midterms Flashcards
(148 cards)
1
Q
Concentration is commonly expressed as
A
percent
solution, molarity, molality, or normality
2
Q
expressed as the amount of solute per 100 total
units of solution
A
Percent solution
3
Q
number of grams of solute per 100 g of solution
A
- Weight per weight (w/w)
4
Q
grams per deciliter (g/dL)
A
- Volume per volume (% v/v)
5
Q
most commonly used percent
solution
A
- Weight per volume (% w/v)
6
Q
of grams of solutein 100 mL of solution.
A
- Weight per volume (% w/v)
7
Q
e number of moles per 1 L of
solution
A
Molarity (M)
8
Q
SI representation for the traditional molar
concentration is
A
moles of solute per volume of
solution,
9
Q
depends on volume, and any significant
physical changes that influence volume
A
molarity
10
Q
temperature and pressure, will also
influence
A
molarity
11
Q
represents the amount of solute per 1 kg of
solvent.
A
Molality (m)
12
Q
always expressed in terms of moles per kilogram
A
Molality
13
Q
often used in chemical titrations and chemical
reagent classification
A
Normality
14
Q
.
- It is defined as the number of gram equivalent
weights per 1 L of solution
A
Normality
15
Q
s equal to the gmw of a
substance divided by its valence.
A
equivalent weight
16
Q
the number of units that can
combine with or replace 1 mole of hydrogen ions
for acids and hydroxyl ions for bases and the
number of electrons exchanged in
oxidation–reduction reaction
A
valence electrons are
17
Q
s previously used for reporting
electrolyte values
A
Normality
18
Q
currently requires chloride to be reported in
mmol/L.
A
College of American Pathologists (CAP)
19
Q
four main electrolytes,
A
Na+,
K+, CO2– (HCO3–), and Cl–
20
Q
A solution is considered saturated when n
A
o more
solvent can be dissolved in the solution.
21
Q
can influence the solubility constant for a
solute in a given solution and thus affect the
saturation
A
Temperature, as well as the presence of other
ions
22
Q
is one in which there is relatively little
solute or one that has a lower solute
concentration per volume of solvent than
the original, such as when making a
dilution
A
- dilute solution
23
Q
- has a large quantity of solute in solution.
A
- concentrated solution
24
Q
A solution in which there is a excess of
undissolved solute particles
A
- saturated solution
25
has an even greater concentration of
undissolved solute particles than a
saturated solution of the same substance
- supersaturated solution
26
supersaturated solution
is
thermodynamically unstable
27
disturbs the
supersaturated solution, resulting in
crystallization of any excess material out
of solution.
crystal of solute or
mechanical agitation
28
roperties related
to the number of solute particles per solvent
molecules, not on the type of particles present.
COLLIGATIVE PROPERTIES
29
The behavior of particles or solutes in solution
demonstrates four properties:
osmotic
pressure, vapor pressure, freezing point, and
boiling point.
30
s the pressure that
opposes osmosis when a solvent flows
through a semipermeable membrane to
establish equilibrium between
compartments of differing concentration
. Osmotic pressure
31
is the pressure exerted
by the vapor when the liquid solvent is in
equilibrium with the vapor.
Vapor pressure
32
is the temperature at
which the first crystal (solid) of solvent
forms in equilibrium with the solutio
Freezing point
33
is the temperature at which
the vapor pressure of the solvent
reachesatmospheric pressure (usually 1
atmosphere).
Boiling point
34
osmotic pressure of a dilute solution is
______ proportional to the concentration of the
molecules in solution
osmotic pressure of a dilute solution is
directly proportional to the concentration of the
molecules in solution
35
which is preferred? osmolality or osmolarity?? why
Osmolality is preferred since it depends on the
weight rather than volume and is not readily
influenced by temperature and pressure changes
36
can be measured as a
function of osmolality
freezing point and vapor
pressure depression
freezing points s preferred since vapor pressure
measurements can give inaccurate readings
37
s preferred since vapor pressure
measurements can give inaccurate readings
Freezing point
38
is a measure of
the ability of a solution to accept or donate
electrons.
oxidation–reduction potential,
39
Substances that donate electrons are called
reducing agents
40
those that accept electrons are considered
oxidizing agents.
