Smartphone "Spectrophotometer"
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- เผยแพร่เมื่อ 29 มี.ค. 2016
- This is a simple experimental set up that allows students to visualize the processes involved in spectrophotometric measurements. As a bonus, excellent results are obtained. Simple materials and a smartphone are used to measure concentrations of Red Dye #40 in Strawberry PowerAde Zero. The experimental design and data analysis mimics several basic features of involved in absorption spectrophotometry and Beer's Law analysis. For further details see pubs.acs.org/doi/10.1021/acs....
- วิทยาศาสตร์และเทคโนโลยี
This is my first time that I write a comment in youtube because this video is great! I´m a teacher and this explanation is very useful for my classes. Thank you!
Thank you for commenting. I am glad you found this video useful.
This is a pretty nice explanation of calibration in general. Thanks for publishing this video!
Thank you for watching and commenting. I also appreciate the feedback.
Thank you for taking the time to post this excellent example
Thank you for commenting, valor36az.
That’s a pretty awesome (and practical) experiment! I’d never thought about taking RGB values from a phone.
Thank you!
Tommy Technetium I actually did this and it worked quite well! My R value was quite close to 1 as well.
@@TommyTechnetium Colorimeters are available cheaper on Amazon India. Can these too be used as spectrometers for reading abs measurements, we need these for cell density in bacterial cultures OD600nm. And quantitation of protein at Abs595nm.
This is a kind of treasure video! Amazing! Your youtube channel is amazing! Thank you so much! Science on the tip of your fingers.
great...congratulations, thanks for sharing this useful information
Great video, thank you!
This is some solid work.
This is insane! I really liked the video. I will test it with my students
Jacob let me know how it works!
Excellent job!!
This is really great!
This is good content. Well done !
Thank you!
Ummm....I hope this doesn't sound inappropriate but I LOVE YOU! I am a postdoc and I have recently started teaching undergraduates part-time as well as volunteering for science outreach programs that work with h.s and middle schoolers. This is awesome! Thanks so much for sharing:) I guess the only downside is restricted to read samples one at a time rather than all at once.
+Francine Morris Thank you for your kind words, Francine. I'm glad you have entered the world of teaching and science outreach! Please do let me know if you figure out any extensions / improvements to this experiment or any others I have posted. I suppose one could measure more samples at once if one constructed a sample box appropriately. I never thought of that before; thanks for the inspiration. Best wishes, Tom
Thank you so much for this. Really helps
Thank you. Great !!! Amazing !!! For the calculations am using Open Office.
Great video
great !
That lock is the Exposure Lock, what it means is just the phone won't change shutter speed or iso while taking the measure (usually the camera does that to adapt to new light conditions).
Thank you, Dan! This is extremely helpful.
Glad I could help!
I did an experiment on filtration focusing on Absorption. I did a solution of 4,000ml of water with 20 drops of food dye of FD& C Red #40. later letting different carbon minerals filter the water. Test the water and got my G. However I require help. How do I find the concentration of the original solution? I require help in finding the concentration of this solution I created. Your equation and video are helping a lot with my science fair project with the statistics parts. I apprentice this video so much. This is my first official High School science fair project and I came up with the project myself. If you can, can you explain how to find the concentration?
Hi Tom. Wow this is really cool! I love the cuvette box, have you tried it with using an actual cuvette? I'm wondering if the data would be more accurate if you used a flat surface cuvette vs the round cup.
Thank you, Firefly Sci. We have used actual cuvettes with good success. We have also used small test tubes. I have not done an in-depth analysis of whether the results are more accurate with one vs. the other. I imagine cuvettes would work the best, but as you can see we still get remarkably good results using just cups. If you like, you can learn more in our article published here: pubs.acs.org/doi/abs/10.1021/acs.jchemed.5b00844
This is so great. I will soon test it.
Thank you! Please know that the app used in the video above no longer works. However, there are others, such as "ColorAnalyzer" that are excellent substitutes. Let me know how it works out for you.
@@TommyTechnetium Thank you for the information. We used an App from the German Paint manufacturer Brillux. Their app ("Brillux") doesn't analyze in real-time, it uses photos. It worked as well. We let the app measure three points in the photo and averaged the measurements. But this was for a practical course in uni. With students, I plan to use "ColorAnalyzer"
We used Brilliant Blue FCF (Blue No. 1) in a food colouring paste, because the Lambert-Beer-Law is teached alongside organic colours in schools where I'm from. The food paste was the only product with just one dye that we could find a supermarket. We used the paper you mention on your blog (pubs.acs.org/doi/abs/10.1021/ed100545v) to measure the concentration of the stock-solution with a photometer. We also tested the concentration of the unknown solution with the photometer.
