Simultaneous determination of total nitrogen and metal elements in tobaccos by high performance ion chromatography

Abstract

Asimple method, developed primarily for simultaneous determination of total nitrogen and inorganic cations by high performance ion chromatographic (HPIC), was optimized for digestion of flue-cured tobaccos, and compared with the traditional Kjeldahl method and atomic absorption spectrometry (AAS). Nitrogen determination by either Dumas method or Kjeldahl method is time-consuming and tedious. Metal elements determination by either inductively coupled plasma-mass spectrometry (ICP-MS) or AAS may be more expensive and requires specialist equipment. The use of HPIC to simultaneous determine total nitrogen as ammonium ion and metal elements as inorganic cations after sample digestion significantly improves the speed of the analysis compared with the conventional methods. The cation-exchange column and suppressed conductivity detector was used for determination of ammonium and inorganic cations in the presence of the elevated levels of sulfuric acid found in digested sample. The propsoed digestionmethod was accurate and precise, and required little investment. The determination of ammonium and inorganic cations was linear from 15 pg·L-1 up to 25 ng·L-1. The results obtained by the HPICmethod were compared with those for the conventional methods approach for the determination of total nitrogen and metal elements. The application of the HPIC method is also demonstrated for a variety of other plant samples matrices.