LC/MS Analysis of Twenty-Two Illicit Phenethylamine and Cathinone “Bath Salts,” including Isobars, in Saliva on Ascentis® Express HILIC after Extraction using SPME LC Tips

LC/MS Analysis of Twenty-Two Illicit Phenethylamine and Cathinone “Bath Salts,” including Isobars, in Saliva on Ascentis® Express HILIC after Extraction using SPME LC Tips

Conditions

sample/matrix Human saliva adjusted to pH 3.0 with formic acid and spiked at 20 ng/mL with the twenty-two Bath Salts compounds. A 200 μL aliquot of saliva was placed into a 300 μL conical 96-well collection plate.
SPME fiber SPME LC Tip
extraction SPME LC fibers were preconditioned in 50:50 methanol:water and placed into sample wells. Extraction was performed for 15 minutes on an IKA VORTEX MS3 shaker at 500 rpm.
sample/matrixr Fibers were then desorbed in 100 μL of 0.5% ammonium hydroxide in methanol for 60 minutes at 500 rpm vortex. (Desorbed samples were then evaporated and reconstituted in 40 μL of acetonitrile and analyzed directly.)
column Ascentis Express HILIC, 5 cm x 2.1 mm I.D., 2.7 μm (53934-U)
mobile phase 5 mM ammonium formate (98:2 acetonitrile:water)
flow rate 0.6 mL/min
pressure 1262 psi (87 bar)
column temp. 35 °C
detector ESI(+), 100-1000 m/z
injection 1 μL

Description

Featured Industry Forensics and Toxicology
Legal Information Ascentis is a registered trademark of Sigma-Aldrich Co. LLCC
suitability application for HPLC
application for LC-MS
application for SPME
Analysis Note The Ascentis Express HILIC column was able to resolve the five groups isobaric compounds under ideal MS conditions. Other coelutions are not a problem because they are not isobaric and will be separated in the mass spectrometer. Regarding sample prep, this experiment successfully demonstrated the potential of new biocompatible SPME LC fibers for extraction of analytes of clinical, bioanalytical or forensic interest from a variety of biological matrices prior to LC/MS analysis. With the spiked saliva samples, SPME LC gave five- to ten-fold increase in detected analytes compared to the traditional "dilute and shoot" method. We also studied spiked plasma samples, compared to standard protein precipitation the SPME LC technique had ten-fold reduction in detected matrix and over two-fold increase in response for the analytes tested.

Materials

     
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