Spectrophotometry

Question 1

Ultraviolet

Answer 1

<400nm

Question 2

Visible light

Answer 2

400-700 nm

Question 3

Infrared

Answer 3

<700 nm

Question 4

Planck’s Formula

Answer 4

E=hv

Question 5

relationship between wavelength and energy

Answer 5

inversely proportional to energy and frequency

Question 6

shortest wavelength = __ energy frequency

Answer 6

↑ energy frequency

Question 7

longest wavelength = __ energy frequency

Answer 7

↓ energy frequency

Question 8

the concentration of a substance is directly proportional to the amount of light absorbed and is inversely proportional to the logarithm of transmitted light

Answer 8

Beer-Lambert’s Law

Question 9

A=abc

what is ‘a’?

Answer 9

molar absorptivity

Question 10

A=abc

what is ‘b’?

Answer 10

light path

Question 11

A=abc

what is ‘c’?

Answer 11

concentration

Question 12

Beer’s formula:

Answer 12

A= 2-log%T

(2 log Tayo after beer)

Question 13

formula to determine the concentration of an unknown analyte

Answer 13

Cu= AuCs/As

(AUq CaSe AmpangetS)

Question 14

distilled water, rgt, sample; sets the spectrophotometer to 0 absorbance

Answer 14

blank

Question 15

• corrects absorbance caused by the color of REAGENTS
• used to 0 the instrument before measuring test samples and other blanks

Answer 15

reagent blank

Question 16

used to subtract the intrinsic absorbance caused by hemolysis, icterus, turbidity, or drug interference

Answer 16

sample blank

Question 17

substance of KNOWN purity and concentration; used to determine the concentration of the unknown analyte

a. standard
b. control

Answer 17

a. standard

Question 18

• soln containing various analytes with known target values;
• analyzed with patient samples to monitor analytical performance (accuracy, precision)
• aka QC sample

a. standard
b. control

Answer 18

b. control

Question 19

values provided by the manufacturer

a. assayed
b. unassayed

Answer 19

a. assayed

Question 20

values determined by the laboratory

a. assayed
b. unassayed

Answer 20

b. unassayed

Question 21

provides polychromatic light

Answer 21

light source

Question 22

deuterium/hydrogen

a. UV, non-colorimetric
b. UV, visible light, colorimetric
c. visible, near IR

Answer 22

a. UV, non-colorimetric

Question 23

Xenon/Mercury

a. UV, non-colorimetric
b. UV, visible light, colorimetric
c. visible, near IR

Answer 23

b. UV, visible light, colorimetric

Question 24

tungsten, LASER

a. UV, non-colorimetric
b. UV, visible light, colorimetric
c. visible, near IR

Answer 24

c. visible, near IR

Question 25

meaning of LASER

Answer 25

light amplification by Stimulated Emission of Radiation

Question 26

prevents stray light

Answer 26

entrance slit

Question 27

wavelength selector/isolator

Answer 27

monochromator

Question 28

continuous, non-linear spectrum, better separation for high-frequency light a. prism b. diffraction gratings

Answer 28

a. prism

Question 29

continuous, linear, uniform separation of wavelengths; most commonly used a. prism b. diffraction gratings

Answer 29

b. diffraction gratings

Question 30

controls bandpass; narrow fraction of the spectrum to reach the cuvette

Answer 30

exit slit

Question 31

sample cell; may be round or square

Answer 31

cuvette

Question 32

quartz/fused silica cuvette a. UV-IR b. UV-visible c. visible; not for UV work

Answer 32

a. UV-IR

Question 33

plastic cuvette a. UV-IR b. UV-visible c. visible; not for UV work

Answer 33

b. UV-visible

Question 34

glass cuvette a. UV-IR b. UV-visible c. visible; not for UV work

Answer 34

c. visible; not for UV work

Question 35

converts the transmitted light energy into an equivalent amount of electrical energy

Answer 35

photodetector

Question 36

processes the electrical signal, performs mathematical operations, and displays the output

Answer 36

read-out device

Question 37

Spectrophotometer QA: if the WAVELENGTH is set to the actual one selected by the monochromator; checked using didymium glass or holmium oxide

Answer 37

wavelength accuracy

Question 38

Spectrophotometer QA: done using glass filters and solutions that have known ABSORBANCE values

Answer 38

absorbance check

Question 39

Spectrophotometer QA: A change in concentration results in a STRAIGHT LINE calibration curve (Beer's law) determined using neutral density filters and dichromate solution

Answer 39

Linearity

Question 40

Spectrophotometer QA: any wavelength outside the band of interest; causes absorbance error and loss of linearity; detected using sharp cut off filters

Answer 40

stray light