Aerts R M, Werdmuller G A
State Institute for Quality Control of Agricultural Products, Wageningen, The Netherlands.
J Assoc Off Anal Chem. 1988 May-Jun;71(3):484-90.
A liquid chromatographic (LC) method previously published for the determination of carbadox in finished feeds and premixes was slightly modified and tested in an interlaboratory study. The feed samples are extracted with methanol-acetonitrile (50 + 50) after wetting with water. The extracts are purified over a short alumina column. An aliquot of the eluate is analyzed with reverse phase liquid chromatography with ultraviolet detection. Before the actual interlaboratory study, a prestudy with 2 familiarization feed samples was performed. For the interlaboratory study, 2 series of meal and pelleted samples were prepared with carbadox from different suppliers. Eight collaborating laboratories received 6 feed samples previously milled and ground and 4 pelleted samples which had to be ground by the collaborator's in-house method. Collaborators also received 3 carbadox concentrates (about 10% w/w) and 4 premix samples derived from the concentrates (about 1% w/w). Coefficients of variation under reproducibility conditions were 8.3% for meal samples and 4.9% for pellets. A minor but significant effect was noted for the influence of pelleting temperature on the carbadox content. A minor and insignificant effect was observed for the influence of the milling and grinding procedure on the carbadox content. Alumina cleanup of 1% premixes was not essential, although the resulting chromatograms were cleaner. A slight difference in reproducibility was observed with concentrates (10%) when 0.2 or 0.5 g sample size was used, although the average carbadox concentration found was the same. For premixes and concentrates, coefficients of variation under reproducibility conditions were low, ranging from 2.9 to 7.5%.
先前发表的一种用于测定成品饲料和预混料中卡巴氧的液相色谱（LC）方法经过了轻微修改，并在一项实验室间研究中进行了测试。饲料样品用水润湿后，用甲醇 - 乙腈（50 + 50）萃取。萃取液通过短氧化铝柱进行净化。取一份洗脱液用带紫外检测的反相液相色谱进行分析。在实际的实验室间研究之前，用2个用于熟悉的饲料样品进行了预研究。对于实验室间研究，用来自不同供应商的卡巴氧制备了2系列的粉状和颗粒状样品。八个合作实验室收到了6个预先研磨好的饲料样品和4个颗粒状样品，后者需要合作实验室用其内部方法进行研磨。合作实验室还收到了3种卡巴氧浓缩物（约10% w/w）和4种由这些浓缩物制得的预混料样品（约1% w/w）。在再现性条件下，粉状样品的变异系数为8.3%，颗粒状样品为4.9%。注意到制粒温度对卡巴氧含量有轻微但显著的影响。观察到研磨和粉碎程序对卡巴氧含量有轻微且不显著的影响。对于1%的预混料，氧化铝净化并非必需，尽管所得色谱图更干净。当使用0.2或0.5 g的样品量时，浓缩物（10%）的再现性存在轻微差异，尽管所测得的卡巴氧平均浓度相同。对于预混料和浓缩物，在再现性条件下的变异系数较低，范围为2.9%至7.5%。
