Forensic Science (Chemistry Concentration)
Lori J. Wilson
A quality assurance and quality control (QA/QC) plan tells the data user the quality level of the generated data or how “good” the data is. A quality control program is implemented to maintain the reliability of the measurement process and reduce errors. Reproducibility is concerned with the ability of a data result to be consistently reproduced or be reliable time after time. Comparability focuses on the ability of a result to be compared with other data or criteria.
Laboratories with a good QA/QC plan will use pure standards, solvents and reagents. When applicable, reference standard solutions will be traceable to National Bureau of Standards. Pure water is used in analytical procedures and the cleaning of glassware. Glassware used will be washed with trace metal grade acid.
In this presentation, the basic components of a QA/QC plan will be reviewed, and we will report the development of a QA/QC plan to EPA Method 365.1.
We applied these principles to develop a QA/QC plan for the measurement of total phosphorous following acid and persulfate digestion over the concentration range of 0-5 ppm in natural waters. The best case LOD was 0.027 ppm P-PO4 and LOQ was 0.088 ppm P-PO4. These are lower than the LOD, 0.108 ppm P-PO4, and LOQ, 0.160 ppm P-PO4, previously reported. The QA/QC Plan developed in these runs used matrix spikes, duplicates, and standard reference materials. The results of each of these will be presented.