Method In Clinical Chemistry Flashcards
Centrifugation
This is a basic ______ technique
separation
Centrifugation is a process in which _____ force is used to separate ____ matter from a ____ suspension.
centrifugal
solid; liquid
The centrifuge consists of a _____ or ____, ______ or ______that are attached to the _________ of a motor and enclosed in a _______ covering.
head or rotor
carriers or shields
vertical shaft
metal
The centrifuge always has a ____ and ______
But,
Some models include a _____ or a built in _______, and some centrifuges are _______.
lid; an on/off switch
brake; tachometer
Refrigerated
A tachometer which indicates _____
speed
Centrifugal force depends on three variables: ______,_____, and ———.
mass, speed, and radius
The speed of the centrifugal force is expressed in ______________ , and the centrifugal force generated is expressed in terms of _________ or _______
revolutions per minute (rpm)
relative centrifugal force (RCF) or gravities (g).
The speed of the centrifuge is related to the RCF by the following equation:
RCF = ___
1.118x 10^-5 X r X (rpm)^2
where 1.118 x 10^-5 is a constant, determined from the ________ and r is the radius in centimeters, measured from the ___________ to the ______________
angular velocity
center of the centrifuge axis to the bottom of the test-tube shield
Centrifuge classification is based on several criteria, including benchtop or floor model, refrigeration, rotor head (e.g., _______,_____,______,_____), or maximum speed attainable (i.e.,_______).
fixed, hematocrit, swinging-bucket, or angled
ultracentrifuge
Centrifuges are generally used to separate
(1)_________ or _____ from the blood cells as the blood samples are being processed
(2) separate a _____ from a ______ during an analytic reaction
(3) separate two _______ liquids, such as a _____-laden sample; or to expel ____
serum or plasma
supernatant; precipitate
immiscible; lipid; air
Centrifuge care includes (daily, weekly or monthly ?) cleaning of any spills or debris, such as blood or glass, and ensuring that the centrifuge is properly _______ and free from any excessive _______.
Daily
balanced; vibrations
Balancing the centrifuge load is mot important .
T/F
F
It is critical!
Many newer centrifuges will automatically ___ease their speed if the load is not evenly distributed, but more often, the centrifuge will _____ and ___ or make (more or less?) noise than expected.
Decr
shake and vibrate
More
centrifuge needs to be balanced based on equalizing both the ____ and ___ distribution across the centrifuge head.
Many laboratories will make up “____” tubes that approximate routinely used volumes and tube sizes, including the ____ on _______ tubes, which can be used to match those needed from patient samples.
volume and weight
balance
A good rule of thumb in centrifuge balancing is one of ___ placement and one of “ ______ .”
even
opposition
The centrifuge cover should remain (opened or closed?) until the centrifuge has come to a complete stop to avoid any _____ contamination.
aerosol Closed
The speed of a centrifuge is easily checked using a ______ or __________
tachometer
strobe light.
The hole located in the lid of many centrifuges is designed for _________ and may also represent an ______ biohazard.
speed verification
aerosol
_______ agencies require periodic verification of centrifuge speeds.
Accreditation
The majority of analytic techniques fall into one of four basic disciplines within the field of analytic chemistry: __________,_______,________ and ________
spectrometry, luminescence , electroanalytic methods and chromatography
spectrometry (including ______,_______ and __________ )
luminescence (including ________,_______, and _________ )
spectrophotometry, atomic absorption, and mass spectrometry
fluorescence, chemiluminescence, and nephelometry
electroanalytic methods (including ___________,_______, and __________ )
chromatography (including _____,_____, and ________ )
electrophoresis, potentiometry, and amperometry
gas, liquid, and thin-layer
SPECTROPHOTOMETERS AND PHOTOMETERS measure __________ passing through a _________.
electromagnetic radiation
solution
Photometers measure ________ without consideration of _________
light intensity
wavelength
Spectrophotometers use filters to select (isolate) a (wide or narrow?) range of the incident _______
Narrow
wavelength
Radiant energy that passes through an object will be ______,______ and _______
partially reflected, absorbed, and transmitted.
Electromagnetic radiation is described as __________ traveling in _____.
photons of energy; waves
The relationship between wavelength and energy E is described by _____formula: E= hv
where h is a constant (______), known as ______ constant, and v is frequency.
