Sciencemadness Discussion Board

Preventing Pipette cross contamination

Rainwater - 27-5-2023 at 04:25

Is there a ready made solution to keep a pipette with its reagent?
Something attached to the bottle or beaker, like a cool way to tye a ruberband or something simple.

Long story:
Ive wasted a few hours this morning purifying nitric acid from a chloride contamination that turned out to be from a pipette that was used with NaCl.
Normally I wouldnt care but this batch is being used to measure silver content in scrap. So I dumped in a bunch of silver nitrate, filtered, distilled. Then tested again. Same contamination. Switched to freshly cleaned everything and finally got the result i was looking for.


[Edited on 27-5-2023 by Rainwater]

Parakeet - 27-5-2023 at 05:12

You can probably use something like this.
https://a.co/d/fTs7AOO

I'm not sure if these can withstand nitric acid vapour though.

unionised - 27-5-2023 at 07:47

The traditional approach is to fix a test tube to the side of the reagent bottle with electrical tape and keep a pipette in that

Rainwater - 27-5-2023 at 07:58

You sir are a genius, thank you

Sulaiman - 27-5-2023 at 21:12

I'm a little wasteful in this respect
- I buy disposable pipettes in bags of 100 pieces.

Edit: I reuse pipettes during an experiment but at cleanup time I dispose of most of them.

For an occasional chemist like me, dust/moisture/CO2 etc. accumulate between experiments.
Plus, many of the liquids used are volatile and corrosive,
I prefer to seal all of my liquids from the atmosphere between experiments.
And one mistake can ruin an entire bottle of stuff.

I can easily imagine environments where usage is so frequent that reuse , or automatic dispensers, are common.

[Edited on 28-5-2023 by Sulaiman]

B(a)P - 28-5-2023 at 14:22

You can buy yourself some dropper bottles and decant an amount of your frequently used reagent into that. You obviously need to check for compatibility between your reagent and the material that the bulb is made from.
Personally I do the same as Sulaiman. It feels wasteful sometimes, though to me the benefits outweigh the additional consumables.

Herr Haber - 28-5-2023 at 20:08

The bulbs from dropper bottles generally dont withstand sh**.

- Deschem's just rot away with time in their box. One bottle had stannous chloride in it and was in the kitchen (sun, heat, grease) it left a red sticky goo between my fingers when I tried to use it.
- Better quality from a lab supplier will last just a bit longer.

Dont store anything volatile or corrosive in them.

I slapped myself in the face when reading Unionised great suggestion. Genius indeed !