Quality Assurance/Quality Control - FAQs
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QA is an integrated system of management activities that involves planning, implementation, documentation, assessment, reporting, and quality improvement to ensure that a process, item, or service is of the type and quality needed and expected by the client.
QC is the overall system of technical activities that measures the attributes and performance of a process, item, or service against defined standards to verify that they meet the stated requirements established by the customer; operational techniques and activities that are used to fulfill requirements for quality.
QC also involves analytical frequency requirements and control limits.
A QAPP is a 24 element document describing in comprehensive detail the necessary QA, QC, and other technical activities that must be implemented to ensure that the results of the work performed will satisfy the stated performance criteria.
A QAPP will provide tables with QC sample requirements and measurement quality objectives (MQOs). It also outlines the ways you will assess and report your data.
View EPA Guidance EPA QA-G5 for more information on QAPPs.
Any documents prepared before the QAPP, such as monitoring plans, data quality objectives, standard operating procedures (SOPs), work plans, literature files, and data sets from other projects, may be appended to this QAPP or incorporated by reference.
MQOs are specific goals defined by data users that clearly describe the data quality that is sought for the project. The quality assurance program should focus on the definition, implementation, and assessment of MQOs that are specified for the sampling, analysis, and verification phases of the project. The MQOs should be defined according to the following six quality assurance objectives and attributes:
- Detection Limit – The lowest concentration of an analyte that a specified analytical procedure can reliably detect.
- Bias – The difference between an observed value and the "true" value (or known concentration) of the parameter being measured; bias is the first component of accuracy, which is the ability to obtain precisely a nonbiased (true) value.
- Precision – The level of agreement among multiple measurements of the same characteristic; precision is the second component of accuracy.
- Representativeness – The degree to which the data collected accurately represent the population of interest (e.g., contaminant concentrations.)
- Comparability – The similarity of data from different sources included within individual or multiple data sets; the similarity of analytical methods and data from related projects across areas of concern (AOCs).
- Completeness – The quantity of data that is successfully collected with respect to the amount intended in the experimental design.
To see MQO tables, please view the Quality Control and Sample Handling Guidelines web page.
These guidelines are also known as Measurement Quality Objectives (MQOs) or MQO Tables.
For the purposes of comparable monitoring, the reporting limit (RL) is defined as the lowest measured value of an analyte, for a chemical analysis, that can be reliably detected and quantified within acceptable limits of precision and bias for a given method. This value is further defined as no lower than the lowest calibration standard performed within the calibration process. Analyte detections between the method detection limit (MDL) and the RL are reported as having estimated concentrations utilizing the qualifier code of "Detected, Not Quantified" (DNQ).
The method detection limit (MDL) is defined as the minimum concentration of a substance that can be measured and reported with 99% confidence that the analyte concentration is greater than zero and is determined from analysis of a sample in a given matrix containing the analyte. - 40 CFR 136, Appendix B
For more information on reporting limits see the webinar training.
An Introduction to the Concept of Reporting Limits (scroll down to 01/19/2012; webinar length - 58 min)
The SWAMP QAPrP serves as an umbrella document for use by each of SWAMP's contributing projects. It describes SWAMP's quality system including elements such as; responsibilities of management and staff; as well as quality control and sample handling guidelines for both laboratory and field activities.
Like a QAPrP, a QAPP follows formal EPA content and format requirements. However, a QAPP's scope addresses project-specific considerations (e.g., logistics, instrumentation), rather than the more generalized needs of a large-scale program.