Modern Mass Spectrometers and the Correlation Coefficient – Are They Compatible?Collaborative Efforts to Improve Environmental Monitoring
Oral Presentation
Prepared by R. Burrows
Eurofins Environment Testing America, 4955 Yarrow St, Arvada, Colorado, 80002, United States
Contact Information: richard.burrows@eurofinset.com; 303-736-0145
ABSTRACT
Modern mass spectrometers, including GC/triple quadrupole (GC-MSMS) and GC/Time of Flight (GC-TOF) offer several advantages relative to single quadrupole instruments currently used for almost all environmental analysis, particularly for routine semivolatiles analysis (methods 8270 and 625). Some of these instruments offer an additional dimension of selectivity through multiple reaction monitoring, and their sensitivity is such that the working range can encompass levels that traditionally require selected ion monitoring in the same run as levels typically analyzed by full scan on single quadrupole instruments.
Previous papers in this series have discussed problems with the use of correlation coefficient and coefficient of determination for evaluation of calibration quality, as required by many EPA methods.
Unfortunately, these problems become even more severe when the instrument working range is extended using modern mass spectrometers. This paper will illustrate that use of the correlation coefficient and coefficient of determination essentially forces the analyst to select inappropriate calibration fits when using extended working ranges. These calibration assessment tools are outdated and need to be removed from EPA methods as soon as possible.
