用“磷－钒－钼酸铵”比色法测定饲料添加剂的均匀度

本试验在四种畜禽微量元素饲料添加剂生产过程中，添加经处理后的同质的磷酸氢钙，其添加量分别为０．５％、０．５％、２．５％、５．０％，添加后，各添加剂含磷分别约为：８００、８００、４０００、８０００ｐｐｍ，与添加剂中铜、铁、锌含量处于相近或相差较大的两种水平。本方法是应用７２１型分光光度计，采用“磷－钒－钼酸铵”比色法测定磷，根据含磷量的变异系数来确定添加剂的均匀度，其方法简介如下：用正确的采样方法，对每个品种采集试样十个，每样５０克，并在实验室中按规定方法进行样品制备。然后精称各制备后试样０．５克左右，放于１００ｍｌ烧杆中，用１：１ＨＣｌ２０ｍｌ和浓ＨＮＯ＿３０．５ｍｌ、煮沸３～５分钟，经反复过滤，收集所有滤液于１００ｍｌ容量瓶中，冷却至室温，再定容，摇匀，即成试样分解液。精取分解液２～４０ｍｌ于５０ｍｌ容量瓶中，加入１０ｍｌ钒钼酸铵显色剂，定容后摇匀，静放１０分钟以上，在４２０ｎｍ波长下，用１０ｍｍ比色池，用７２１型分光光度计进行测定光密度，并对照标准曲线，计算含磷量和添加剂均匀度的变异系数。另应用原子吸收光度计，测出添加剂的铜、铁、锌含量，并计算它们的变异系数（均匀度）。本实验方法的结果表明：无论含磷量与?

MEASURMENT OF UNIFORMITY OF FEED ADDTIVES BY USING METHOD OF″(NH_4)_3PO_4·NH_4VO_3·16MoO_3 CoLOR-DEVELOPING″

During the production of 4 kinds of feed addtives,0.5%,0.5%,2.5%and 5%treated CaHPO_4 wereadded to respectively. The concentrations of P in the 4feed addtives were 800 , 800, 4000 , 8000ppm , which weresimilar to or higher than the concentrations of Cu,Fe,Zn in feed addtives. The concentration of P was determined byusing″(NH_4)_3PO_4·NH_4VO_3·16MoO_3color-developing″ method with a 721 Spectrophotometer.The uniformity ofthe feed addtives was difinited according to the c, v of concentrations of P,The method was brietly introduced asfollows:The samples of 50g were collected from each feed addtive. , According to the normal methods ,the samples were prepare.0.5g prepared samples from samples of each feed addtive were put into 1 00ml bcakers.20 ml 1: 1 HCIand HNO_3 of high concentrating were added in each beakers. The solutions were boiled for 5 min , then wererepeated filtered. Each filtered solution was collocted into a 100ml volumetric flask and cooled to room tempreture,then the volume was deterimed at 100ml. This kind of soluttion of samples were called solution of decomposition.2to 40ml solution of deconposition was added to a volumetric flask,then 10ml colo-developing agent calledAmmonium Vanawdate-Molybdate was added to the volumetric flask. The total volume was deterimed to 50ml.The volumetric flask was still for 10 min, The concentration of P of each sample was measurment with the 721spectrophotometer underthe weave length of 420 nm. The C. V of P concentraion was calculated. The concentrations of Cu,Fe, Zn were measured with atomic absorbtion spectrometer. The C. V of concentration of Cu, Fe,Zn were calculated.The results showed that , no matter how big the difforen of the coneentrations between P and Fe, Cu, Znin the foed addtives was , the uniformity of the feed adtive measured by″(NH_4)_3PO_4 · NH_4VO_3·16MoO_3 color-dereloping″ method a 721 spectrophotometer and atomic absorbtion spectyometry was same ,The relative error waslass than 3%. Therefore the″(NH_4 )_3PO_4·NH_4VO_·16MoO_3 color-developing″ method can be used to measurethe uniformity of feed addtive.