As light source we used the page academo.org/demos/wavelength-to-colour-relationship/ and set the colour to the absorption maximum of Brillant Blue FCF (630 nm). With the app, we analyzed the red and the green value, so we had two calibration curves and calculated the concentration of the unknown solution twice. The average from those two calculations was within 10% of the concentration that was measured with the real phometer.
We really like this setup and are looking forward to using it in school :)
@@Everyyoueverymiau Fantastic! I am pleased this experiment worked for you. Thank you so much for sharing your results with me - this is extremely helpful.
Tom, great video! I liked the way you walked us through the data analysis as well, rather than just assuming anyone who cared enough to do the data analysis could probably figure it out. I am puzzled by one thing in the data. Your unknown comes out with a higher G value than the nearest point on the std curve, which would make me think it's conc should be a little less. However, your calc conc of the unknown comes out a little higher than that of that nearest point. Am I missing something obvious here?
Hi Alvin, great question and thank you for commenting. You are right. Comparing the G value of the unknown (116) with the nearest G value on the curve (111) leads one to believe the concentration of the unknown should be a little less than 4.83 micromolar. However, the comparison of the unknown is done with ALL of the points on the curve. All of the points on the curve yield the equation y = 0.0592x + .0093, and this equation is what was used to find the unknown concentration.
thanks buddy
How to Determine the concentration??
You need a series of known concentrations across a low to high range. Use these to plot a standard curve of absorbance vs concentration. Read across the absorbance of your known concentration and down at where it meets the standard curve to find to concentration of your unknow sample.
Did you find out?
Thanks sir.. ur explain very simple
If you read this comment, I would like to ask if you can have and idea of setup for experiment, to measure (or just differentiate) the polarized light rotation angle, by a solution of some compound. To demonstrate the optical activity of some chemical isomers? I think a thin plastic films, that is sandwiched in LCD screens could be used. There should be two different polarizing films. And I guess a solutions of corn syrop and sugar must behave different, as corn syrop is mostly consist of one stereoisomer of glucose. I'm sorry for my poor english interpretation.
This is a very good idea. I don't know if it will work, but I'd say it is worth trying. Polarizing filters are quite inexpensive to purchase. I may be trying this out on my own. If you try it, please let me know how it works!
I have a question, so I have this research topic but it needs a spectrophotometer, and this video is really helpful, but can this also be used in measuring biomass? or only for uv lights?
This method is useful for analyzing samples that absorb either red, green, or blue light
you need to lock the white balance on the camera if you ever do this
This is a really cool and useful procedure! Would this work to determine the amount of formaldehyde in a solution or is there another step to that?
If you can first chemically treat the formaldehyde in a manner that produces a color change related to formaldehyde concentration, then yes
@@TommyTechnetium thank you so much! Are there any household chemicals that can produce a color change?
@@markaylaengland5603 Do you mean household chemicals that produce a color change when treated with formaldehyde? If so, I'm not aware of any. Nevertheless you might find this article to be interesting www.sciencedirect.com/science/article/pii/S1877705810008702?back=https%3A%2F%2Fwww.google.com%2Fsearch%3Fclient%3Dsafari%26as_qdr%3Dall%26as_occt%3Dany%26safe%3Dactive%26as_q%3Dcolorimetric+detection+of+formaldehyde%26channel%3Daplab%26source%3Da-app1%26hl%3Den
Hii Mr Tomy, that was a wonderfull experiment. One question.
Can I identifiy material from this. For example, I have an unknown type of plastic, and I want to know the type of plastic that may be from its density or what. Can I possibly do it?
Thank you for your question, Ade. This technique cannot be used to determine a specific compound that is present in a sample. Rather, it is used to determine how much of a known compound is in a sample.
2019 Update - "Colorometer" App is NOT available in my app store. What alternatives do you suggest?
Thank you for noting this. I currently use "Color Name". "Color Analyzer" also works. Let me know if you find other apps that seem to work well.
Any way of using similar approach to sample Reflectance (a series of reflectance values at various wavelenghts) Curve of a color sample on paper to mimic an expensive spectrometer used for measuring color and pigments reflectance ? Would make a great and inexpensive tool.
That's a good idea. I'll have to think about this for awhile. My hunch is that a similar approach would not work for reflectance, but of course I haven't tried...
I will try this on biofilm assay
Hi there! I was wondering, how did you prepare your working solutions? how did you know how much water to dilute to get a certain concentration?
Hi Hani, thank you for your question. I often use different flavors of PowerAde as stock solutions. You can see the concentrations of dyes in various flavors of PowerAde listed in "Further Tips #5" found in the post at this link: www.chemedx.org/blog/use-your-smartphone-absorption-spectrophotometer. If you scroll down to the comments, you can see how I determined the various Powerade concentrations.
