1) Section 5.9.1 of the Guidelines discusses use of CRMs and RMs as quality control samples. What level of traceability is required for an organism used as a QC sample/positive control to
determine method accuracy for microbiological tests, and how can the microbial count be determined?
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).
2) Appendix A, Table 1 contains a requirement for weekly conductivity verification of DI systems. Does the requirement for weekly verification apply to the conductivity meter that is used to monitor the DI system?
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.
3) Appendix A, Table 1 contains a requirement for weekly conductivity verification of DI systems. Does a continuous conductivity monitor meet the requirements of weekly monitoring?
Section 5.5.2 states that Appendix A, Table 1 provides minimum requirements. Greater frequencies or continuous will fulfill this requirement.
4) Appendix A, Table 1 contains a requirement to verify detector response of chromatographic systems with an analytical standard at mid‐range concentration with each batch. Does this allow for use of an analytical standard at the lower end of the calibration curve to match sample concentrations rather than at mid‐range of the calibration curve?
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.
5) Appendix A, Table 1 contains a requirement for weekly conductivity testing of DI systems. Some laboratories may go more than a week without operation. Was the intent of the requirement to be “week of use”?
Yes, the intent is that the water be tested each week of use.
6) Does ALACC:2015 Section 5.9.1 require the use of a QCS (full method, in matrix and known value) for qualitative microbiological methods?
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.
7) Appendix A, Table 1 has a requirement that safety cabinets and laminar airflow cabinets “(if used for culture or sterility work)” must have an open media control during each use. What is considered “culture or sterility work”?
It is sterility work (i.e., sterility testing as defined by the USP) or culture work in support of sterility work. In these cases it is critical to minimize and detect cross contamination.
8) Appendix A, Table 1 contains a requirement for verifying autoclave pressure with each load. Does this mean pressure gauges and thermometers associated with autoclaves need to be calibrated?
Pressure gauges and thermometers associated with autoclaves do not require calibration, because the uniformity and stability requirements for autoclaves are sufficient to confirm proper performance.
9) Section 5.9.1 of the Guidelines states that the laboratory “shall participate in at least one PT event annual for each test, type of test/method and /or technique”. Does this mean that, except when an external relevant PT program is not available, the laboratory must participate in a PT event for each method on its Scope of Accreditation (i..e., for microbiology every method and every organism, for chemistry each method unless it can be shown that these represented the same method with different matrices)?”
The terms, “test” and “type of test” were included in an effort to accommodate the increasing use of flexible scopes. Unfortunately, it has led to confusion for laboratories. The AOAC guidelines state that the laboratory “shall participate in at least one PT event annually for each test, type of test/method and /or technique”. This means the laboratory is required to demonstrate competence through the participation in proficiency testing based upon the type of scope they have. For a defined scope, the laboratory is required to participate in one proficiency testing event each year for each method on the scope. In contrast, a flexible scope specifies each measurement principle (e.g., GC/MS, LC/MS, ICP/MS, PCR, ECL, etc.). In this case the laboratory is required to participate in one proficiency testing event annually for each measurement principle listed on its scope of accreditation. Note that these measurement principals rest upon several assumptions that are explicitly or implicitly involved: The first is that the property of interest is measurable by the specified measurement process. A second assumption is that suitable reference materials are available. A third assumption is that the measurement or comparison study is meaningful and can be reproduced within describable limits. Those laboratories having a flexible scope can modify, up-date or create new methods so long as they do not incorporate new measurement principles not covered by the original description of the scope.