[aeacfm]

i performed analysis of formation water samples ( measured 10 cations , 3 anions , TDS , pH , gravity , resistivity ) and my boss told me that the relation between TDS and resistivty of water shown by my analysis is not correct and exceeds a factor !!!!


i asked him about such factor or the equation he derived this factor he told me nothing and said u will get it by experience
finally he said this factor must be between 2+0.05 !!!!!!!!!!!

do any body know any thing about that

[Pradeep]

TDS = K (conductivity or 1/resistivity) under normal conditions. K is the factor he is referring. What we do in conductivity meter calibration is entering the value of K by using a standard.

Your TDS measurments are valid only in the range of pH= 6-8. Because at lower pH protons  which has highest mobility gives the highest contribution to the conductivity than the contribution form TDS.

At high pH OH- which has relatively higher mobility gives the highest contribution to the conductivity than the contribution form TDS.

Once you analyzed cations and anions from other analysis (Eg AAS, Ion selective electrodes) that give more accurate answer. Once you compare those results if you are getting a higher results that is due the unsuitable pH value.