Analytical Methods and Instrumentations Flashcards
1
Q
Two primary considerations in
every colorimetric analysis:
A
- Quality of the color
- Intensity of the color
2
Q
Special dye that changes color on the reactions
A
Chromogen
3
Q
4 basic disciplines on Analytical Chemistry
A
Spectrometry
Luminescence
Electroanalytic Methods
Chromatography
4
Q
Examples of Spectrometry
A
Spectrophotometry
Atomic Absorption
Mass Spectrometry
5
Q
Examples of Luminescence
A
Fluorescence
Chemiluminescene
Nephelometry
6
Q
Examples of Electroanalytic Methods
A
Electrophoresis
Potentiometry
Amperometry
7
Q
Examples of Chromatography
A
Gas
Liquid
Thin-layer
8
Q
2 Categories in Colorimetry
A
Visual Colorimetry
Photoelectric Colorimetry
9
Q
Types of Photoelectric Colorimetry
A
Spectrophotometric Measurement
Photometric Measurement
10
Q
Measurement of light intensity in a narrower wavelength.
A
Spectrophotometric Measurement
11
Q
Measurement of light intensity at multiple wavelengths.
A
Photometric Measurement
12
Q
Detection of light as a potential marker of concentration of analyte
A
Luminescence
13
Q
Our of the 4 disciplines of Analytical Chemistry, what are the disciplines that uses light or radiant energy?
A
Spectrometry
Luminescence
14
Q
Spectrophotometric uses what type of monochromators?
A
Prisms
Diffraction Gratings
15
Q
Photometric uses what type of monochromators?
A
Filters
16
Q
Measurements of Radiant Energy:
A
Emitted
Transmitted
Absorbed
Scattered
Reflected
17
Q
Transmitted via electromagnetic waves that
are characterized by their frequency and Wavelength
A
Energy
18
Q
The distance between two successive
peaks and it is expressed in terms of nanometer
A
Wavelength
19
Q
Wavelength on visible spectrum?
A
400-700 nm
20
Q
Wavelength on ultraviolet region?
A
<400 nm
21
Q
Wavelength on infrared region?
A
> 700 nm
22
Q
The relationship between wavelength and energy is described by _____
A
Planck’s Formula
23
Q
Planck’s Formula:
A
E=hv
24
Q
In Planck’s formula (E=hv), the E is _____ and the V is _____
A
E - is the energy of a photon in Joules or constant
V- frequency
25
Value of E in the Planck''s formula:
6.626 x 10^27 erg sec
26
Types of Radiant Energy
Cosmic rays
Gamma rays
X-rays + Visible
Ultra-violet (UV)
Infrared (IR)
Radio, TV, microwave, etc.
27
The number of vibrations of wave motion per second
Frequency
28
The _____ the wave frequency, the longer the
wavelength.
Lower
29
The lower the wave frequency, the _____ the
wavelength.
Longer
30
The _____ the wavelength, the higher the
frequency and energy.
Shorter
31
The shorter the wavelength, the _____ the
frequency and energy.
Higher
32
Represents the wavelength in nanometers at peak transmittance.
Nominal Wavelength
33
Used to calibrate wavelength; quality control.
Didymium
Holmium Oxide Filters
34
Measurement of the light transmitted by a solution to determine the concentration of the light-absorbing substances in the solution.
Spectrophotometry
35
Ratio of the radiant energy transmitted, divided by the radiant energy incident on the sample.
Transmittance
36
Formula for Transmittance:
%T=(It/Io) x 100
37
In the formula for Transmittance (%T=(It/Io) x 100, the It is the _____ and the Io is the _____
It- radiant energy that is transmitted
Io - light that will pass through the exit slit towards the cuvette
38
The amount of light absorbed; proportional to the inverse log of transmittance.
Absorbance
39
Absorbance is mathematically derived from _____
%T
40
Formula for Absorbance:
A = 2 – log%T
A = -log%T
A = 1/log%T
41
States that the concentration of a substance is directly proportional to the amount of the light absorbed or inversely proportional to the logarithm of transmitted light.