Planck’s
6.62x 10-27 ; Planck’s
Because the frequency of a wave is (directly or inversely?) proportional to the wavelength, it follows that the energy of electromagnetic radiation is (directly or inversely?) proportional to wavelength
inversely
inversely
Visible light falls in between, with the colour ______ at _____-nm and ____ at ___- nm wavelengths being the approximate limits of the visible spectrum.
violet; 400
Red; 700
The spectrophometer and the flame photometer measure _______ of radiant energy to determine ___________.
absorption
concentration of atoms or molecules
The relationship between absorption of light by a solution and the concentration of that solution has been described by ___________
Beer and colleagues
Beer’s law states that the _____ of a substance is directly proportional to the ___________ or inversely proportional to the _________
concentration
amount of light absorbed
logarithm of the transmitted light.
Percent transmittance is the ratio of
the ________________ divided by the ________ on the sample (I).
radiant energy transmitted (T)
radiant energy incident
if all light is absorbed it will result in __% T.
0
A level of ___% T is obtained if no light is absorbed.
100
Step 1
In practice, the solvent (with or without?) the constituent of interest is placed in the light path. The electrical readout of the instrument is set arbitrarily at 100% T, while the light is passing through a “___” or _____
Without
blank
reference
Step 2
The sample containing ______ to be measured is placed in the light path. The difference in amount of light transmitted by the blank and that transmitted by the sample is due only to the ____________
absorbing molecules
presence of the compound being measured.
The % T measured by commercial spectrophotometers is the ratio of the ______________ beam divided by the __________ beam.
sample transmitted
blank transmitted
As concentration of the sample increases, % T ___eases in a ______ manner.
Decr
logarithmic
Absorbance A is the amount of light _____.
absorbed
Absorbance can be measured directly by a spectrophotometer
T/F
F
It can not
Absorbance can be mathematically derived from % T as follows:
From Beer’s law, absorbance is inversely proportional to the ______________
logarithm of the transmitted light.
According to Beer’s law, absorbance is ______ proportional to concentration
A ∞ C
A = _____ x C
where _____ is constant
directly
e x b
e and b are
A = e x b x c
where e , the ___________ is the ____ of a _______ of light absorbed by a given type of molecule
b is the _____ of light path through the solution
C is the ________ of absorbing molecules.
molar absorptivity
fraction ; specific wavelength
length
concentration
Components of a Spectrophotometer: (1) A _______
(2)________
(3)A _____-
(4)________
Light Source
Monochromators
sample cell
photodetectors
Components of a Spectrophotometer
A LIGHT SOURCE
The most common source of light for work in the visible and near-infrared region is the ________ or _______ lamp.
The lamps most commonly used for ultraviolet (UV) work are the _________ lamp and the ______ lamp.
incandescent tungsten or tungsten-iodide
deuterium-discharge; mercury-arc
Components of a Spectrophotometer
MONOCHROMATORS
_______ of __________ of light is an important and necessary function of a monochromator.
The degree of wavelength isolation is a function of the type of device used and the ________ and _______
Isolation of individual wavelengths
width of entrance and exit slits.
Numerous devices are used for obtaining monochromatic light. The least expensive are ______ filters. You also have ______ filters, ______ and ________ etc
coloured-glass
interference
glass prisms
diffraction gratings
Components of a Spectrophotometer
SAMPLE CELL
The next component of the basic spectrophotometer is the sample cell or cuvet, which may be _______ or ____
The _____ must be kept constant to have absorbance proportional to concentration
round or square.
light path
Cuvets with scratched optical surfaces will ________ and should be ______.
scatter light
discarded
Inexpensive glass cuvets can be used for applications in the _____ range, but they ______ light in the UV region.
visible
absorb
______ cuvets must, therefore, be used for applications requiring UV radiation.
Quartz
Components of a Spectrophotometer
Photodetectors
The purpose of the detector is to ______________________
convert the transmitted radiant energy into an equivalent amount of electrical energy.
Photodetectors
The least expensive of the devices is known as a _______ cell, or ________.
barrier-layer
Photocell
The photo cell is composed of a film of light-sensitive material, frequently ____, on a plate of _____.
Over the light-sensitive material is a (thin or thick?) , (transparent, translucent or opaque?) layer of ____.
When exposed to light, electrons in the __________ are excited and released to flow to the ________
selenium
iron; thin
Transparent ; silver
light-sensitive material
highly conductive silver.
Photodetectors
The produced current is not proportional to incident radiation.
