When the product demand does not allow for a complete clean up after each batch, a campaign cleaning validation must be conducted. A back to back cleaning is performed between batches in a campaign, and a complete cleaning at the end of a campaign. Sampling of the equipment is performed after the last batch in a campaign, and all test results must meet predetermined acceptance criteria as per campaign cleaning validation protocol. Samples for residual active may be taken after back to back cleanings where possible, for information only . Microbiology samples may be taken after back to back cleanings in a campaign to ensure that there is no excessive microbial growth on the equipment.
Why western Blot samples turn yellow and precipitate? Sample appears to be acidic. Bromophenol blue in the loading buffer turns to yellow at acidic pH (below 3). Try to adjust the pH by adding NaOH [ 1 ]. Reason for that is proteins may be getting degraded due to heat exposure. One researcher had the same problem and so instead of keeping samples at 95 ° c he started warming at 60-65 ° C. So anyone can try it out and as [ 1 ] said check the pH as well of the loading dye [ 2] . Heating a sample also changes pH. An altered pH is not only responsible to turn the sample color yellow, but may also precipitate the proteins. Keeping SDS containing samples in ice is another common mistake to see this precipitation [ 3 ]. Another researcher said that he has got to do more with the total protein concentration in the lysate. He faced the same problem of precipitation upon denaturation at 100 ° c . He added 1/10th volume of 10% SDS and then boiled. Protein did not precipitate. T
Important of sampling during blending: Sampling plays a great role in achieving the accurate results of analysis. Sampling must and procedure must be defined in validation protocols and training should be provided to the concerned staff before the validation activities start. Samples are representative of the whole batch. So it should be handled and weight carefully because segregation may occur during weighing and transpiration. Sample quantity should not be more than the required and whole mass sample should be used in the analysis. Fig: Blending Machine Sampling for blend: Blends are tested for their homogeneity. Homogeneity of the blend is critical for the quality of the final product. The sample should be taken from at least 10 locations in the blender. The sampling location should be selected according to the difficulty of the blending. Ares of poor blending must be covered in sampling. Corners and discharged point must have sampling location.
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