual compounds can be can assessed as well, such as for amino acids and other nitrogen and oxygen containing compounds.
The CAIS uses the Thermo 253 IRMS coupled to a Thermo Trace 1310 GC and combustion interface for structure identification and compound confirmation. Unknown materials can be sampled using direct GC injection in appropriate solvent, headspace sampling analysis and even solid phase extraction techniques. This capability allows a thorough characterization of the C, H, N or O isotopic composition of a range of organic molecules from a myriad of sources for process elucidation.
A further and extremely valued technique the CAIS offers is compound specific 14C via AMS measurement. Although a much larger sample volume is required for processing individual compounds relative to gas chromatographic techniques, a preparative GC or HPLC instrument can be applied to yield appropriate quantities of selected compounds for further processing.
Complex samples are first analyzed using GC/IRMS technique to ascertain purity of individual compounds relative to other compounds in the mixture and their individual isotopic value such as the δ13C value. Individual compounds are collected using a Gerstel preparative fraction collector while monitoring the peak collection efficiency on the GC’s FID detector. Individually collected compounds can then be assessed for purity and lack of fractionation during this processing by both GC/MS and GC/IRMS of the individual compound. Once confirmed, collected compounds are converted to graphite for analysis on a AMS instrument.
|GC/IRMS up to 10 compounds||Call for TAT, $200|
|GC/AMS||Call for TAT and cost|
PROSPECTIVE CLIENTS MUST CONTACT US BEFORE SUBMITTING SAMPLES FOR THIS ANALYSIS
The Center for Applied Isotope Studies is and always has been a tracer-free facility: we do not accept, handle, graphitize or count samples containing Tracer or Labeled (Hot) 14C due to the risk of cross-contamination.