Have you tried using this technique to quantitatively award a "palest possible pink" for a phenolphthalein titration lab? I wonder if the green light reflected from the paper would begin to be absorbed before the equivalence point, and invisible to the naked eye.
What an interesting idea!
This is so so helpful for my project! I have a question though: if I'm examining a solution with blue dye, what should the color of the paper be? I was thinking orange (complementary), but I'm not sure since orange has red and green in it.
We have successfully used red backgrounds when analyzing blue dyes. For an example of this in a kinetic setting, see www.chemedx.org/blog/chemical-kinetics-smartphone
I know this is an old video but I am doing a project based on this video and is there a way you can tell me how you found the molarity of the Powerade? I understand what it is and how you would calculate it IF you had the moles of the Powerade. I know you have the volume but how do you know how many moles you have? Thanks Tom, great video!!
Hi Tyler, thank you for your question. You can see the Powerade concentrations listed in If "Further Tips #5" found in the post at this link: www.chemedx.org/blog/use-your-smartphone-absorption-spectrophotometer. If you scroll down to the comments, you can see how I determined the various Powerade concentrations. Let me know if you need further clarification. Let me know how things work out in your project!
So basically what you're saying the website is tha byou know the molarity of the Fruit Punch Powerade Zero is 95 +or- 5 x 10^-6 M? If so two questions. One, how did you know this? Two, how did you figure out the molarity once you diluted the solution? Did you divide the "95+or-..." by the solute (water). Thanks AGAIN!
Tyler Voyer That is right, the molarity of Red Dye #40 in Fruit Punch Powerade Zero is about 0.000095 M.
Tom Kuntzleman and you found out the molarity when you diluted it how?
By diluting known volumes of the Powerade with known volumes of water. For example, if 1 mL of powerade was diluted to 10 mL total with water, the resulting solution was 0.0000095 M (9.5 micro molar).
Hi dear,
Instead of using paper we use laser ( as improvements) in your knowledge how do u think it will be effects?
Hi maman. It is likely that the cell phone camera will be saturated with light when trying to detect laser light. Therefore, I would guess that you'll need to attenuate the laser light somehow prior to sending it through your samples for detection.
Interest video. But I have a comment about your data analysis: we can notice that a higher concentration results in a lower intensity. If you measured that an intensity of 111 would give you 4.83 of concentration, a higher intensity of 116 have to give you a lower concentration than 4.83. However, from your data analysis you have found it to be slightly higher (4.85). This is due to the linearization you have done, converting into absorbance and extracting a straight line. In this case, there is actually no need for converting into absorbance at all. Using a 4th grade polynomial equation in Excel to correlate between intensity and concentration resulted in a R=1 equation that was used to calculate the concentration of 3.74 for an intensity of 116.
I am curious about how you measured the concentration of the dye in the first standard of power aid, before the dilution. Could you share that info with us?
Hi Thiago, thank you for your question; great observation! You are indeed correct that a higher concentration results in a lower absorbance; this is observed quite often in experiments such as the one presented in the video. You should note, however, that a 4th order polynomial will perfectly fit any set of 5 data points (try it an see). So while fitting the 5 data points with a 4th order polynomial gives me an excellent fit, it does not give me much confidence that a 4th order polynomial faithfully represents my data. In the data analysis displayed in the video, I am using Beer's Law, which is often used by chemists to fit absorbance vs. concentration curves. Occasionally we will use a second order polynomial to fit the data, because as you note the data tend to become non-linear at higher concentrations. If we wished to fit data to a 4th order polynomial, we would need to take a very large number of data points to gain confidence in our fit. Generally this is not done.
I totally agree with you that the general behavior of the physical-chemistry of the 4th order polynomial would not be representative at all (unless infinite points are given), even with the best fit possible. But I often find that for a small data analysis, using Beer-lambert law its just unnecessary and could lead to inaccurate results, but could be extrapolated out of the data range (of course, taking in consideration possible non-linearities in higher concentrations) because it does match the physics, while the 4th order polynomial doesn't. Anyway, great stuff and I will definitely be using your method on my home brewing system for color analysis. Do you mind sharing how you measured the first concentration of the Power Aid?