41
how well electricity passes through a
solution.
CONDUCTIVITY
42
depends
principally on the number of respective charges of
the ions present
solution’s conductivity quality
43
, the reciprocal of conductivity, is a
measure of a substance’s resistance to the
passage of electrical current
Resistivity
44
The primary application of resistivity in the clinical
laboratory is for a
ssessing the purity of water
45
resistance and conductivity is expressed as
Resistivity (resistance) is expressed as ohms and
conductivity is expressed as ohms−1
46
remains one of the primary areas of
preanalytic errors
The process of specimen collection, handling, and
processing
47
specifies
that procedures for specimen submission and
proper handling be documented, including the
disposition of any specimen that does not meet
the laboratories’ criteria of acceptability
The Clinical Laboratory Improvement
Amendments Act of 1988 (CLIA 88)
48
- the inverse of exponential functions
Logarithms
49
inverse of the logarithm.
antilogarithm or antilog
50
part(s) of concentrated material to
the total final volume of a solution.
DILUTION
51
e parts of the substance being
diluted in the total numbers of parts of the
solution.
DILUTION
52
aio refers to part substance to part
substance
ratio
53
The most common dilution uses
one
part patient serum plus one part salin
54
reciprocal of the dilution
which is known as the
55
are required when the result is above the
linearity of the assay
Dilutions
56
There is an _____ relationship between the
dilution factor and concentration
There is an inverse relationship between the
dilution factor and concentration
57
extremely useful when the volume of
concentrate or diluent is in short supply and its
use needs to be minimized, or when a number of
dilutions are required, such as in determining a
titer
serial dilution
58
needed to ensure that
sufficient sample is available for analysis. The
serial dilution is initially made in the same manner
as a simple dilution
serial dilution
59
criterias of serial dilution
e total
volume desired, the amount of diluent or
concentrate available, the dilution factor, the final
concentration needed, and the support materials
required
60
is the process that guarantees
that the laboratory results are as accurate as
possible and includes all three phases of testing:
pre-analytic, analytic, and post-analytic
Quality assurance
61
s the specific process of
monitoring and assessing the analytical phase of
testing
Quality control
62
is used to verify the
acceptability of new methods prior to test
implementation and reporting patient results.
method evaluation
63
numerical values that summarize a given data set.
descriptive statistics,
64
, monitoring of analytic methods is
performed by
assaying stable control materials
and comparing their determined values with their
expected values
65
The expected values are represented by
intervals of acceptable values with upper
and lower limits, known as
control limits.
66
principles of visualizing QC data were initially
applied to the clinical laboratory in the
1950s by
Levey and Jennings.
67
Specimens analyzed for QC purposes are known
as
QC materials, commonly referred to as
controls
68
QC for general chemistry assays generally uses
??? levels of control, while immunoassays
commonly use ??? levels of control.
QC for general chemistry assays generally uses
two levels of control, while immunoassays
commonly use three levels of control.
69
give expected target
ranges, often including the mean and SD
using common analytic methods, MORE
EXPENSIVE BUT ALLOWS ANOTHER
EXTERNAL CHECK OF METHOD
ACCURACY
Assayed controls
70
do not have
assigned analyte values provided by the
manufacturer. The laboratory, rather than
the manufacturer, assigns expected
results to unassayed QC materia
unassayed QC materials
71
incomplete mixing control materials for recon yields
a
partition of supernatant liquid and
underlying sediment and will
result in incorrect control values.
72
do not require
reconstitution but may behave differently
from patient specimens
Stabilized frozen controls
73
s usually
more expensive, but it does remove any
variation due to the preparation of the QC
materials
manufactured liquid QC
74
graphically represent the observed
values of a control material over time in the
context of the upper and lower control limits
Control charts g
75
- Control limits are expressed as the
mean ± SD
76
A common method to assess the determination of
control materials over time is by the use of a
Levey-Jennings control chart
77
monitor analytic variations that can occur
QC system i
78
The QC
program can be thought of as
a three-stage
process:
1. Establishing or verifying allowable statistical limits
of variation for each analytic method 2.
2. Using these limits as criteria for evaluating the QC
data generated for each test 3.