Beer's Law orBeer-Lambert's Law
42
Formula for Beer's Law orBeer-Lambert's Law:
A=abc
43
In the formula of Beer's Law or Beer-Lambert's Law (A=abc), this is identified as the absorbance
A
44
In the formula of Beer's Law or Beer-Lambert's Law (A=abc), this is identified as the molar absorptivity
a
45
In the formula of Beer's Law or Beer-Lambert's Law (A=abc), this is identified as the length of light through the solution
b
46
In the formula of Beer's Law or Beer-Lambert's Law (A=abc), this is identified as the concentration of absorbing molecules/solution
c
47
It is the simplest type of absorption spectrometer designed to make one measurement at a time at one specified wavelength.
Single Beam Spectrophotometer
48
An Instrument that splits the monochromatic light into two components - one beam passes through the sample, and the other through a reference solution or blank. The additional beam corrects for variation in light source
intensity.
Double-beam Spectrophotometer
49
2 Types of Double-beam Spectrophotometer:
Double-beam in Space
Double-beam in Time
50
A type of Double-beam Spectrophotometer that has 2 photodetectors, for the sample
beam and reference beam.
Double-beam in Space
51
A type of Double-beam Spectrophotometer that has one photodetector and alternately
passes the monochromatic light through the sample cuvet and the reference cuvet using a chopper or rotating sector mirror.
Double-beam in Time
52
7 basic components of single or doublebeam configuration spectrophotometer:
1. Stable source of radiant energy
2. Filter that isolates a specific region of the electromagnetic spectrum
3. Cuvets
4. Sample holder
5. Radiation detector
6. Signal processor and
7. Readout device
53
It provides polychromatic light and must generate sufficient radiant energy or power to measure the analyte of interest.
Light/Radiant Energy
54
To give accurate absorbance measurements throughout its absorbance range, its response to change in light intensity must be _____
Linear
55
2 Types of Light/Radiant Source:
Continuum Source
Line Source
56
A light source that emits radiation that changes in intensity; widely used in the laboratory.
Continuum Source
57
Examples of Continuum Source:
Tungsten
Deuterium
Xenon Lamps
58
Commonly used light source in the visible and near infrared region
Tungsten Light Bulbs
59
Routinely used light source to provide UV radiation in analytic spectrometers.
Deuterium Lamps
60
Light source that produces a continuous source of radiation, which covers both the UV and the visible range.
Xenon Discharge Lamp
61
Type of light source that emits limited radiation and wavelength.
Line Source
62
Examples of Line Source:
Mercury and sodium vapor lamps in
spectrophotometers
Hollow cathode lamp
63
LASER stands for _____
Light Amplification by Stimulated Emission of Radiation
64
It minimizes unwanted or stray light and prevents the entrance of scattered light into the monochromator system.
Entrance Slit
65
Refers to any wavelengths outside the band
transmitted by the monochromator; it does not originate from the polychromatic light source; it causes absorbance error.
Stray Light
66
The most common cause of loss of linearity at
high-analyte concentration.
Stray Light
67
Factors for choosing a light source:
1. Range
2. Spectral distribution within the range
3. The source of radiant production
4. Stability of the radiant energy and
5. Temperature
68
It isolates specific or individual wavelength of light.
Monochromator
69
Alternatives for Tungsten Bulb:
Mercury arc (visible and UV)
Deuterium lamp (165nm) - UV
Hydrogen lamp - UV
Xenon lamp - UV
Merst glower -IR
Globar (silicone carbide) - IR
70
These are wedge-shaped pieces of glass, quartz or sodium chloride.
Prisms
71
Mercury Arc uses what type of radiant energy?
Visible
Ultraviolet
72
Deuterium Lamp uses what type of radiant energy?
Ultraviolet
73
Hydrogen Lamp uses what type of radiant energy?
Ultraviolet
74
Xenon Lamp uses what type of radiant energy?
Ultraviolet
75
Merst Glower uses what type of radiant energy?
