Re: [PLOTS] Desktop Spectrometry Kit abilities

[Jeffrey Warren]

Hi, great opp to talk about subtraction. My best proposed process at the moment is to 

* upload an image with two side-by-side cuvettes (hopefully you'll be able to distinguish the two spectra)

* calibrate it (using a calibration from the same setup)

* use the v2.0 interface (see the button along the bottom of the graph to switch into 2.0 preview)

* **clone** the spectrum so you have two copies

* use "set cross section" on each to choose your two different cross-sections of the spectrum, one for each cuvette, pressing "Apply" to accept the new cross-section

* use the "Subtract" tool to subtract one from the other

I'm VERY willing to help out in this process, as it's very much prototype code, and may still be buggy. Eventually, I'd like to use Sreyanth's Procedures code to help guide ppl through this process and automate some parts. 

Please, if someone wants to copy this procedure into a research note and try it out, and post results, that would be GREAT.

Jeff

On Mon, Oct 5, 2015 at 12:08 PM, Gwill Jones <gwill...@gmail.com> wrote:

Hi Mark,

I am interested in garden soil analysis, and plant tissue analysis, so our interests are very similar.

Currently I am investigating the possibility of using two cuvettes alongside each other, resulting in two spectra alongside each other. My aim is to subtract one spectrum from the other in order to be able to eliminate the spectra due to the light source, and the solute, that I happen to be using. I have not got to the stage of using subtracting software yet, but Jeff Warren is helping me with the software.

Gwill Jones

On 5 October 2015 at 15:58, Gretchen Gehrke <gret...@publiclab.org> wrote:

Hi Mark, 

The Spectrometry Kit enables analysis of light emission and fluorescence in the visible range (and we are working on quantifying color intensity for colorimetric analyses too).  For Na, it emits light in the visible range when excited, generally through flame ionization.  The set-up for flame ionization is not part of the spectrometry kit, and can be pretty dangerous, so I would definitely caution you if you are unfamiliar with how to do that.  A great research note about this can be found here: http://publiclab.org/notes/Frikkie/03-05-2015/multi-parameter-analysis-using-a-diy-spectrometer.  If you do not excite the Na through flame ionization, and instead want to measure Na+ in solution directly, I would recommend using a conductivity meter rather than a spectrometer.  

For analyses of plant extracts, it is likely that you would detect fluorescence spectra, but we currently don't have a guide for identifying which spectra result from which compounds.  That would be an awesome project for you to start though!  One of the current limitations is that the materials in the kit absorb UV light and the webcam picks up visible range wavelengths, so we can't quantify (or, at this point, even qualitatively record) UV fluorescence.  It will be difficult (impossible?) to classify organic matter without being able to include data from the UV range in addition to the visible range. 

To find out the capabilities of the spectrometry kit, check out the research notes tagged with "spectrometry" here: http://publiclab.org/search/spectrometry. 

Best, 
Gretchen

On Mon, Oct 5, 2015 at 7:10 AM, timoso san <timo...@gmail.com> wrote:

You can detect virtually everything related to RD/QC. If properly constructed i suppose building up your database with ample baselines and calibration curves will be (apart from proper construction) the most laborious part of the job.

To put it short, expect as much use of any diy spectrometer as you put effort into creating it. It can in most cases perform very well even in telling apart the different spectrums of hydrogen and deuterium (the difference is just one neutron) focus on calibration and reference databases, they will be vital ☺

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