SPECTROSCOPY: UV Flashcards
what is UV spectroscopy?
Interaction between matter and electromagnetic radiation to produce spectra
Determination of drug purity
when may a photon be released?
rom S1(excited singlet stage) or T1(Excited Triplet State ) to S0(ground state) , resulting in luminescence.
what is the equation for the energy of the wave?
E=h x c x gama
what is the equation for transmittance?
light put in /light that comes out
what is the equation for absorbance?
log (P0(light in)/ P(light out)) = -log T
what does LUMO and HOMO mean?
lowest unoccupied mol orbital
highest occupied mol orbital
what are the two types of lamps used and their absorbances?
Deuterium lamp (190 –350nm) Tungsten lamp (350 nm –800nm)
what are the 3 limitations of UV spectroscopy?
1- prone to interferences
2-Can improve specificity by modifying analyte and exploiting spectral change
3-Limited to drugs having a chromophore (Derivatization)
what is a red shift?
Bathochromic shift
shift to a longer wavelength/ lower energy
what is a Hypsochromic shift (blue shift)?
Shift to shorter wavelength/higher energy
what is a Hyperchromic shift?
increase in absorbance
what is a Hypochromic shift?
decrease in absorbance
what does the beer-lambert law state?
For a given molecule, the absorbance is proportional to the concentration of the sample.
if conc is given in moles/l what would you use to calculate?
molar absorptivity (e)
if conc is given in % w/v what do you use to calculate?
A11 (specific absorbance)
beer lambert law only applies to solutions of absorbance less that ?
1.5
what is the calibration curve method?
slope gives Molar absorptivity
how would you carry out the comparative method?
Absorbance sample/ Conc.sample= Absorbstd/ Conc.std
what is the absolute method?
Calculations can be carried out by measuring absorbance of the unknown under defined conditions and using a known specific absorbance
A = A(1%,1cm) x l x Conc(%w/v)
Conc(%w/v) = A / A(1%,1cm)
radiation imputed is not the same in fluorescence true/false
true- it is lost through vibrating and the photo of light released is not proportional to imput
what are 4 applications of UV spectroscopy
Selective, sensitive detector for HPLC
Chemiluminescence
Assay of medicines with low levels of active
Limit for aluminium in water (BP)
