Selecting the Swab Sampling Area

beiwei5du

December 2005Selecting the Swab Sampling Area

This Cleaning Memo addresses the question of the specific surface area to swab in a cleaning validationprotocol. For clarification, this will address the size of swab area, not the location of the swab area. Mostcompanies will swab areas of 25 cm2(4 square inches) to 100 cm2(16 square inches), although I have seenswab areas as large as 400 cm2.
There are no regulatory guidelines for selecting the size of the area to be sampled. Note, however, that therehas been at least one FDA 483 citation for using too small an area for sampling environmental surfaces forpenicillin. It should be noted that this concern was specific to this situation, in which it was probably believedthat swabbing a smaller area was less likely to detect penicillin contamination on environmental surfaces.
What are the advantages and disadvantages of different swab areas for swabbing? For simplicity, we willconsider sampled areas of 25 cm2as a small area and 100 cm2as a larger area. In each point discussed below,it will be considered on an “other things being equal” basis.
One advantage of swabbing a larger area is that the residue limit in the analytical sample will be higher. Thismeans that the limit of detection or limit of quantitation of the analytical limit could be higher. For example, ifI swab 100 cm2and then desorb it into 20 mL of solvent, the residue limit in the analytical sample will be fourtimes larger than the residue limit if only 25 cm2 were sampled and the swab desorbed into 20 mL of solvent.Note that while the limit in the analytical sample is higher with the larger surface area, there is no difference interms of the risk of passing or failing (because the amount of residue potentially swabbed from the surface willbe four times as great with the larger surface area).One advantage of swabbing a smaller area is that I am more likely to get a higher recovery. As a generalprinciple, the larger the surface area the lower the recovery. This may be due to the fact that when I use a wetswab (as is usually the case), I am going to leave a finite amount of liquid on the swabbed surface. The largerthe area swabbed, the more liquid will be left behind. It should be noted that the difference may be small incomparison to the overall recovery. One way to minimize this effect is to use two swabs on the same surfacearea, with the second swab being dry.
Another factor in the use of a larger area is that there may be less variability in the actual area sampled. If I amoff by a length of 0.5 cm in each direction for my swabbing, then the variability of area coverage may be asmuch as ± 10% for a swab area of 100 cm2. If I am off by the same 0.5 cm in each direction for a swab area of25 cm2, then the variability of area coverage may be as much as ± 20%. This effect can be negated if I were touse a template for controlling the sampled area (instead of using the “eyeball” method).
A final consideration is that by selecting the smaller surface area (25 cm2), the more likely it is that allsampling locations will have that area available. With a larger surface area of 100 cm2, the more likely it willbe that there will be certain locations where I can’t sample a full 100 cm2(for example, perhaps only 80 cm2isavailable for swabbing). In addition, the smaller the swabbed area the more likely it will be that I will be ableto sample a location that would be square (for example, 10 cm X 10 cm as opposed to 5 cm X 20 cm). Thisissue is situational, and may or may not be significant. Note also that I am not addressing the issue of how to handle recovery if a different swabbing shape is used. I am just stating that the situation of having to use a different shape (other than square) is more likely to occur the larger the swabbed area.
These are some of the considerations in selecting the size of the swabbed area in a validation protocol.Needless to say, for training and consistency reasons, one should generally select one specific size forswabbing in protocols and in recovery studies.
The purpose of this Cleaning Memo is not to proscribe or prescribe a certain size for swabbing purposes. Thepurpose is cover various features of swab sampling that are impacted by the size selected for swabbing.

syhorchid

路过

黎明曙光

关于清洁验证的啊，呵呵，都是英文看着费劲

等待神的苦无

黎明曙光 发表于 2016-11-1 08:55
关于清洁验证的啊，呵呵，都是英文看着费劲

简单翻译如下，FYI：
本文主要关注于“擦拭取样的面积”而非“擦拭取样的位置”。
很多公司擦拭面积为“从25cm2到100cm2”，我甚至见过400cm2的。没有取样面积的指南，但如果用“太小的面积”来忽悠，则FDA肯定弄你。需要说明，以下所有的比较分析，是基于“其他条件相同”。
从方法上讲，擦拭面积无论大小都有好处，如果擦拭的面积大，则检测精度可以适当高一些，毕竟100cm2擦拭面积回收样品的量肯定比25cm2的多。而如果擦拭面积小，则回收率会更高，毕竟擦的越多，溶剂浪费越多-所以，多几个棉签擦，比如前面一个湿擦后面一个干擦。
大面积擦拭的另个好处是，取样结果与实际结果接近。比如用100cm2擦拭面积，可能以为设备上有1坨，而25cm2擦拭时，会认为是2坨。
而最终的探讨，是需要考虑实际，比如总共只有80cm2，必须擦不出来100cm2。另外，虽然10cm*10cm和5cm*20cm都是100cm2，但这可能会也可能不会影响结果，需要分情况考虑。
以上就是在选择擦拭面积时候的考虑因素。毫无疑问，出于培训和一致性原因，在各种文件里必须选择特定的擦拭尺寸。

globle001

学习了

wang82888

楼主，能不能表达一下你的观点。

小金库

非常给力的资料,多谢分享