Average content analytical error

Calibration of FAGE1 from a static reactor (a Teflon film bag that collapses as sample is withdrawn) has been reported (78). In static decay, HO reacts with a tracer T that has a loss that can be measured by an independent technique T necessarily has no sinks other than HO reaction (see Table I) and no sources within the reactor. From equation 17, the instantaneous HO concentration is calculated from the instantaneous slope of a plot of ln[T] versus time. The presence of other reagents may be necessary to ensure sufficient HO however, the mechanisms by which HO is generated and lost are of no concern, because the loss of the tracer by reaction with whatever HO is present is what is observed. Turbulent transport must keep the reactor s contents well mixed so that the analytically measured HO concentration is representative of the volume-averaged HO concentration reflected by the tracer consumption. If the HO concentration is constant, the random error in [HO] calculated from the tracer decay slope can be obtained from the slope uncertainty of a least squares fit. Systematic error would arise from uncertainties in the rate constant for the T + HO reaction, but several tracers may be employed concurrently. In general, HO may be nonconstant in the reactor, so its concentration variation must be separated from noise associated with the [T] measurement, which must therefore be determined separately. 

The relative standard deviation for measurements of the total alkaline earths in ocean waters is reported to be less than 0.1 % (Pate and Robinson, 1961 Culkin and Cox, 1966). In the case where an automatic titration system is applied, the author found a comparable coefficient of variation (c.v.) of 0.15 %. However, for water of lower salinity with an average magnesium content of 0.205 g/kg, a c.v. of only 0.65 % was measured by the author. Although the determination of the magnesium concentration is based on the difference between titrations, errors caused by the measurements of calcium and strontium can be neglected, when the analytical procedure described in Section 11.2.1 is used. 

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