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QC 2 LEC > M3 > Flashcards

M3 Flashcards

1
Q

SPECTROSCOPY is the study of ____

A

spectra

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2
Q

it is often used in physical and .analytical chemistry for identification of substances, through the spectrum emitted or absorbed

A

SPECTROSCOPY

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3
Q

A branch of spectrometry which embraces the measurement of absorption by chemical species of radiant energy of definite and narrow wavelength, approximating “monochromatic radiation”

A

UV-VIS SPECTROSCOPY

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4
Q

it refers to the analysis of colored solutions that absorb light at a specific wavelength

A

UV-VIS SPECTROSCOPY

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5
Q

INSTRUMENTS USED IN UV-VIS SPECTROSCOPY

instruments which have a radiant energy dispersing device, such as prism or grating, and the associated electronics that permit the measurement of wavelenght and radiant power

A

SPECTROPHOTOMETER & SPECTROMETER

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6
Q

INSTRUMENTS USED IN UV-VIS SPECTROSCOPY

are instruments that permit measurement of radiant power but use a filter instead of a prism or grating for the purpose of increasing the sensitivity of the measurement

A

COLORIMETER & FILTER PHOTOMETER

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7
Q

INSTRUMENTS USED IN UV-VIS SPECTROSCOPY

  • a device used for measuring colors
  • it measures the absorbance of difference wavelengths of light in a solution
  • it can be used to measure the concentration of a KNOWN solute
A

COLORIMETER

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8
Q

INSTRUMENTS USED IN UV-VIS SPECTROSCOPY

COLORIMETER is used to measure the concentration of ____ solute

A

known

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9
Q

INSTRUMENTS USED IN UV-VIS SPECTROSCOPY

a device that measures the bintensity of light (brightness) produced by an UNKNOWN solution in terms of a standard source

A

PHOTOMETER

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10
Q

PARTS OF SPECTROPHOTOMETER

a simple transformer that provides current at the proper voltage for several components such as the detector, radiant devices, and lamps

A

POWER SUPPLY

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11
Q

PARTS OF SPECTROPHOTOMETER

  • the “light source”
  • it generates a broad band or electromagnetic radiation
  • TYPES:
    * Tungsten
    * Deuterium
    * Xenon
A

LAMPS

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12
Q

PARTS OF SPECTROPHOTOMETER

LAMPS for vis

A

tungsten lamp

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13
Q

PARTS OF SPECTROPHOTOMETER

LAMPS for uv

A

deuterium lamp

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14
Q

PARTS OF SPECTROPHOTOMETER

LAMPS for alternative source

A

xenon lamp

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15
Q

PARTS OF SPECTROPHOTOMETER

  • used to isolate the desired wavelength from the broadband radiation
  • it consists of the following:
    * entrance slit
    * dispersion device
    * exit slit
A

MONOCHROMATOR

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16
Q

PARTS OF SPECTROPHOTOMETER

MONOCHROMATOR consists of:

3

A

entrance slit
dispersion device
exit slit

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17
Q

PARTS OF SPECTROPHOTOMETER

  • it produces a current in response to the light impinging upon it and converts a light signal into electrical signal
  • it contains a light sensitive surface that releases electrons in numbers proportional to the intensity of light impinging upon it
A

DETECTOR / MICROPROCESSOR

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18
Q

PARTS OF SPECTROPHOTOMETER | DETECTOR TYPES

  • also known as “barrier layer cell” or “selenide cell”
  • the simplest of all detectors
A

PHOTOCELL

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19
Q

PARTS OF SPECTROPHOTOMETER | DETECTOR TYPES

PHOTOCELL is also called as

A

barrier layer cell
selenide cell

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20
Q

PARTS OF SPECTROPHOTOMETER | DETECTOR TYPES

  • it consists of a curved cathode of metal coated with a photosensitive material
  • more sensitive than the photocells
A

PHOTOTUBE

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21
Q

PARTS OF SPECTROPHOTOMETER | DETECTOR TYPES

  • it combines signal conversion, with several stages of amplification in the body of the tube
  • it is required when low levels of light or quick bursts of light must me measured
  • it is sensitive and produce a fast response
A

PHOTOMULTIPLIER TUBE

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22
Q

PARTS OF SPECTROPHOTOMETER | DETECTOR TYPES

  • small, durable, and capable of high amplification
  • newest of the light detectors
A

