Some links and info about spectrophotometers on hackteria wiki
we have collected random information on spectrophotometers, colorimeters, turbiditymeters... which in the end is all the same concept of using light and it's interactions with matter/molecules for analytical purposes.
start here, mostly about spectroscopy: http://hackteria.org/wiki/DIY_spectroscopy
and more here, even simpler approaches on light absorbtion: http://hackteria.org/wiki/DIY_turbidity_meters
and specific info on the most simple LED -LDR absorbtion setup used for colorimetric tests: http://hackteria.org/wiki/SATW-DIY
i got some other tests with me. not estrogens but nitrogens, but maybe we can get our hands wet by doing a mini-workshop with that test-kit, to get some more intuitive feeling about what sensing stuff in water samples generally could look like: http://hackteria.org/wiki/Plant_Analysis#Quick_Nitrate-N_Tests