ABSTRACT
A determination method of nosiheptide in formula feeds by HPLC-FL was developed and validated, including an inter-laboratory study. Formula feeds were extracted with acetone after adding acetic acid. Liquid chromatographic separation was performed using a ZORBAX Eclipse XDB-C18 column, with acetonitrile and water containing acetic acid as the mobile phase. Detection of NH was carried out with a fluorescence detector. Recovery tests and an inter-laboratory study were conducted using chicken and swine formula feeds fortified with nosiheptide at 0.5-27 mg-potency/kg. Mean recoveries in recovery tests ranged from 91.4 to 103%, and the repeatability in terms of relative standard deviation was within 7.8%. Mean recoveries of the inter-laboratory study ranged from 98.4 to 108%, the repeatability and reproducibility in terms of the relative standard deviations were within 8.1% and 13% respectively, and the HorRat values ranged from 0.21 to 0.75.
Subject(s)
Animal Feed/analysis , Chromatography, High Pressure Liquid/methods , Food Analysis/methods , Laboratories , Observer Variation , Reproducibility of Results , Thiazoles/analysis , Thiazoles/isolation & purificationABSTRACT
The present research was intended to determine the suitability of the CALUX assay as a screening method for dioxins in fish oil used as a feed ingredient in Japan. Alteration of TEQ in fish oil according to newly proposed toxic equivalency factors (TEF) is also discussed. In the analysis, polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in 41 fish oil samples were determined by using high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS) and CALUX bioassay. The mean TEQ values derived from 1998 WHO-TEF of PCDD/Fs and DL-PCBs were 2.6 and 9.9 pg g(-1) (ww), respectively. The levels of TEQ derived from the recently re-evaluated 2005 WHO-TEF were slightly lower than those of the former in both groups. Notably, the contribution of mono-ortho DL-PCBs to total 2005 WHO-TEQ was considerably decreased compared to the case of 1998 WHO-TEQ, resulting from the reduction in its TEF values, while the non-ortho DL-PCBs contribution was increased. The mean TEQ determined by CALUX assay for PCDD/Fs was approximately three times higher, whereas DL-PCBs was approximately two times lower than WHO-TEQ determined by HRGC/HRMS; the sum of PCDD/Fs and DL-PCBs was very similar by both methods. The correlation coefficients of TEQ between the CALUX assay and HRGC/HRMS analysis were 0.84, 0.89, and 0.90 for PCDD/Fs, DL-PCBs, and the sum, respectively. These results suggest that the CALUX assay is a very useful method for the screening of dioxin-related compounds in fish oils.