Infrared
76
Globar (Silicone Carbide) uses what type of radiant energy?
Infrared
77
These are the most commonly used monochromators; better resolution than prism. These are made by cutting grooves (parallel grooves) or slits into an aluminized surface of a flat piece of crown glass.
Diffraction Gratings
78
Principle of Diffraction Gratings:
- Wavelengths are bent as they pass a sharp corner.
- Produces linear spectrum and therefore maintaining a constant and pass which is simple.
- Can be used in the regions of spectrum where light energy is absorbed by glass prism.
79
These are simple, least expensive, not precise but useful monochromators. These are made by placing semi-transparent silver films on both sides of a dielectric such as magnesium fluoride.
Filters
80
Filters are made by placing semi-transparent silver films on both sides of a dielectric such as _____
Magnesium fluoride
81
Filters produce monochromatic light based on the principle of _____.
Constructive Interference
82
Constructive Interference principle:
Light waves enter one side of the filter and are reflected at the second surface.
83
Other term for Cuvet:
Absorption Cell
Analytical Cell
Sample Cell
84
Holds the solution whose concentration is to be measured.
Cuvet
85
Enumerate the Kinds of Cuvets:
Alumina Silica Glass
Quartz/Plastic
Borosilicate Glass
Soft Glass
86
A most commonly used cuvet.
Alumina Silica Glass
87
A cuvet used for measurement of solution
requiring visible and ultraviolet spectra
Quartz/Plastic
88
A cuvet that is used in acidic solutions.
Borosilicate Glass
89
A cuvet that is used for alkaline or base solutions.
Soft Glass
90
Silica cuvettes transmit light effectively at _____
Wavelengths 220mm
91
The path length of cuvets is _____
1cm
92
It contains cathode and anode enclosed in a glass case; it has a photosensitive material that gives off electron when light energy strikes it; requires an external voltage for operation.
Phototube
93
It detects and converts transmitted light into
photoelectric energy.
Photodetector
94
It detects the amount of light that passes through the sample in the cuvet.
Photodetector
95
It is the most commonly used detector that measures visible and UV regions.
Photomultiplier Tube (PMT)
96
It is the simplest detector; least expensive; temperature-sensitive.
Barrier Layer Cell
97
Other term for Barrier Layer Cell:
Barrier Layer Cell
Photocell
Photovoltaic Cell
98
Barrier Layer Cell is used in _____ with a wide bandpass.
Filter Photometers
99
Barrier Layer Cell is a basic phototransducer that is used for detecting and measuring radiation in _____
Visible Region
100
Type of Photodetector that is not as sensitive as PMT but with excellent linearity.
Photodiode
101
Photodetector that measures light at a multitude of wavelengths - detects less
amount of light.
Photodiode
102
Photodetector that has a lower dynamic range and higher noise compared to Photo Multiplier Tube.
Photodiode
103
Photodetector that is most useful as a simultaneous multichannel detector.
Photodiode
104
It displays output of the detection system
Meter or Read-out Device
105
Examples of Meter or Read-out Device:
Galvanometer
Ammeter
LED Display
106
The amount of light absorbed at a particular wavelength depends on molecular and
ion types present and may vary with:
Concentration
pH
Temperature
107
Turbidity readings on a spectrophotometer are greater in the _____ than in _____ of the spectrum.
Blue Region
Red Region
108
It measures the light emitted by a single atom burned in a flame.
Flame Emission Photometry
109
Principle of Flame Emission Photometry:
Excitation of electrons from lower to higher energy state.
110
Light Source in Flame Emission Photometry:
Flame
111
Method used in Flame Emission Photometry:
Indirect Internal Standard Method
112
Internal Standard in Flame Emission Photometry:
Lithium/Cesium
113
In Flame Emission Photometry, this indicated changes in the fuel reading of the instrument.
Flickering Light
114
Flame Emission Photometry is used for the measurement of excited ions such as:
Sodium
Potassium
115
Purpose of Flame in FES:
Breaks the chemical bond to produce atoms. Source of energy absorbed by the atoms to enter an excited state.
