Methods and apparatus are provided to measure isotopic characteristics of a number of sample types. Embodiments of the invention combine novel and existing components to produce more accurate isotopic information. Further, embodiments of the invention allow for isotopic readings to be taken and analyzed outside of a laboratory. An example of such an embodiment is an apparatus comprising a combustion furnace; a reactant tube passing through the combustion furnace; an injector coupled to one, or a combination of, the combustion furnace, and reactant tube, to introduce a sample; a laser isotopic measurement device coupled to the reactant tube on the exit end; and a processor electrically coupled to one, or a combination of, the injector, the combustion furnace, the reactant tube, and the isotopic measurement device, in which a carrier gas transports the sample through the apparatus.