PASCO Specialty & Mfg. CI-6734 User Manual download pdf (Page 19)

012–06615A Sodium Ion Selective Electrode

Symptom Possible Causes Next Step

“Incorrect Answer” incorrect scaling of semilog paper plot voltage potential on the linear axis.

(but calibration curve On the log axis, be sure concentration

is good) numbers within each decade are increasing

with increasing concentration.

incorrect sign be sure to note sign of millivolt reading

correctly

incorrect standards prepare fresh standards

wrong units used apply correct conversion factor:

1.0X10

-3

M = 23.0 ppm as Na

sample pH too acidic adjust pH with ISA

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PASCO Specialty & Mfg. CI-6734 User Manual Page 19