Appendix A Standard Operating Procedures - University of Rhode ...

Corrective Action
If the %RPD is greater than 20% then the deviation is noted on the data sheet. The processing
time to determine the sample value is greater than the holding time for the samples. Therefore
the samples will not be reanalyzed unless contamination is suspected as shown through a non-
compliant method blank.
5.2.4 Positive Plates
Calibration is completed in a qualitative way through an assessment of false negatives.
Bacteria from a known plate of E. coli are plated at a dilution of 10 -7 using the procedure
outlined under Section 5.2.5.1, steps 1 through 6 and 8 only. The inoculated plates are then
treated as samples and referred to as positive plates; 2 positive plates are prepared per sample
batch. After incubation these plates must exhibit growth.
Corrective Action
The inoculated plates (positive plates) must show growth after incubation. If the plates do not
show growth then it is assumed that the run was in error and the batch of samples is
reanalyzed. The field samples will be out of compliance with holding times if samples need to
be reanalyzed. This will be noted on the data sheet
5.2.5 Incubators
The temperature of the 35 °C and 44.5 °C incubators are checked twice a day at least 4 hours
apart, when in use. Initial and final temperatures for incubations of samples are recorded on the
project data reporting sheet (see Section 8.0). The acceptable temperature range for the 35 °C
incubator is 35 +/- 0.5 °C. Acceptable temperature for the 44.5 °C incubator is 44.5 +/- 0.2 °C.
Corrective Action
The incubator temperature must remain in the range specified above. If the incubator
temperature is found to be outside the acceptable range, contact Elizabeth Herron and adjust
the incubator temperature control. Professional maintenance of the incubator may be
necessary if adjustment of the temperature control does not rectify the problem.
5.2.6 Germicidal Unit (UV Box)
The UV light box efficiency will be tested quarterly with a UV light meter. Each lamp will be
tested individually. A lamp will be replaced if it emits less than 70% of its initial output. All
efficiency checks will be recorded on the “Quarterly UV Germicidal Tube Record” data sheet
(see Section 8.0 Documentation) and will be available for review.
Corrective Action
If a UV lamp is found to emit less than 70% of its initial output then it will be replaced. The date
of replacement will be recorded on the efficiency check data sheet.
5.2.7 Sterility Check on Sample Bottles
Sample bottles after sterilization must be checked for sterility before being placed with the
general stock of sterilized bottles. A bottle sterility check will be completed at a frequency of
one sample bottle per sterilization run. Sterility checks will be completed by selecting one
sterilized sample bottle at random after the sterilization run has been completed. The sample
bottle will then be filled with Ultrapure water capped and mixed. Once the water has been
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Ambient Waters Microbiological Procedure SOP 007
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