Stable Carbon and Oxygen Isotope Analysis of Carbonates and DIC Using the Delta Ray Isotope Ratio Infrared Spectrometer (IRIS): Precise and Accurate Measurements Applying a 3-Point Calibration and Standard Bracketing.

ABSTRACT:

Rationale

The Delta Ray Isotope Ratio Infrared Spectrometer enables to determine δ¹³C and δ¹⁸O values of CO₂. The measurements are calibrated against internal reference gas standards. For discrete carbonate or dissolved inorganic carbon (DIC) samples, the manufacturer recommends a calibration against two isotopically different carbonate standard materials (i.e., a 2-point calibration). Here, we show that this method is not sufficient because the measured values may drift significantly over the duration of a measurement run (i.e., 58 samples in approximately 24 h).

Methods

We developed a new measurement routine applying a 3-point calibration and a tight standard-bracketing. In addition, we present an R code to automatically evaluate and calibr

SUBMITTER: Hansen M 

PROVIDER: S-EPMC12748363 | biostudies-literature | 2026 Mar

REPOSITORIES: biostudies-literature