3.2 Laboratory Preparation Prior to Sample Analysis
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concentration value from the database. Nevertheless, sample measurements
taken beyond the specified holding time should be flagged.
Each laboratory should have detailed documentation of the steps used in
sample processing. An example list of sample-processing steps follows:
1. Obtain chain-of-custody forms that have assigned SSNs and aliquot
labels that correspond to the processing selected for the project.
Initiate a laboratory data sheet.
2. Retrieve clean aliquot containers and place appropriate numbered
dots or label tape on them. Put on gloves, empty the containers, and
rinse them with DIW, if applicable.
3. Retrieve the field samples to be filtered from the refrigerator. If there
is insufficient sample volume to prepare all of the required aliquots, be
sure to follow the procedure for low-volume samples.
4. Shake the field sample bottle. Rinse the aliquot bottles with a small
volume of the sample. Fill aliquot containers with raw sample for the
aliquots that do not require filtering. Fill in the letter code that corresponds to the aliquots on the laboratory data sheet to document the
processing method.
5. Retrieve the filtering apparatus from the DIW soak and rinse it well
with DIW. Set up the filtering apparatus on the vacuum manifold.
6. Place an appropriate filter (handling the edge of the filter only) on
the apparatus with tweezers that have been rinsed with DIW. For 0.4and 0.1-μm filters, place the shiny side up where appropriate (filters
are sometimes packaged shiny side down). Filter 10 ml of DIW, then
rinse the inside of the chamber with 10 ml of sample and filter into a
waste container. Discard filtrate.
7. Place proper aliquot container under filtering apparatus. Filter
5–10 ml of sample into container, rinse, and then discard the filtrate.
8. Filter an appropriate amount of sample into container. If another aliquot
of the same sample requires the same filter, repeat starting at step 7. Fill
in the letter code that corresponds to the aliquots on the laboratory data
sheet. Discard the used filter and rinse the filtering apparatus with DIW.
9. Repeat steps 6 through 8 for each sample aliquot. If the filter clogs,
replace with a new filter following step 6, then go to step 8.
10. After samples have been processed, rinse the filtering chambers with
DIW and place them in DIW soak buckets. Replace the DIW in the
buckets weekly.
11. Store the remaining sample volume for possible reanalysis, at least
until QA/QC analyses have been completed. Once it has been determined that the analysis meets DQOs, discard the remaining sample in
field sample bottles and bring the bottles to the bottle-washing room.
89
concentration value from the database. Nevertheless, sample measurements
taken beyond the specified holding time should be flagged.
Each laboratory should have detailed documentation of the steps used in
sample processing. An example list of sample-processing steps follows:
1. Obtain chain-of-custody forms that have assigned SSNs and aliquot
labels that correspond to the processing selected for the project.
Initiate a laboratory data sheet.
2. Retrieve clean aliquot containers and place appropriate numbered
dots or label tape on them. Put on gloves, empty the containers, and
rinse them with DIW, if applicable.
3. Retrieve the field samples to be filtered from the refrigerator. If there
is insufficient sample volume to prepare all of the required aliquots, be
sure to follow the procedure for low-volume samples.
4. Shake the field sample bottle. Rinse the aliquot bottles with a small
volume of the sample. Fill aliquot containers with raw sample for the
aliquots that do not require filtering. Fill in the letter code that corresponds to the aliquots on the laboratory data sheet to document the
processing method.
5. Retrieve the filtering apparatus from the DIW soak and rinse it well
with DIW. Set up the filtering apparatus on the vacuum manifold.
6. Place an appropriate filter (handling the edge of the filter only) on
the apparatus with tweezers that have been rinsed with DIW. For 0.4and 0.1-μm filters, place the shiny side up where appropriate (filters
are sometimes packaged shiny side down). Filter 10 ml of DIW, then
rinse the inside of the chamber with 10 ml of sample and filter into a
waste container. Discard filtrate.
7. Place proper aliquot container under filtering apparatus. Filter
5–10 ml of sample into container, rinse, and then discard the filtrate.
8. Filter an appropriate amount of sample into container. If another aliquot
of the same sample requires the same filter, repeat starting at step 7. Fill
in the letter code that corresponds to the aliquots on the laboratory data
sheet. Discard the used filter and rinse the filtering apparatus with DIW.
9. Repeat steps 6 through 8 for each sample aliquot. If the filter clogs,
replace with a new filter following step 6, then go to step 8.
10. After samples have been processed, rinse the filtering chambers with
DIW and place them in DIW soak buckets. Replace the DIW in the
buckets weekly.
11. Store the remaining sample volume for possible reanalysis, at least
until QA/QC analyses have been completed. Once it has been determined that the analysis meets DQOs, discard the remaining sample in
field sample bottles and bring the bottles to the bottle-washing room.