What's in the little liquid pods in the home tests?

[GreenBinLid]

Is it something household common.

Have a set of tests but without the liquid pods.

Double check they are not folded up into the booklet. Mine always seem to be stuck there.

Dunno. But my dog ate one recently and is still with us!

Yes, check they are not hidden in the booklet because mine always are.

Good question though, I have no idea what the fluid is!

I've flicked it in my eye twice and it didn't burn. If that helps at all.

Buffer solution.
Test doesnt work with water.

Echoing the others: check in the booklet.

I have no idea, used to work at a (small) test LFT centre, and have googled extensively and no luck. It’s called extraction fluid if that helps. I have a feeling it’s just distilled water

I thought mine were missing on Thursday but they were, as pp said they might be, in the folded up leaflet.

@FelicityBeedle I had some random tests left over, that some (stupid) person had opened the protective foil for. So I played. Tried water, week acid and strong acid.
Water and strong acid didnt work (no control line appeared).
Week acid got a control line, but negative result.
If we m up a swab at home, and I have Kiwi in, I want to try a test with kiwi juice - aparently that produces a positive!

Have a good search, it's probably in the box somewhere, it's small and often gets caught up with the paper work.

Yes I threw a box away thinking it had no liquid in Then realised in the next box it was folded up with the instruction booklet. I’d forgotten how small that bag is! I assumed it was saline or similar

@Funfortheroad

I've flicked it in my eye twice and it didn't burn. If that helps at all.

That's handy to know as I'm slightly worried I will mix it up with my eyedrops.

Like a PP above, I assumed just a saline solution

I've done a lot of googling and think it is a buffered distilled water or buffered saline..
I may (ahem) have experimented with the solution that comes with single use contact lenses. That does produce a control line.

This is what’s in the extraction buffer for one of the kits:

Extraction solution which comes with the lab test kit contains the following components:
NA2HPO4 (disodium hydrogen phosphate), NaH2PO4 (sodium phosphate monobasic), NaCl (Sodium Chloride)

AKA phosphate buffered saline or PBS. All harmless, just designed to protect the antigens that the kits detect. When the kits were developed there would have been a lot of testing to decide what buffer to use. If you use something else it might well work, but possibly with lower sensitivity.

Oh interesting.

Definitely not in the instruction booklet as I was reading them. It's a set of tests that's been used so I'm assuming kids have thrown them accidentally rather than them being missing from box.

I think it actually might be something more than PBS because when you squeeze it out of the tube you get little frothy bubbles. So it has some kind of surfactant in it too - perhaps something like Tween or a copolymer like Brij or similar.

@Thisusedtobeaniceneighbourhood Yes that seems likely if it makes little bubbles. That list I posted was from just one kit, I expect they vary a bit between brands.

So what actually is it? This is more Jessica Fletcher than covid itself!

It’s still a buffer. PBS or similar, with variations between different kit brands. Basically the job of these solutions is to stabilise the “active ingredients” so that the test works properly.

Having descended into the deepest depths of test kit nerdishness, I’ve now ascertained that the Innova kit uses PBS and the LumiraDx one uses Tris buffer + detergent.

Which is probably not interesting to many people at all

@FictionalCharacter well, it’s interesting to me 🤣 but then I did spend a whole chapter of my PhD on buffer optimisation. The worst ingredient is spermidine (not envy)

Good research FictionalCharacter!

I think this thread showcases some of the wide range of talents people in MN have to offer. It's awesome!

Love this thread, nice work!

@Thisusedtobeaniceneighbourhood I did a bit of assay development way back - but a whole chapter on buffer optimisation is impressive Hat tip!
I got thinking about this, how there will have been thousands of experiments to develop, optimise and validate the LFTs and how people will have spent many working days running the same tests with different buffer recipes (and other variables). Then when they have completed validation, off it all goes for large scale manufacturing which involves another lot of testing and checking. It’s been done impressively fast, just like vaccine development. I bet they have been working flat out.

@OhYouBadBadKitten this is why I love MN! There’s always someone who knows the fine details about something I have no idea about.