[GardenGuy]

Hello,

This is my first post so included is a little background about myself. Currently I'm an undergraduate at a public university majoring in biology. As my name suggests, gardening is a strong interest of mine and I really enjoy understanding gardening from a chemistry perspective. My chemistry background up to this point has been completion of a year of freshman chemistry, year of organic chemistry, several biology courses and accompanying lab coursework for those classes. Currently I'm taking my first semester of biochemistry and a plant biology lab where we learn about stuff like SDS-PAGEs and tissue cultures.

I enjoy learning about and experimenting with hydroponic gardening in particular. Basically gardening without soil. Because of "cultural" reasons most of the fertilizers and related products that are sold to hobbyist hydroponic gardeners are often accompanied with a minimal description of what the product actually contains and a maximum amount "Super secret specifically engineered formulation of patented vitamins that will amazingly bla bla bla..."

I don't believe that miracles come packaged in bottles, I believe that chemistry does. I'm looking for particular ideas or resources to get started testing different products to identify and quantify ingredients that may or may not be stated on the label. Sometimes a MSDS may be available that lists all or some of the ingredients, sometimes it's hinted at by a product description while other times it's a shot in the dark what you actually have.

So far my lab courses have felt more or less like crash courses in using IR-spectrometers, doing titrations and so forth. My expectation is that it will be a challenge to take the skills from my labs and apply them to answering my own questions. Most often the lab courses have felt like cookbook chemistry akin to "We are going turn X into Y, first add 5ml of..."

Some big questions I have.

Based on what I have described, does this fall within the domain of analytical chemistry?

How difficult is it to say with a reasonable level of confidence that there isn't anything else left to be discovered in an initially unknown mixture? For example, black strap molasses is sold to hydroponic gardeners as a source of carbohydrates for microorganisms. This is kept as a secret to the best extent possible but it's speculated by some that these companies add something extra to enhance to molasses and help plants grow. Possibly detecting the presence of an "extra-ingredient" that may or may not be present could further be complicated by how molasses already contains a variety of things vitamins, micro nutrients and possibly hormones. How plausible is it to test something like this and say "This stuff is the exact same thing as store bought molasses because we know what it contains in addition to what it doesn't" This could apply to virtually any fertilizer, surfactant, enzyme, etc. really so it's one I have spent some time thinking about and asking grad students but haven't made much progress with.

Any sort of good references or resources where I can search and find information about techniques, protocols and procedures based on keywords? Quality books would work too. Let's say I have an aqueous mixture of phosphoric and citric acid and I would like to know about testing the concentrations of both and/or separating the two. It's not too difficult to find an article describing how to determine the concentration of phosphoric acid, it's something else to know whether or not that same protocol would hold true given a special circumstance like the case of a mixture with citric acid.

There's dozens of different products and just as many questions that I have about their nature. I'm basically wondering where does one get started learning about this sort of work? Sometimes these may be mixtures of mineral salts like potassium nitrate and calcium sulfate, other times enzymes (I believe cellulases), maybe some plant growth hormones, humic acids, wetting agents and many more things that I would like to understand in a quantitative nature. 

Hope this isn't too vague or anything. I can be more specific with particular examples if needed. Possibly the first thing I might do is compare the concentrations of different brands of phosphoric acid that people buy to adjust the pH of their hydroponic nutrient solutions and determine if any brands are more watered down than another. There's one brand that has citric acid in addition to phosphoric acid so that's why it was mentioned in that case.

Thank you!

GardenGuy

[billnotgatez]

Do you intend to try to analyze organic fertilizers like Cottonseed meal, blood meal, fish emulsion, manure and sewage sludge?

[Borek]

Based on what I have described, does this fall within the domain of analytical chemistry?

Yes. Absolutely.

But it is not an easy task. What you are describing needs a fully blown analytical lab, as you may have mixtures of inorganic compounds in huge quantities mixed with traces of complicated organic compounds. You use completely different methods for both types of substances. This can be very challenging.

Basci knowledge is usually divided between two courses - something like Analytical Chemistry 101 and Instrumental Analysis 101 (or whatever they will be called). But that's only background.