T/F
F
It is
Photodetectors
_____ signals are processed ______ to produce absorbance readings.
Digital
electronically
flame photometry
The flame-emission photometer, which measures ______ by ______, was widely used to determine concentration of ___,___,___
light emitted
excited atoms
Na, K, or Li.
With the development of ___________ for these analytes(Na,K,Li) , flame photometers are no longer routinely used in clinical chemistry laboratories.
ion selective electrodes
Ion-selective Electrodes
An ISE universally used in the clinical laboratory is the _____
The basic components of a pH meter are the ______ electrode, the _____ electrode, the ____ and the _____ meter.
indicator
Reference
Liquid junction
Read-out Meter
Potentiometric methods of analysis involve the _______ of electrical potential due to the activity of ________
direct measurement
free ions.
Ion-selective electrodes (ISEs) are designed to be insensitive toward individual ions.
T/F
F
(1) The indicator electrode : The indicator electrode of a pH meter consists of a ______ wire coated with ____, immersed into an internal solution of 0.1 mmol/L ____, and placed into a tube containing a ___________ tip.
silver; AgCl; HCl
special glass membrane
special glass membrane
This membrane is only sensitive to _______ ions
hydrogen
Glass membranes that are selectively sensitive to Hydrogen ions consist of specific quantities of _____,_____,____,____,or _____ oxides in ______
lithium, cesium, lanthanum, barium, or aluminum
silicate
When the pH electrode is placed into the ____ solution, movement of H near the ____ of the electrode produces a potential difference between the _______ and the _______
test
Top
internal solution and the test solution
The Reference Electrode
Reference electrodes generally consist of a ____ and its ____ in contact with a solution containing the same anion
metal; salt
All reference electrodes must generate a _____________ potential.
stable electrical
The reference electrode commonly used is the ______ electrode.
calomel
Calomel, a paste of predominantly ________, is in direct contact with _________ in an electrolyte solution of ______.
mercurous chloride
metallic mercury
potassium chloride
The Liquid junction
Electrical connection between the ______ and ______ electrodes is achieved by allowing a (slow or rapid?) flow of electrolyte from the tip of the reference electrode.
A junction potential is always set up at the boundary between _________ solutions because of positive and negative ions diffusing across the boundary at (equal or unequal?) rates.
indicator and reference
Slow
two dissimilar
Unequal
In liquid junction
Electromotive force produced by the reference and indicator electrodes in the test solution is in the ______ range and read by
millivolt
The Readout meter are converted to concentration units using the _____ equation.
In the Clinical Chemistry lab, the ___ is used to determine the concentration of ions such as Na, H, K, Ca, HCO3, CL, etc
Nernst
ISE
Chromatography refers to the group of techniques used to separate complex mixtures on the basis of different ___________ between the individual compounds and the _______ of the system.
physical interactions
stationary phase
The basic components in any chromatographic technique are
(1) the ______ phase (_____ or _____), which carries the complex mixture (sample)
(2)the _____ phase ( ____ or ____), through which the _____ phase flows
(3) the _____ holding the ______ phase
(4)The ______________
mobile ; gas or liquid
stationary; solid or liquid
mobile
column; stationary
separated components (eluate).
Modes of separation in chromatography: Adsorption
Adsorption chromatography, also known as _____ chromatography, is based on the competition between the _____ and the ____ phase for _________ on the (solid or liquid?) _______ phase.
liquid-solid
sample; mobile
adsorptive sites
solid stationary
Modes of separation in chromatography: Adsorption
The molecules that are most soluble in the mobile phase, move (slowest or fastest?) ; the least soluble, move (slowest or fastest?) .
Thus, a mixture is typically separated into classes according to _______
Fastest
Slowest
polar functional groups.
Modes of separation in chromatography: Adsorption
The stationary phase can be either acidic polar (e.g., ____), basic polar (e.g., _______ ), or nonpolar (e.g.,____).
The mobile phase can be a single solvent or a mixture of two or more solvents, depending on the analytes to be desorbed.
silica gel
alumina
charcoal
Modes of separation in chromatography: partition
Partition chromatography is also referred to as ______ chromatography.
Separation of solute is based on relative solubility in an ____ (nonpolar) solvent and an _____ (polar) solvent
liquid-liquid
organic
aqueous
Modes of separation in chromatography: partition
Molecules containing polar and nonpolar groups in an _____ solution are added to an immiscible _____ solvent.