I used the known molar absorptivity of Red Dye #40 and Blue Dye #1 found in the reference listed here:(pubs.acs.org/doi/abs/10.1021/ed100545v). I then used our Hitachi U-2900 absorption spectrometer to measure the absorbance of the Fruit Punch PowerAde Zero and Blueberry Pommegranate Gatorade. The concentrations of Red Dye #40 in the PowerAde and Blue Dye #1 found in the Gatorade were then found using A = ebc (A is absorbance, e is molar absorptitivity, b is pathlength of cuvette, c is concentration). The results for the concentrations I found using this method were very close to what was found at this article: (Amounts of Artificial Food Colors in Commonly Consumed Beverages and Potential Behavioral Implications for Consumption in Children: Revisited September 2013 Clinical Pediatrics 53(2)). Again, thank you for your questions and insight and let me know how this works out in your home brewing!
hi! this is such an interesting concept! Is it possible to calculate absorbance if the background color used is a secondary color that isn't red, green, or blue? If so, how would you do that?
For one example...I'd try using a violet background for a yellow solution. Then I'd take the sum of the red and blue transmitted, and use this to find the absorbance
@@TommyTechnetium thank you so much !!
Hello Sir. Greetings of Benevolence! I have a question about the spectrophotometer. What if one of the samples is clear (i.e Aloe Vera Extract), should I use all the values of the R, G, and B or only one of the three values will do to have reliable results for the absorbance? Anyway, this is such a great video and it really helps a lot especially for students and teachers. Thank You, Sir.
Thank you for your kind words and question, Brent. Does the Aloe Vera extract have any color to it at all? Or is it completely colorless? This method only works with colored samples. If your sample is completely colorless, you could try reacting the samples with something so as to develop a color to be analyzed.
Hello Sir. Yes, the sample is completely coloreless. Maybe I will try other colored plant extract or search for a chemical that will react with the sample to produce a color that will be appropriate for this method. Thank you, Sir, for the immediate response and recommendation. Stay Safe.
how can i measure the concentration of red dye 40 in a drink in order to use it as a stock solution ? thank you for your great video
Hi Maryam, thank you for your question. I have measured the concentration of Red Dye #40 found in Fruit Punch PowerAde Zero to be 95±5 micromolar Red Dye #40. I have also used Blueberry Pommegranate Gatorade as a stock solution of Blue Dye #1, measured at 12±1 micromolar Blue Dye #1. I have also measured the concentration of Blue Dye #1 in Mountain Berry Blast PowerAde to be 4.3±0.5 micromolar Blue Dye #1 and the concentration of Red Dye #40 in Strawberry PowerAde Zero to be 4.5±0.5 micromolar Red Dye #40. To learn a bit more how I did these measurements, see the comments in the post linked here: www.chemedx.org/blog/use-your-smartphone-absorption-spectrophotometer
de donde sale el 116?
very informative video! i just have one question: is it necessary to plot a graph? and if it is why?
Thank you. One only needs the mathematical relationship between absorbance and concentration; graphing just helps you see the relationship. So it's technically not necessary, but it is helpful
@@TommyTechnetium okay thank you so much! one more thing: can the equations in the video be used to measure the color strength of a material?
Hi! One question How did you get the micromole data from your stock solution? I used an envelope of powder for water.
Hi Nieves: I used the known molar absorptivity of Red Dye #40 and Blue Dye #1 found in the reference listed here: pubs.acs.org/doi/abs/10.1021/ed100545v. I then used our Hitachi U-2900 absorption spectrometer to measure the absorbance of the Fruit Punch PowerAde Zero and Blueberry Pommegranate Gatorade. The concentrations of Red Dye #40 in the PowerAde and Blue Dye #1 found in the Gatorade were then found using A = ebc (A is absorbance, e is molar absorptitivity, b is pathlength of cuvette, c is concentration). The results for the concentrations I found using this method were similar - to within the error I cited in the blog - to what was found at the reference found here: www.researchgate.net/publication/256612178_Amounts_of_Artificial_Food_Colors_in_Commonly_Consumed_Beverages_and_Potential_Behavioral_Implications_for_Consumption_in_Children_Revisited. If you do some experimenting and find that my cited concentrations are off, please do let me know so that I can list better values.
@@TommyTechnetium Ok, thank you very much for the information:)
Hi, Mr. Kuntzleman.
I am in the ninth grade and using this app for a research project.
I tested a multitude of solutions of water containing different levels of lead in them, and my initial data showed that as the level of lead went up, each RGB value increased as well. Since my solution is clear (water w/ lead), I used the colorometer to test each solution 3 different times - once w/ each primary color background as there is technically no complimentary color to clearness. With every background color- the corresponding color value increased as the level of lead increased, so I was very encouraged. However, when I went to test the data a second time - to ensure accuracy, the R, G, B values were quite varied in comparison to my initial data. I feel that this is a problem as I would like to use this to present as a household way to test for lead in water.
Any ideas as to why there wasn't consistency with the readings? Would you be able to help?
Thanks!
