Determination of leucogentian violet in chicken fat by liquid chromatography with electrochemical and ultraviolet detection: interlaboratory study.

A laboratory trial was completed for a liquid chromatographic method that can quantitate leucogentian violet (LGV) in chicken fat at 10 ppb. With this method, LGV is isolated from the fat matrix by a series of liquid-liquid extractions. This trial evaluated 2 detection systems: electrochemical (EC) and ultraviolet (UV). The participating laboratories determined incurred residues at 2 levels as well as fat samples fortified at 5, 10, and 20 ppb. Using UV detection, the 3 laboratories reported the following range of recoveries: 71.0-89.6% at 5 ppb, 74.7-83.9% at 10 ppb, and 77.2-79.0% at 20 ppb. When these same samples were chromatographed with EC detection, the 2 reporting laboratories obtained the following average recoveries: 79.0 and 92.5% at 5 ppb, 75.9 and 85.4% at 10 ppb, and 77.3 and 79.8% at 20 ppb. The average concentrations found for the first level of incurred sample were 6.3, 6.3, and 5.4 ppb with coefficients of variation (CVs) of 2.4, 7.6, and 33.7%, respectively, when UV detection was used. Samples chromatographed with EC detection averaged 6.3 and 6.4 ppb with CVs of 4.0 and 8.2%, respectively. The second level of incurred sample gave average concentrations of 27.6, 29.0, and 10.9 ppb with CVs of 11.0, 5.0, and 42.8%, respectively, when the UV detection system was used. With the EC detector, the concentrations averaged 27.2 and 30.7 ppb with CVs of 15.7 and 3.5%, respectively.