Although the terms “Quality Control (QC)” and “Quality Assurance (QA)” are often used interchangeably, the terms are in fact quite different, but related. Donald E. King defined the concepts in Credibility: The Consequence of Quality Assurance, from the May 1982 DATA Quality Report Series, Ontario (Canada) Ministry of the Environment.

Quality assurance is described as a management function which rests on the documentation and establishment of quality control protocols, and on the evaluation and summarization of their outcomes.

Quality control is a technical, operational function which investigates and confirms the proper conduct of all those procedural components necessary to a successful conclusion.

Quality control is a variety of techniques that the sampler and analytical chemist perform to verify that the sampling and analytical protocols meet the desired goals for data quality. Quality control functions help to ensure data validity and traceability. Quality assurance is the system for checking and ensuring the quality control criteria are met and what actions are taken in the event they fail to meet criteria.

A quality assurance system can be divided into components:

• Inputs,
• Processes, and
• Outcomes.

The following table subdivides each of the components into its basic elements.

The paper examines the quality assurance elements that must be addressed by laboratories and their customers when samples are submitted for analysis. The quality assurance processes begin at the sampling design stage and include:

• Chain-Of-Custody procedures & sample tracking
• Sample handling & storage procedures including; holding times & preservation
• Method validation
• Method verification
• Instrument calibration
• QC samples & standards procedures including; frequency and performance evaluation
• Internal audits
• Personnel training & qualification
• Equipment capabilities & maintenance program