SPECTROSCOPY: UV

Question 1

what is UV spectroscopy?

Answer 1

Interaction between matter and electromagnetic radiation to produce spectra
Determination of drug purity

Question 2

when may a photon be released?

Answer 2

rom S1(excited singlet stage) or T1(Excited Triplet State ) to S0(ground state) , resulting in luminescence.

Question 3

what is the equation for the energy of the wave?

Answer 3

E=h x c x gama

Question 4

what is the equation for transmittance?

Answer 4

light put in /light that comes out

Question 5

what is the equation for absorbance?

Answer 5

log (P0(light in)/ P(light out)) = -log T

Question 6

what does LUMO and HOMO mean?

Answer 6

lowest unoccupied mol orbital

highest occupied mol orbital

Question 7

what are the two types of lamps used and their absorbances?

Answer 7

Deuterium lamp (190 –350nm)
Tungsten lamp (350 nm –800nm)

Question 8

what are the 3 limitations of UV spectroscopy?

Answer 8

1- prone to interferences
2-Can improve specificity by modifying analyte and exploiting spectral change
3-Limited to drugs having a chromophore (Derivatization)

Question 9

what is a red shift?

Answer 9

Bathochromic shift

shift to a longer wavelength/ lower energy

Question 10

what is a Hypsochromic shift (blue shift)?

Answer 10

Shift to shorter wavelength/higher energy

Question 11

what is a Hyperchromic shift?

Answer 11

increase in absorbance

Question 12

what is a Hypochromic shift?

Answer 12

decrease in absorbance

Question 13

what does the beer-lambert law state?

Answer 13

For a given molecule, the absorbance is proportional to the concentration of the sample.

Question 14

if conc is given in moles/l what would you use to calculate?

Answer 14

molar absorptivity (e)

Question 15

if conc is given in % w/v what do you use to calculate?

Answer 15

A11 (specific absorbance)

Question 16

beer lambert law only applies to solutions of absorbance less that ?

Answer 16

1.5

Question 17

what is the calibration curve method?

Answer 17

slope gives Molar absorptivity

Question 18

how would you carry out the comparative method?

Answer 18

Absorbance sample/ Conc.sample= Absorbstd/ Conc.std

Question 19

what is the absolute method?

Answer 19

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)

Question 20

radiation imputed is not the same in fluorescence true/false

Answer 20

true- it is lost through vibrating and the photo of light released is not proportional to imput

Question 21

what are 4 applications of UV spectroscopy

Answer 21

Selective, sensitive detector for HPLC
Chemiluminescence
Assay of medicines with low levels of active
Limit for aluminium in water (BP)