First of all you have to dilute your sample or change (decrease) pathlength cause the error of your measurment could be really high working with th strong solutions.

Secondly try to accumulate some measurments of the same sample to improve signal/noise ratio. It seems to be really noisy.

Measuring series of samples with variyng concentrations of your compound you can plot the graph A (C) = E*C where A - absorption, C - consentration, E - extinction coefficient you canc use to find concentration of your compound.

It could be heplfull.

Best wishes

Actually, i want to measure the concentration of Graphene in the solvent with the help of Beer Lambert Law. For that i need a specific value of Absorption so that i can do calculation, but as you see there are many peaks in the spectra so thats why i am confused for absorption.

Thank you for your comments.

First of all you have to dilute your sample or change (decrease) pathlength cause the error of your measurment could be really high working with th strong solutions.

Secondly try to accumulate some measurments of the same sample to improve signal/noise ratio. It seems to be really noisy.

Measuring series of samples with variyng concentrations of your compound you can plot the graph A (C) = E*C where A - absorption, C - consentration, E - extinction coefficient you canc use to find concentration of your compound.

It could be heplfull.

Best wishes

All the above from Nikitas and Thomas is correct. You are obviously using quartz cuvettes, but remember that your solvent (depending on what it is, will start absorbing at some point in the UV, and quartz is only transparent to about 190nm. A 2 beam measurement with solvent/cuvette is vert important, but if you want to check your solvent/cuvette, run it on its own (no graphene) as a sample with the reference bleak blank.

In addition to answers by Nikita and Thomas, which I find correct, let me mention that the low signal to noise ratio in two portions of your spectrum (around 200 nm,  and  beyond 1000 nm) is probably caused by strong solvent absorption (low light level in the sample and reference beams), while in the region around 350 nm it is caused by the graphene absorption exceeding the  absorbance range of the spectrophotometer equal to 4.  In order to improve the signal to noise ratio and avoid cutting off of the peak of your spectrum, you can just decrease the graphene concentration appropriately.. Eliminating the noise in the regions of 200 nm and beyond 1000 nm  may be however difficult if not impossible and would require changing the solvent.

Good luck.

An alternative way to decrease your absorption to bring it at least below the limit of 2 is to decrease the pathlength (just by changing the cuvette). This will decrease the contribution both of the graphene and the solvent.

The blank correction will be helpful, but if you see that even only the blank exceed the limit of 2 unit of absorbtion, you are forced to decrease the pathlength.

Thank you guys for your answering. i will try and i hope i will get desire results.

I believe that a 10 times dilution at least is needed, because the peak is best to derive in adsorption level close to 0.4

As we know UV-VIS follow the Lambert beers law so its concentration dependent. For an ideal condition absorption should not above 0.8. (0.6-0.8 ) but in practical absorption less than 1.5 is not a problem. High concentration saturate the detector and get distorted spectra. So be careful about concentration and if it high concentration than use higher path lenth. OD=ACL (aborptivity, concentration and pathlength).

The spectrum is really noisy. You could average the signal and get an approximate value, which won't be very good if the absorbance is too high.  Follow the suggestions from the first two responders, dilute the sample, and try that.   You don't say what particular wavelengths you are interested in.  So, make sure your detector is responding correctly in the region you are interested in.   Looks like it "cuts off" somewhere around 300-400.  You won't get a reliable measurement if the detector isn't suitable for a particular wavelength.

It appears that you have overwhelmed the detector with the sample that you placed in the instrument.  I would dilute this sample by approximately 10 fold and then run the sample again, this way more light gets to the detector.  Since the absorption is flat-lining at a value of ~4 A.U. this dilution would take the peak down to about 0.4 A.U., which should be a value high enough to give you a good signal to noise.  One other consideration is that your solution needs to be clear.  If you have particulates that are not dissolved, but rather suspended, the scattering losses will give you a noisier spectrum.   

Dilution is necessary here, take effort to chose solvent in which graphene is uniformly soluble and not absorbing in wavelength range you are working, also perform a blank reading for idea on such signal to noise ratio.

Dilution is first thing to do, every sample which has absorption more than 2 AU need to be diluted. 

thank you all for your valuable suggestions...

i think i will dilute and check..

Make sure the material used to make your sample cell is appropriate for the region you are interested in.  

Another point not explicitely mentioned in the other comments is the optical window of the solvent. Most solvents (and, by the way, use spectroscopy grade solvents) absorb below 230-200 nm. You can determine it by running a spectrum of the solvent against air. If you need to go into the far UV, then you will need a vacuum spectrometer: air absorbs at wavelengths shorter than 160 nm, a reason why most commercial UV-vis spectrometers stop at around 180-160 nm.

Therefore the observed cut-off in your spectrum could as well come from solvent absorption.

Muhammad: Did you solve the problem? How look the spectrum at lower concentration?

To sum-up the advises: In case you are in doubt:

1) Check the transparency of the cuvette (= measure empty cuvette against air as reference)

2) Check the trasparency of the solvent (mixture); knowledge of a solvent cut-off really helps, e.g.: https://www.researchgate.net/post/What_is_the_UV_cut-off

When working under normal condition, air a limitation, because O2 and N2 molecules absorbs below 190 nm, water starts to absorb above 900 nm (IR stretches); in addition to a solvents limitations.

3) Try to construct the dilution plot and check its linearity (Beer-Lambert law)

4) If your sample is heavily turbid (check that with bare eyes) than it's time to re-think the method of sample inspection...

Dilute it. And Below UV means below 200nm the sample can not be measured by this method

below 200 nm common spectrophotometer are not able to reveal good signal, both for poor lamp emission and poor detector sensitivity at these wavelengths.

IF you would like to try to go below 200 nm, try to use a spectropolarimeter (circular dichroism measurements), that is able to collect at the same time elipticity and trasmittance (hence, absorbance).