[GardenGuy]

Do you intend to try to analyze organic fertilizers like Cottonseed meal, blood meal, fish emulsion, manure and sewage sludge?

That would certainly be interesting! As an example, something both hydroponic and organic gardeners can use is an extract of brown algae (ascophyllum nodosum) since it seems to contain a number of substances that are beneficial for plants. It's fairly well discussed in primary literature for turf management and horticulture. I start asking myself questions about whether a certain company might water down their algae extract or if algae from one particular area might be nutritionally superior to others due to possibly ecological reasons. Often the products that are the most poorly labeled are those that were derived from an organic source material. Need to hold together some composted tree bark in the shape of a plug so people can use it for starting seeds? Mix in some latex, never mention it's latex and say something like "held together by an all-natural plant derived polymer."
 

My expectation was that testing for the wide variety of compounds that could be in these organic materials would favor the more challenging and expensive side of testing. If I were wrong that would be awesome.

There appears to be several courses similar to what you are describing Borek. Quantitative analysis, instrumental methods and several more beyond there. It wouldn't count towards my program but I will have to check into taking them. It would mostly be a question of time and money. For the approximately thousand dollars it would cost to take a course with a lab, one could buy a few used textbooks on amazon and some equipment of their own. Although you don't have a person with you advising you on proper technique in that case and it's purely self motivation.

[Borek]

My expectation was that testing for the wide variety of compounds that could be in these organic materials would favor the more challenging and expensive side of testing. If I were wrong that would be awesome.

Unfortunately, your intuition was correct.

Quantitative analysis, instrumental methods and several more beyond there. It wouldn't count towards my program but I will have to check into taking them. It would mostly be a question of time and money. For the approximately thousand dollars it would cost to take a course with a lab, one could buy a few used textbooks on amazon and some equipment of their own.

That's about right when it comes to quantitative analysis, but it doubt it will work for instrumental methods. Hardware can be pretty expensive. And you should check whether owning chemical equipment and reagents won't make you a criminal. In Texas you can be arrested for possessing test tubes.

[GardenGuy]

That's about right when it comes to quantitative analysis, but it doubt it will work for instrumental methods. Hardware can be pretty expensive. And you should check whether owning chemical equipment and reagents won't make you a criminal. In Texas you can be arrested for possessing test tubes.

It's unfortunate when something like an analytical balance costs in excess of $4,000 or a decent pipettor $250. There's probably several HNMRs on my campus that cost more than the average house from my hometown. In Michigan I haven't been able to find anything approaching the level of legal absurdity absurdity as you have described. One would have less trouble collecting rocket launchers in Texas than lab glassware, I believe.

 

[Borek]

On eBay you can find some reasonably priced used equipment, but I have no idea what will be the maintenance cost. I am afraid buying there can be a good idea only if you are an experienced DIY type, able to deal with precise mechanics, optics and electronics.

[GardenGuy]

On eBay you can find some reasonably priced used equipment, but I have no idea what will be the maintenance cost. I am afraid buying there can be a good idea only if you are an experienced DIY type, able to deal with precise mechanics, optics and electronics.

I have been able to win a couple Hach DR 2010 spectrophotometer bids on ebay. They turned out to be nonfunctional but it was straight forward to repair them with some parts from an electronics store. Anything more complicated than the simple problems I ran into would probably require getting 2-3 of the same item and then cannibalizing components in hopes of getting 1-2 functional instruments out of the deal. When it comes to things I have less experience using it's difficult to judge by the pictures and descriptions just what you might be getting from the auction.

Baby steps would probably be best so I should start with the simplest and least expensive test and go from there. My guess is that an acid-base titration to determine the concentrations of some phosphoric acid and potassium hydroxide solutions would fit the bill? That's something we did in our freshman chemistry lab and I think I would just need a pipette, stopcock, stock solutions for the titration and the pH probe/meter (already have a decent one of those). Suppose I should start reading more about that procedure since it's been a couple years.

Makes me wonder how much of this I could get access to in a lab at school if I asked the right person.

[macman104]

Chatting up faculty, or even the admin staff (they hold more power than you think) might help.