Does the TOC & conductivity increase of purified water upon storage

(Pankaj Sathe) #1

Does the TOC & conductivity increase of purified water upon storage?
If yes what are the reason for same.

(Ankur Choudhary) #2

Yes upon storage of purified water TOC and conductivity increase because atmospheric carbon dioxide (CO2) dissolves in water and increase its TOC and conductivity.

(Pankaj Sathe) #3

Dear Ankur thank a lot for information.
Ankur I want to generate hold time data for purified prior to use.
I wanted to now that how long can we store purified water in tightly closed condition.
We want to generate the hold time data for holding of purified water for usage.
what methodology is to be applied for creation of data, what are the test recommended.
& as per which guideline

(Ankur Choudhary) #4

@Pankaj_Sathe I had done validation for purified water hold time for 4 hours in refrigerator when I was working in pharmaceuticals but you should do study yourself. Take sample and test it for all parameters at different time intervals like 2, 4, 6, 8, 10, 12 hrs.

(Manish Sharma) #5

@Ankur @Pankaj_Sathe
sir I want to a question regarding the TOC Analyzer that “why we use only Potassium hydrogen Pthalate in calibration of TOC Analyzer”.

This question asked to me in an interview.

(Ankur Choudhary) #6

Potassium hydrogen pthalate is not used in TOC calibration.

(Parvesh Mehta) #7

Dear sir what are the resion of increase the TOC

(Nimesh Mistry) #8

In DM water regeneration we are using 800 gm NaOH in 20 liter of water for anion and 5 liter HCL in 20 liters of water for cation. This method has been doing for many years but now suddenly we are facing problem in conductivity, TDS and Chloride test. They are not stable. Conductivity increase, TDS increase and chloride present. If any solution do you have kindly share it…

(Rabar omer) #9

Dear Mr.Ankur
IC Measurment should be taken into consideration.IC is inorganic carbon,dissolved CO2 is a part of IC but TOC measure carbon of the organics ample .
Why does TOC even increase upon storage of water(PW,WFI)?

(Arun) #10

As per my knowledge in TOC analyzer(shimadzu model) IC will be purged out and in water only two forms of carbon remains that is NPOC(non purgable organic carbon) and POC(purgable organic carbon).

TOC=NPOC-POC, POC is present only in low quantity so it was neglected,


TOC increases due to microbial proliferation in water due to storage.

So increase in TOC means microbial contamination also high,

(Meenakshi Gupta) #11

What is ic here?

(Rabar omer) #12

Mr Arun
how about dissolving CO2 from atmosphere,
is there any relation between dissolved CO2 and TOC result?

(Arun) #13

Certainly… infact water for toc analysis were sampled in tight container without airgap.

(Arun) #14

Ic is inorganic carbon…

(Rabar omer) #15

I think dissolved CO2 is a part of IC .is it right?

(lalpratap) #16

Inorganic carbon

(Arun) #17

Not exactly…

(Rabar omer) #18

Why not?

(Arun) #19

it can be organic…

(Arun) #20

In TOC analyser total organic carbon is convert to co2 and detected by NDIR detector.