PHOTODIODES

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23
Q

PARTS OF SPECTROPHOTOMETER

  • relay or focus light through the instrument
  • uses either:
    • achromatic lenses
    • concave mirrors
A

OPTICS / OPTICAL SYSTEM

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24
Q

PARTS OF SPECTROPHOTOMETER

OPTICS / OPTICAL SYSTEM uses either

2

A

achromatic lenses
concave mirrors

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25
Q

PARTS OF SPECTROPHOTOMETER

  • measures the magnitude of the current generated by a detector
  • examples:
    • galvanometer
    • ammeter with a meter needle
    • recorder
    • digital readout
A

READOUT DEVICES

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26
Q

PARTS OF SPECTROPHOTOMETER

  • also known as “cells”
  • it contains the solution to be analyzed
A

CUVETTE

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27
Q

PARTS OF SPECTROPHOTOMETER

CUVETTE for visible

A

glass
plastic

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28
Q

PARTS OF SPECTROPHOTOMETER

CUVETTE for UV

A

quartz or fused silica

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29
Q

PARTS OF SPECTROPHOTOMETER | TYPE OF CELLS/CUVETTES

  • rectangular cell
  • 10nm is the most popular pathlength used
A

OPEN - TOPPED

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30
Q

PARTS OF SPECTROPHOTOMETER | TYPE OF CELLS/CUVETTES

most popular pathlength used

A

10nm

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31
Q

PARTS OF SPECTROPHOTOMETER | TYPE OF CELLS/CUVETTES

for limited volume of samples

A

APERTURED CELL

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32
Q

PARTS OF SPECTROPHOTOMETER | TYPE OF CELLS/CUVETTES

for extremely limited samples, it can reduce the aperture of the sample to a very small cross-section area

A

MICRO CELL

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33
Q

an opening or a hole

A

aperture

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33
Q

PARTS OF SPECTROPHOTOMETER | TYPE OF CELLS/CUVETTES

for automated applications

A

FLOW THROUGH CELL

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34
Q

FOR ACCURATE AND PRECISE READINGS:

cuvettes must be:

A
  • clean
  • no fingerprints, scratches or any spills on the optical surface
  • no bubbless in the inner surface
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35
Q

INSTRUMENTS USED IN UV-VIS SPECTROSCOPY

  • operates like a single-beam spectrophotometer but they are designed to bcompensate for possible variations in intensity of light-source
  • accomplished by splitting the light beam from the lamp and direting one portion to a reference cuvette and the other to the sample cuvette
A

DOUBLE BEAM SPECTROPHOTOMETER

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36
Q
  • measured different types of inter-atomic bond vibrations at different frequencies
  • useful in organic chemistry analysis of IR absorption spectra, for the identification of the types of chemical bonds present in the sample
A

INFRARED (IR) SPECTROSCOPY

37
Q

IR SPECTRUM REGIONS

interest in the ____ has grown in recent years particularly in the food and feedstuff industry where it is routinely used for quantitative analysis

38
Q

IR SPECTRUM REGIONS

  • most widely used region with molecular vibration typically involved in organic molecules
  • it provides a wealth of structural information ad well as quantitative data
39
Q

IR SPECTRUM REGIONS

principally concerned with rotational spectral and crystal lattice vibrations

40
Q

IR | FUNDAMENTAL VIBRATIONS

  • 8 - 15 um
  • a region that gives a spectrum and identification of the molecule as a whole
A

SKELETAL VIBRATIONS

41
Q

IR | FUNDAMENTAL VIBRATIONS

  • 3 - 8 um
  • a rgion that gives a spectrum and identification of the functional groups found in organic compounds
A

CHARACTERISTIC GROUP VIBRATIONS

42
Q

____ is NOT USED as a solvent
* it strongly absorbs most of the IR radiation
* it would destroy the sodium chloride cells which hold the sample

43
Q

METHODS OF PREPARING SAMPLE IN IR SPECTROSCOPY

  • also known as “mull tehcnique”
  • a general sample handling technique useful with samples that undergo ion exchange
  • relatively inexpensive compared to KBr pellets because there is no need for accessories like dies and presses
A

