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Improved GC Analysis of Derivatized Amphetamines

Featured Application: Derivatized Amphetamines on Rxi-5Sil MS

  • Ideal selectivity for GC analysis of amphetamines.
  • Exceptional inertness means good peak shape/response and better sensitivity.
  • Robust, low-bleed phase results in longer column lifetime.

Many drug assays, such as GC analysis of amphetamines, require that compounds be derivatized prior to analysis. Derivatization allows compounds that are not otherwise amenable to GC to be analyzed by this technique, and it also helps to produce unique, high molecular weight fragments that assist with GC-MS quantitation. While derivatization has its advantages, derivatization reagents and their byproducts are extremely harsh and can reduce GC column lifetime by damaging the stationary phase. Phase damage usually manifests as increased bleed and tailing of active compounds. The GC analysis of derivatized amphetamines shown below illustrates the low bleed levels, good peak responses, and symmetrical peak shapes that can be obtained by using a highly inert Rxi-5Sil MS column.

The unique Rxi-5Sil MS stationary phase, with its embedded arylene groups, provides a more rigid structure that is less likely to be damaged by drug derivatization reagents or their byproducts. Internal lifetime testing at Restek has demonstrated that after 400 injections of HFAA, a reagent used to derivatize amphetamines and other drugs prior to analysis, no changes in bleed or inertness were observed. The enhanced stability of Rxi-5Sil MS columns reduces phase bleed, resulting in longer column lifetimes and improved chromatographic performance for the GC analysis of derivatized amphetamines and other drugs of abuse with sensitive mass spectrometry detectors.

c = contaminant
ColumnRxi-5Sil MS, 30 m, 0.25 mm ID, 0.25 µm (cat.# 13623)
Diluent:Butyl chloride
Conc.:500 ng/mL HFAA derivatives
Inj. Vol.:1 µL splitless (hold 1 min)
Liner:3.5 mm splitless taper w/wool
Inj. Temp.:250 °C
Purge Flow:28 mL/min
Oven Temp.:75 °C to 300 °C at 15 °C/min
Carrier GasHe, constant linear velocity
Linear Velocity:45 cm/sec, 13.5 psi, 93.1 kPa @ 75 °C
Transfer Line Temp.:250 °C
Analyzer Type:Quadrupole
Source Temp.:200 °C
Electron Energy:70 eV
Solvent Delay Time:4 min
Tune Type:PFTBA
Ionization Mode:EI
Scan Range:40-300 amu
Scan Rate:5 scans/sec
InstrumentShimadzu 2010 GC & QP2010+ MS
NotesLiner cat.# 22286-200.1 was used to produce this chromatogram, but has since been discontinued. For assistance choosing a replacement for this application, contact Restek Technical Service or your local Restek representative.