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Topic: Testing Soil with a Spectrophotometer  (Read 2028 times)

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FireflySci

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Testing Soil with a Spectrophotometer
« on: August 11, 2015, 04:41:23 PM »
Hello everyone.  I recently planted a vegetable garden in our backyard.  It's amazing seeing how plants grow and seeing how the veggies change color as they ripen.  Anyway, The spot I used has grass that was treated with lime and who knows what other chemicals.  Now I don't want to eat the vegetables in case they have something that is not safe. 

I know you can test the soil using a spectrometer, but can you test the soil and/or produce with a spectrophotometer?  Our lab does not have a spectrometer. 

I've been trying to find a local lab who has a spectrometer but no one has gotten back to me.

Basically I want to know if the food is safe to eat.  I would like to test for heavy metals and any other harmful chemicals.

Any ideas on how I can do this?

Thank you for the *delete me*

Offline Corribus

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Re: Testing Soil with a Spectrophotometer
« Reply #1 on: August 11, 2015, 04:59:15 PM »
You can test anything with anything - but you need to know what you are looking for. Spectrophotometers come in all shapes and sizes - what do you hope to find with this tool? It is generally not a good general tool for finding low concentrations of specific substances in complex matrices.

If you want to look for heavy metals (which ones?), ICP-MS would be the method of choice. But sample preparation is necessary (you can't nebulize a red pepper), so you'll need at the least a good hot plate, some concentration high grade acid, and a fume hood. Better would be an ashing oven and better than that would be a microwave digester. There are contract labs that will do this kind of thing.

Organic contaminants can also be analyzed, but here specifying what you want to find is even more important. Pesticides? Which ones?  LC/MS or some variation is probably what you'd want to use, but broad "I want to find out if anything is in there" studies are pretty unrealistic.
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman

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