verticity
I'm interested in things
I've been working on an amateur science project for acetone testing kava varieties. Here I will describe the apparatus I made (that you could make too!) and show that it works, but there won't be any groundbreaking information about unknown kava samples. (Spoiler alert: Papa Ele Ele is noble; Isa is not)
The instrument is a spectrometer, which is an instrument for measuring the intensity of light that something absorbs as a function of wavelength. This is basically a poor man's version of the spectrophotometer that Deleted User uses for his tests.
Here is a schematic diagram showing how the spectrometer works.
The light source passes through a narrow slit, to create a thin beam of light. It then goes through a diffraction grating, which disperses it by wavelength. This is the same effect that a prism has. The rainbow pattern then is imaged by a detector, and the relative intensity of various wavelengths can be determined.
Here is my spectrometer:
And here is a look inside the black box:
From left to right, there is a regular webcam as the detector, with a fragment of DVD stuck in front of it, which acts as a diffraction grating. The glass thing is the sample cuvette, and then an acetate entrance slit (0.12 mm). Illumination is provided by a halogen lamp. This design is inspired by the work at Public Laboratory, which has instructions for making something like this, and also sells kits. I got the slit from there. Sample cuvettes can be ordered from vendors on Amazon for ~ $10 (for the cheap ones). Data analysis is done by a computer program that checks the intensity at different positions on the webcam images. For these results I averaged 100 images together to smooth out the noise.
And this contraption actually works. First it needs to be calibrated so that the wavelengths that the pixels on the webcam correspond to are known. To do this you can use a compact fluorescent lamp, which emits light at specific, known, wavelengths. Here's a CFL spectrum I took:
FWHM means "Full Width at Half Max", which is a measure of resolution. This instrument has a resolution of ~3 nm, which is not bad, sufficient for our purposes here.
For analyzing kava samples, I want to look at the absorbance spectra. Absorbance is a measure of how much light is absorbed by a sample. Deleted User's results are based on transmittance which indicates how much light passes through a sample, and thus the color that we see. But absorbance has the advantage of being directly proportional to the concentration of substance in your sample. So, theoretically if the "tudei" peak of a particular sample is half the size of the tudei peak of pure tudei, that would mean there is half as much of whatever substance causes the orange tudei peak, and so would be a good indication of adulteration.
So, here's my results. This just compares Papa Ele Ele - a known Hawaiian noble -- with Isa -- a known tudei, both extracted in a 1-to-3 ratio with acetone (by volume). Both samples are from @Gourmet Hawaiian Kava. Chris doesn't sell Isa for human consumption, but generously provided a sample for testing.
Notice that PEE has a peak at 424 nm, but for Isa, the peak looks similar on the blue side, but the max is shifted to 445 and the overall absorbance is higher, so it looks like there is actually a second substance (or substances) in the Isa with a slightly different spectrum than the yellow substance in PEE. If we assume that Isa contains the same amount of yellow substance as PEE, and assume that the orange substance is completely absent from PEE, we can take the difference of the two spectra (just subtract the PEE from the Isa curves), to see what the spectrum of the orange (tudei) stuff by itself would look like:
In the future, when I get some more free time (lol), I hope to measure some spectra of noble kava adulterated by various percentages of tudei, to see if I can prove what I said that absorbance is proportional to concentration, and then do some "unknown" samples.
So, it's actually possible to do "Deleted User style" acetone tests with inexpensive equipment, some of which you probably already have laying around the house.
The instrument is a spectrometer, which is an instrument for measuring the intensity of light that something absorbs as a function of wavelength. This is basically a poor man's version of the spectrophotometer that Deleted User uses for his tests.
Here is a schematic diagram showing how the spectrometer works.
The light source passes through a narrow slit, to create a thin beam of light. It then goes through a diffraction grating, which disperses it by wavelength. This is the same effect that a prism has. The rainbow pattern then is imaged by a detector, and the relative intensity of various wavelengths can be determined.
Here is my spectrometer:
And here is a look inside the black box:
From left to right, there is a regular webcam as the detector, with a fragment of DVD stuck in front of it, which acts as a diffraction grating. The glass thing is the sample cuvette, and then an acetate entrance slit (0.12 mm). Illumination is provided by a halogen lamp. This design is inspired by the work at Public Laboratory, which has instructions for making something like this, and also sells kits. I got the slit from there. Sample cuvettes can be ordered from vendors on Amazon for ~ $10 (for the cheap ones). Data analysis is done by a computer program that checks the intensity at different positions on the webcam images. For these results I averaged 100 images together to smooth out the noise.
And this contraption actually works. First it needs to be calibrated so that the wavelengths that the pixels on the webcam correspond to are known. To do this you can use a compact fluorescent lamp, which emits light at specific, known, wavelengths. Here's a CFL spectrum I took:
FWHM means "Full Width at Half Max", which is a measure of resolution. This instrument has a resolution of ~3 nm, which is not bad, sufficient for our purposes here.
For analyzing kava samples, I want to look at the absorbance spectra. Absorbance is a measure of how much light is absorbed by a sample. Deleted User's results are based on transmittance which indicates how much light passes through a sample, and thus the color that we see. But absorbance has the advantage of being directly proportional to the concentration of substance in your sample. So, theoretically if the "tudei" peak of a particular sample is half the size of the tudei peak of pure tudei, that would mean there is half as much of whatever substance causes the orange tudei peak, and so would be a good indication of adulteration.
So, here's my results. This just compares Papa Ele Ele - a known Hawaiian noble -- with Isa -- a known tudei, both extracted in a 1-to-3 ratio with acetone (by volume). Both samples are from @Gourmet Hawaiian Kava. Chris doesn't sell Isa for human consumption, but generously provided a sample for testing.
Notice that PEE has a peak at 424 nm, but for Isa, the peak looks similar on the blue side, but the max is shifted to 445 and the overall absorbance is higher, so it looks like there is actually a second substance (or substances) in the Isa with a slightly different spectrum than the yellow substance in PEE. If we assume that Isa contains the same amount of yellow substance as PEE, and assume that the orange substance is completely absent from PEE, we can take the difference of the two spectra (just subtract the PEE from the Isa curves), to see what the spectrum of the orange (tudei) stuff by itself would look like:
In the future, when I get some more free time (lol), I hope to measure some spectra of noble kava adulterated by various percentages of tudei, to see if I can prove what I said that absorbance is proportional to concentration, and then do some "unknown" samples.
So, it's actually possible to do "Deleted User style" acetone tests with inexpensive equipment, some of which you probably already have laying around the house.
I can't wait till you make a homemade HPLC 
