eSeparation Times Volume 19, Number 5 

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Agilent service contracts can cover other manufacturer’s LCs. It’s true! Say “goodbye” to the 16-bit original and “hello” to the more powerful 32-bit ChemStation! 2-D Heartcutting GC/MS: A cost-effective alternative to GC/MS/MS.

2-D Heartcutting GC/MS:
A cost-effective alternative to GC/MS/MS

Bruce D. Quimby, Ph.D.
Senior Applications Chemist

GC/MS using a quadrupole mass spectrometer is the instrument of choice for many labs. Some samples, however, have severe matrix interferences that prevent successful analysis. For these samples, techniques like GC/MS/MS and LC/MS/MS are often used. The higher level of selectivity afforded by a secondary mass spectral step is used to overcome interferences. Alternately, the use of two dimensional (heart cutting) GC with a single quadrupole MS can often be a simpler and more cost-effective means of analysis.

	FID signal from first column (DB-1MS)
	SIM chromatograms of TMS derivatives of THC and D3-THC (used as internal standard)
	10 ng/mL THC in oral fluid matrix. (Click here to see these images larger.)

Agilent now offers the Oral Fluids Analysis Kit for the 5975 GC/MSD system (option 652), an integrated two dimensional (heart cutting) GC/MS system. It consists of a standard quadrupole GC/MS system to which a Deans Switch and air cooled focusing trap have been added. The hardware is fully integrated, factory tested, and supported by Agilent’s world class service organization.

The primary GC column is a non-polar DB-1MS and the second column a polar DB-17MS. Upon injection into the GC, the analyte(s) and matrix separate on the first column. The Deans Switch is time programmed to heart cut the analyte(s) onto the second column, where they are focused by the air cooled trap. When the trap is heated, the analyte(s) are separated from the matrix compounds that co-eluted with them on the first column. The focusing trap is used to improve both resolution and sensitivity.

The detection of drugs of abuse in oral fluids serves as a good example of where GC/GC/MS can be used. The example shown shows the separation of the TMS derivative of tetrahydrocannabinol(THC) from simulated oral fluid matrix. Drugs such as phencylidine and opiates can also be determined this way.