D9 drug detection and analysis Flashcards
what are steroids
lipids w 4 fused rings in structure – steriodal backbone
2 examples of steriods
T-
C-
testosterone
cholesterol
what is testosterone
male steroid hormones, performance enhancing drugs
most common method for detection of steorids in blood? (for drug tests)
gas chromatography
mass spectrometry
what does mass spec do vs gas chromatography
mass spec: identifies and quantifies the components
gas chromatography: seperates chemical mixture into pure chemicals
3 steps for mass spectromatry
- mass spectrometer vaporises the sample, generating positive ions from components
- ions are accelerated an deflected in a magnetic field, seperated
- molecules fragment intor structures identifiable by charge to mass ratio
what does gas chromatography do
seperates the chemical MIXTURE into PURE chemicals
what property of the mixture (urine) allows for gas chromatograpy
the components have different affinities for the stationary and mobile phase
stationary vs mobile phase
stationary: microscopic layer of non-volatile liquid (usually polymer), coated on the walls of an inert solid support
mobile: inert carrier gas eg helium
describe how gas chromatograpy works
1 components of mixture seperated – determined by diff rates at which they move thru the chromatography apparatus
2 rates differ bc boiling points and solubilities – determine relative associations with stationary and mobile phases (liquid and gas)
what factors for the components matter for gas chromatograpy that determines whether theyre stationary or mobile phase
boiling point and solubility
molecules w more time in gas phase = move quicker
incr bp + incr sol = liquid = slower
why is the temperature in the column controlled in gas chromatography
so some components condense and dissolve in the liquid (stationary) phase on the column walls
- changing temp controls retention times = changes amt of seperation
what is retention time in terms of gas chromatography
the specific interval of time in which each component of the mixture is eluted
name the 3 methods for organic structure analysis and identification
mass spectroscopy
infrared spectroscopy
proton NMR
what is ethanol is breath
ethanol established equilibium in the lungs between the solution in the blood anf the gas released in exhaled breath
C2H5OH (aq) <=> C2H5OH (g)
what instruments are used to measure ethanol conc in breath
breathalysers
alcosensor
what type of reactions happen in breathalysers
redox
what ions and reaction causes the colour change in breathalysers
ethanol oxidised by potassium dichromate (VI)
potassium dichromate (VI) reduced to chromate (III)
orange (VI) to green (III)
6 –> 3
steps for breathalyser
- ethanol oxidised by potassium dicromate 6
- potassium dicromate 6 reduced to 3
- orange to green
- extent of colour cahnge measured w photocell - determines ethanol conc
breathalysers are preliminary tests, which can lead to further testing using ?
intoximeters
what is an alcosensor
an instrument that uses electrochemistry in a fuel cell to measure ethanol conc
what reactions occur in an alcosensor when exhaled breath is passed over the cell
ethanol oxidised to ethanoic acid at anode
C2H5OH + H2O –> CH3COOH + 4H+ + 4e-
protons and electrons go to cathode, oxygen reduced to water
O2 + 4H+ + 4e- –> 2H2O
electric current produced by the reactions in an alcosensor is used to calculate?
blood alcohol concentration
what is blood alcohol concentrations units
mass per volume
mg of ethanol / cm3 of blood
what is the overall reaction of the oxidation in the alcosensor
ethanol oxidised to ethanoic acid and water
C2H5OH + O2 –> CH3COOH + H2O
account for differences in solubilities of organic molecules in different solvents
polar organic compounds dissolve in WATER by HYDROGEN bonding
non polar organic molecules dissolve in ORGANIC solvents (eg hexane, benzene) thru LONDON forces
why does solvenet extraction work
uses the fact that a solute may show the greatest differece between 2 immicisble solvents
(Extraction = choosing a solvent which selectively dissolves a particular component)
what is partition (in solvent extraction)
when a solute is given the chance to dissolve in both immiscible solvents, solute becomes unequally distributed
4 steps solvent extraction
1 product mixture is aq sol, contains desired product X (which has high sol in hexane than in water)
2 mixture added to seperating funnel, vol of hexane added + shaken + left to settle = hexane upper layer bc less dense than water
3 X dissolved more in hexane – lower layer drained away = leaves hexane layer w high amt of dissolved X
- evap of hexane = X recovered
how is solvent extraction used in preperation of penicillin
penicillin is extracted from aq solution using trichloromethane as a solvent
drug isolation and purification can be caried out using differences in? 2
volatility and solubilities in diff solvents
2 concepts that differences in volatility uses
molecular size: incr size = decr volatility bc incr london forces
polarity: more polar functional grps = decr polarity bc incr abiltiy to form h bonds or dd interactions
why does fractional distillation work
exploits differences in volatility
- concepet of evaporation and condensation as the simple distillation process
what are fractions in fractional distillation
contain a mixture of liquids whihc boil within a narrow temperature range
2 processes where fractional distillation is used
isolation of drug products from liquid mixtures
seperation of chemical feedstock
what does Raoult’s Law state
that the VAPOUR PRESSURE of a volatile substance in a SOLUTION = vapour pressure of PURE subtance MULTIPLIED by MOLE FRACTION in solution
what is vapour pressure
pressure exterted by a vapour in equilibiurm with its liquid at a given temp in a closed system
what is mole fraction
the fraction of moles of the substance in a mixture
mole fraction = moles of solute / total moles of solution
when does raoult’s law only apply?
ideal solutions – those containing fully miscible liquids
how to calculate total vapour pressure of a solution
= sum of component vapour mixtures
how to calculate vapour pressure in mixture
= mole fraction of A x vapour pressure of pure A
