Hey, this is just one of the studies that were linked here (thanks
@readalot)
"In this experiment, we found a coring rate of 10% when a 18-G needle without a filter was used for aspiration, independent of the needle diameter used for fluid ejection. Using a 23-G needle for aspiration led to a coring rate of 33%. Rubber particles in the injection fluid could be completely avoided by using a needle with 5 μm filter to withdraw the fluid from the vial.
Therefore, our first hypothesis, that coring may be reduced if a thinner needle is used for injection than for aspiration could not be confirmed. Using a needle with a 5 μm filter for fluid withdrawal eliminated vial coring completely, confirming the second hypothesis of this study.
The data of this study shows that the term “coring” is somewhat misleading. One would expect a particle of the size of the inner diameter of the needle. In fact, the inner diameter of the 18-G needle used in this study was 950 μm and that of the 23-G needle was 390 μm. The rubber particles created by the 18-G needle had a mean diameter of 77 μm with a maximum of 214 μm. Therefore, even the largest particles could easily pass the smaller diameter injection needle used for group two. The small size of the rubber particles is most likely caused by stretching of the rubber stopper when the needle is inserted and subsequent contraction of the resulting core.
Interestingly, using a thinner 23-G needle for aspiration resulted in a threefold coring rate. This result is in accordance with the available literature, as Asakura et al. found a coring rate of 73% in primary aspirations of insulin through a rubber stopper using a 31-G needle [22]. This data and our results suggest that thinner needles lead to higher coring rates."