116
Breaks up the solution into finer droplets so that the atom will absorb heat energy from the flame and get excited.
Atomizer or Burner
117
Means the blank contains serum but without the reagent to complete the assay.
Blanking Technique
118
Corrects absorbance caused by the color of the reagents - the absorbance of reagents is automatically subtracted from each of unknown reading.
Reagent Blank
119
Measures absorbance of the sample and reagent in the absence of the end product, and corrects the measurement for optical interference absorbing the wavelength of measurement.
Sample Blank
120
_____ interfere mainly by increasing light blocked turbidity.
Lipids
121
Methods or Procedures that is performed to correct for artifactual absorbance readings.
"Blanking" Procedures
Dual-wavelength Methods
122
Interference Filters as Monochromators:
Na Filter
K Filter
Lithium
123
Na Filter transmits what color of light at what wavelength?
Yellow Light
589 nm
124
K Filter transmits what color of light at what wavelength?
Violet Light
767 nm
125
Lithium transmits what color of light at what wavelength?
Red Light
761 nm
126
Preferred internal standard; also acts as a radiation buffer in FES.
Lithium
127
Reasons why Lithium is preferred:
- Its emission characteristics are similar to those of Na+ and K+
- Normally present as a trace element in human tissues and does not present interferences in the determination.
128
Purpose of Lithium as a Quality Control in FES
To achieve stability where there is fluctuations caused by changes in fuel of air pressure which affects flame temperature and rate of sample aspiration.
129
Used for measuring abundant large particles (proteins) and bacterial suspensions.
Turbidimetry
130
Principle of Turbidimetry:
It determines the amount of light blocked (reduction of light) by a particulate matter in a turbid solution.
131
Turbidimetry depends on:
Specimen Concentration
Particle Size
132
Solutions requiring quantitation by turbidimetry are measured using:
Visible Photometers
Visible Spectrophotometers
133
3 Sections in the Laboratory that utilizes Turbidimetry: (provide its uses in each sections)
1. Clinical Chemistry - measure proteins
2. Bacteriology - determination of bacterial growth
3. Hematology - detect clot formation
134
It measures the light absorbed by atoms dissociated by heat. Principle: Element is not excited by merely dissociated from its chemical bond and place in an unionized, unexcited, ground state
Atomic Absorption Spectrophotometry (AAS)
135
Light source in Atomic Absorption Spectrophotometry (AAS):
Hollow-cathode Lamp
136
Interferences in in Atomic Absorption Spectrophotometry (AAS):
Chemical
Matrix (differences in viscosity)
Ionization
137
Atomic Absorption Spectrophotometry (AAS) is used for measurement of unexcited trace metals such as:
Calcium
Magnesium
138
An atomizer such as _____ or _____ is used to convert ions to atoms while a _____ is used to modulate the light source.
Nebulizer
Graphite Furnance
Chopper
139
What is added to samples to form stable complexes with phosphate.
Lanthanum
Stronium Chloride
140
This is used for measuring the amount of antigen-antibody complexes (proteins)
Nephelometry
141
Principle of Nephelometry:
It determines the amount of scattered light by a particulate matter suspended in a turbid solution
142
In Nephelometry, light scattering depends on:
Wavelength
Particle Size
143
Most antigen-antibody complexes have a diameter of _____ and the wavelengths used are _____, thus light is scattered forward.
250-1500nm
320-650m
144
Detector used in Nephelometry:
Photomultiplier Tube
145
Components of Nephelometer:
Light Source (Mercury Arc Lamp, Tungsten-Filament Lamp, Light Emitting Diode
LASER)
Collimator
Monochromator
Sample Cuvete
Stray Light Trap
Photodetector
146
Principle of Volumetric:
The unknown sample is made to react with a
known solution in the presence of an indicator.
147
Schales and Schales Method is used for _____
Chloride Test
148
EDTA Titration Method is used for _____
Calcium Test
149
Is the migration of charged particles in an electric field. It separates proteins on the basis of their electric charge and densities.
