 Hello and welcome to this video about the UV-Vis. In this particular video we're using a Shimatsu UV-1900, but in principle most of the things that we're explaining here will remain the same between UV machines. This particular UV machine has a space in here which you can open, and then when we look inside we can see multiple things. In the center here we have two holders for our samples, and while in principle happens while we're running this machine, the light comes from this side, passes through your sample, your sample absorbs bits of the light, and goes out the other side towards the detector and the machine will tell you how much light has been absorbed at the specific wavelength. So how are we going to measure this? To measure any UV things what we generally do for liquids is using qubits. And qubits come in various methods. So we have quartz qubits, or you can have qubits made out of plastic, and they all have different properties and of course price ranges. Quartz is a lot more expensive than these disposable plastic qubits. So why would you want to use different qubits? So every qubit that you have of course absorbs its own light. So the better quality qubit you have the less amount of light it absorbs. So to show this we will first use the machine to just measure the absorbance of air and then compare the absorbance of our both our qubits. So first of all when you're measuring or when you're measuring the baseline you have to close the machine. So you close the cover and then you go to either the computer or the onboard compound and you go to settings, so that's in this machine it's called methods, and you can set a wide range of instruments. What most important at this point is the range that we're measuring in between, we're measuring in this case between 500 nanometers and 200 nanometers. And 200 nanometers is into the UV, 500 nanometers more towards normal visible light. And then you press baseline. We'll ask you again where you have to measure, you can just click OK. And it will ask and then it will measure. So in the bottom here you can see where it currently is and it will quickly go from 500 to 200 nanometers and measure everything. And then we replace our air with our qubits. So let's try the quartz qubit first. So you put it in, in the first holder, close the machine and press start. It will then request you a file name, you can immediately press OK or you can change the file name to what you want it to be and then press OK. And in the screen in the center you will see the measured absorbance. So you see this yellow line here which is the absorbance of our quartz qubit compared to the absorbance of air. And you can see that it doesn't absorb a lot of light all over the spectrum. So if we then replace our quartz qubit with a plastic qubit and we do the same thing, so we press start, press OK. And we'll now measure the plastic qubit which is the black line. You can clearly see that on the left hand side here we have the absorbance and on so on the y-axis absorbance x-axis is wavelength. You can see that the absorbance goes up very high and if we right click and then select outer scale we can see that it actually goes to the maximum absorbance this machine has for four. When you're measuring any UV absorbance you always want to keep it below one. So if you have anything that absorbs below 300 then you should not use a plastic qubit. But we're measuring a yellow sample in this video so we can use plastic qubits because they absorb around 400. So how are we going to measure our actual samples the next step? So we're changing first of all our measuring range to 300, 500 to 300 and we replace our empty qubit with the qubit of the solvent that we're using. In this case the solvent we're using is water with a bit of potassium carbonate which is just a clear solution. And you place it in the holder, close the machine and press baseline. And then once more to measure our sample we replace the baseline sample with the sample that contains our compound in this case this nice yellow compound. Put it in and press start and let's remove the spectra of the qubit. So here we have the spectrum of our yellow compound which has an absorbance at around 400 nanometers. And you can read off the file by selecting the peak pick button on the top. A different method of using the UV machine would be using the in-built display. This works almost exactly the same as the one on the computer where it has a touch screen. When working with touch screens in the lab do not forget to take off your gloves and only use your bare hands on the touch screen. So you press the button on the bottom left and then you get this nice selection menu and what we want to do is the button called the spectrum. And then you get just like on the computer program you get the parameters that you want so you can select the range that you want to be measuring in and to be consistent we'll measure between 500 and 300 while we're already doing. And then we have to select our baseline so we select base correction on the bottom and it will be now in progress we well I didn't put in the qubit but while it's doing that I can explain you something more about the qubit. So this plastic qubits they have two sides to them so you have one side where you're measuring through the one centimeter path length from here to there or you can rotate it and then it's measuring through this very tiny pathway which is not the one that we want to be using because in the formula of Lambert beer we use one centimeter which makes it a lot easier to calculate. Also do not put any fingerprints on this side of the qubit or this side of the qubit because the fingerprints will also absorb some light so always hold it on the top or on the top and bottom at the same time like this. So put in the empty qubit well not the empty qubit the qubit with just our solution currently there's the qubit with the yellow compound so our baseline solution and click baseline correction we'll make some beeping noises and then it's done when it beeps again and then we replace our baseline solution with the solution that we're actually measuring so again the yellow solution put in close to lid and press start and we see the nice curve that we had also on the pc so in here we can do some operations for example if you click on operation we can say peak pick and it will tell you here under peak that there's a peak at 399 nanometers and has an absorbance of 0.417 so we found out the peak pick so now we want to save our file we have to get out of peak picking and press cancel then we're back to our system and we plug in a usb key and then you see this button usb lighting up and you say save curve you say that you want to save it to the usb key you can type in your file name so test in this case test so and you can save this dot spc which opens in spectrograph and you can also save it as comma separated file which you can open for example in excel you click save and it's now saved to our usb key we can remove the usb key and take it home and do our analysis so that's how you use the uv machine with the inbuilt display and this is everything about using the uv machine