Combustion of organic samples by infrared furnace for carbon isotope analysis.
An apparatus for converting organic samples to carbon dioxide is described. It is especially designed to determine stable carbon isotope ratio of field samples. Unlike previous apparatus of similar configuration, a "Craig-line," it is free from the deposition of charred carbon on the line that results from an incomplete conversion. It includes an infrared furnace that heats both a CuO column and a sample tube. A removable, stainless-steel tube is present around the heated area, and this particular configuration makes it possible to begin every combustion procedure from room temperature, and consequently, to achieve a complete evacuation of air from the line even for heat-labile samples. The apparatus also includes a column that eliminates contaminating oxides such as nitrous oxide. The time necessary to process a sample is less than 30 min, and the precision of the carbon isotope measurement is comparable with that of "Craig-line." The coefficient of variation of carbon content determinations was no more than a few percents for most samples examined. An incidental finding was made that an isotopic fractionation of uric acid occurred during its preparation from penguin excreta by a high-performance liquid chromatography.
D000983:Antipyrine / Q000032:analysis; D002244:Carbon / Q000032:analysis; D002247:Carbon Isotopes; D000458:Cyanobacteria / Q000032:analysis; D006358:Hot Temperature; D007553:Isotope Labeling; D010944:Plants / Q000032:analysis; D012987:Soil / Q000032:analysis
D002247:Carbon Isotopes; D012987:Soil; D002244:Carbon; D000983:Antipyrine