A Fast GC/MS/MS MRM Method for Semivolatiles that Meets EPA 8720D/E Requirements

New Environmental Monitoring Techniques for Organics
Oral Presentation

Presented by A. Smith Henry
Prepared by

Contact Information: melissa_churley@agilent.com; 408-553-7827


Triple quadrupole GC/MS/MS for semivolatiles analysis allows for a highly sensitive, ten-minute analytical method. The use of Multiple Reaction Monitoring (MRM) mode results in the ability to pass initial calibration requirements over the range of 0.02 ppm - 160 ppm in a single calibration run. Increased selectivity allows for faster batch review due to the elimination of matrix interferences that might be present when extracting ions in scan mode. Low compound RF %RSDs are predictive of an extended continuing calibration, which reduces cost of operation, and increased speed translates to greater laboratory productivity. The methodology is applicable to other regions worldwide in addition to United States EPA Method 8270D/E.
An Agilent 7000C or D mass spectrometer, coupled to a model 8890 or 7890B GC with 240V oven for fast temperature programming, was autotuned using the etune algorithm. A low pressure-drop GC liner with glass wool and a 20m x 0.18 mm x 0.18 Ám, 5% phenyl (polysiloxane) column were used. Injection was 1 ÁL into a SSL inlet using a 1:20 split. Twelve calibration levels ranging from 0.02 to 160 ppm were prepared using a 77-compound mix, and ISTDs were added at 4 ppm. Dynamic MRM acquisition mode was used for efficient use of instrumental analytical time.
Initial calibration results from several laboratories were evaluated for acceptability. Passing criteria are that the average RF %RSD must be ? 20; if not, R2 ? 0.990 is required for a linear curve fit. A quadratic fit may be used. In a representative data set, 68 compounds passed the average RF %RSD requirement, a linear fit was used for three compounds and five required a quadratic fit. There were cases in which no quadratic fits were required; e.g., 68 compounds passed average RF %RSD and nine passed by using a linear curve fit.