3.2 Laboratory Preparation Prior to Sample Analysis
85
3.2.1.1 Cleaning Bottles Used for Sample Collection in
the Field
1. Remove sediment and other particles from the bottle with tap water,
using a soft plastic brush if necessary, then rinse once with DIW. Note
that use of a stiff bottle brush can scour the inside of the bottle, allowing contaminants to more easily adsorb to the bottle wall.
2. Fill with 2% HCl and let stand for 15 to 30 min in a separate bottlewashing room, away from analytical instrumentation. The need to use
HCl in a separate bottle-washing room, away from analytical instrumentation, is because HCl can become volatilized and thereby contaminate nearby samples and, eventually, damage equipment.
3. Pour out the HCl and rinse thoroughly four times with DIW.
4. Fill with DIW and store for at least 24 h.
5. To prepare for transport to the field, empty the bottle and rinse once
with DIW, then fill with DIW for transport to the field.
6. Before filling the bottle, the bottle should subsequently be rinsed three
times in the field with the sample that is being collected.
3.2.1.2 Cleaning Bottles Used for General Laboratory Use,
Unacidified Aliquots
1. Empty any remaining sample.
2. Fill with 2% HCl for 15 to 30 min.
3. Pour out the HCl and rinse thoroughly four times with DIW. (HCl can
be reused for multiple washings but should be replaced and properly
disposed of when it becomes discolored.)
4. Fill with DIW and store for at least 1 week.
5. To prepare for use, empty and then rinse twice with DIW.
3.2.1.3 Cleaning Bottles Used for General Laboratory Use,
Acidified Aliquots
1. Pour out any remaining sample.
2. Rinse four times with DIW.
3. Fill with 2% HCl for 15 to 30 min.
4. Pour out the HCl and rinse thoroughly four times with DIW.
5. Fill with DIW and store for at least 24 h.
6. To prepare for use, empty and rinse once with DIW.
Some labs avoid the acid wash step for aliquots to be analyzed for Cl − , NH 4
+ , or
dissolved organic nitrogen (DON), and instead rely on DIW leaching to remove
any contaminants from the bottles. Depending on the intended use of sample
aliquot bottles, the recommended number of rinses can vary. These differences
are summarized in Table 3.1. As indicated, specific conductance should be
85
3.2.1.1 Cleaning Bottles Used for Sample Collection in
the Field
1. Remove sediment and other particles from the bottle with tap water,
using a soft plastic brush if necessary, then rinse once with DIW. Note
that use of a stiff bottle brush can scour the inside of the bottle, allowing contaminants to more easily adsorb to the bottle wall.
2. Fill with 2% HCl and let stand for 15 to 30 min in a separate bottlewashing room, away from analytical instrumentation. The need to use
HCl in a separate bottle-washing room, away from analytical instrumentation, is because HCl can become volatilized and thereby contaminate nearby samples and, eventually, damage equipment.
3. Pour out the HCl and rinse thoroughly four times with DIW.
4. Fill with DIW and store for at least 24 h.
5. To prepare for transport to the field, empty the bottle and rinse once
with DIW, then fill with DIW for transport to the field.
6. Before filling the bottle, the bottle should subsequently be rinsed three
times in the field with the sample that is being collected.
3.2.1.2 Cleaning Bottles Used for General Laboratory Use,
Unacidified Aliquots
1. Empty any remaining sample.
2. Fill with 2% HCl for 15 to 30 min.
3. Pour out the HCl and rinse thoroughly four times with DIW. (HCl can
be reused for multiple washings but should be replaced and properly
disposed of when it becomes discolored.)
4. Fill with DIW and store for at least 1 week.
5. To prepare for use, empty and then rinse twice with DIW.
3.2.1.3 Cleaning Bottles Used for General Laboratory Use,
Acidified Aliquots
1. Pour out any remaining sample.
2. Rinse four times with DIW.
3. Fill with 2% HCl for 15 to 30 min.
4. Pour out the HCl and rinse thoroughly four times with DIW.
5. Fill with DIW and store for at least 24 h.
6. To prepare for use, empty and rinse once with DIW.
Some labs avoid the acid wash step for aliquots to be analyzed for Cl − , NH 4
+ , or
dissolved organic nitrogen (DON), and instead rely on DIW leaching to remove
any contaminants from the bottles. Depending on the intended use of sample
aliquot bottles, the recommended number of rinses can vary. These differences
are summarized in Table 3.1. As indicated, specific conductance should be