M3 Flashcards
(90 cards)
1
Q
SPECTROSCOPY is the study of ____
A
spectra
2
Q
it is often used in physical and .analytical chemistry for identification of substances, through the spectrum emitted or absorbed
A
SPECTROSCOPY
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
4
Q
it refers to the analysis of colored solutions that absorb light at a specific wavelength
A
UV-VIS SPECTROSCOPY
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
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
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
8
Q
INSTRUMENTS USED IN UV-VIS SPECTROSCOPY
COLORIMETER is used to measure the concentration of ____ solute
A
known
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
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
11
Q
PARTS OF SPECTROPHOTOMETER
- the “light source”
- it generates a broad band or electromagnetic radiation
- TYPES:
* Tungsten
* Deuterium
* Xenon
A
LAMPS
12
Q
PARTS OF SPECTROPHOTOMETER
LAMPS for vis
A
tungsten lamp
13
Q
PARTS OF SPECTROPHOTOMETER
LAMPS for uv
A
deuterium lamp
14
Q
PARTS OF SPECTROPHOTOMETER
LAMPS for alternative source
A
xenon lamp
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
16
Q
PARTS OF SPECTROPHOTOMETER
MONOCHROMATOR consists of:
3
A
entrance slit
dispersion device
exit slit
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
18
Q
PARTS OF SPECTROPHOTOMETER | DETECTOR TYPES
- also known as “barrier layer cell” or “selenide cell”
- the simplest of all detectors
A
PHOTOCELL
19
Q
PARTS OF SPECTROPHOTOMETER | DETECTOR TYPES
PHOTOCELL is also called as
A
barrier layer cell
selenide cell
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
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
22
Q
PARTS OF SPECTROPHOTOMETER | DETECTOR TYPES
- small, durable, and capable of high amplification
- newest of the light detectors
A
PHOTODIODES
23
Q
PARTS OF SPECTROPHOTOMETER
- relay or focus light through the instrument
- uses either:
- achromatic lenses
- concave mirrors
A
OPTICS / OPTICAL SYSTEM
24
Q
PARTS OF SPECTROPHOTOMETER
OPTICS / OPTICAL SYSTEM uses either
2
A
achromatic lenses
concave mirrors
25
# **PARTS OF SPECTROPHOTOMETER**
* measures the **magnitude** of the current **generated by a detector**
* examples:
* galvanometer
* ammeter with a meter needle
* recorder
* digital readout
READOUT DEVICES
26
# **PARTS OF SPECTROPHOTOMETER**
* also known as **"cells"**
* it **contains** the **solution to be analyzed**
CUVETTE
27
# **PARTS OF SPECTROPHOTOMETER**
CUVETTE for **visible**
glass
plastic
28
# **PARTS OF SPECTROPHOTOMETER**
CUVETTE for **UV**
quartz or fused silica
29
# **PARTS OF SPECTROPHOTOMETER | TYPE OF CELLS/CUVETTES**
* **rectangular** cell
* **10nm** is the **most popular pathlength** used
OPEN - TOPPED
30
# **PARTS OF SPECTROPHOTOMETER | TYPE OF CELLS/CUVETTES**
most popular pathlength used
10nm
31
# **PARTS OF SPECTROPHOTOMETER | TYPE OF CELLS/CUVETTES**
for **limited volume** of samples
APERTURED CELL
32
# **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**
MICRO CELL
33
an **opening** or a **hole**
aperture
33
# **PARTS OF SPECTROPHOTOMETER | TYPE OF CELLS/CUVETTES**
for **automated** applications
FLOW THROUGH CELL
34
# **FOR ACCURATE AND PRECISE READINGS:**
cuvettes must be:
* clean
* no fingerprints, scratches or any spills on the optical surface
* no bubbless in the inner surface
35
# **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**
DOUBLE BEAM SPECTROPHOTOMETER
36
* 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 presen**t in the sample
INFRARED (IR) SPECTROSCOPY
37
# **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**
NEAR IR
38
# **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**
MID IR
39
# **IR SPECTRUM REGIONS**
principally concerned with **rotational spectral** and **crystal lattice vibrations**
FAR IR
40
# **IR | FUNDAMENTAL VIBRATIONS**
* **8 - 15 um**
* a region that gives a spectrum and identification of the molecule **as a whole**
SKELETAL VIBRATIONS
41
# **IR | FUNDAMENTAL VIBRATIONS**
* **3 - 8 um**
* a rgion that gives a spectrum and identification of the **functional groups** found in organic compounds
CHARACTERISTIC GROUP VIBRATIONS
42
____ 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
WATER
43
# **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
DISPERSING THE FINELY GROUND SOLID IN LIQUID PETROLATUM
44
# **METHODS OF PREPARING SAMPLE IN IR SPECTROSCOPY**
DISPERSING THE FINELY GROUND SOLID IN LIQUID PETROLATUM is also known as
mull technique
45
# **METHODS OF PREPARING SAMPLE IN IR SPECTROSCOPY**
DISPERSING THE FINELY GROUND SOLID IN LIQUID PETROLATUM **mulling agents**:
* a **white** hydrocarbon **mineral** oil
NUJOL
46
# **METHODS OF PREPARING SAMPLE IN IR SPECTROSCOPY**
DISPERSING THE FINELY GROUND SOLID IN LIQUID PETROLATUM **mulling agents**:
* a **perfluorinated** hydrocarbon oil
FLUOROLOBE
47
# **IR | DISPERSING THE FINELY GROUND SOLID IN LIQUID**
a small amount of sample (**100mg**) should be placed in an ____
AGATE MORTAR
48
