Cannula usage

Question

Hi, What is the recommendation for using cannula in manual sampling?
How it can be assured that the cannula is clean and dry inside?
At which point the cannula should be inserted into dissolution vessel?
Should the cannula be primed in any way before the final sample is pulled?
Can you provide a technical opinion on the risk of “contamination” or unrepresentative sampling that could occur if we are taking multiple samples from the same vessel (i.e. 5min, 10min, 15min) using the same cannula?
Is the sampling procedure the same when using cannula filters and syringe filters?
Thank you

kenboda · Accepted Answer

Hi Anna, 
 The cannulas should be cleaned per your SOPs. Usually, cannulas would be rinsed with DI Water, alcohol, or a mixture of the two. You can prove this through a cleaning validation if you'd like, but typically this isn't necessary. 
 The cannula should be inserted in the vessel at the time of sampling. Sampling in the USP can be +/-2% from the set point. 
 I'm not sure what you mean by primed, but typically no priming is needed. The cannula should be empty each time before use. 
 The risk of contamination should be minimal using the same cannula for a vessel, so long as it is dried between each time point. This can just be a attaching a new syringe and blowing air out through it. If there are droplets in the cannula left over, you could determine potential contamination depending on the volume of your samples. If pulling a 10mL aliquot for example, a couple drops likely would be <0.05mL and so you would have <1% potentially carryover. For a 1.5mL sample though, you may have something like 1-2% potential carryover if you don't take care to empty the cannula. 
 The sampling procedure is the same regardless of filter being used. Regardless of the approach, filtration should occur as soon as possible after sampling if it isn't being done simultaneously.

Cannula usage

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