Dissolved organic carbon water blank

The dissolved organic carbon reservoir in natural waters represents a very significant component of the carbon cycle but reliable quantitative determination of this parameter has proved to be difficult particularly in seawater. Commercially available systems are better suited to freshwaters though obtaining accurate results is still not a trivial exercise and great care must be taken to ensure that blanks are satisfactorily and consistently low and that precision remains consistent. 

LOCC water blanks are run between sets of standards and samples to give an analysis baseline. If samples containing dissolved organic carbon in excess of 400 pmol/L DOC are to be analysed, a significant amount of sample carryover may be encountered, and two LOCC water samples in succession may be required to establish a true baseline. Standards are usually run after every ten samples and an example of a typical trace from an analysis is shown in Fig. 16-6. 

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