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Precision and Accuracy of Analysis
Published in Pradyot Patnaik, Handbook of Environmental Analysis, 2017
The laboratory quality control program has several components: the documentation of standard operating procedures for all analytical methods, the periodic determination of method detection levels for the analytes, the preparation of standard calibration curves and the daily check of calibration standards, the analysis of reagent blank, the checking of instrument performance, the determination of precision and accuracy of analysis, and the preparation of control charts. The determination of precision and the accuracy of analysis and method detection limits are described under separate subheadings in the following sections. The other components of the quality control plan are briefly discussed below.
Evidence of canister contamination causing false positive detections in vapor intrusion investigation results
Published in Soil and Sediment Contamination: An International Journal, 2018
Thomas E. McHugh, Carlyssa Villarreal, Lila M. Beckley, Sharon R. Rauch
This calculation is different from the relative percent difference (RPD) calculation typically used for evaluation of laboratory quality control results where the difference in concentration is divided by the average of the two concentration results. When the difference in concentration is small, the two calculations yield similar results; for example, a pair with an RPD of 30% yields a percent difference value from Equation (1) of 35%. However, when the concentration difference is large, the RPD approaches a maximum value of 200% while the percent difference calculation is not bounded. For example, a pair with a 10× concentration difference yields an RPD of 164% and a percent difference of 900%. Thus, our percent difference calculation provides greater resolution for sample pairs showing large concentration differences.
Role of aquifer media in determining the fate of polycyclic aromatic hydrocarbons in the natural water and sediments along the lower Ganges river basin
Published in Journal of Environmental Science and Health, Part A, 2020
Srimanti Duttagupta, Abhijit Mukherjee, Joyanto Routh, Laxmi Gayatri Devi, Animesh Bhattacharya, Jayanta Bhattacharya
The quality assurance and quality control (comprised laboratory quality control procedures including analysis of the reference material (laboratory grade sand and kaolinite), field blanks and laboratory blanks, and spiked (1 µg L−1) PAHs (naphthalene, phenanthrene, and fluoranthene) added to the samples. Laboratory-grade kaolinite and quartz were considered for laboratory blanks. Deuterated-perylene and chrysene were injected with a concentration of 0.5 and 1 µg L−1, respectively (Appendix Tables A4 and A5). The recovery percentages were 79% for the water samples and 74% for the sediment samples. Laboratory blanks were also used for extraction and PAH analyses were conducted following the similar procedure.
Spatial distribution, contamination levels, sources, and potential health risk assessment of trace elements in street dusts of Urumqi city, NW China
Published in Human and Ecological Risk Assessment: An International Journal, 2020
Gulbanu Hini, Mamattursun Eziz, Weiwei Wang, Anwar Ili, Xinguo Li
The analytical data quality was analyzed by the laboratory quality control methods, including the use of reagent blanks, duplicates and standard reference materials for each batch of street dust samples. For the precision of the analytical procedures, a standard solution of elements was used to compare samples to national standards (Chinese national standards samples, GSS-12). The recoveries of samples that were spiked with standards ranged from 92.35% to 105.86%. All of the street dust samples were tested repeatedly, and the determined consistency of the repeated element measurements was about 94.5%.