Two Methods Described in Section

X = 560 and 522 nm and the X = 560 and 506 nm method. The results are given in Table 13. In this table each value of So, is the mean of a duplicate determination. The standard deviations of the duplicate determinations have been calculated for both methods. Using X = 560 and 522 nm a standard deviation of 1.5% saturation was found in the case of X = 560 and 506 nm the standard deviation was 1.4% saturation. The isobestic points were established at X = 522.2 0.2 nm (n = 100) and at X = 506.0 0.4 nm (n = 15), respectively. Finally, when comparing the two methods, the standard deviation of the difference between the corresponding saturation values (Table 13) was calculated at 1.4% saturation. 

It should be borne in mind that establishment of the isobestic point at X = 522 nm should be performed extremely carefully, as both the t/X curves of Hb and of HbOa are quite steep in this region (Fig. 12). Accurate wavelength calibration of the spectrophotometer used is thus an absolute requirement. 

Comparison of So, Measured Spectrophotometrically at X = 560 AND 522 NM AND DETERMINED BY VaN SlYKE s Manometric Method 

In a series of 30 blood samples taken during heart catheterization the So, was determined using Van Slyke s manometric technique and the two-wavelength method using X = 560 and 522 nm. The results are given in Table 14. The mean difference between the spectrophotometric and manometric methods was -t-0.57% saturation with a standard deviation of 2.8% saturation. 

Comparison of So, as Measured by Van Slyke Analysis and by Spectrophotombtric Measurement at X = 560 and 522 nm 

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