CANFAS : 2nd collaborative study for the determination of nicarbazin in a premixture by HPLC
Year: 2002
Type: report
Abstract: This report describes the results of a 2nd collaborative study of an HPLC method for the coccidiostat nicarbazin in one premixture.The collaborative study forms part of the EU-project "Development and Validation of HPLC-methods for the official control of Coccidiostats and Antibiotics used as Feed Additives (CANFAS-SMT4-CT98-2216).The results of the first collaborative study showed that the reproducibility of the method was not satisfactory for the premixture (the HORRAT ratio for the premixture was too high).During the evaluation meeting it was decided that a new small collaborative study had to be organised with a modified method in which the sample weight and the extraction volume are doubled compared to the original method.In the modified method the calibration method is also more strict described stating that the concentration of the premixture extract should be in the middle of the calibration curve.The principle of both the original and the modified method is as follows: samples are extracted by heating in a waterbath, mechanical shaking and sonoration using an acetonitrile/methanol mixture.The mixture is transferred in a volumetric flask.After settlement of the solids, an aliquot is filtered and assayed using a reverse-phase isocratic method, which measures the 4,4'dinitrocarbanilide (DNC) moiety at a wavelength of 350 nm.For the collaborative study 1 premixture with declared content of 0,75 % nicarbazin was prepared.The premixture was sent to the participants as a single sample.The participants were asked to analyse the premixture in duplicate.Results were reported by 17 laboratories.Statistical evaluation was performed according to ISO 5725.During the first collaborative study satisfactory results for recovery, blind blank feed and feedingstuffs were obtained.The results of the second collaborative study show that with the modified method for premixtures acceptable results are obtained for repeatability.Statistical evaluation of the data with regard to reproducibility shows that it is very important to follow the method strictly.If only the results are taken into account of the laboratories that applied the method in sufficient detail, a Horrat ratio < 2 is obtained.It can be concluded that the reproducibility of the modified method is satisfactory, provided that it is followed strictly.The following points seem to be of special importance: -Weight of the premixture (1 g) -Range of the calibration curve (1-10 mgAg) -Quality (correlation coefficient) of the calibration curve The final method can be recommended for adoption as an official method and, together with the results of the collaborative studies, it will be sent to the European Commission (CEMA), CEN and ISO.
Authors: J. de Jong, J.J.M. Driessen, M.J.H. Tomassen, H.J. Keukens
Language: English
Subfield: Analytical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2144353349