3. Taking action to remedy errors real time when
indicated
a. Finding the cause(s) of error
b. Taking corrective action c. Reanalyzing
control and patient dat
79
The use of the statistical process control chart
(Levey-Jennings) was pioneered by
Shewhart in
the 1920s
80
Control rules indicate the number of control
observations per analytic run, followed by the
control amount in subscript.
Control rules
81
One control value
exceeds the mean by more than 2
standard deviations
1-2s Rule
82
: One control value
exceeds the mean by more than 3
standard deviations
1-3s Rule:
83
Two consecutive
control values exceed the mean
by more than 2 standard
deviations, either in the same or
opposite direction.
■ 2-2s Rule:
84
: The range (difference)
between two consecutive control
values exceeds 4 standard
deviations
R-4s Rule
85
Four consecutive
control values exceed 1 standard
deviation from the mean, in the
same direction.
4-1s Rule:
86
Error varies from sample to sample. Causes
include instrument instability, temperature
variations, reagent variations, handling
techniques, and operator variables
Random error
87
Predictable error resulting from inaccuracy in a
method; results in constant or proportional bias.
Systematic error
88
exists when
there is a continual difference between
the test method and the comparative
method values, regardless of the
concentration. t
Constant systematic error
89
is the type of
systematic error where magnitude is
dependent on analyte concentration
Proportional error
90
Mechanism of spectrophotometer
Light source produce intense reproducible constant
beam of light. White light - different wavelengths of light
Isolates and segregates white liht into different wavelength
to produce different colors if light. This diff wavelength light
will pass through exit slit which sill serve as wavelength
selector.one light pass through sample solution, it will eat
the light due to analytes inside it thereby affecting
absorbance reading.then it will pass through photo
detector and convert this light energy to electrical signal.
Then received by digital display or meter para mabasa.
91
states that the concentration of a substance is directly
proportional to the light absorbed and inversely
proportional to the light transmitted
BEER'S LAW
92
Produces an intense, reproducible,
constant beam of light
Light Source
93
Most common, used in visible and near
infrared (IR) regions
Incandescent tungsten or tungsten-iodide
lamp -
94
For ultraviolet (UV) region
deuterium discharge lamp and the mercury arc
lamp -
95
- with both
ultraviolet (UV)
and visible lines
Low-pressure mercury lamps
96
ultraviolet
(UV) to the mid-visible region
Medium and high-pressure mercury lamps -
97
solation of individual wavelengths of
ligh
Monochromators
98
MONOCHROMATOR OF SPECTROPHOTOMETER
Diffraction gratings and Prisms
99
MONOCHROMATOR OF Photometers
* Glass filters and Interference filters
100
- The light path must be kept
constant to have absorbance proportional to
concentration.
Sample cells/cuvets
101
ransmission and absorption of light by
analyte at ultraviolet range range
Quartz
102
* Glass cuvettes - visible region
* Glass cuvettes -
103
Converts light energy transmitted by a
solution into an electrical signal
Photodetectors
104
- Iron plates coated with Se and Ag
Photocell
105
- Also contains photosensitive materials
- Cathode and anode enclosed in a glass ca
Phototube
106
Detects and amplifies the light energy,
composed of cathodes and chains of dynodes,
each having successively high voltage
* Photomultiplier tube
107
- 200x more sensitive that phototube
* Photomultiplier tube
108
Electrical energy coming from a
detector is displayed on some type of digital display or
readout system
READOUT DEVICE
109
absorbance reading from the
sample must be blanked using an appropriate reference
solution
- bl
SINGLE-BEAM Spectrophotometry
110
permit automatic
correction of sample and reference absorbance
DOUBLE-BEAM Spectrophotometry -
111
he wavelength indicated on the control dial is the actual
wavelength of light passed by the monochromator
wavelength accuracy
112
Standard solutions & Filters e.i Didymium or Holmium
oxide
Standard solutions & Filters e.i Didymium or Holmium
oxide
113
any wavelengths outside the band transmitted by the
monochromator.
