(1) The sampling method of wiping, which is on the assumption that the pollutants are distributed into the surface of the equipment. When sampling, use a sampling stick whose bottom with an inert material (usually cotton or the similar) to wipe. Usually, one side of the sampling swab was pressured at the sample point and that was slowly and effectively wiped the surface of the equipment according to the first step. Then, wipe the other side of the sampling swab based on the graphical representation. The sampling point of the area is not fixed and can be changed from various types of the equipments. The usual wiping area is 10 times 10 square centimeters.
Sampling requirements:
It is required that the sampling rate of the surface sampling is known and there is no interference between sampling methods. Each device has at least 3 sampling points, each of the points are representatives.
Selection of the sampling points
Selection principle of the sampling point is: the sampling points will show the distribution of pollutants through residual quantity on the surface of the equipment which is estimated from the sampling points. Improper operation may cause unacceptable risks of related sectors or positions which include high concentration areas, areas which is difficult to clean, and so on.
(2) Rinse sampling method
It is a kind of indirect sampling method and can take samples from areas which are hard to get or sector which is difficult to remove. It is also can do an easy and unprofessional test for residue of the cleaning solution.
(3)Blank group method
Blank group method refers to produce a series of margin sample and check the residue from previous products. This method should be combined with the rinse sampling method and the sampling method of wiping. Its shortcoming is that it is hard to ensure the contaminants’ equal falling off from the surface of the device, it is laborious and expensive, and it is rarely used.
(4) Sampling and assessment of the microorganism
Microbiological assessment and chemical assessment are equally important in the enterprise strategy, which be involved in the field of the microorganism risk assessment analysis. The storage time of cleaning equipments, the storage time and conditions of cleaning equipment which have been cleaned should be taken into account.  The equipment after cleaning should be without hydrops and residue in any case.