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The microbiological QCS organism is traceable from date of possession, preferably to a
Type culture collection such as ATCC, NCTC, etc. The working culture is inoculated
into an enrichment broth, and after a defined incubation period (ex. overnight), is diluted
and the density is determined (e.g. by enumerating using non-selective media or by using
a densitometer, spectrophotometer, McFarland standard or equivalent) to estimate the
CFU/mL of inoculum. Once the density of the inoculum has been verified by one of
these means, it may be used for either media QC or sample batch QC as a measure of
relative recovery (note: inoculum density may be determined concurrently with testing).
The requirement for DI systems is for verification of the water. Requirements for
verification of conductivity meters are contained in the Table 1 section on “pH meters,
ion selective, and related conductivity equipment.” The laboratory sets an appropriate
frequency for conductivity meter verifications with consideration of the criticality of the
measurement (i.e., is it a reported result?) and accreditation body requirements.
Section 5.5.2 states that Appendix A, Table 1 provides minimum requirements. Greater
frequencies or continuous will fulfill this requirement.
Table 1 sets a minimum requirement. Use of an analytical standard at a level below the
mid‐range of the calibration curve is more difficult due to increased method variability
as you approach the LOQ and would meet the minimum requirement of Table 1.
Yes, the intent is that the water be tested each week of use.
No. The first paragraph of Section 5.9.1 of the ALACC Guidelines provides a number of
examples of quality control samples, but does not require the use of specific types in specific
situations. The use of qualitative quality control samples (e.g., positive/negative controls) is
suitable for qualitative methods.