where \(\delta_{\text{raw}\left(\text{sample}\right)}\) is the measured isotope composition (Rmeasured ) of the sample relative to the working gas (wg ) and\(\delta_{\text{true}\left(\text{wg}\right)}\) is the actual isotope composition of the working gas specified by the operator. Per convention, the relative difference of isotope ratios (δ ) for N and C are expressed in parts per thousand (‰)26. Although it is possible to quantify\(\delta_{\text{true}\left(\text{wg}\right)}\) and thus calculate the true isotope composition of the sample\((\delta_{\text{true}\left(\text{sample}\right)})\) via a one-point anchoring using the working gas alone, identical treatment principle dictates replacing Eq. 2 with replicate analyses of combusted reference material according to the following equation: