Laboratory Analyses
84
in contact with wash acid for 30 min or less. Therefore, preserved sample
aliquot bottles require longer periods of DIW leaching. Plastic bottles should
not be used if the caps have liners because the liners can become a source
of contamination. Glass bottles, such as those needed for dissolved organic
carbon (DOC) aliquots, usually have caps with removable plastic liners. The
plastic liners must be removed from the caps for washing and be soaked
in DIW for the same length of time that the bottle is soaked before being
replaced in the cap.
Because the required cleaning procedure depends on the specific use of the
bottle, a set of cleaning procedures needs to be developed and documented by
the laboratory. Appropriate procedures to clean the various types of collection
and aliquot bottles are listed here and summarized in Table 3.1. Although different laboratories may use different or modified procedures, it is critical to
document the specific procedures used and to provide assurance that sample
bottle contamination has been avoided.
Additional precautions may be needed when washing with acid solutions,
such as hydrochloric acid (HCl). Local regulations may require separate disposal of acid (or basic) waste products (depending on the concentration), rather
than pouring them down the sink. The possible need for special waste disposal
procedures may affect the laboratory budget and may influence decisions
regarding bottle-washing procedures.
TABLE 3.1 SUMMARY OF A TYPICAL BOTTLE-RINSING PROTOCOL FOR
LOW-NUTRIENT, LOW-IONIC STRENGTH SAMPLES
Bottle
Acid Wash? Rinses
DIW Soak Period
60-ml plastic (cations,
acidified)
Yes
4
1 wk, 2X rinse, 24-h soak
30-ml plastic (anions)
No
6
24 h
250-ml plastic (pH, ANC)
Yes
4
24 h
30-ml plastic (total Al,
acidified)
Yes
4
1 wk, 2X rinse, 24-h soak
30-ml plastic (NH 4 or DON)
No
6
24-hr
40-ml glass (DOC)
Yes
4
24-hr
DOC caps and liners
Yes
6
24-hr
1-L plastic ( field, manual
collection)
Yes
4
24-hr
500-ml plastic ( field,
autosample)
Yes
4
24-hr
1-L plastic ( field, autosample)
Yes
4
24-hr
84
in contact with wash acid for 30 min or less. Therefore, preserved sample
aliquot bottles require longer periods of DIW leaching. Plastic bottles should
not be used if the caps have liners because the liners can become a source
of contamination. Glass bottles, such as those needed for dissolved organic
carbon (DOC) aliquots, usually have caps with removable plastic liners. The
plastic liners must be removed from the caps for washing and be soaked
in DIW for the same length of time that the bottle is soaked before being
replaced in the cap.
Because the required cleaning procedure depends on the specific use of the
bottle, a set of cleaning procedures needs to be developed and documented by
the laboratory. Appropriate procedures to clean the various types of collection
and aliquot bottles are listed here and summarized in Table 3.1. Although different laboratories may use different or modified procedures, it is critical to
document the specific procedures used and to provide assurance that sample
bottle contamination has been avoided.
Additional precautions may be needed when washing with acid solutions,
such as hydrochloric acid (HCl). Local regulations may require separate disposal of acid (or basic) waste products (depending on the concentration), rather
than pouring them down the sink. The possible need for special waste disposal
procedures may affect the laboratory budget and may influence decisions
regarding bottle-washing procedures.
TABLE 3.1 SUMMARY OF A TYPICAL BOTTLE-RINSING PROTOCOL FOR
LOW-NUTRIENT, LOW-IONIC STRENGTH SAMPLES
Bottle
Acid Wash? Rinses
DIW Soak Period
60-ml plastic (cations,
acidified)
Yes
4
1 wk, 2X rinse, 24-h soak
30-ml plastic (anions)
No
6
24 h
250-ml plastic (pH, ANC)
Yes
4
24 h
30-ml plastic (total Al,
acidified)
Yes
4
1 wk, 2X rinse, 24-h soak
30-ml plastic (NH 4 or DON)
No
6
24-hr
40-ml glass (DOC)
Yes
4
24-hr
DOC caps and liners
Yes
6
24-hr
1-L plastic ( field, manual
collection)
Yes
4
24-hr
500-ml plastic ( field,
autosample)
Yes
4
24-hr
1-L plastic ( field, autosample)
Yes
4
24-hr