DISPERSING THE FINELY GROUND SOLID IN LIQUID PETROLATUM

44
Q

METHODS OF PREPARING SAMPLE IN IR SPECTROSCOPY

DISPERSING THE FINELY GROUND SOLID IN LIQUID PETROLATUM is also known as

A

mull technique

45
Q

METHODS OF PREPARING SAMPLE IN IR SPECTROSCOPY

DISPERSING THE FINELY GROUND SOLID IN LIQUID PETROLATUM mulling agents:
* a white hydrocarbon mineral oil

46
Q

METHODS OF PREPARING SAMPLE IN IR SPECTROSCOPY

DISPERSING THE FINELY GROUND SOLID IN LIQUID PETROLATUM mulling agents:
* a perfluorinated hydrocarbon oil

A

FLUOROLOBE

47
Q

IR | DISPERSING THE FINELY GROUND SOLID IN LIQUID

a small amount of sample (100mg) should be placed in an ____

A

AGATE MORTAR

48
Q

IR | DISPERSING THE FINELY GROUND SOLID IN LIQUID

the sample must be ground vigorously until ____ appearance

49
Q

IR | DISPERSING THE FINELY GROUND SOLID IN LIQUID

PETROLATUM**

STEPS

A
  1. ground until glossy
  2. drops of liquid petrolatum – mayonnaise consistency
  3. transfer to NaCl plate, cover w/ 2nd NaCl plate & mounted
  4. absorption specturm is run
  5. repeat procedure using reference standard
50
Q

IR | DISPERSING THE FINELY GROUND SOLID IN LIQUID

the mull should be ____ to visible light

A

SEMI-TRANSPARENT

51
Q

METHODS OF PREPARING SAMPLE IN IR SPECTROSCOPY

CRITERIA FOR GOOD SOLVENT

A
  • good solubilizing property
  • chemically onert
  • solvent transparency
52
Q

METHODS OF PREPARING SAMPLE IN IR SPECTROSCOPY

Sample handling: KINDS OF CELLS

A

Demountable cells
Sealed cells

53
Q

METHODS OF PREPARING SAMPLE IN IR SPECTROSCOPY

a technique that is very useful for solids and powders and for analysis of limited amount of samples

A

INCORPORATING THE SOLID IN KBr PELLET

54
Q

METHODS OF PREPARING SAMPLE IN IR SPECTROSCOPY

MATRIX MATERIALS FOR PELLET-MAKING

A

KBr
KCl
NaCl
Csl

55
Q

IR | INCORPORATING THE SOLID IN A KBr PELLET

why do we need to mix the sample rapidly

A

to avoid the CHRISTIANSEN-EFFECT

56
Q

IR | INCORPORATING THE SOLID IN A KBr PELLET

STEPS

A
  1. 5mg sample & 500mg IR-quality KBr in a a mortar, mixed rapidly until glossy
  2. transfer into a die & form the pellet
  3. remove the pellet, transfer to holder, obtain an absorption spectrum
  4. repeat w reference standard
57
Q
  • it is used in the assay of metallic elements in the blood (Na, K, Li, Ca)
  • it is useful in clinical chemistry
A

FLAME SPECTROSCOPY

58
Q

TYPES OF FLAME SPECTROSCOPY

A

Atomic emission spectrophotometry
Atomic absorption spectrophotometry

59
Q

FLAME SPECTROSCOPY

  • also known as “flame photometry”
  • it deals wwith the measurement of emitted light whose intensity is proportional to the number of atoms
  • it is used to identify a certain element
A

ATOMIC EMISSION SPECTROPHOTOMETRY

60
Q

FLAME SPECTROSCOPY

Atomic EMISSION spectrophotometry is also known as

A

FLAME PHOTOMETRY

61
Q

FLAME SPECTROSCOPY | ATOMIC EMISSION

the sample is diluted with a ____ containing a specified conc. of a cesium or lithium salt

A

NONIONIC DETERGENT (wetting agent)

62
Q

FLAME SPECTROSCOPY | ATOMIC EMISSION

reduces the viscosity of the solution and improves aspiration of the sample

63
Q

FLAME SPECTROSCOPY | ATOMIC EMISSION

used as an internal standard to compensate for the variations in sample feed, gas pressure or fuel

A

cesium or lithium

64
Q

FLAME SPECTROSCOPY

  • it is the measurement of the absorption of light by free metallic atoms
  • commonly used for the analysis of certain trace elements in aqueous samples and various liquid samples
  • its advantages include good sensitivity and selectivity
A

