|
CHAPTER
5 DATA UNCERTAINTIES
| 5.1 |
VOCS |
| |
|
|
The
method detection limit of 0.2 ppbv for each target VOC
was achieved. One collocated sample was collected every
three months for evaluation of method precision, including
both sampling and analysis performance. Tables 5.1a and
5.1b illustrates that the percentage difference between
field samples and collocated samples were all below 20%
for all target compounds, with the exception of trichloroethylene
on 22nd April, 1999 (20.89) and 1,3-butadiene on 19th
October, 1999 (20.29). But they remain acceptable under
the precision test. The average percentage difference
of methyl chloride, 1,3-butadiene, benzene, trichloroethylene
and tetrachoroethene were 11.84%, 18.36%, 7.54%, 20.89%
and 8.40% respectively.
Table
5.1b Summary of Percentage Difference Between
VOCs Field Samples and Collocated Samples |
| Compounds |
Average
Percentage Difference (%) |
| Methyl
chloride |
 11.84 |
| 1,3-Butadiene |
18.36 |
| Benzene |
7.54 |
| Trichloroe
thylene |
20.89 |
| Te
trachloroe thylene |
8.40 |
|
| |
|
|
|