BS ISO 21322-2020 Cosmetics一Microbiology一Testing of impregnated or coated wipes and masks.
4.3 Selection of the method
The method should be conducted according to an appropriate procedure based on the specifics of the product (size, volume, single unit/multi- unit package, level of b.oburden. etc.) and should ensure that a representative sample is evaluated.
Selection of the method shall be according to Al and Al.
4.4 Recovery of microorganisms from the test sample
The degree to which microorganisms adhere to the test sample surface is dependent on the wipe or mask in which the liquki portion of the formulation has been either impregnated or coated. Preliminary treatments may be necessary to separate microorganisms from the test sample.
Regardless of the treatment, the verification of recovery method should be performed in order to demonstrate that the method can release microorganisms from the test sample without having an adverse effect on their viability (see Clause 11)
4.5 Enumeration of aerobic mesophilic microorganisms
The enumeration of aerobic mesophilic microorganisms includes bacteria, yeasts and moulds.
Based on the nature of the test sample, the volume of diluent used to immerse the test sample and the expected level of bioburden, two types of counting methods may be used:
— plate count method:
membrane filtration method.
4.5.2 Plate count method overvIew
PLate Count method consists of either using a pour plate or spread plate method. Each method consists of the following steps,
– – Prepare the agar plates and diluent using a non-selective agar medium for plating the diluent in
which the sample was immersed.
— Incubate the plates for enumeration and/or detection.
— Count the number of colonies forming units (CFLJ) based on the number of aerobic mesophilic microorganisms recovered per unit org.
45.3 Membrane filtration method overview
Membrane filtration consists of the following steps.
— Transfer the diluent or a defined quantity of diluent In which the test sample was Immersed to a filtration apparatus wetted with a small volume of an appropriate sterile diluent.
— Alter filtration and rinsing_ transfer the membrane filter onto the surface of plates with non- selective agar medium.
Aerobic incubation of the plates.
— Count the number of colony forming units (CFJJ) and calcuLate of the number of aerobic mesophilic microorganisms per g or unit.BS ISO 21322 pdf download.