Method for the analysis of delta18O in water.
A new method has been developed for the oxygen isotopic analysis of water utilizing the exchange of oxygen atoms with nitrite followed by conversion of nitrite to nitrous oxide by hydrazoic acid. This method is analogous to that employing carbon dioxide equilibration in that the analyte is added as a reagent to the water sample and exchanges oxygen isotopes with the water. In this procedure, however, the equilibration is more rapid and less sensitive to changes in ambient temperature, as the exchange is terminated by conversion of nitrite to nitrous oxide prior to analysis. The nitrous oxide is then analyzed using an on-line purge and trap system coupled to an isotope ratio mass spectrometer. This method makes use of previously established methods for nitrite isotopic analysis and commercially available equipment. It has high throughput, relatively low standard deviation (0.1 per thousand or better), and small sample size (down to 100 microL), is simple, and is applicable to both fresh- and seawater samples.
Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, Massachusetts 02543, USA. mmcilvin@whoi.edu
Matthew R
MR
McIlvin
Karen L
KL
Casciotti
D001386:Azides / Q000737:chemistry; D009573:Nitrites / Q000737:chemistry; D009609:Nitrous Oxide / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D010103:Oxygen Isotopes / Q000032:analysis*; D015203:Reproducibility of Results; D012623:Seawater / Q000032:analysis* / Q000737:chemistry; D012680:Sensitivity and Specificity; D013696:Temperature; D014867:Water / Q000032:analysis* / Q000737:chemistry
D001386:Azides; D009573:Nitrites; D010103:Oxygen Isotopes; D014867:Water; C007972:hydrazoic acid; D009609:Nitrous Oxide; D010100:Oxygen