Block 8: Critical Zone Sampling

Question 1

What is Scanning Electron Microscopy & how does it work?

Answer 1

SEM focuses an electron beam on a sample’s surface & records resultant scattering patterns to determine elemental abundances & create magnified images

Question 2

What is X-Ray Diffraction & how does it work?

Answer 2

XRD focuses angled rays at powdered samples & records positive interference to plot mineralogy as diffraction peaks. Diffraction angles can also be used to map mineral structure

Question 3

How do Inductively Coupled Plasma & Optical Emission Spectroscopy analyse samples?

Answer 3

Samples are passed through an ICP & atomised, emitting electromagnetic radiation at specific wavelengths. OES detectors separate wavelengths & determine elemental composition

Question 4

How does ion chromatography work & what is it used for?

Answer 4

Ions are passed through ion-exchange resin & classified based on rate of movement, which depends on charge & molecular mass

Question 5

What are calibration standards & a standard’s matrix?

Answer 5

Calibration standards are solutions containing known concentrations of an analyte
Standard’s matrices are the substances present in the standard along with the analyte

Question 6

How do chromatography & mass spectrometry combine to determine the composition of compounds & organic mixtures?

Answer 6

Molecules are individually eluted to determine m/z (mass to charge ratio) peaks based on extent of attraction to a magnet

Question 7

What is Multi-Collector Inductively Coupled Plasma Mass Spectrometry & how does it work?

Answer 7

MC-ICP-MS separates isotopes by m/z using a large magnet