Statistics for forensic toxicology - analytical techniques - gas chromatography

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This quiz has been taken 3 times
The average score is 4 of 48

Answer Stats

Hint	Answer	% Correct
what is gas chromatography used for?	the analysis of compounds that can be vaporised (without decomposition) into a gas state	100%
what is the mobile phase of gas chromatography?	a carrier gas such as helium or hydrogen	67%
	extraction into a volatile solvent (e.g. methanol)	33%
what are the most common types of detector used in gas chromatography?	flame ionisation detector (FID)	33%
what does it involve?	initial extraction with solvent (acetonitrile)	33%
	it is then inserted into the injector of the gas chromatogram where the analytes are volatised	33%
	mass spectrometer	33%
	Quick	33%
what is the most important parameter to consider in selection of the column for gas chromatography?	the polarity of the sample	33%
what is the most common column chosen for gas chromatography?	5% phenyl 95% methyl-polysiloxane (5ms column)	0%
what does it involve?	a fibre coated with an extraction phase (e.g. liquid polymer or solid sorbent)	0%
what is the stationary phase of gas chromatography?	a layer of liquid or polymer contained within a column made of glass or metal	0%
what is QuEChERS, and what does it stand for?	a multistep extraction process for sample preparation	0%
TCD	analyte elution causes a drop in thermal conductivity, that can be detected	0%
FID	as organic compounds elute, they are pyrolysed (incinerated) in the flame, forming cations & electrons	0%
	Cheap	0%
	chemical treatment	0%
	cleaning using dispersive solid-phase extraction	0%
	Easy	0%
	Effective	0%
how do these work?	electrodes are placed next to a hydrogen or air generated flame at the end of the column	0%
how must samples be prepared for gas chromatography?	in a liquid or gas state	0%
what will choosing the appropriate column give you?	increased separation and resolution	0%
how does gas chromatography use temperature to separate the sample?	isothermal analysis (temperature stays the same)	0%
how does it work?	it injects the sample into a heated chamber	0%
	it is inserted into a liquid or gas sample & analytes are extracted onto the fibre	0%
how does separation primarily occur in gas chromatography?	on the basis of differences in boiling point	0%
	partitioning using a salt mixture	0%
what is the relationship between the rate at which the sample passes through the column and the temperature of the column?	proportional	0%
	Rugged	0%
	Safe	0%
what is SPME?	solid-phase microextraction	0%
which part of the inlet pushes all the sample into the column?	splitless (split mode is used to analyse only part of the sample (e.g. 10%))	0%
what are the most common type of inlet in gas chromatography?	split/splitless (S/SL) inlet	0%
what is derivatisation?	the addition of non-polar groups to a molecule to reduce its boiling point	0%
	the carrier gas (e.g. Helium) sweeps the sample into the column	0%
	then	0%
	thermal conductivity detector (TCD)	0%
what is the inlet of gas chromatography?	the syringe that injects the sample into the gas flow	0%
	they need to be volatile at the temperature of the inlet (e.g. 300°C)	0%
	this causes	0%
FID	this generates a current between the electrode, that is detected	0%
what is the purpose of a column oven?	to maintain precise temperature control	0%
what does derivatisation allow us to do?	use gas chromatography on molecules that would otherwise not be possible	0%
	using a temperature gradient (most common method)	0%
how do we perform data analysis?	using the peak area of a chromatogram	0%
how do we achieve this if the samples do not meet these requirements?	vaporisation	0%
	volatisation of the sample	0%