Chemistry Project

Question

Hi,

I am looking for a way to use arduino or raspberry Pi to detect Chemical Elements in water, but not sure how to do it or where to start.

I have both plus mac and Windows server.

this is a new project and need some advice.

Mick

beacon_dave · Answer

There is an Arduino water quality monitoring and notification project documented at: https://create.arduino.cc/projecthub/eani/water-quality-monitoring-and-notification-system-f85d23 which may be a good starting point. You will likely need to swap the sensors used with ones which can detect the specific chemical elements you are interested in detecting/measuring.

beacon_dave · Answer

Chapter 11 of this book on sensor technology gives amongst other things a summary of sensors used for: physical water sensing chemical water sensing biological pathogen water sensing Sensor Technologies Healthcare, Wellness and Environmental Applications By Michael J. McGrath , Cliodhna Ni Scanaill ISBN13: 978-1-4302-6013-4 Sensor Technologies - Healthcare, Wellness and Environmental Applications The eBook is available as a free download through ApressOpen.

Former Member · Answer

It's a simple matter of finding the appropriate sensor, calibrating it before each test and then scaling the voltage (or current) reading by the appropriate calibration factor. You can do this for pH (concentration of hydrogen ions) with some difficulty (very high impedance instrumentation amplifier required to sense mV signal, calibration required for each use, adjustment of calibration curve for sample temperature. But it goes down hill from there pretty fast. Let's take sodium, for example, as there is some sodium in almost all water samples. There are electrodes which respond to sodium down to mg/L but they cost hundreds of dollars, take up to 20 minutes to stabilize, and, like pH electrodes, have to be calibrated every time they are used and require very high impedance instrumentation amplifiers.There are techniques for detecting mg/L levels of many of the ions found in water some of which, like sodium, involve ion selective electrodes but for others things like ion couples plasma, absorption spectometry and visible spectrometry are required. Etc. Moving on to the organics which are, these days, a major concern in water analysis, we move on to gas chromatography and GC followed by mass spectrometry. All doable but not at the level of an Arduino/Rasberry pi hobbyist. DAB: apparently you have somehow missed the last, say, 70 years in physics nor do you seem to grasp the basic ideas behind current thinking in this discipline. Periodic tables do include deuterium and trititium as well as protium. The listed atomic weight is an average which includes these two isotopes (that's what we call something with the same proton number as another form of the same element with a different atomic number) weighted by their relative abundance. Any good periodic table will list all the isotopes (or at least the most abundant ones) of each element. Nobody (well, nobody with fundamental understanding) has though of electrons as orbiting the nucleus in 'layers' for years. That was a model, the first one, and it didn't last long, perhaps because it isn't a very good one. The modern model (nucleus made up of protons and neutrons made up of quarks surrounded by an electron cloud) is based on quantum mechanics but you must understand that it is, though to date never contradicted by experiment, just a model and, as such, subject to later refinement or perhaps replacement by a better model (unified theory?, string theory?) but you cannot say it is wrong as it is only a model. You can say it is not a good model if you can present data that contradicts it.

Former Member · Answer

Wow. That's a very tall order! If you genuinely want to test for every element, the only way I could think to do that would be heating the sample to a plasma and analyzing the emission spectrum. That's a pretty heavy duty proposition involving some very expensive equipment to do it properly. My wife does ICP mass spectrometry to test for metals in soil and water samples, and the equipment she uses runs into tens of thousands of dollars even without support contracts, a supply of consumables, etc. An ICP/M-S will typically have a full computer built into it running specialized a LIMS (laboratory information management software) package.

If you're looking to identify compounds instead of just base elements (which would likely give you more useful information), now you're talking about an entire laboratory. Different processes and equipment are used to test for different compounds, so now you're talking about hiring a staff of chemists, not something that you can do in your garage with an Arduino.

If you want to test for biologicals, that's a whole other layer on top of that involving multi-day sample digestion, more consumables, more equipment, and more people.

I don't mean to be a nay-sayer, but until we have some sci-fi level nanotechnology I don't think it's feasible to duplicate the functions of an entire well-funded environmental laboratory using a single board computer. :-(

Chemistry Project

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