4 - Understanding the analytical laboratory

Abstract

This chapter deals with laboratory analysis and laboratory QA/QC by identifying the critical aspects of chemical analysis and emphasizing their importance for data quality. Using various analytical techniques, laboratories routinely identify and quantify hundreds of organic and inorganic analytes in an assortment of environmental matrices while adhering to the requirements of specific QA/QC protocols. The perceived validity of obtained data is based on the observance of specific requirements, whereas the actual validity of the data depends on the solid qualitative and quantitative analysis and on the adherence to standard analytical laboratory QA/QC protocols. A full-service analytical laboratory is a complex organization because some of the laboratory personnel may not fully understand the relationship between different laboratory functions or production units. Different laboratories have different internal organizations, but all laboratories have two things in common: the general process by which environmental samples are transformed into data and a laboratory quality system. Internal data review is the most effective mechanism for avoiding errors of interpretation and procedure. The various analytical methods used by environmental laboratories for different types of organic and inorganic pollutant determinations include gas chromatography, flame ionization detector, photo-ionization detector, electrolytic conductivity detector, nitrogen-phosphorus detector, flame photometric detector, mass spectrometer, liquid chromatography, ultraviolet/visible photometer, diode array detector, and ion-exchange chromatography. Two important components of a quantitative analysis of environmental samples are the determination of method-detection limits and instrument calibration. Quality assurance is a set of operating principles that enable laboratories to produce defensible data of known accuracy and precision