Table 10-8.Recommendation for Sample Volume and Preservation of SampleContinued
Settleable Matter PC
HNO3 to pH 2
2 ml zinc
Det. on site
*Type G sample = Grab.
**P, G = Plastic or Glass.
***4°C = 4 Celslus.
****PC = Proportional Composite.
1 If samples cannot be returned to the lab in less
31f the sample is stabilized by cooling, it should
than 6 hours and holding time exceeds this limit,
be warmed to 25°C for reading, or temperature
the final reported data should show the actual
correction made and results reported at 25°C.
2 Mercuric chloride may be used as an alternate
Note: It has been shown that certain samples
preservative at a concentration of 40 mg/1,
properly preserved may be held beyond the
especially if a longer holding time is requried.
recommended holding time. Consult designated
However, mercuric chloride should not be used
if something better is available.
then the milliliters required for the first sample
could be figured like this:
To get the best results, samples should
be analyzed as soon as possible after they
are collected. Some tests, such as DO, temper-
ature, and pH must be performed at the time
of collection since the results can change
while the sample is being carried to the lab.
Some other tests may be delayed if the sample
is properly stored. The most common means
of preserving a sample is to cool it to 2°C to
10°C. Table 10-8 shows some ways to preserve