| Date | November 2016 | Marks available | 4 | Reference code | 16N.3.hl.TZ0.29 |
| Level | HL | Paper | 3 | Time zone | TZ0 |
| Command term | Describe and Determine | Question number | 29 | Adapted from | N/A |
Question
The use of performance-enhancing drugs presents a challenge in the world of competitive sports. New regulations have lowered the acceptable concentrations of certain drugs in athletes’ bodies.
Suggest what may have led to these changes in acceptable concentrations.
One class of performance-enhancing drugs is the anabolic steroids. Detection of these drugs in urine samples uses a combination of gas chromatography and mass spectrometry (GC/MS).
(i) Describe how gas chromatography enables the components of urine to be analysed.
(ii) The structures of two steroids, testosterone and nandrolone, are given below.
With reference to the molar masses of the two steroids, determine, with a reason, which can be identified from the mass spectrum below.
Markscheme
improvements in technology/instrumentation/analytical techniques/precision of measurements
Accept “greater awareness/knowledge of the negative effects of the drugs”.
i
«components have» different affinities for/partition between 2 phases/mobile and stationary phase
move at different rates through instrument
OR
have different retention times
ii
nandrolone M = 274 «g mol–1»
OR
testosterone M = 288 «g mol–1»
nandrolone identified because «molecular ion peak of» m/z = 274
Accept non-integer molar masses, ie, 274.44 «g mol–1» and 288.47 «g mol–1».
Accept also “m/z = 275” for “m/z = 274” in M2.
Accept “absence of peak with m/z = 288”
