Question 18M.3.sl.TZ2.3b
| Date | May 2018 | Marks available | [Maximum mark: 2] | Reference code | 18M.3.sl.TZ2.3b |
| Level | sl | Paper | 3 | Time zone | TZ2 |
| Command term | Discuss | Question number | b | Adapted from | N/A |
Inductively Coupled Plasma (ICP) used with Mass Spectrometry (MS) or Optical Emission Spectrometry (OES) can be used to identify and quantify elements in a sample.
ICP-MS is a reference mode for analysis. The following correlation graphs between ICP-OES and ICP-MS were produced for yttrium and nickel.
Each y-axis shows concentrations calculated by ICP-OES; each x-axis shows concentrations for the same sample as found by ICP-MS.
The line in each graph is y = x.
Discuss the effectiveness of ICP-OES for yttrium and nickel.
[2]
effective for yttrium «but less/not for nickel»
points on nickel graph do not lie on «y = x» line
OR
cannot be used for low concentrations of nickel
OR
concentration of nickel is lower than recorded value
Accept “ICP-OES is more accurate for lower yttrium concentrations than higher concentrations” for M1.
Accept [Ni] and [Y] for concentrations of nickel and yttrium.
Accept “detection limit for yttrium is lower than for nickel” for M2.
Award [1 max] for “more accurate for yttrium at lower concentrations AND nickel at higher concentrations”.
[2 marks]