Electrophoresis
150
Components of Electrophoresis:
Electrical power
Support Medium
Buffer
Sample
Detector Buffer: Barbital (pH 8.6)
151
Has a net charge that can be either
positive or negative depending on pH conditions
Amphoteric
152
The movement of buffer ions and solvent relative to the fixed support
Electroendosmosis/Endosmosis
153
The migration of small charged ions
Iontophoresis
154
The migration of charged macromolecules
Zone Electrophoresis
155
Factors Affecting Rate of Migration:
1. Net electric charge of the molecule
2. Size and charge of the molecules
3. Electric field strength
4. Nature of the supporting medium
5. Temperature of operation
156
A Supporting Media that separates by molecular size
Cellulose Acetate
157
A Supporting Media that separates by electrical charge; it does not bind protein.
Agarose Gel
158
A Supporting Media that separates on the basis of charge and molecular size; separates proteins into 20 fractions; used to study isoenzymes.
Polyacrylamide Gel
159
Amido black is used to visualize _____
Protein
160
Ponceau s is used to visualize _____
Protein
161
Oil Red O is used to visualize _____
Fats
162
Sundan Black is used to visualize _____
Fats
163
Fat Red 7B is used to visualize _____
Fats
164
Coomassie Blue is used to visualize _____
CSF Protein
165
A stain that is very sensitive even to nanogram quantities of proteins
Gold/Silver Stain
166
It measures the absorbance of stain - concentration of the dye and protein fraction; it scans and quantitates electrophoretic pattern.
Densitometry
167
It separates molecules by migration through a pH gradient; it is ideal for separating proteins of identical sizes but with different net charges.
Isoelectric Focusing
168
pH gradient is created by adding _____ to the anodic area of the electrolyte cell and adding _____ to the cathode area.
Acid
Base
169
Supporting Media for Isoelectric Focusing:
Agarose Gel
Polyacrylamide Gel
Cellulose Acetate
170
Advantages of for Isoelectric Focusing:
1. The ability to resolve mixture of proteins.
2. To detect isoenzymes of ACP, CK and ALP in serum.
3. To identify genetic variants of proteins such as alpha-1-antityrpsin.
4. To detect CSF oligoclonal banding.
171
In this method, sample molecules are separated by electro-osmotic flow (EOF); it utilizes nanoliter quantities of specimens.
Capillary Electrophoresis
172
Capillary Electrophoresis utilizes _____ quantities of specimens.
Nanoliter
173
Uses of Capillary Electrophoresis:
Separation
Quantitation and determination of molecular weights of proteins and peptides
Analysis of Protein products
Analysis of organic and inorganic substances and drugs
174
It involves separation of soluble components in a solution by specific differences in physical-chemical characteristics of the different constituents.
Chromatography
175
Bases of Separation:
1. Rate of Diffusion
2. Solubility of the solute
3. Nature of the solvent
4. Sample volatility/solubility
5. Distribution between 2 liquid phases
6. Molecular Size (molecular sieving)
7. Hydrophobicity of the molecule
8. Ionic attraction
9. Differential distribution between two immiscible liquids
10. Selective separation of substances
11. Differences in adsorption and desorption of solutes
176
2 Forms of Chromatography:
Planar
Column
177
It is used for fractionation of sugar and amino acid.
Paper Chromatography
178
Sorbent for Paper Chromatography
Whatman Paper
179
It is a semiquantitative drug screening test.
Thin Layer Chromatography (TLC)
180
What samples can be used for Thin Layer Chromatography (TLC)?
Blood
Urine
Gastric Fluid
181
Sorbent for Thin Layer Chromatography (TLC)
Thin plastic plates impregnated with a layer of silica gel or alumina.
182
It is used for separation of steroids, barbiturates, blood, alcohol and lipids; useful for compounds that are naturally volatile or can be easily converted into a volatile form.
Gas Chromatography (GC)
183
In Gas Chromatography (GC), the samples are introduced into the GC column using a _____ or _____
Hypodermic Syringe
Automated Sampler
184
Separation occurs based on differences in absorption at the solid phase surfaces.
