InSPECtor is an iOS app that, together with InSPECtor SPECS device (http://undanova.com/inspector.html) allows for quantitative analysis of contaminants in water by analyzing the color of water samples that have been tested with colorimetric test kits.
To use InSPECtor attach the InSPECtor SPECs to your iPhone and then take a photo of sunlight through them, giving you a full color spectrum. Then, add your sample and take a photo of the sunlight going through the sample. With just these two photos InSPECtor can calculate the absorbance values between the two photos and then calculate the amount of chemical contaminants in your sample!