After vigorous shaking, the two phases are _________
Polar molecules remain in the _____ solvent; nonpolar molecules are extracted in the _______ solvent
aqueous
organic
allowed to separate.
aqueous
organic
Partition chromatography
The ratio of the concentration of the solute in the two liquids is known as the _____________
partition coefficient
Partition chromatography is applicable to any substance that ____________________________
may be distributed between two liquid phases.
partition chromatography works best with (ionic or non-ionic?) compounds
With reason
Non-ionic
Because ionic compounds are generally soluble only in water
Modes of Separation: steric conclusion
Steric exclusion, a variation of _________ chromatography, is used to separate solute molecules on the basis of ________
liquid-solid
size and shape.
Modes of Separation: steric conclusion
The chromatographic column is packed with _________
A sample containing different-sized molecules moves down the column dissolved in the _____ solvent.
Small molecules enter the pores in the packing and are ________.
Large molecules are excluded from the small pores and so move quickly between the ______.
porous material.
mobile
momentarily trapped
particles
Modes of Separation: ION exchange chromatography
In ion-exchange chromatography, solute mixtures are separated by virtue of the ________________
magnitude and charge of ionic species.
Modes of Separation: ION exchange chromatography
The stationary phase is a ____, consisting of large polymers of substituted _____,________ or ________ derivatives, with charged functional groups
The mobile phase may be made of _______ or _________
resin
benzene, silicates, or cellulose
cation exchange resins or anion exchange resins.
Ion-exchange chromatography is used to _______________, to ____________ solutions, and to __________ of charged molecules, such as amino acids.
Changing pH and ionic concentration of the mobile phase allows separation of mixtures of organic and inorganic ions.
remove interfering substances from a solution
concentrate dilute ion
separate mixtures
Chromatographic Procedures: Thin-Layer Chromatography
A thin layer of _____, such as alumina, silica gel, cellulose, or cross-linked dextran, is uniformly coated on a ______
Each sample to be analyzed is applied as a _____ near one edge of the plate.
The mobile phase (solvent) is usually placed in a _________ until the atmosphere is ______________
sorbent
glass or plastic plate.
spot
closed container
saturated with solvent vapor.
Thin-layer chromatography (TLC) is a variant of _____ chromatography.
column
TLC
The solvent migrates up the thin layer by ______, dissolving and carrying sample molecules.
Separation can be achieved by any of the four processes previously described, depending on the sorbent (thin layer) and solvent chosen.
After the solvent __________, the ____ is removed and dried.
Sample components are identified by comparison with standards on the same plate.
capillary action
reaches a predetermined height
plate
TLC
The distance a component migrates, compared with the distance the solvent front moves, is called the _______
retention factor, Rf
TLC is most commonly used as a __________ screening test.
semiquantitative
Chromatographic Procedures: High-Performance Liquid Chromatography
High-Performance liquid chromatography uses _____ for fast separations, controlled temperature, in-line detectors, and gradient elution techniques.
pressure
High-Performance Liquid Chromatography
The basic components are:
1) ____
(2) _____
(3)_______
(4)______
(5)______
Pumps
Columns
Sample injectors
Detectors
Recorders
High-Performance Liquid Chromatography
Pumps: A pump forces the ____ phase through the _____ at a much (lesser or greater?) velocity than that accomplished by ________ columns.
mobile
column
Greater
gravity-flow
High-Performance Liquid Chromatography
Columns: The ______ phase is packed into long _________columns. Fine, uniform column packing results in ______ but requires _______ to force the mobile phase through.
stationary
stainless steel
sharper peaks
pressure
High-Performance Liquid Chromatography
Sample Injectors : A (small or large ?) syringe can be used to introduce the sample into the path of the _____ phase that carries it into the column. loop injectors can also be used and can be programmed for _______ of samples.
Small
mobile
automatic injection
High-Performance Liquid Chromatography
Detectors: Modern HPLC detectors monitor the eluate as it leaves the column and, ideally, produce an _____ signal proportional to the ______ of each separated component.
electronic
concentration
Spectrophotometers that detect absorbances of visible or UV light can be used as detectors
T/F
T
High-Performance Liquid Chromatography
Recorders: The recorder is used to record ——- signal versus the time the __________, starting from the time of _______
detector
mobile phase passed through the instrument
sample injection.
High-Performance Liquid Chromatography
The graph is called a _______.
The _______ is used to identify compounds when compared with _______ run under identical conditions.
chromatogram
retention time
standard retention times
High-Performance Liquid Chromatography
Peak area is proportional to ________ of the compounds that produced the peaks.
concentration