Gas Solid Chromatography (GSC)
185
Separation occurs by differences in solute partitioning between the gaseous mobile phase and the liquid stationary phase.
Gas Liquid Chromatography (GLC)
186
Detector used for Gas Liquid Chromatography (GLC)
Flame Ionization
187
It is based on the fragmentation and ionization of molecules using a suitable source of energy; it can also detect structural information and determination of molecular weight.
Mass Spectroscopy (MS)
188
It is the gold standard for drug testing.
Gas Chromatography-Mass Spectroscopy (GC-MS)
189
Gas Chromatography-Mass Spectroscopy (GC-MS) can also be used for:
Xenobiotics
Anabolic Steroids
Pesticides
190
Can detect 20 inborn errors of metabolism from a single blood spot.
Tandem Mass Spectroscopy (MS/MS)
191
It is based on the distribution of solutes between a liquid mobile phase and a stationary phase.
Liquid Chromatography
192
The most widely used liquid chromatography.
High Performance Liquid Chromatography (HPLC)
193
It uses pressure for fast separations, controlled temperature, inline detectors and gradient elution technique.
High Performance Liquid Chromatography (HPLC)
194
Uses of High Performance Liquid Chromatography (HPLC):
- Fractionation of drugs, hormones, lipids, carbohydrates and proteins
- Separation and quantitation of various
hemoglobins associated with specific diseases (e.g., thalassemia)
- Rapid HbA1c test (within 5 minutes)
195
In reverse phase HPLC, the _____ is more polar than the _____
Mobile Phase
Stationary Phase
196
It is for detecting nonvolatile substances in body fluids.
Liquid Chromatography-Mass Spectroscopy (LC-MS)
197
It is utilized to confirm positive results from screening of elicited drugs - it is a complementary method to GC-MS.
Liquid Chromatography-Mass Spectroscopy (LC-MS)
198
Used in therapeutic drug monitoring, toxicology and studies of drug metabolites.
Liquid Chromatography-Mass Spectroscopy (LC-MS)
199
Interface in Liquid Chromatography-Mass Spectroscopy (LC-MS):
Electrospray (ES)
Atmospheric Pressure Chemical Ionization (APCI)
200
_____ is used in HPLC and GC methods to
compensate for variation in extraction.
Internal Standard
201
The mechanism in this type of chromatography is the exchange of sample ions and mobile-phase ions with the charged group of the stationary phase.
Ion Exchange Chromatography
202
Used for separation of amino acids, proteins and nucleic acids.
Ion Exchange Chromatography
203
Separation of nucleic acids and proteins depends primarily on:
Charge
Ionic Charge Density
204
Separation of compounds is based on their partition between a liquid mobile phase and a liquid stationary phase coated on a solid support.
Partition Chromatography (Liquid-Liquid
Chromatography)
205
Used for separation of therapeutic drugs and their metabolites.
Partition Chromatography (Liquid-Liquid
Chromatography)
206
It uses immobilized biochemical ligands as the
stationary phase to separate a few solutes from other unretained solutes.
Affinity Chromatography
207
This type of separation uses the so-called lock-and-key binding that is widely present in biologic systems.
Affinity Chromatography
208
Used for separation of lipoproteins, carbohydrates and glycated hemoglobins; antibodies.
Affinity Chromatography
209
Separation is based on the differences (competition) between the adsorption and desorption of solutes at the surface of a solid particle.
Adsorption Chromatography (LiquidSolid Chromatography)
210
In Adsorption Chromatography (LiquidSolid Chromatography), the compounds are adsorbed to a solid support such as:
Silica
Alumina
211
It measures the amount of light intensity present over a zero background.
Fluorometry/Molecular Luminescence
212
Principle of Fluorometry/Molecular Luminescence:
It determines the amount of light emitted by a molecule after excitation by electromagnetic radiation.