Hi Mukund. I am quite impressed with your work. I'm actually a little surprised that you were able to detect increases in lead if your solutions were colorless (We chemists like to say that, clear is not a color - red Kool-Aid is clear. Clear means transparent, and transparent doesn't necessarily mean no color). My hunch is that something else was affecting your RGB values other than lead. If your lead solutions contained no color, then I don't see how RGB values could reliably with lead concentration. Could you see ANY color in these lead solutions at all? I am specifically interested if perhaps you observed a very faint blue? Could you send me a little more information regarding how you prepared your samples that contained lead?
Thank you so much for the response! Sorry in advance as well - this response might be a little long!
I created my lead solutions with my AP chemistry teacher. He had a lead compound I was able to use for the solutions which was lead nitrate. I calculated the molar mass of lead nitrate(331.2098) and then the molar mass of lead(207.2). I then divided the molar mass of lead nitrate by the molar mass of lead(331.2098/207.2) and got the number 1.5985. I made solutions at 15,30,45,60, and 75 ppm so I then multiplied 1.5985 by 0.015, 0.03, 0.045, 0.06, and 0.075 to obtain the amount of lead nitrate needed to be dissolved in 1 Liter of water to get that amount of lead. For ex : 0.015 * 1.5985 = about 0.024 or 24 ppm - therefore, 24 ppm of lead nitrate needs to be dissolved in 1 Liter of water to obtain 15 ppm of lead in that solution. I then just measure out those values and made the solutions with 1 L of distilled water.
As for the colorimetric science behind this, my thought process is that as the lead increases in the solution being tested, it would make sense that the RGB values increase, as lead is a heavy metal and would increase the absorbance level of the light. I do not think I really see any slight color in my solutions - it looks pretty clear to me. Although, I did read an article talking about how scientists do believe that the closest tint/color to water is a very slight/light blue.
I do have two quick questions as well -
1. Is this colorimeter measuring light that is being reflected or absorbed? - I learned in chemistry that the light we see, is light being reflected, and every other color is being absorbed by that object so we don't see any color except for what is being reflected. Is that correct?
2. Is the background paper that is complimentary to the color of the solution being used to control absorption or reflection of light?
Lots of good stuff here, Mukund. I think you will need to somehow react your samples with something to get a color change. Colorless solutions won't work with the cell phone spectrophotometer. One possibility for you to get color is to react the lead samples with sodium rhodizonate. See pubs.acs.org/doi/abs/10.1021/i560110a034?journalCode=iecac0. However, reaction of lead with rhodizonate might form precipitates, which might throw off your results. You might try adjusting pH to avoid formation of precipitates.
Now for your questions. Perception of color is a tricky phenomenon. What you have said about us observing light that is reflected is correct. Keep in mind, however, that if an object reflects blue and red light simultaneously, it will likely be observed as some shade of purple (red + blue = purple).
With solutions, we observe the light that passes through the solution (is transmitted through the solution), but not the light that is absorbed by the solution. To a good approximation, the color a solution absorbs will be complementary to the color it appears. Thus, a red solution absorbs green light very well, and a green solution absorbs red light very well. Yellow solutions absorb violet light (and violet solutions yellow); blue solutions absorb orange light (and orange solutions blue). These are not hard and fast rules, but rather guiding principles.
In a spectrophotometer, light from a source is sent through samples and then detected. We mimic this in the cell phone experiment. In the cell phone experiment experiment, light that is reflected off of the background paper is sent through the samples and is detected by the cell phone RGB analyzer. If your samples have no color, then essentially no light will be absorbed. If you treat your lead samples with sodium rhodizonate, it is likely you will get a red colored solution. If this is the case, use a green background, and measure the G value in the RGB analyzer. This way, you'll be measuring the green light that is transmitted.
If you google my name you should be able to find my email at the university where I work. If you email me, I will be happy to send you and your teacher a lot more information on this.
Thanks so much for the response - i sent you an email.
Where did you get concentration value from??
How did determine the that Fruit Punch was 94um?
Sir Tom Kuntzleman! Hey there! I am interested of using this for this application. Please do comment for your suggestions on feasibility, among other things to point out.
I am going to utilize this mechanism to create a smartphone app capable of detecting body fat level. Using the smartphone camera light, the light, after passing through a pinched part of the arm, (causing a reddish glow), will be detected using the colorimeter. The concentration will be based on the caliper reading. Using the formula for absorbance, this will be plotted into a graph.
To test this, there will be samples without using the caliper, and simply relying on the formulas to find out the percentage level of body fat. :)
Please answer ASAP!!! 😄
+Tom Kuntzleman
Hi Kenneth. Using a smart phone to detect % body fat is an interesting idea. However, at this point I can't imagine how to do this using the method described in this video.
