The Analytical Laboratory Accreditation Criteria Committee (ALACC) is called upon occasionally by the users of the "AOAC INTERNATIONAL Guidelines for Laboratories Performing Microbiological and Chemical Analyses of Food and Pharmaceuticals" (ALACC Guide) to clarify requirements. These questions and the answers are posted as Frequently Asked Questions (FAQ) so that the information is available to everyone.
ALACC has instituted the following system for posting of ALACC Frequently Asked Questions (FAQ) questions and answers. When new questions and answers are posted, they are organized by section corresponding to the appropriate section in ISO/IEC 17025: 2005. Each section has the most recent questions first. New questions are posted in red so that it is clear when new information has been added. The date the FAQ is finalized will be included. The listing of the date when the FAQ is finalized and the posting of additions in red makes it easier for users to determine when FAQ are added to the list. It is suggested that users review the FAQ regularly to look for additions and thus keep up to date with ALACC requirements.
The FAQs related to the 2006 version of the ALACC guide has been removed from the web site. FAQs 1 to 12 with the exception of FAQ 6 deal with the 2006 version of the ALACC Guide and have been addressed in the 2010 version of ALACC Guide. The reader should use the latest version of the ALACC guide. FAQ 6 and 13 address issues in the guide, "How to Meet ISO 17025 Requirements for Method Verification" and will remain on the website.
How to Meet ISO 17025 Requirements for Method Verification
Measurement Uncertainty for Microbiology Measurement uncertainty is a parameter associated with the result of a measurement that characterizes the dispersion of the values that could reasonably be attributed to the measurand, in other words, the variance or standard deviation of the result or the degree of confidence in an analytical result. Calculation of MU is more reliable with a minimum of 30 observations in order to obtain the 95% confidence limits of the overall precision of the method. Therefore it is not unreasonable to expect that each of the required performance characteristics would also be based on 30 observations.
The requirements for microbiological methods imply that 30 data points is the minimum number acceptable, but it is not stated explicitly.
Is the minimum number 30, or do we have some latitude (e.g. 20 - 50)?
The recommendation to use 30 data points is based on the specification for calculating Measurement Uncertainty and is applicable to quantitative methods. 30 data points should provide sufficient information on the variability of a quantitative method to permit a decision on method performance and its fitness for purpose.
The lab must document and justify its decisions as to how many data points to use. The use of fewer than 30 data points should not be routine but may be justified under special circumstances. In this case, as more data is collected the charts should be updated/recalculated to reflect a minimum of 30 points.
Fewer data points (10-15) would be appropriate for verifying qualitative methods. Again, the lab must document its justification for how many data points are used.
Topic: Method verification of a category 3 limit test.
Should Table 4 include LOQ in the performance requirements that need to be verified for a Category 3 limit test?
The Table requires that both LOD and LOQ be verified. However, for validation, as listed in Table 1, only LOD is required.
No, LOQ is not required for the verification of a category 3 limit test.
Also, the wording on page 2 for the description of a category 3 limit test should refer to LOD and not LOQ.
In the 2010 revision of ALACC, the relevant section is Table 1.
Mass measurement - Calibrated reference weights
Daily a with internal calibration or with a working weight
a) Can the internal calibration function of a balance be used for the equipment performance verification of balances in regards to Table 2 of the AOAC ALACC document?
b) Is there a requirement regarding the class of weight that is used to calibrate a balance? We do have a class 1 weight set however for larger investment weights such as 5 kg, is it acceptable to use less than a class 1 weight, i.e. class F?
a) The "internal calibration" function of a balance may not be used to verify the balance performance.
The internal calibration function does not include the placement of an external weight on the balance pan. The internal calibration does not provide an "as found" indication of the balance performance. For many modern balances the internal function is automatic and is part of the normal operation of the balance. The internal calibration weight is not independent of the balance. Because of these reasons the internal calibration is not suitable for verifying balance performance.
b) The balance must be calibrated with weights that have appropriate tolerance. Standards such as ASTM E617-97 Standard Specification for Laboator Weights and Precision Mass Standards provide the appropriate tolerance for each use. The balance should be calibrated using a weight with a class tolerance factor greater than the readability of the balance.
For example: A milligram balance with readability of 0.001g may be calibrated with a weight having a known tolerance of at least 0.0009g.
Procedures shall be established to prevent the production of unauthorized reports or other documents. These steps would include the restriction of access to word processing packages and company letterhead to authorized people. Electronic records, electronic signatures, and handwritten signatures executed to electronic records shall be equivalent to proper records and handwritten signatures executed to paper. For pharmaceutical laboratories, electronic records and signatures must meet the requirements of USA Title 21, Code of Federal Regulations, Part 11.
Topic: Electronic Signature
As part of preparing a report, the electronic file of the laboratory director`s signature is attached to the report. Three individuals have authority to use the electronic file in this way. Does this practice meet section 5.10 where it states that "electronic signatures...executed to electronic records shall be equivalent to...handwritten signatures executed to paper"?
