Precision, blank determination and detection limits

12JLL5 Precision, blank determination and detection limits 

The precision of the method was determined by several sets of replicate measurements of NASS reference materials (see Section 12.1.6) and open North Atlantic surface waters. The coefficients of variation have been found to be between 5 % and 10 % for all elements discussed here. 

The blanks should be determined by parallel extraction of previously processed seawater or purest distilled water following the same procedure. It is also worthwhile to distinguish between the reagent blank and the total procedural blank values to identify the factors contributing to the blank. 

The evaluation of detection limits (3s of the mean total blank values see also Chapter 1) for the elements discussed here have been achieved under clean room conditions and been 

As Table 12-1 shows, seawater may contain Mn concentrations of 0.1 nmol/kg. Therefore, for most oceanic samples a pre-concentration step is necessary before analysis. (For the measurement of higher Mn concentrations in seawater by a spectrophotometric method see Section 12.5.) Here a relatively simple and widely used solvent extraction procedure is outlined. The method is based on the extraction of Mn oxinate into chloroform and was first described for seawater by Slowery and Hood (1971), but more extensively by KlinUiammer (1980) and Landing and Bndand (1980). 

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