Hi! Thanks for your nice video. I would like to ask you why the background color should be complementary color of the solution!
Thank you for your question. A solution of a particular color best absorbs light that is its complementary color. Thus, red best absorbs green, and green best absorbs red. This is helpful to maximize the "signals" you get during the experiment.
Tom Kuntzleman Thank you for your answer! I have more questions. I'm doing an experiment about antioxidant effacement of several extracts from food. For this experiment, I heard that I need to measure the absorbance of each solution.
1. In previous researches, they said I need to measure the absorbace level at specific wavelength(like at 510nm). So I wonder how I can regulate the wavelength with this spectrophotometer. As complementary colors for each solution are different, I think the wavelength would be different as well. Is there any advice for my situation?
2. How can I measure the absorbance if the solution is clear? For some extracts, they have no color.
3. I'm not sure if the results (absorbance measured by this) can exactly show the antioxidant effacement. What's your opinion about this?
Thanks for reading these long questions:-)
1. Try this site for specific wavelengths: academo.org/demos/wavelength-to-colour-relationship/
2. If the solution is colorless, then the absorbance will be zero.
3. If you see color changes during the course of the experiment, then this method will work. Otherwise, it won't.
Tom Kuntzleman Thank you. Sorry but I have two more questions.
1. How did you determine the molarity of powerade?
2. And in my experiment, I am using several extracts from onions, watermelons, etc. Then how can I know the molarity of them?
1. See the comments section at the blog post here: (www.chemedx.org/blog/use-your-smartphone-absorption-spectrophotometer )
More specifically, I used the known molar absorptivity of Red Dye #40 and Blue Dye #1 found in the reference listed here (pubs.acs.org/doi/abs/10.1021/ed100545v). I then used our Hitachi U-2900 absorption spectrometer to measure the absorbance of the Fruit Punch PowerAde Zero and Blueberry Pommegranate Gatorade. The concentrations of Red Dye #40 in the PowerAde and Blue Dye #1 found in the Gatorade were then found using A = ebc (A is absorbance, e is molar absorptitivity, b is pathlength of cuvette, c is concentration). The results for the concentrations I found using this method were similar - to within the error I cited in the blog - to what was found at the reference found here (www.researchgate.net/publication/256612178).
Hello Sir Tom! I am currently incoming grade 10, and would want to explore the possibilities of measuring hemoglobin concentration using spectrometry. I have tried researching the Beer's Law and how smartphones using IR sensors were already tried for and were successful in measuring hemoglobin levels. These are noninvasive techniques that explore wavelengths at 650nm, and of which the amounts absorbed, and through machine algorithms measure the hemoglobin content. I want to investigate this thing by recreating a similar test, this time, in hopes of maybe even measuring other components such as maybe glucose, or maybe even cholesterol? However, I'm not really sure where to start. I saw your video and am humbly asking if this method may be applicable to rudimentarily measure hemoglobin percentages as compared to known hemoglobin percentages, and graph it? What do you think sir? :)
Hemoglobin appears red in solution, which means it will absorb green light well. Therefore I think that you could, in principle, use this technique to measure hemoglobin concentrations. The trick would be you would have to purchase pure hemoglobin to make your standard curve - and I imagine it would be quite expensive to do so. Also, the technique you see in the video is not likely to be useful in a non-invasive technique.
Thank you :)
Hi Tommy, help me, if I want to measure a chlorophyll solution instead of red40, what color sheet do I need?
I think I have to insert a red sheet? Correct me pls
Hi valeria. Yes, I would use light reflected off of a red sheet of paper for chlorophyll. Chlorophyll absorbs red light quite well.
Hello! Thanks for your helpful video. Can I quantify the absorbance of proteins in the biuret solution using this smartphone based spectrophotometer? Are the results accurate in this technique?
I imagine you could do this. What color develops when the protein interacts with the biuret solution? Yes, we find one can get quite accurate results when using this technique along with proper sample set up.
Really?! You could do it? How accurate was it?
sir? Good day :-)
1. If my sample is KMnO4 (purple in color) what should I use as a background color?
2.What if my sample is blue in color then?
3. can I use the white color instead as a background for all colors?
Hi Reb, good question. If you look up the absorption spectrum of KMnO4, you will notice it absorbs very well in the green region. Therefore, I would use green as my background color if analyzing KMnO4. I have achieved very good results using a red background for blue colored solutions. Let me know how your experiments work out!
Thank you sir for responsed 😁
We plan to build a set-up for this Idea.Turning it to instrument type. It is subject for our experiment as an alternative way to measure absorbance. Having different color solution, we expect to have a different background also. What can I use instead for conveniency, so that I will not change the background screen everytime I change the color of sample solution?
