Spectrophotometry Explained For Beginners

Spectroscopy is the study of how light interacts with matter and subsequently, spectrophotometry works thanks to the fact that light gets absorbed by matter. When a light passes through a solution, some of it will get absorbed in this manner. The higher the concentration of the substance in the solution, the more light will get absorbed and the less light gets transmitted through the solution or in other words, the less light will shine through.

It gives us an absorption spectrum which shows us how much light and at which wavelength gets absorbed by our sample. On the y-axis, the absorbance is displayed and on the x-axis, the different wavelengths. Where peaks occur, not as much light is reaching the detector, or in other words, light of these particular wavelengths get absorbed. In addition to this spectrum, most photospectrometers give the absorbance value as just a number. This is what we use to calculate the concentration of the sample solution.

To calculate the specific concentration of the solution used in the spectrometer, we use Beer’s law: $A = ebc$, A = absorbance, e = molar absorptivity, b = path length, c = concentration.

So why is this useful? Well as we just demonstrated together spectrophotometry can be used to quantify the amount of a certain substance in a solution. In addition it is especially useful when we want to measure the change in concentration of a solution over time. It is widely used in chemistry, physics, biology, biochemistry as well as material and chemical engineering…

[LucasLearnz]

Please let me know what you would like me to cover next. And remember to please, PLEASE ask me questions if you have them!

[HaramAbdelgadir]

thank you very much this was sooo helpful

[oluwabusayoidowu]

Thanks a lot for the simple explanation. I found this video helpful

[Aristothink]

Very nice explanatory video. Thank you for sharing it with us !

[sith-jrrq]

It was very hard to understand but now 😍

[scootermom]

Does the paint store use a spectrometer to match paint? If so, how does that work when the paint sample you provide is solid and opaque?

[Ranposnecktie]

this is the topic that i am going to report. Is 0.8 the value of concentration? I am looking for the value of concentration. The given are 0.9 for the absorbance, 0.36 for molar absorptivity, and 3 for the length of light path. Please, kindly reply. Thank you.

[你好嗨囉]

How about the od600 in microorganism?
It seems like they don't use ''absorb'' the light, they use ''scattered''.
So it means the more microorganism in the suspension the more light will scattered, and the detector will detect less light. So absorbance will increase?
Besides, why use 600nm to measure microorganism, is there some specific reason?

[asbaDoce]

How come you are the very same graphic as Prof Daniel?
are you using a textbook?