Cat urine collection
This is a bit trickier than in dogs. This technique will only work if your cat will use litter trays.
a) Place something which will not absorb water in the tray. Examples include polystyrene balls (care around children or small dogs!!!), cut up drinking straws. Sometimes using a tiny bit of litter can still allow some urine to be collected. There is a link here to an alternative method suggested by the owener of a diabetic cat (click here). You can try using the tray with no litter at all but some cats will be stubborn and not wee.
b) Restrict your cat to one room with a litter tray until he/she urinates.
c) Put the urine into sealed container, avoiding contamination as much as possible.