Kits can go off?

[PGTips]

Quote by Mystryman in another thread
If it is older then 8 months then it will bubble on all pill testing due to the fact of the chemical going bad. I've had this experience

Really? I know conc. sulphuric acid can absorb water from the air being so hydroscopic but can the chemicals in the kit go off enough to give false results?
I've had my kit a year and have always put the tops back on immediately. I can't see how they would have oxidised enough to be altered. The air in the vials can't possibly contain enough of anything to taint all the liquid in there can it?

I don't remember what chemicals are in the other vials (I've the Extreme kit) but none of them struck me as "oh, thats unstable" when I did read what they were about a year ago. I've only A Level Chemistry so limited organic knowledge.

Any comments would be great

/edit to change name of person, I got that wrong

 

[johnboy]

From what i understand (and I have a kindergarten level of chemistry knowledge) it is the formadehyde in Marquis that "goes off" and makes the kit more sensitive.

 

[djfriendly]

Both Marquis and Mecke can be checked by testing the numerous household chemicals listed on the NIJ color chart.


EZ-guys, got any tips for checking Simon's or Robadope for aging? I know that DDL, the lab which tests for us at DS, stopped bothering testing with Simon's because they kept having to replace the reagents much more often than Marquis or Mecke. What will Simon's and/or Robadope do differently as they go 'bad'?

 

[lusid25]

I can confirm that the simons can go off with age. After a year of no use (and safe storage) I found my simons regent to be muddy colored and full of chunks. Which is unfortunate because I would like to only replace the simons and not the whole kit but this doesn't seem to be an option (unless someone has a suggestion on where to by the regents seperately).

 

[Soma]

I'm not sure bubbling is a sign of the kits going 'bad'. I suppose if you look at it in the context of 'very slow reaction leads to slow formation of gasses where the liquid and the sample meets which can lead to gradual build up of air to form bubbles like in a mud pool' then it could be the case. Once you get to this stage then colour change is too slow and it all gets Too Hard. Your kit should of been replaced a long time ago.

Marquis is typically the reagent that will go 'off' . It should be stored in a cool dark place - the fridge is perfect
Mandellen is a lot more stable and will keep a lot longer, and shouldn't be stored in the fridge, just the cupboard will do.

 

[Sunray]

I had the E1 and E2 test and the E2 test went off in about a year. It just started showing light green for everything.

The E1 test well, that kinda went off, sorta worked but the colours were not as strong.

My Original EZ Test which I bought ages ago, ummm blimy 6 years ago, still seems to be delivering the goods. Just used it.

Sunray

 

[easy e]

I cannot speak for other producers but my experiences tell me that if stored properly all our tests will last for a very long time.
with marquis it is the formaline that becomes unstable. there is not much you can do about it. on the other hand, I have tests that are at least 6 years old and they still work fine..
mandelin and mecke are stable for an even longer period.
simon's and robadope also last for a very long time, i.e. I have yet to find one that has become unstable and those things are really old! they are supposed to look dark. when you see chunks in the liquid it does not mean that the tests are no good anymore. this is simply a result from cool storage, it affects solubility of the ingredients (recrystallization), but this should not interfere with the reaction.

 

[DiSturBeD_1]

Both Marquis and Mecke can be checked by testing the numerous household chemicals listed on the NIJ color chart.


EZ-guys, got any tips for checking Simon's or Robadope for aging? I know that DDL, the lab which tests for us at DS, stopped bothering testing with Simon's because they kept having to replace the reagents much more often than Marquis or Mecke. What will Simon's and/or Robadope do differently as they go 'bad'?

Simons went bad in my kit after 6 months
It has gone a light green colour, does not react and has chunks in it. The buffer appears ok but then i'm not sure cos it is clear but the simmons is definately dead.

Marquis went funny on me to but after a year, thats why i bought the extreem one. Should robadope and simmons be kept in the fridge too?