You mention "the color of sheet must be closely matches the complimentary color of solution"
why is that?
and secondly
what exactly the value of R, G, B represents in that app??
1. The light reflected off of the sheet should be easily absorbed by the solution. This is best accomplished when the color of the sheet is complimentary to the color of the solution. 2. The R, G, and B values represent the number of R, G, and B pixels required to match the color of the pixels inside the circle displayed on the app screen. The color inside the circle represents an average color.
thank you!
Hi Rija
I am spreading more about this area of colorimetry.
Watch the video and understand a little about brighter and darker light in automotive paints
th-cam.com/video/MkmJ2JnobhM/w-d-xo.html
th-cam.com/video/_u3uPN1Iz5s/w-d-xo.html
did not find the coloremeter app in google store.....suggest other which is available
We have used this one with good success: itunes.apple.com/us/app/color-analyzer-get-info-from-image-with-camera/id1160206848?mt=8
what is the application on your iphone? thx
It is called "colorometer".
Hey there! So, I'm trying out this experiment with a smartphone-based spectrophotometer and we will be comparing the result of the smartphone spectrophotometer to a spectrophotometer. But, I'm kinda stuck on how to figure out the absorption of our sample using the smartphone one. Any ideas?
The analysis portion at the end of this video describes how I used the smartphone data to find absorbance. Is this what you are asking or something a bit different?
Could you please share the link to the article in the video discription?
pubs.acs.org/doi/10.1021/acs.jchemed.5b00844 Thanks for the suggestion
How can I improve this to give more accurate measurements?
Thank you very much
Hi Salim, thank you for your question. I need a little more information to answer your question. What color is the solution you are measuring? What color background are you using? What smartphone app are you using? What kind of R-squared values are you getting for your standard curve?
Tommy Technetium
I’m using pink solution, and the background is blue. The name of the application is ( ColorMeter) I buy it from the app store.
The r-squared value = 0.9752
I appreciate your help ❤️
@@salimalwardi4331 With your R-squared value, it sounds like you are doing pretty well! First try these things: 1) Try to get the B-value for the blank to be above 200, but below 240. 2) Make certain you are standing and holding your body (arms, etc) in the same position every time you take measurements. Because the app measures light reflected off of the background, the amount of light incident on the background needs to stay constant. Holding your arms or standing in different positions while taking measurements can change this incident light. 3) Take the average of 3 measurements for each sample.
Let me know if these tips help out.
hello! what's the importance of using the complementary color of the solution as a background???
This is very important...solutions absorb light complementary to their own color, and it is the light reflected off the background that is measured here
@@TommyTechnetium ohhh i see, now i understand. Thanks so much!!! Please keep on making these kind of videos. 😊
This is more a smartphone colorimeter.
Yes, you are correct.
How can I use your analysis in a practical situation? Is red dye #40 bad for humans?
Hi FASB CPA. This analysis could be used to detect just about any colored compound, as long as you could make up known concentrations of the compound of interest. It is safe to consume the amount of red dye 40 that is placed in foods. The LD50 for Red 40 is greater than 10 grams per kilogram of body weight. So an average person would need to consume enormous amounts of red 40 (roughly a kilogram) in one sitting to experience ill effects. You can learn more by looking at the msds for red 40 here: www.sciencelab.com/msds.php?msdsId=9924020
How did you get the concentrations?
Thank you for this experimental set up. Great
I would like to know how to measure Deuterium concentration in ppm in water.
Thank you
Thank you for your comments, Sandy. I can't think of a way to colorimetrically detect deuterium in water, so I doubt this method will work for that.
Thank you Tom, but do you know which instrument or machine can detect deuterium at his best
Sandy, try looking through the papers mentioned here: www.researchgate.net/post/How_to_measure_deuterium_in_water_qualitative_and_quantitative
Thank you
Could you just use different colors for the water instead of drinks?
Yes, I have done this experiment using food dyes at different concentration. When using various colored dyes, be sure to use the correct complimentary color for the background.
Hello, may i know the name of this app ? Because i can’t find it on my iphone. Where can i download it ? Thank you :)
The app featured in this video is no longer available. Try Color Name, Color Analyzer, or any other app that records RGB values in real time
@@TommyTechnetium Woah, Thank you very much for your response. I'm happy to hear that. I am interested in using this application as my undergraduate final project. but I'm still looking for references about this application. Thanks again for the response 😊
@@azwafadilla4434 you might find the paper at the following link to be useful pubs.acs.org/doi/abs/10.1021/acs.jchemed.5b00844
Hello @@TommyTechnetium , i came back here just wanted to say thank you. Because of the information you gave me, i was able to find various references that i need to complete my undergraduate final project. And now, i can finish my project and my paper will be published soon. Once again, thank you, it mean so much to me 😊
@@azwafadilla4434 Fantastic! Send me a link to the paper once it's completed
i want to know hypothesis of this experiment?
