A direct injection high efficiency nebulizer interface for microbore high-performance liquid chromatography-inductively coupled plasma mass spectrometry
A simple, relatively low-cost interface is investigated for high-performance liquid chromatography using inductively coupled plasma mass spectrometry (ICP-MS) detection. The interface consists of a one-piece micronebulizer (direct injection high efficiency nebulizer, DIHEN), positioned in the ICP torch for the direct nebulization of solution into the base of the argon plasma. Microcolumn separations were performed in two modes: one, reverse-phase separation of three naturally occurring cobalamin species (hydroxocobalamin, cyanocobalamin, and adenosylcobalamin); and two, ion-pairing reverse-phase separation of five organolead and organomercury species [triethyllead (Et3Pb+), triphenyllead (Ph3Pb+), methylmercury (MeHg+), ethylmercury (EtHg+) and phenylmercury (PhHg+)]. For a 10 µL injection, absolute sensitivity in the ion pairing mode ranged from 2430 counts pg−1 (EtHg+) to 35880 counts pg−1 (Ph3Pb+) and peak area reproducibility (%RSD, n = 5) ranged from 0.7% (EtHg+) to 5.1% (PhHg+). Absolute detection limits were in the low- to sub-picogram range. Importantly, no plasma instability or carbon deposition on the nebulizer tip was observed using organic modifiers in the mobile phase of up to 20%.