It's just a monoclonal antibody It's quite common. Even if the buffer solution of the preparation is used, this situation will still occur if no surfactant is added. After the third purification step, it will appear again. The floc you see is generally protein, but in this case, the concentration cannot be distinguished. Only when a large number of protein aggregates, the whole sample turns white, and the detection concentration will be significantly reduced. I once encountered a stranger phenomenon. The sample after affinity is extremely turbid. After standing for one night, a lot of sediment can be clearly seen at the bottom of the bottle, but this phenomenon will not appear again after filtering. At that time, it was suspected that it was caused by HCP, DNA, etc. However, the values of HCP and DNA are relatively normal, which are not much different from those of other items. In the first step, affinity is not used, and anion treatment is used after treatment. At this time, the content of HCP and DNA is much higher than that of affinity collection, but it is very clear. After anion, the sample is affinity and the sample is clear. Protein's performance in the buffer is indeed varied, because there is no further analysis result.