Electronic signatures have been interpreted in two ways.
1) The pasting of a graphic of a signature onto a report.
2) Approval of data in which the person has to re-enter the user ID/password to indicate the intent to sign (shows awareness that he/she is executing a signature). This signing becomes part of the electronic data.
The company certifies that the intent is that all electronic signatures executed by its employees are the legally binding equivalent of traditional handwritten signatures. This password is not shared.
Definition 1, the pasting of a graphic, is not considered an "electronic signature" in the meaning of ALACC Section 5. Hence, the requirement that "electronic signature...executed to electronic records shall be equivalent to...handwritten signatures executed to paper" does not apply.
The process of merely attaching an image to a document as means of identifying the signer should be considered as part of the "company letterhead" and would be subject to the control of company letterhead as stated in section 5.10.
5.10 These steps would include the restriction of access to word processing packages and company letterhead to authorized people.
What is the requirement for air flow monitoring in fume hoods?
If the performance of the fume hood could impact testing results, then the fume hood air flow must be monitored at installation and quarterly. If the fume hoods are being used for safety reasons, then the fume hoods fall outside the scope of the accreditation.
In a pathology laboratory the analysts perform H& E (Hematoxiln/Eosin) staining and other immunostaining methods with processed slides of tissues from animals. There is a positive control slide accompanying each staining process. The control slides are maintained as long as and together with the sample slides that they served as the control for. The results of these controls are not recorded in any other way. Our questions are following:
Does this practice fulfill the requirements of the ALACC/ISO 17025 standards of record keeping?
Could a physical slide serve as a record of the method’s control result?
How is using a physical slide as a record handled by a LIMS system?
The method contains an instruction that the positive control slide meets certain criteria.
The method contains an instruction that the test is “invalid” if the control slide does not meet the criteria, so there is no test result for the sample, and the test must be repeated.
The analyst signs that they have executed the method as written.
This signature would be analyst's ascertation he/she confirmed the positive control slide meets the criteria. The method and analyst's signature would be the record for the positive control slide. There would be no need for a "recording of the observation" of the positive control slide. Keeping the slide is very good practice, but not required.
If the above assumptions are not true, a record of the observation is required. The slide itself can be a record, if and only if, the INTEGRITY of the slide with H& E Stains can be ensured, for the same retention period assigned to hard copy sample records, by criteria determined by the laboratory. The lab would defend its rationale for setting these criteria to the technical assessor during an audit. If not, an observation sheet created when "reading" the slides would constitute the record.
If a LIMS is used, then the LIMS must meet the requirements of 5.10, "Electronic records, electronic signatures, and handwritten signatures executed to electronic records shall be equivalent to proper records and handwritten signatures executed to paper."
What is the distinction between the daily, each load and weekly requirements?
If the records for “daily” include requirements for temperature, time and sterility, then is not the “weekly” requirement for sterility (spore vials or strips) redundant? Also, does not this present wording imply that vials or strips should be used for each load (since autoclave tape is not an indicator of sterility, just temperature).
Autoclave records must be verified for temperature, time and sterility as
Each Load – review the information (printout or written record) from each autoclave run to ensure the correct parameters were achieved (correct temperature for the correct amount of time). Use autoclave sterility indicator strips and record the results.
Weekly, use spore vials as an additional check to confirm autoclave function.
Table 1 of ALACC’s AOAC International Guidelines for Laboratories Performing Microbiological and Chemical Analysis of Food and Pharmaceuticals lists “sterile” as a requirement for petri dishes. Certificates from the manufacturers are considered acceptable proof for records. Currently, manufacturers of petri dishes utilize multiple processes to produce petri dishes. As such, there are multiple terms used to describe the probability of contamination resulting from each process. The term sterile is reserved for describing processes with a terminal chemical treatment. Petri dishes without a terminal chemical treatment may have an acceptable probability of contamination for many laboratory processes, making them fit for purpose. Can the criteria be revised to allow for laboratory designation of the acceptable probability of laboratory contamination as it fits the purpose of the testing process?
While it is agreed that sterility is a complex concept, the sterility described as a requirement in Table 1 describes sterility in general and not any one, specific definition. The needs of the method will dictate the extent and manner of sterilization. In cases where chemical sterilization is required, the laboratory is expected to meet that requirement. If the use of non-chemical treatments is fit for the purposes used, then that would still be acceptable.
The batch size is, defined in the document for quantitative methods as "usually 20 samples or less", is that a maximum number that the lab must meet or alternatively can the size of the batch be determined as appropriate for the type of testing activity the laboratory is conducting?
ALACC 5.9 states:
For quantitative methods, accuracy and precision should be demonstrated to be acceptable; at a minimum, the laboratory shall run a quality control sample (QCS) with each batch of samples (usually of 20 samples or less). If a QCS is not available the lab must choose an alternate control sample such as a sample duplicate or reference material with each batch of samples (usually of 20 samples or less). For qualitative tests controls, such as QCS's, should be included to demonstrate that the test worked. The suitability of the controls used should be justified by the lab.
