This document discusses quality assurance and quality control procedures for laboratories. It defines quality assurance as the planned and systematic implementation of a quality management system, while quality control checks that lab methods are performing as expected. It outlines several key aspects of a quality system including standardized methods, quality control samples, equipment maintenance, trained staff, corrective actions, and data management. The document also provides specific examples of quality control procedures laboratories can implement, such as running blanks, replicates, reference materials, and inter-laboratory comparisons. The goal is to ensure quality, accuracy, and consistency in laboratory testing.