Q1(c). Matching techniques with sources and detectors
Some instrumental analytical techniques are listed in Column I. Names of sources and transducers or detection systems are listed in Column II. Items in Column I may match with one or more items in Column II. Match the items in Column I with those in Column II. Column I: (i) Infrared spectrophotometry, (ii) X-ray fluorescence spectroscopy, (iii) Atomic absorption spectroscopy, (iv) Inductively coupled plasma-mass spectrometry. Column II: (p) Lead sulphide, (q) Photomultiplier tube, (r) InGaAsP, (s) Electrode discharge lamp, (t) Quadrupole magnetic analyzer, (u) Deuterated triglycine sulphate, (v) Molybdenum, (w) Nernst glower, (x) Faraday cup.
Answer in brief
(i) → p, r, u, w; (ii) → v, q; (iii) → q, s; (iv) → t, x.
Key points
- Infrared: Nernst glower is the source; DTGS is the pyroelectric detector of FTIR; PbS and InGaAsP are near-IR detectors.
- X-ray fluorescence: molybdenum is the target (anode) of the X-ray tube; the scintillation counter uses a photomultiplier tube.
- Atomic absorption: the electrodeless discharge lamp is an intense line source; the photomultiplier tube is the detector.
- ICP–MS: the quadrupole is the mass analyser (dc and radio-frequency fields, no magnet); the Faraday cup is the ion detector.
The full model answer
As written for the answer booklet: the diagram carries the working, the lines stay short. Read here only; it is not offered as a download.
CoversNernst glowerDTGS detectorelectrodeless discharge lampquadrupole mass analyserFaraday cupphotomultiplier tube
All parts of Question 1
- 1(a) Accuracy and precision5 marks
- 1(b) Phases in GLC and choice of carrier gas5 marks
- 1(c) Matching techniques with sources and detectors5 marks
- 1(d) Cold-vapour atomisation for mercury5 marks
- 1(e) Components of a thermogravimetric analyser5 marks
- 1(f) X-rays from radioactive isotopes5 marks
- 1(g) Generation of the argon plasma in ICP–MS5 marks
- 1(h) Manganese in pyrolusite by redox back-titration5 marks