IH Equipment

Question 1

Atomic absorption is good at at analyzing…

Answer 1

Metals

Question 2

What is XRF

Answer 2

An X-ray fluorescence (XRF) spectrometer is an x-ray instrument used for routine, relatively non-destructive chemical analyses of rocks, minerals, sediments and fluids.

A combination of atomic emission and atomic absorption

Question 3

What is a fluorescence detector?

Answer 3

• Measures emission of light by fluorescing elements.
• Light source raises energy of electrons that decay emitting light at longer wavelengths.

Question 4

What is mass spectometry?

Answer 4

• A technique for separating substances based on the mass of the molecule.
• Molecules are given an electrical charge and are accelerated into an electromagnetic field.
• Molecules are selected based on the mass/charge (M/z) ratio.

Helpful in identifying unknowns.

Question 5

How does UV absorbance work

Answer 5

Measures the amount of UV light absorbed by a sample. The amount of light absorbed is proportional to concentration of absorbing material.

Question 6

Spectrophotometers use the following…

Answer 6

Spectrophotometry is a group of analytical techniques which utilize electromagnetic radiation to conduct qualitative or quantitative analysis based on the measurement of the reflection or transmission properties of a material as a function of wavelength. Spectrophotometry uses spectrophotometers that can measure the intensity of a light beam at different wavelengths

UV light
Infrared light
Visible light
x-ray
Ultraviolet
Microwave

Question 7

What is gas chromatography?

Answer 7

• A technique used to separate chemical substances.
• Chemicals move through the column at varying rates.
• A gas is used as the carrier medium.
• Used frequently for hydrocarbons.

Used for volatile compounds because they easily evaporate at room temperature.

Question 8

What is HPLC?

Answer 8

Similar to gas chromatography except that the carrier medium is a liquid. Contaminant must be soluble in mobile phase.

Question 9

What is ion chromatography?

Answer 9

A form of liquid chromatography that uses ion-exchange resins to separate atomic or molecular ions based on their interaction with the resin.

Question 10

What is ion chromatography used for?

Answer 10

Anionic and cationic species, ions of alkali and alkaline earth metals, inorganic compounds, and aldehydes

Question 11

The major law of chemistry upon which visible and ultraviolet spectrophotometry is based is?

Answer 11

Spectrophotometry is based upon Beer’s Law which states: Absorbance at a particular wavelength is equal to the chemicals molar absorptive constant times the path length of the cell times the concentration of the chemical.

Question 12

What are two major disadvantages of ion chromatography?

Answer 12

• Inability to analyze non-ionic species
• Interference with ions of a similar selectivity/exchange coefficient

Question 13

What is a main characteristic of ion chromatography?

Answer 13

• It provides analysis of several ionic species from a single sample

Question 14

Which materials cannot be used as a prism in an infrared spectrophotometer?

Answer 14

• Sodium chloride
• Potassium bromide
• Cesium iodide

Question 15

Filter sample submitted for light microscopy or TEM analysis must be lightly loaded and on what type of filter paper?

Answer 15

Cellulose ester

Question 16

When a welding fume sample is analyzed and a metal scan is requested, an analytical technique is used to quantitate multiple metals simultaneously. This analytical technique is is called:

Answer 16

ICP or inductively coupled plasma discharge has made multiple simultaneous metal analyses possible.

Question 17

What diameter can be determined directly from the cumulative distribution plot of cascade impactor data?

Answer 17

Cascade impactors distribute particles to the various stages based on their aerodynamic diameter, and the stages are weighed to determine the mass of particles collected in each size range. The cumulative distribution plot of cascade impactor data will thus yield the mass median aerodynamic diameter at the 50% point of the distribution.

Question 18

What law does UV absorbance follow?

Answer 18

Beer-lambert law

Question 19

What law does fluorescence detector use?

Answer 19

Beer-lambert law

Question 20

What is eV and where is it used?

Answer 20

eV = electron volt and it’s used for PIDs

An eV is a unit of measurement contained in a photon generated by a UV lamp. Example: a 10.6 eV lamp will generate photons with an energy of 10.6 eV

Question 21

What are PID advantages?

Answer 21

• Immediate qualitative results
• Quantitative results for individual known contaminants
• Can analyze a wide range of chemicals
• Unaffected by atmospheric conditions

Question 22

Compare / contrast PID to FID

Answer 22

• hydrogen / oxygen / carrier gas ionizes instead of a UV light
• FIDs more difficult to operate than PIDs
• FIDs respond to more chemicals than PIDs and are linear over a greater range

Question 23

What is activated charcoal desorbed with?

Answer 23

CS2

Question 24

Is silica gel hydrophilic or hydrophobic?

Answer 24

Hydrophilic - loves and binds to H2O

Question 25

What can cause solid sorbent breakthrough?

Answer 25

• High humidity
• Concentration too high
• Migration of chemicals
• High temperature
• Channeling
• High flow rates