A simple, practical methodology for routine VSMOW/SLAP normalization of water samples analyzed by continuous flow methods

Normalization of stable isotope data is important for meaningful inter-laboratory comparisons of data, especially for waters where there may be large natural variations in isotope ratios of oxygen and hydrogen. As a result, large, systematic errors may arise in continuous flow applications without correction, whereas normalization to the VSMOW/SLAP scale can facilitate inter-laboratory comparison and can be accomplished by a simple procedure in which secondary laboratory standards, carefully calibrated, are analyzed along with unknown samples. Delta values for these standards, as analyzed, are plotted against the calibrated values and a linear regression is performed. The resulting equation is applied to unknown samples to achieve the normalization. The one-sigma 1sigma] standard deviation for replicate samples by this normalization method using a Finnigan Gasbenchll should be