Nitrogen-selective detector for high-performance liquid chromatography

Abstract

A nitrogen-selective detector for high-performance liquid chromatography (HPLC) is described. The HPLC effluent is introduced into a furnace using a concentric atomizer. Organic nitrogen is converted to ammonia by reaction in hydrogen over a nickel catalyst. The ammonia is collected into water-alcohol and the ammonium ion is measured with a Tracor Hall electrolytic conductivity detector. The limit of detection is 1 ng nitrogen per sec injected onto the chromatographic column. The carbon to nitrogen selectivity ratio is 10,000. Precision is 3.4% relative standard deviation when 0.56 μg nitrogen are injected. The detector is linear over a narrow range. Deviation from linearity is most likely due to incomplete partitioning and ionization of ammonia in the conductivity solution. Applications using both normal and reversed-phase conditions are discussed.