Some more info...
Yesterday I received a package with 5 E-Z Tests small returned from the USA. The guy who had ordered them had apparently moved and it was returned to me.
These E-Z Tests small had turned brownish and they were four months old.
I decided to test a pill (containing mdma only) and to see what the reaction was like with an old E-Z Test.
I scraped of a bit, put a light on it and dropped the brownish liquid on the scraping.
The reaction seemed hard to distinguish in the brownish liquid. It also seemed a little slower but then after 5-7 seconds, a purple color started to come out quite clear.
Since I know my sample contained mdma only, I know it is OK.
For people inexperienced with these reactions, it might raise some doubt.
You might think it contains some speed as well.
It is a problem of the plastic of the E-Z Tests small (the LARGE ones are in glass and do not have this problem !)
Since a 2 ml glass package simply doesn't exist, they are packed in a special kind of plastic. When kept cold and dark, the liquid stays clear and 100% reliable.
But when they are kept warm and/or in light, they turn brownish after a while and when that happens, the reaction might be harder to distinguish for some people.
Now the solution

The E-Z Test LARGE is packed in glass.
Though still recommended to keep cool and dark, the liquid will always stay perfectly clear (because packed in glass, not plastic).
I have one standing here for a month now, in the heat and light, and it is still clear and works perfect.
The E-Z Test small was originally designed for The Netherlands, you can buy it in many smartshops all over Holland and if you have a pill, you just buy an E-Z Test small test somewhere, use it and throw away.
Now that we are selling abroad as well, they tend to be kept longer as many people order 3, 5 or more small ones per order.
The E-Z Test LARGE should cover these problems. They can be kept a (very) long time and you can test 150-200 samples.
It is therefore recommended to order LARGE ones. Though a bit more expensive, they offer good value for money.
Anyway, this is not intended as a sales story, just to explain what is going on.
I hope it clarified some things

Anyway, if someone can find us a 2 ml glass bottle with a solid lid than we would really like to know.
Then we could/might consider/start repacking the small ones in glass.
By the way, I had a good night at Milky Way with Luke Slater last night ;-)
Regards
aj