stray light
114
-Cut-off filters
stray light
115
- demonstrated when a change in concentration results in
a straight line calibration curve
Linearity
116
- Neutral density filters
Linearity
117
used to measure concentration by detecting the
absorption of electromagnetic radiation by atoms
Atomic Absorption Spectrophotometer
118
- based on the principle that each element absorbs light at
caertain wavelength corresponding to their electronic
energy lette
Atomic Absorption Spectrophotometer
119
measures light emitted by excited atom
* Flame Photometry - aka "flame emission photometer"
120
Concentrations of solutions containing
fluorescing molecules are measured and the amount of
Fluorescence is directly proportional to concentration
Fluorometry
121
part of the chemical energy
generated produces excited intermediates that decay to a
ground state with the emission of photons. The emitted
radiation is measured with a PM tube, and the signal is
related to analyte concentration
Chemiluminescence
122
- based on emission of light due to chemical
reaction
Chemiluminescence
123
is used to produce
light when it reacts with enzyme.also common to
immunoassay.linked to antibody
chemiluminescence substrate
124
- Amount of light blocked by suspension of
particles which is dependent on particle size &
concentration
Turbidity
125
LIGHT SCATTERED at an angle to the
beam incident on the cuvet by the particle is measured
Nephelometry
126
- the migration of charged solutes
or particles in an electrical field
ELECTROPHORESIS
127
is the mechanisation of the steps in a
procedure
Automation
128
Advantages to automating procedures
1. Increase the number of tests performed
2. Minimise variation in results
3. Eliminates potential errors of manual analyses
4. Only small amount of sample is required
5. Only small amount of reagent is used
129
Three basic approaches with instruments
1. CONTINUOUS FLOW
2.CENTRIFUGAL ANALYSIS
3. DISCRETE ANALYSIS
130
Uses centrifugation force to transfer and
contain liquids in separate cuvette for
measurement at the perimeter of a
spinning rotor
Centrifugal analysis
131
most capable of running multiple samples,
one test at a time, in a batch (batch
analyses)
Centrifugal analysis
132
Running multiple samples, one Test at a time
(batch) Or multiple tests, one sample at a time
C. Discrete analysis
133
Most popular and most versatile analyzer
C. Discrete analysis
134
IDENTIFICATION AND PREPARATION
1. Sample identification
- This is usually done by reading the bar code. This
information can be entered manually.
2. Determine tests) to perform
- The LIS communicates to the analyzer which
tests) have been ordered
135
CHEMICAL REACTION
3. Reagent systems and delivery
One or more reagents can be dispensed into the reaction
cuvet.
4. Specimen measurement and delivery
A small aliquot of the sample is introduced into the
reaction cuvet.
5. Chemical reaction phase
The sample and reagents are mixed and incubated.
136
DATA COLLECTION AND ANALYSIS
6. Measurement phase
18
-
-
-
Optical readings may be initiated before or after all
reagents have been added.
7. Signal processing and data handling
The analyte concentration is estimated from a calibration
curve that is stored in the analyzer.
8. Send results) to LIS
The analyzer communicates results for the ordered tests
to the LIS.
137
Reagents pipeted by the instrument and mixed
with the samples
1. Wet Chemistry/liquid reagents
138
- lyophilized reagents or tablet form (Dimension®)
- Single use slides/films (Vitros®
DRY CHEMISTRY
139
- Mixing of sample and reagents occur in cuvets
- Reaction temperatures and time may vary for
each analyte (30 deg. C and 37 deg. C are most
commonly used)
Testing Phase
140
- Concentration is based on the change in
absorbance over time
- Youll need to read multiple absorbance
readings
1. Kinetic assays
141
- Absorbance of coloured products is read
and compared with the standard for
calculation of analyte concentration
- Only one reading necessary
2. End-point/Colorimetric assays
142
is defined as those
analytical patient-testing activities provided within the
institution, but performed outside the physical facilities.of
the clinical laboratories.
Point-of-care testing (POCT)
143
- non dstructive analytic technique used to
determine phys and chem property by measuring a,ount of
light reflected from material
Reflectance
144
- relationship
of electric current and chemical reactions
Electrochemistry, electrical impedance
145
- measurs concentration antigen
and antibody bsed on degree of turbidy that forms when
antigen antibody complex forms
Immunoturbidimetry
146
nephelometry
. Light scattering/ optical motion
147
. molecular bio tech that
amplifies segment of nucleic acid particularly dna throughr
epeated cycle of heating and cooling. Very common.
Polymerase chain reaction -
148
