ATOMIC SPECTROSCOPY

Question 1

Atomic absorption spectroscopy quantifies

Answer 1

the absorption of electromagnetic radiation by well-separated atoms in the gaseous state

Question 2

Atomic emission spectroscopy measure

Answer 2

emission of radiation from atoms excited by heat or other means

Question 3

Individual elements can be identified and quantified in the presence of other atoms or ions because

Answer 3

each element has unique discrete energy
lines

Question 4

all elements are present as
compounds or complexes and must be

Answer 4

atomized before atomic absorption or emission measurements can be made

Question 5

Atomic absorption spectroscopy is a method based on

Answer 5

the absorption of ultra-violet or visible radiation by free atoms in the gaseous state

Question 6

Two types of atomization are commonly used in AAS:

Answer 6

 flame atomization
 graphite furnace atomization

Question 7

For measurement to be specific for a given element

Answer 7

the radiation source is chosen so that the emitted radiation contains the emission line of that corresponds to one of the most intense lines in the atomic spectrum of the element being measured

Question 8

nebulizer-burner system:

Answer 8

convert a solution of the sample into an atomic vapor

Question 9

• The primary combustion zone:

Answer 9

rich in gas combustion products that emit radiation, limiting its usefulness for atomic absorption

Question 10

The interzonal region:

Answer 10

rich in free atoms and provides the best location for measuring
atomic absorption

Question 11

The hottest part of the flame is typically 2–3 cm above the primary combustion zone.

Answer 11

As atoms approach the flame’s secondary combustion zone, the decrease in temperature
allows for formation of stable molecular species

Question 12

Electrothermal AAS is identical to flame AAS except for

Answer 12

atomization process.

Question 13

Chopper

Answer 13

to discriminate between these
two sources by positioning a chopper perpendicular to the light path
between the lamp and the flame.

Question 14

Monochromator

Answer 14

s to isolate the resonance line of interest from
the rest of the radiation coming from the flame or furnace and the lamp so that only radiation of the desired wavelength reaches the detector

Question 15

Spectral Interferences

Answer 15

an analyte’s absorption line overlaps
with an interferent’s absorption line or band

Question 16

Spectral Interferences is due to

Answer 16

(a)Absorption of source radiation (overlapping spectral lines)
(b) Background absorption of source radiation

Question 17

Non-spectral Interferences

Answer 17

(a)Transport interference
(b) Solute volatilization Interferences
(c) Ionization Interferences

Question 18

Atomic Emission Spectroscopy

Answer 18

method based on the emission of ultra-violet or visible radiation by excited atoms who fall back to lower energy states.

Question 19

DIGESTION

Answer 19

refers to decomposing complex samples into simpler forms, typically by dissolving or breaking down the matrix or
compounds present in the sample

Question 20

DIGESTION function to

Answer 20

facilitate digestion by rapidly and efficiently heating the sample using microwave radiation.

Question 21

STEPS

Answer 21

1. Sample Preparation
2. Addition of Digestion Reagents
3. Sealing the Digestion Vessel:
4. Microwave Heating:
5. Digestion Process:
6. Cooling and Ventilation:
7. Filtration and Dilution:

Question 22

1. EXTERNAL STANDARD METHOD:

Answer 22

-A calibration curve is constructed by plotting the instrumental response (e.g., absorbance) against the known concentrations of the standard solutions.
-The concentration of the analyte in the sample is then determined by measuring its instrumental response and using the calibration curve to interpolate or extrapolate the corresponding concentration

Question 23

2. STANDARD ADDITION METHOD

Answer 23

A fixed volume of the sample is taken, and varying amounts of the standard solution of the analyte are added incrementally to
the sample.