The ALACC guide in section 5.9 does not intend to define the size of a batch. The intent of this statement was to explain that in a batch, of whatever number of samples, Quality Control Samples (QCS) shall be included at a frequency defined, documented and justified by the lab. For many test methods, the QCS is included every 20 samples.
The lab must determine for itself the maximum number of samples that can be analyzed in one batch, or run contiguously between QCSs. The lab must document and justify its decision.
Labs use different terminology to define the number of samples that are either analyzed together in a group, such as samples on an ELISA plate or are run contiguously, such as liquid samples presented to an instrument. Some labs use the term batches, other labs use the term lots. Any term is acceptable; but, the lab must define the term unambiguously.
For qualitative tests, is it imperative that "controls such as the QCS...be included" or can it be left up to the lab to decide what is appropriate for a given test and whether controls are necessary?
Answer: Controls are necessary for qualitative tests. It is up to the lab to decide what is appropriate for a given test. This decision must be documented and justified. If no Quality Control Samples exist, the lab must do the best it can do.
Section 5.10.8 "Format of Rand Certificates" should state 5.10.8 "Format of Reports and Certificates."
184.108.40.206 Previously the section for Technical Records (formerly 4.12.2) stated that "All records shall be traceable to the analysis performed on a particular sample...". The new revision states that "the chain of custody for all records shall be unbroken from the time a laboratory takes responsibility for the sample until the result is reported to the customer..." The question thus concerns the intent of this clause and whether this is meant to be referring to all records or just to those records that pertain to the sample?
This section, 4.13.2 deals with Technical Records, and the ISO 17025 wording is "The records for each test or calibration shall contain sufficient information to facilitate, if possible, identification of factors affecting the uncertainty and to enable the test or calibration to be repeated under conditions as close as possible to the original.", so 4.13.2 deals with the records of the test. Section 4.13.1 deals with General Records. Therefore, 220.127.116.11 is meant to refer to those records that pertain to the sample.
Also in Section 5.9: For determining the accuracy and precision associated with quantitative methods, paragraph two states that a QCS must be run if one is available or that an alternate control sample (such as a sample duplicate or Reference Material) if one is not. Going on, paragraph four states that replicate tests shall be used if suitable Reference Material is available, and the sixth paragraph states that statistical process control charts shall be prepared for the QCS sample analyses and for the duplicate analyses if duplicates are used. Does this mean that both a QCS and a duplicate sample or a Reference Material replicate be run with each batch of samples or is a single QCS or RM acceptable?
If possible both a QCS and a duplicate sample should be run with a batch of samples because the QCS does not capture the variability unique to the sample(s). If either a QCS or sample duplicates are not available, the lab must explain this, demonstrate they tried their best to obtain/develop a suitable QCS or use sample duplicates and explain what they are doing instead.
Table 1 Since temperature holding equipment, in particular incubators often differ greatly in volume, should there be a point below which, where the volume of the unit is sufficiently small that it becomes irrelevant to require that they undergo temperature uniformity and stability studies? Similarly, for most uses of freezers, should there also be a lower limit at which their volume renders the determination of uniformity of temperature irrelevant?"
The last note in Table 1 addresses this point.
Due to size, use or design, some refrigerators and freezers may not need to be temperature and stability calibrated annually and may not need the demonstration of temperature uniformity and stability. In these cases the laboratory should justify the reason for an alternate frequency of calibration or for not demonstrating temperature uniformity and stability"
Yes, due to size, a point below which, where the volume of the unit is sufficiently small, the lab does not need to demonstrate temperature uniformity and stability. It is up to the lab to determine this size and justify not performing the temperature uniformity and stability studies.
ISO 17025 Section 5.2.1, first paragraph, second sentence reads, "When using staff who are undergoing training, appropriate supervision shall be provided." and ALACC states "Personnel shall have demonstrated their competency prior to working on customer samples."
Can actual samples be used in training or when demonstrating competency?
In the ALACC statement, the phrase "working on" means the analyst performs the analysis of customer samples independently with the intention of reporting the results. Ideally, during the training and demonstration of competency no customer samples would be used; however, in some cases customer samples may be used. Whenever a trainee is performing tasks on customer samples, the trainee must do so under the supervision of a trained analyst and it is the trained analyst who takes responsibility for these tasks. The lab must be able to defend to an auditor that the trainee performing the tasks does not impact the analysis. Examples of cases where a trainee may perform tasks on customer samples Simple tasks such as pureeing plant material such as lettuce; the task has a distinct endpoint that the trained analyst can observe and ensure the trainee has performed correctly. Entering sample sets into a computer, the trained analyst can verify the information is correct and entered correctly before the analysis takes place.