Why doesn’t the QbD1200 report TIC?
QbD fully removes TIC before analysing TOC.
TOC measured directly, not calculated
(Note: TIC is not required to be measured by EP or USP)
Sievers Calculates TOC
TOC = TC – TIC = 4.41 – 1.38 = 3.03ppb
Sievers needs to report TIC because it calculates TOC:
TOC = TC - TIC
Sievers has fixed analysis times. Too much TIC ‘carries-over’ into TOC measurement, so they need to know how much TIC to be sure the measurement was accurate.
From the Sievers Manual
Measurement accuracy looks OK, but…
Accuracy of measurement +/-2%
Sievers needs to report TIC because it calculates TOC:
Calculated TOC = TC – TIC
Also, the user needs to know TIC to make sure it is within the safe operating range for the Sievers unit
Calculated TOC = TC – TIC
e.g. 1900ppb TIC and 100ppb TOC can give an error on the calculated TOC of 22ppb to 178ppb
Sievers calculated TOC inaccurate!
IC = 12300ppb +/-2% = 12054ppb to 12546ppb
TC = 12900ppb +/-2% = 12642ppb to 13158ppb
Reported TOC = 1104ppb to 96ppb