Fecal Coliform Testing (per
Standard Methods 9222 D.)
1.
mFC Broth* (3.7 grams per 100
ml of distilled water) in 250 ml flask.
-
heat to
beginning boil and pull flask off heater.
-
Let cool & measure pH after
calibrating pH meter (should be 7.4 + 0.2).
*Is going to purchase pre-made mFC
media
2
Turn on the 44.5° C water bath.
3
Determine how many samples are to be tested after including pre, post,
lab replicates (one after every 10 samples is typical), and field replicates
(may be called duplicates). Line them
up. Get the blank log sheet at the back of the Dungeness Bay WQ Tests (black
notebook).
4
Look at list (to determine amount of dilution) of the previous entries
of the samples listed in the same site locations listed in the Dungeness Bay WQ
Tests (black notebook). The latest are at the front.
5
Pipet 1.8 – 2.0
ml of broth into 50x9 mm disposable petri dishes and
numerate
them with the sample numbers.
6
Record on the petri dishes the dilution
factor, such as ½ for only using 50 ml of sample or 1/10 for using only 10 ml
of sample etc. based on the previous entries.
For example, if the previous entry was TNTC, you may want to only use
1/10 ml sample this time to avoid a repeat and want to be able to numerate the
amount of fecal colonies in the sample.
7
Setup the MF apparatus and equipment:
-
membrane filter funnel (located under-counter)
-
Gelman membrane filters
“
-
Bunsen burner (using denatured alcohol) “
-
1000 ml pyrex vacuum flask (located in
cabinet above the phone)
-
tweezers & matches (located under the cabinet)
-
rinse water (located in above cabinet located next the paper towels)
8
Run samples, making sure that you rinse the membrane funnel with 3
swirls between runs
9
After running the samples through and making sure there are no bubbles,
stuff them upside down (into layers
of 2) into 3 layers of ziplock bags while minimizing the air prior to ziplocking.
Afterward, gently insert the bags into the test-tube racks & bind
them in with the long rubber bands prior to submersing
them with weighted rocks into the preheated 44.5° C water bath for 24 hrs.
10
Wash hands (smile).
Next Day….
11
Read via numerical counting.
Count only the blue colonies (yes, even the ones that are tiny and ones
with transparent rings around them).
12 Don’t forget to wash
your hands (smile)
13 Record results on data
log sheet and double check for accuracy.
If sample had high level of atypical colonies (non-blue), make a note of
it on the log book.
14 Photocopy results and file in log book. Send or forward originals to samplers.