Kjeldahl is one of the most commonly used techniques to determine the protein content in food and feed samples or the nitrogen content in soil, sludge, and water samples. The detection and quantification limits are important characteristics of analytical methods. The impact of the concentration of boric acid, the addition of potassium chloride, and the concentration of the titration solution on the detection and quantification limits were investigated. The best results were obtained by using 2 % boric acid with 3 g potassium chloride per liter. A titration solution of 0.005 M HCl worked best. With these parameters, detection limits for distillation of standard solutions as low as 0.008 mg nitrogen and quantification limits of 0.02 mg nitrogen can be achieved.