Page 18 - 6_TOC in daily practice

SCA-130-609

■ Sampling method ■ Practical test
Incorrect measurement values often already In a practical test, two sample streams with dif-
occur due to carryover effects in the sample ferent matrices and TOC contents were ana-
inlet line or in the sampler. Biological growth lyzed. To demonstrate sample carry-over be-
and deposits in the inlet line constitute a fur- tween these sample streams, they were alter-
ther risk of contamination. To minimize this, nately sampled and analyzed 90 times respec-
the sample should be directed to the sampler tively.
at a flow rate of higher than 1 m/s. Inspection
openings and valves for manual or even auto- Stream S#1 S#2
mated flushing of the tubing should be pro- Matrix Pure water 3% NaCl-
vided for. The sampler should be constructed Target conc. 1 mg/l solution
1000 mg/l
of inert materials. Automated rinsing steps be- Parameter NPOC NPOC
tween individual samplings further reduce time Acid added 100µl 100µl
expenditure by the operator. To reduce prob- Inj.Volume 150µl 50µl
lems during operation, it is important to pay Dilution None Factor 10
particular attention to sampling during the pro-
ject development phase. ■ Conclusions
S#1 S#2
Mean Value TOC 1,02 992,67
(mg/l)
Standard deviation 0,07 13,32
(mg/l)

Even with significant concentration and matrix
differences between both sample streams, the
TOC-4200 operated free from carry-over
thanks to its inert construction and automated
rinsing function.

■ Recommended analyzer / Configuration
TOC-4200
Individual sampling system

2000 1000mg/L TOC 1mg/L TOC 10
9
1500 8
7 TOC[mg/L] low range
6
TOC[mg/L] high range 1000 5
4
500 3
2
1
0 0
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87