ATOMIC ABSORPTION SPECTROPHOTOMETRY

65
Q
  • also known as fluorometry or spectrofluorometry
  • a type of electromagnetic spectroscopy that analyzes fluorescence from a sample
  • it involves the use of a beam of light that excites the electron/s in a certain compound that causes them to emit light of lower energy
A

FLUORESCENCE SPECTROSCOPY

66
Q
  • in chemistry, it is used in the analysis of organic compounds
  • in medicine, it is used in differentiating malignant from benign skin tumors
  • in pharmacy, it is the official method for analysis for vitamins like Vitamin B1 thiamine and B2 riboflavin
A

FLUOROMETRY

67
Q

FLUOROMETRY | COMPONENTS

  • light source
  • types:
    • mercury arch discharge lamp
    • xenon arc tube
68
Q

FLUOROMETRY | COMPONENTS

  • uses a phototube or photomultiplier tube
  • it is placed at right angles to the beam of light from the lamp to the sample
69
Q

FLUOROMETRY | COMPONENTS

allows the passage of light of the proper wavelength for the absorption by the molecule

A

EXCITATION MONOCHROMATOR

70
Q

FLUOROMETRY | COMPONENTS

transmits light of specific wavelength emitted by the sample

A

EMISSION MONOCHROMATOR

71
Q
  • a branch of spectrometry which deals with the measurement of transmitted light by a turbid solution or suspension
  • based on an optical detection system that measures turbidity
A

TURBIDIMETRY

72
Q

PRINCIPLES OF TURBIDIMETRY

a light beam that passes throough a solution is ____, depending on the degree of turbidity

73
Q

PRINCIPLES OF TURBIDIMETRY

measures the reduction in the intensity of the light beam

A

photodetector

74
Q

PRINCIPLES OF TURBIDIMETRY

the transmitted light represents a ____

(more turbid the solution, more light will be absorbed, the less light will be transmitted)

A

decreased signal

75
Q

PRINCIPLES OF TURBIDIMETRY

ABSORBANCE is ____ in quantity, in relation to the concentration of the sample

A

increasing

76
Q

TURBIDIMETRY: APPLICATIONS

official method of assay for majority of ____ since it indicates microbial growth

A

antibiotics

77
Q

TURBIDIMETRY: APPLICATIONS

official method of assay for ____ and ____

A

calcium pantothenate
cyanocobalamin (vit b12)

78
Q
  • a branch of spectrometry which deals with the measurement of the brightness of light relfected by a turbid solution
  • used in the clinical laboratory to quantitate the rate of insoluble antigen-antibody complex formation during the assay of specific serum proteins
A

NEPHELOMETRY

79
Q
  • analytical technique for the determination of the elemental composition of a sample or molecule
  • used for the elucidation of the chemical structures of molecues (peptides or other chemical compounds)
  • it relies on the production of ions from a parent compound and the susbequent chaaracterization of the patterns that are produced
A

MASS SPECTROMETRY

80
Q

in order for mass spectrometry to function, it must be conducted under vacuum conditions of ____ torr

A

10⁻⁴ to 10⁻⁵ torr

81
Q

MASS SPECTROMETRY | COMPONENTS

a small sample of compound is ionized, usually to cations, by loss of an electron

A

ION SOURCE

82
Q

MASS SPECTROMETRY | COMPONENTS

the ions are sorted and separated according to their mass and charge

A

MASS ANALYZER

83
Q

MASS SPECTROMETRY | COMPONENTS

the seperated ions are then detected and tallied and the results are displayed on chart

84
Q

NATURE OF MASS SPECTRA

a mass spectrum is usually presented as a ____

85
Q

NATURE OF MASS SPECTRA

each bar represents an ____

86
Q

NATURE OF MASS SPECTRA

the ____ indicated the relative abundance of the ion

A

bar length

87
Q

MASS SPECTROMETRY: APPLICATIONS

identification of ____

A

UNKNOWN compounds

88
Q

MASS SPECTROMETRY: APPLICATIONS

determination of the ____ of elements in a molecule

A

ISOTOPIC COMPOSITION

89
Q

MASS SPECTROMETRY: APPLICATIONS

determination of the structure of a compound by observing its ____

A

FRAGMENTATION

QC 2 LEC (7 decks)

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