Lecture 3 - Challenges of CVD disease - formulation and practice

Question 1

what are strengths and limitations of use of UV/vis spectroscopy in pharmacy?

Answer 1

strengths
- easy to use, cheap and robust
- quantitive measurements used in formulation
- routine methods to asses the physicochemical properties of the drug

limitations
- drug must have a chromophore
- only moderately selective
- not readily applicable to analysis of mixtures

Question 2

what is a spectroscopy?

Answer 2

a spectroscopy is the study of molecular structures and dynamics through absorption, emission and scattering of light

Question 3

what is the beer lamber law? define each term

Answer 3

A = a b c

A is absorption

a or ε is the molar absorption or molar coefficient

b is the path length

c is the analyte solution of the concentration

Question 4

what are two forms of absorptivity?

Answer 4

molar absorptivity and specific absorptivity

Question 5

define molar absorptivity

Answer 5

ε is the molar absorptivity or molar coefficient

ε is measured in Lmol-1cm-1

A(1%,1cm) is the absorbance of a 1g/ 100ml (%w/v) solution in a 1cm cell. the units are 100cm-3cm-1g-1

Question 6

single absorbance substance - what are the two ways of determining the concentration of an unknown solution?

Answer 6

1. literature value absorbance (1%, 1cm) or ε
2. by a calibration curve

Question 7

when is the literature value typically used? what is assumed?

Answer 7

the literature value is typically used when there is an unknown concentration - pure standard is unavailable

it assumes that the beer lambert law is obeyed

A = A(1%, 1cm) b c

A, A(1%, 1cm) and b are known, c is unknown.

Question 8

what does the calibration line check?

Answer 8

the calibration line checks the validity of the beer Lambert law equation using 5 standard solution

• must use pure standard –> prepare standard solution

equation used is:

y. = m x + c

y is the absorbance
m is the slope of the lien
x is the concentration (how far along)
c is the y intercept

c should be 0 or negligible
slope = A(1%, 1cm) or ε

Question 9

Name absorbing components in pharmacological samples

Answer 9

active ingredients

excipients
- disintegrates
- binders
- preservatives/ antioxidants
- colouring/ flavourings

impurities from syntheis
- starting materials
- by product
- intermediates

decomposition products

Question 10

what is the difference between standard, soluble and enteric coated tablets?

Answer 10

standard tables are released over time in the body, soluble tablets are soluble or dissolved within 5 minutes go the body and enteric coated tablets are designed to be released in a amore basic environment. the stomach is acidic - they are erased further down.

Question 11

what is Uv/vis spectroscopy?

Answer 11

UV/vis spectroscopy is a technique used to analyse the interaction of light with molecules. in this method, a beam of light in the ultraviolet or visible region of the electromagnetic spectrum is passed through a sample and the intensity of transmitted or absorbed light is measured.

Question 12

what does it mean by UV/Vis spectroscopy lacks specificity ?

Answer 12

UV/vis light lacks spectroscopy. this means that is cannot solely be used to identify specific molecules or compound in a complex mixture. UV/Vis spectroscopy gives information about the electronic transition of a molecule, which gives indication of functional groups or chromophores present.