Dear Darwin Reyes,

If you have doubt about the purity of salbutamol sulfate you can confirm it with MASS SPECTRA. If you want to make analysis, the provided spectra and maximum abosorbance is at 223 nm you can make analysis at 223nm the Linear Formula of salbutamol sulfate is C26H42N2O6 · H2SO4 the Molecular Weight 288.35 if its confirms with mass spectra that the molecuar weight is same then please reveiw your reagents and analysis protocols.

Regards

Amir

thanks sir Amir!

ya, Amir Is right and i am 100% agree with his answer, all the best Darwin and Thank you

The lamda maximum prediction of salbutamol based on Woodward-Fieser rules can be calculated as followed:

the parent structure [homo annular cisoid = 253 nm] + one exocyclic doublebond [= 5 nm] + three alkyl substituents [15 nm], that makes 273 nm. This value is rather close to your experimental 276 nm.

The high peak at the left side [223 nm] probably comes from the solvent.

Thank you for all the responds.

Assuming you have subtracted the UV spectra of the solvent:

Concidering the structure of Salbutamol I think it is quite reasonable to find a strong absorption peak around 220 nm corresponding to the benzene/phenol group in the molecule. So I think you have the right chemical. Try to compare the measured absorbance in your sample with the the calibration curve in the linked paper to see if your quantification fits.

http://scholarsresearchlibrary.com/aasr-vol2-iss3/AASR-2010-2-3-207-211.pdf

Your spectrum looks identical to the one in a database on drugs

http://mtnviewfarm.net/drugs-poisons-1482.html

What you have to remember is that a deloicalised benzene derivative molecule has a number of energy states. Normally the the lowest energy state is quoted which is your 276 nm band. Usually conjugated bond molecules also have higher states, You can think of superimpoistion of 6 QM state functions, one for each C atom in the ring so there are a number of combination of signs of these states and the one with all the signs the same is the lowest energy state. Depending on symmetry and substituted groups on the ring not all states are spectroscopically allowed and have zero dipole strength so no absorption which will explain why 3 bands and not more.

rather than doing calculations for spectra which are useful but rarely definitive due to experimental conditions- solvent ph etc, you could google the spectrum. I did and saw the same spectrum you have shown- except your resolution is low

Dear Darwin

Please, take a look at the following paper for a recent absorption spectra of salbutamol at different pHs: http://www.sciencedirect.com/science/article/pii/S0045653511000762

Dear Darwn Reyes

Before answering problem i would like to attract your attention you may have filtered solution through whatman filter paper or similar

please use nylon filter of 0.45 or 0.22 micron

Do you know what is the solvent they have chosen ? So it differs naturally with the solvent. You have done the UV spectra with PBS. kindly confirm the solvent what they have used. & it is official in IP . please check with IP whether it is coinciding with that

No doubt, Darwin, it is Salbutamol sulfate and its absorption maxima at 276nm as per ur attached spectra. There was a peak at 228 nm is due to molecular excitations of the Salbutamol itself, but they may not follow beer's law and for any concentration, u obtain the same peak at 228nm with same Optical density. Where as at 276nm it follows beer's law exactly.

Thank you very much!

By the way, the additional band that you see ~350 nm might be due to light-induced degradation of salbutamol, as shown in Fig. 3 in the paper that I sent you earlier: http://www.sciencedirect.com/science/article/pii/S0045653511000762 . Did you salbutamol solution was exposed to room or sun-light before you took the absorption spectrum?

Sir, it was exposed to room light.

Okay, then you have to check the emission spectrum of the lamp in the room. If it emits all the way to ~300 nm (not many lamps do), then, the absorption band at ~350 nm in your spectrum could potentially be due to product formation (photo-product). You might also prepare a fresh solution that has not been exposed to room light and re-take the absorption spectrum to test this hypothesis. Good luck.

Thanks sir :)

The absorptions for wavelength higher than 380 nm are less than 0.1 so we consider them as negligeable. It remainds two max one caracteristic of salbutamol at 276 nm and the second at lower wavelength . Can u tell me what you take as bblank to do the experiment and the solvent u used to disolve yr compund ?

i used pH 7.4 phosphate buffer solution as the solvent and i use it also as the blank. the instrument is a double beam spectrophotometer.

Dear Darwin actually Problem with your interpritation, Please excuse me for sending suggestio. i apereciate every ones answer and sharing and helping Efforts .

In British Pharmacopoeia 2012 Ultraviolet and visible absorption spectrophotometry (2.2.25).

they clearly wrote that Spectral range 230-350 nm. --> Then Why you do full Scan

Ab sorption maximum At 276 nm.

so this data is more authentic then third party's COA if u required then download this Official document

Thanx and Regards

Dr vipul

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