# **IR | DISPERSING THE FINELY GROUND SOLID IN LIQUID**
the sample must be **ground vigorously** until ____ appearance
GLOSSY
49
# **IR | DISPERSING THE FINELY GROUND SOLID IN LIQUID**
PETROLATUM**
STEPS
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
# **IR | DISPERSING THE FINELY GROUND SOLID IN LIQUID**
the **mull** should be ____ to **visible light**
SEMI-TRANSPARENT
51
# **METHODS OF PREPARING SAMPLE IN IR SPECTROSCOPY**
CRITERIA FOR GOOD SOLVENT
* good solubilizing property
* chemically onert
* solvent transparency
52
# **METHODS OF PREPARING SAMPLE IN IR SPECTROSCOPY**
Sample handling: KINDS OF CELLS
Demountable cells
Sealed cells
53
# **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**
INCORPORATING THE SOLID IN KBr PELLET
54
# **METHODS OF PREPARING SAMPLE IN IR SPECTROSCOPY**
MATRIX MATERIALS FOR PELLET-MAKING
KBr
KCl
NaCl
Csl
55
# **IR | INCORPORATING THE SOLID IN A KBr PELLET**
why do we need to mix the sample **rapidly**
to avoid the CHRISTIANSEN-EFFECT
56
# **IR | INCORPORATING THE SOLID IN A KBr PELLET**
STEPS
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
* it is used in the **assay** of **metallic elements** in the **blood** (Na, K, Li, Ca)
* it is useful in **clinical chemistry**
FLAME SPECTROSCOPY
58
TYPES OF **FLAME SPECTROSCOPY**
Atomic **emission** spectrophotometry
Atomic **absorption** spectrophotometry
59
# **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**
ATOMIC **EMISSION** SPECTROPHOTOMETRY
60
# **FLAME SPECTROSCOPY**
Atomic **EMISSION** spectrophotometry is also known as
FLAME PHOTOMETRY
61
# **FLAME SPECTROSCOPY | ATOMIC EMISSION**
the sample is **diluted** with a ____ containing a specified conc. of a **cesium** or **lithium salt**
NONIONIC DETERGENT (wetting agent)
62
# **FLAME SPECTROSCOPY | ATOMIC EMISSION**
**reduces** the **viscosity** of the solution and **improves aspiration** of the sample
DETERGENT
63
# **FLAME SPECTROSCOPY | ATOMIC EMISSION**
used as an **internal standard** to compensate for the variations in sample feed, gas pressure or fuel
cesium or lithium
64
# **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**
ATOMIC **ABSORPTION** SPECTROPHOTOMETRY
65
* 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**
FLUORESCENCE SPECTROSCOPY
66
* 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**
FLUOROMETRY
67
# **FLUOROMETRY | COMPONENTS**
* **light source**
* types:
* mercury arch discharge lamp
* xenon arc tube
LAMP
68
# **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
DETECTOR
69
# **FLUOROMETRY | COMPONENTS**
**allows** the **passage of light** of the p**roper wavelength** for the absorption by the molecule
**EXCITATION** MONOCHROMATOR
70
# **FLUOROMETRY | COMPONENTS**
**transmits light** of specific wavelength emitted by the sample
**EMISSION** MONOCHROMATOR
71
* 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**
TURBIDIMETRY
72
# **PRINCIPLES OF TURBIDIMETRY**
a light beam that passes throough a solution is ____, depending on the **degree of turbidity**
scattered
73
# **PRINCIPLES OF TURBIDIMETRY**
measures the **reduction** in the **intensity** of the light beam
photodetector
74
# **PRINCIPLES OF TURBIDIMETRY**
the **transmitted light** represents a ____
## Footnote
(**more turbid** the **solution**, **more light** will be **absorbed**, the **less** light will be **transmitted**)
decreased signal
75
# **PRINCIPLES OF TURBIDIMETRY**
ABSORBANCE is ____ in **quantity**, in relation to the **concentration** of the sample
increasing
76
# **TURBIDIMETRY: APPLICATIONS**
**official method of assay** for majority of ____ since it indicates **microbial growth**
antibiotics
77
# **TURBIDIMETRY: APPLICATIONS**
**official method of assay** for ____ and ____
calcium pantothenate
cyanocobalamin (vit b12)
78
* 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**
NEPHELOMETRY
79
* 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
MASS SPECTROMETRY
80
in order for **mass spectrometry** to function, it must be conducted under **vacuum conditions** of ____ torr
10⁻⁴ to 10⁻⁵ torr
81
# **MASS SPECTROMETRY | COMPONENTS**
a small sample of compound is **ionized**, usually **to cations**, by **loss** of an electron
ION SOURCE
82
# **MASS SPECTROMETRY | COMPONENTS**
the ions are **sorted** and **separated** according to their **mass** and **charge**
MASS ANALYZER
83
# **MASS SPECTROMETRY | COMPONENTS**
the seperated ions are then **detected** and **tallied** and the results are **displayed on chart**
DETECTOR
84
# **NATURE OF MASS SPECTRA**
a **mass spectrum** is usually presented as a ____
BAR GRAPH
85
# **NATURE OF MASS SPECTRA**
each **bar** represents an ____
ION
86
# **NATURE OF MASS SPECTRA**
the ____ indicated the **relative abundance** of the ion
bar length
87
# **MASS SPECTROMETRY: APPLICATIONS**
identification of ____
UNKNOWN compounds
88
# **MASS SPECTROMETRY: APPLICATIONS**
determination of the ____ of elements in a molecule
ISOTOPIC COMPOSITION
89
# **MASS SPECTROMETRY: APPLICATIONS**
determination of the **structure of a compound** by observing its ____
FRAGMENTATION
