Abstract: Objective: To establish a simple rapid method for determining Kjeldahl nitrogen content by 1st order differential coefficient single sweep polarography. Method: The digested liquid was diluted and pipetted into a solution of formaldehyde in an acetate buffer. The hexamethylenteramine produced by ammonium and formaldehyde reaction was determined electrochemi- cally at –824 mV. The nitrogenous quantity was obtained by the method of standard curve. Results: The polarographic wave of 1st order differential was determined. The relative standard deviation was 3.3%.The recovery rate of nitrogen was 98.6%～ 102.6%.10 different foods were analysed. There was no significant difference between the result by this method and Kjeldahl method (p>0.1). Conclusion: It is a simple, rapid and accurate method for determining Kjeldahl Nitrogen in foods.

Key words: single sweep polarography, determination, Kjeldahl nitrogen, foods