Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1247405 | Talanta | 2006 | 6 Pages |
Abstract
An on-line system with vapour generation (VG) and Fourier transform infrared (FTIR) spectrometric detection has been developed for the determination of free ammonium and organic nitrogen in agrochemical formulations containing hydrolyzed proteins. Commercial samples were digested, in batch mode, with sulphuric acid and the obtained solution was alkalinized on-line to transform the NH4+ to NH3 that was continuously monitored by FTIR. Free ammonium was determined in the same system after simple dilution of undigested samples with water. Different gas phase separators were assayed in order to introduce gaseous NH3 into a home made IR gas cell of 10 cm pathlength, where the corresponding FTIR spectra were acquired by accumulating 10 scans per spectrum. The 967.0 cmâ1 band was used for the quantification of ammonia. The figures of merit of the proposed method involve a linear range up to 100 mg Lâ1, a limit of detection (3Ï) of 1.4 mg Lâ1 of N, a limit of quantification (10Ï) of 4.8 mg Lâ1 of N, a precision (R.S.D.) of 3.0% for 10 replicate determinations of a 10.0 mg Lâ1 of N and a sample measurement frequency of 60 hâ1. The method was successfully applied to the determination of free ammonium and total N in commercial amino acid formulations and results compare well with those obtained by the Kjeldhal method.
Keywords
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
N.M.M. Coelho, S. Garrigues, M. de la Guardia,