Topic Four ~ Sample Preservation
Sample Storage
-
Water
chemical parameters affected by sample storage before analysis
-
Heavy
metals absorbed into glass wall of container
-
Hence,
kept in clean polyethylene bottle acidified pH 2 by HNO3
-
Sometimes
lost into atmosphere, or used for growth
-
Some
determined in-situ (temperature, pH,
gas)
-
Microorganisms
& plankton changes:
o
BOD
o
Nutrients
o
pH
o
DO
o
Oxidation
state
o
Precipitation
/ dissolution
-
Other
organisms changes:
o
Water
quality
-
Water
samples preserved to minimize changes
-
Sediment
samples preserved to maintain infaunal community
Preservation
Techniques
-
Minimize
potential for quality change
o
Precipitation
/ dissolution
o
Adsorption
o
Biodegradation
o
Chemical assimilation
-
Steps:
o
Kept in
packed ice 4°C before/after filtration with 0.45μm filter paper within 24hrs
o
Non-interfere
preservation chemicals (stop biological activities, chemical reactions, gas
volatilization)
-
Standard
methods:
o
(APHA)
American Public Health Association: Std. Methods for Examination of Water &
Waste Water (freshwater)
Parsons, T.R., Y.Maita, C.M.Lalli: Manual of
Chemical & Biological Methods for Seawater Analysis
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