Did you find out?
Hello,
I did this several times with the concentration of alcohol with Ceric Ammonium nitrate. Never do I get a "linear" absorbance. Every time I get an incredibly high value for 100% and a negative value for 50%. The highest absorbance is for 38% alcohol! And every time that is the outcome. I did everything correctly, I am sure. How is this possible???
Hi and thank you for commenting. I think I need more information in order to try to answer your question. What is the concentration of the ceric ammonium nitrate you are using to make up the 100% solution? What color is the solution? Are you certain that all material is dissolved? What app are you using for your color analyzer? Are you using R, G, or B channel on your color analyzer to monitor the solution?
@@TommyTechnetium the c.a.n. makes the clear solution (just alkohol and water) turn red. When measuring the G-value of the green backround and inserting into the formula I get negative absorption which does not even exist! But every time I get the same relations with DIFFERENT green backrounds... I am so confused..
@@TommyTechnetium I am using "Colormeter free" dir Android
@@TommyTechnetium the only thing I did differently to you is that I had a Light Source behind the liquid as well to have "controlled" light being reflected by the green
I would try this without the light source behind the samples. It is possible that the light source is too bright and you are saturating the camera on the cell phone. This is especially true if your G values are all close to 255. You want your highest G-value (which should be viewed through alcohol only) to be somewhere in the range of 200 - 250. I have found that this experiment works best when just allowing room light to reflect off of the background and into the detector on the phone. I have also successfully used light from a computer screen as the light source. See academo.org/demos/wavelength-to-colour-relationship/ Let me know how your next few attempts turn out.
I need to know what app you used to perform the analysis on the smart phone. Thank you
On the iphone we use "colorometer". On an Android, try "ColorMeter Free".
Thank you so much
Can you help me for the concentration how can i know this value?
Hi, and thank you for your question. You can see the concentrations of dyes in various flavors of PowerAde listed in "Further Tips #5" found in the post at this link: www.chemedx.org/blog/use-your-smartphone-absorption-spectrophotometer. If you scroll down to the comments, you can see how I determined the various Powerade concentrations.
I cannot find the colormeter app. Can anyone suggest an app that works?
Hi Renee. I currently use "Color Name". "Color Analyzer" also works. Let me know if you find other apps that seem to work well.
@@TommyTechnetium Thank you! I am in AP Chem training today and we are watching your video! So I will share this. :-)
8:11
Great example. The analysis is not correct. The curve must go through the origin. Therefore the intercept must be set to zero in the Trend menu. By selecting a 2nd order polynomial one get y=0.0641 x - 0.00126 x*x. and with Excel data goal seek, one gets c=4.56 uM.
The presented value of 4.85 is too high as one can observe from the experimental data. The exp. data indicate for c=4.85 uM a value below 111.
Indeed a second order plot will likely fit absorbance vs concentration data better than a first order plot. However, this exercise is mostly intended for students of General Chemistry who are just learning about Beer's Law (linear)
Anyone found a similar app for Android phones?
Yes. Some apps that have worked for Android are called "Colorimeter" and "Colormeter Free". Basically, any RGB analyzer that displays RGB values in real time should work. You can find more information here: www.chemedx.org/blog/use-your-smartphone-absorption-spectrophotometer
@@TommyTechnetium sir can I used this for nanoparticles such as - graphite & gold ?
@@rahilhasan7600 For nanoparticles I think you'd want to measure the light scattered by the mixture.
@@TommyTechnetium sir can u plz give me your mail ?? So that I can tell u what I try to tell uh☹️
@@rahilhasan7600 Can you message me through TH-cam?
"red dye 40"
Cancer has entered the chat.
can you explain the all equations comes from?
and give me a references?
thx very much
Absorbance =-log(I/I0) comes from the definition of absorbance. Absorbance is simply a measure of how much light DOES NOT get through the sample. It turns out that absorbance is linearly related to concentration, thus absorbance = m(conc) + b (think y = mx + b from algebra). You can read about this more in depth in Quantitative Chemical Analysis, 7th edition by Daniel C. Harris (p. 382). You can actually get a free pdf copy of this online here: www2.fc.unesp.br/lvq/LVQ_experimentos/analitica_qualitativa/material%203.pdf
me know if you have questions.
thank you so much tom
last week i use my sister id to ask the question to you
diana is my sister
Great; glad to help
es muy es tupido
Maricela Nava como tu analfabetismo :v