Caps up or down - Curious what other people do... (Aug/18/2008 )
I regularly work in a BioSafety Cabinet, and was originally taught to place caps with their inner surface facing up when putting them down in the hood. However, I've talked to people in other labs that place caps with their inner surface facing down, so I was wondering what everyone here does with the caps to containers they can't hold in their hands: inner surface facing up, or down?
Ian Freshney who wrote the "Culture of Animal Cells" bible, prepared a great video a few years back where there was a discussion about this exact issue.
He said that leaving caps facing up could increase chance of contamination if your hands etc. went over the top of the exposed cap. He suggested placing the up-facing cap as far away from "work" area to minimise exposure. He also suggested that when picking this up, you slide your palm-facing up hand along the base of the hood, using two fingers to pick it up and then place onto tube/flask.
He also stated that caps facing down could also introduce contamination because the rim could come into contact with contaminants and you could introduce this into your flask, tube etc when replacing the cap.
After seeing this, and after many years of playing the violin, I seem to be able to hold all tubes/flasks and caps in the one hand and therefore do not have to decide how to place my caps.
BUT when I teach students, I suggest that they place the caps at the back of the work area, facing up :-)
I agree with AussieUSA (and the Gospel according to Freshney). I prefere to pay attention not to pass on the cap while moving more than risking contamination by allowing the rim to touch the hood surface.
My vote is for: up and put aside!
We put the caps face down at our lab and the arguement is same as said before. . less chance of contamination when passing over it and that the rim of the cap that touches the surface does not touch the mouth of the flask/tube.
(I think there was already a thread on this. Anyone can find it?)
My personal preference is cap down. I always thoroughly wipe down the hood with alcohol before starting any work so I don't worry about any contamination being present on the hood surface itself.
One vote here for caps up and to the back of the work area.
SK
I always put the cap down. My logic is the hood should be sprayed down to decrease risk of contaminants getting onto the rim, and the caps should be placed on the bottles exactly, without the rim ever touching the mouth. Media is never poured from the bottle, and pipet tips should never touch the mouth either.
Oh dear,
CAPS SHOULD BE NEVER PUT UP OR DOWN IN THE CLASS II CABINET. Caps should always be held in the finger tips when doing any manipulations in the hood. Good aseptic technique covers all eventuallity. Any questions ?
Rhombus.
Oh dear,
CAPS SHOULD BE NEVER PUT UP OR DOWN IN THE CLASS II CABINET. Caps should always be held in the finger tips when doing any manipulations in the hood. Good aseptic technique covers all eventuallity. Any questions ?
Rhombus.
Yes, holding caps in fingertips is the most desirable method of dealing with caps. However, one occasionally has to open and use something whose cap is ungainly to hold, or train new people who aren't yet up to holding caps in their fingers while manipulating things in the hood. Hence the original post.