213
Light detector for Fluorometry/Molecular Luminescence:
Photomultiplier Tube or Phototube
214
Use of Fluorometry/Molecular Luminescence:
Porphyrins
Magnesium
Calcium
Catecholamines
215
How many monochromators does Fluorometry/Molecular Luminescence use?
2 monochromators
- The wavelength that is best absorbed by the solution to be measured is selected by the primary filter; the incident light is prevented from striking the photodetector by the secondary filter.
216
Fluorometry/Molecular Luminescence is affected by quenching such as:
pH and temperature changes
Chemical contaminants
UV light change
217
Light Source in Fluorometry/Molecular Luminescence:
Mercury arc lamp
Xenon lamp
218
Emission of light is created from a chemical or
electrochemical reaction, and not from absorption of electromagnetic energy.
Chemiluminescence
219
Principle of Chemiluminescence:
The chemical reaction yields an electronically
excited compound that emits light as it is ground state, or that transfers its energy to another compound, which then produces emission.
220
Use of Chemiluminescence:
Immunoassays
221
Photodetector in Chemiluminescence:
Photomultiplier tube (luminometer)
222
It is the measurement of the osmolality of an aqueous solution such as serum, plasma, or urine.
Osmometry
223
Principle of Osmometry:
It is based on measuring changes in the colligative properties of solutions that occur owing to variations in particle concentration.
224
Osmotic Particles:
Glucose
Urea nitrogen
Sodium
225
Colligative properties of the solution:
Osmotic pressure
Boiling point
Freezing point
Vapor pressure
226
As the osmolality of a solution increases the following reactions occur: osmotic pressure _____; boiling point is _____; freezing point is _____; and the vapor pressure is _____.
Increases
Elevated
Depressed
Depressed
227
The most commonly used method for measuring the changes in colligative properties of a solution.
Freezing-point Depression Osmometry
228
A 1.0 mOsm/kg solution has a freezing point depression of _____ when compared with pure solvent (usually water).
0.00186 degree Celsius
229
Blood plasma, with an osmolality of about _____, has a freezing point of about _____.
285 mOsm/kg
-0.53 degree Celsius
230
The measurement of current or voltage
generated by the activity of a specific ion.
Electrochemistry Techniques
231
It is the measurement of electrical potential due to the activity of free ions - change in voltage indicates activity of each analyte.
Potentiometry
232
The measurement of differences in voltage (potential) at a constant current
Potentiometry
233
Reference electrodes for Potentiometry:
Calomel
Silver-silver Chloride
234
Use of Potentiometry:
pH test
pCO2 test
235
It is an electrochemical transducer capable of responding to one given ion.
Ion Selective Electrode (ISE)
236
ISE analyzers measure the _____ dissolved in the fluid phase of the sample in _____.
Electrolyte
mmol/L of plasma water
237
2 types of Ion Selective Electrode (ISE):
1.Direct ISE (without sample dilution)
2.Indirect ISE (with sample dilution)
238
Components of an ISE Membrane:
Glass aluminum silicate (sodium), valinomycin gel (potassium) organic liquid membrane ion exchangers (calcium and lithium) gas and enzyme electrodes
239
Causes of Malfunctions of ISE:
Defective ISE membrane, buildup of counter voltages from liquid junction potentials at the salt bridge and buildup of proteins at the electrodes
240
It is the measurement of the amount of
electricity (in coulombs) at a fixed potential.
Coulometry
241
It is an electrochemical titration in which the
titrant is electrochemically generated and the
end point is detected by amperometry.
Coulometry
242
Uses of Coulometry:
Chloride test in CSF, serum, and sweat
243
Interference in Coulometry:
Bromide
Cyanide
Cysteine
244
It is the measurement of the current flow
produced by an oxidation-reaction
Amperometry
245
Use of Amperometry:
pO2
Glucose
Chloride
Peroxidase Determination
246
It is the measurement of differences in current at a constant voltage.
Polarography
247
The measurement of current after which a
potential is applied to an electrochemical cell.
Voltammetry
248
Type of Voltammetry test used for lead and iron.
Anodic stripping voltammetry
