A) which are the things you should take care of before, while and after running your analyses? b) what do you need control reactions for? what do you use for a good control reaction? c) sample homogeneity is important for running most of the analyses. why? in which situation might it be advantageous to exploit a sample inhomogeneity? d) why is it useful to read any type of label that comes with an 'unknown' or suspicious substance? e) which information can you find in the pharmacopoeia?