Thin-layer chromatography combined with diode laser thermal vaporization inductively coupled plasma mass spectrometry

• Novel coupling of TLC to diode laser thermal vaporization ICP MS.
• Simple design and inexpensive instrumentation.
• Cobalamins separated on cellulose TLC plate were scanned with a 1.2 W diode laser.
• Vaporized analytes were carried to ICP MS providing detection down to 2 pg.
• The technique was demonstrated on quantitation of cobalamins in a vitamin supplement.

Here we present a novel coupling of thin-layer chromatography (TLC) to diode laser thermal vaporization inductively coupled plasma mass spectrometry (DLTV ICP MS). DLTV is a new technique of aerosol generation which uses a diode laser to induce pyrolysis of a substrate. In this case the cellulose stationary phase on aluminum-backed TLC sheets overprinted with black ink to absorb laser light. The experimental arrangement relies on economic instrumentation: an 808-nm 1.2-W continuous-wave infrared diode laser attached to a syringe pump serving as the movable stage. Using a glass tubular cell, the entire length of a TLC separation channel is scanned. The 8-cm long lanes were scanned in ∼35 s. The TLC – DLTV ICP MS coupling is demonstrated on the separation of four cobalamins (hydroxo-; adenosyl-; cyano-; and methylcobalamin) with limits of detection ∼2 pg and repeatability ∼15 % for each individual species.