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House Clinical Pathology > Method In Clinical Chemistry > Flashcards

Method In Clinical Chemistry Flashcards

1
Q

Centrifugation

This is a basic ______ technique

A

separation

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2
Q

Centrifugation is a process in which _____ force is used to separate ____ matter from a ____ suspension.

A

centrifugal

solid; liquid

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3
Q

The centrifuge consists of a _____ or ____, ______ or ______that are attached to the _________ of a motor and enclosed in a _______ covering.

A

head or rotor

carriers or shields

vertical shaft

metal

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4
Q

The centrifuge always has a ____ and ______
But,

Some models include a _____ or a built in _______, and some centrifuges are _______.

A

lid; an on/off switch

brake; tachometer

Refrigerated

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5
Q

A tachometer which indicates _____

A

speed

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6
Q

Centrifugal force depends on three variables: ______,_____, and ———.

A

mass, speed, and radius

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7
Q

The speed of the centrifugal force is expressed in ______________ , and the centrifugal force generated is expressed in terms of _________ or _______

A

revolutions per minute (rpm)

relative centrifugal force (RCF) or gravities (g).

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8
Q

The speed of the centrifuge is related to the RCF by the following equation:

RCF = ___

A

1.118x 10^-5 X r X (rpm)^2

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9
Q

where 1.118 x 10^-5 is a constant, determined from the ________ and r is the radius in centimeters, measured from the ___________ to the ______________

A

angular velocity

center of the centrifuge axis to the bottom of the test-tube shield

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10
Q

Centrifuge classification is based on several criteria, including benchtop or floor model, refrigeration, rotor head (e.g., _______,_____,______,_____), or maximum speed attainable (i.e.,_______).

A

fixed, hematocrit, swinging-bucket, or angled

ultracentrifuge

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11
Q

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 ____

A

serum or plasma

supernatant; precipitate

immiscible; lipid; air

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12
Q

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 _______.

A

Daily

balanced; vibrations

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13
Q

Balancing the centrifuge load is mot important .

T/F

A

F

It is critical!

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14
Q

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.

A

Decr

shake and vibrate

More

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15
Q

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.

A

volume and weight

balance

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16
Q

A good rule of thumb in centrifuge balancing is one of ___ placement and one of “ ______ .”

A

even

opposition

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17
Q

The centrifuge cover should remain (opened or closed?) until the centrifuge has come to a complete stop to avoid any _____ contamination.

A

aerosol Closed

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18
Q

The speed of a centrifuge is easily checked using a ______ or __________

A

tachometer

strobe light.

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19
Q

The hole located in the lid of many centrifuges is designed for _________ and may also represent an ______ biohazard.

A

speed verification

aerosol

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20
Q

_______ agencies require periodic verification of centrifuge speeds.

A

Accreditation

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21
Q

The majority of analytic techniques fall into one of four basic disciplines within the field of analytic chemistry: __________,_______,________ and ________

A

spectrometry, luminescence , electroanalytic methods and chromatography

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22
Q

spectrometry (including ______,_______ and __________ )

luminescence (including ________,_______, and _________ )

A

spectrophotometry, atomic absorption, and mass spectrometry

fluorescence, chemiluminescence, and nephelometry

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23
Q

electroanalytic methods (including ___________,_______, and __________ )

chromatography (including _____,_____, and ________ )

A

electrophoresis, potentiometry, and amperometry

gas, liquid, and thin-layer

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24
Q

SPECTROPHOTOMETERS AND PHOTOMETERS measure __________ passing through a _________.

A

electromagnetic radiation

solution

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25
Q

Photometers measure ________ without consideration of _________

A

light intensity

wavelength

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26
Q

Spectrophotometers use filters to select (isolate) a (wide or narrow?) range of the incident _______

A

Narrow

wavelength

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27
Q

Radiant energy that passes through an object will be ______,______ and _______

A

partially reflected, absorbed, and transmitted.

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28
Q

Electromagnetic radiation is described as __________ traveling in _____.

A

photons of energy; waves

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29
Q

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.

A

Planck’s

6.62x 10-27 ; Planck’s

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30
Q

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

A

inversely

inversely

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31
Q

Visible light falls in between, with the colour ______ at _____-nm and ____ at ___- nm wavelengths being the approximate limits of the visible spectrum.

A

violet; 400

Red; 700

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32
Q

The spectrophometer and the flame photometer measure _______ of radiant energy to determine ___________.

A

absorption

concentration of atoms or molecules

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33
Q

The relationship between absorption of light by a solution and the concentration of that solution has been described by ___________

A

Beer and colleagues

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34
Q

Beer’s law states that the _____ of a substance is directly proportional to the ___________ or inversely proportional to the _________

A

concentration

amount of light absorbed

logarithm of the transmitted light.

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35
Q

Percent transmittance is the ratio of

the ________________ divided by the ________ on the sample (I).

A

radiant energy transmitted (T)

radiant energy incident

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36
Q

if all light is absorbed it will result in __% T.

A

0

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37
Q

A level of ___% T is obtained if no light is absorbed.

A

100

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38
Q

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 _____

A

Without

blank

reference

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39
Q

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 ____________

A

absorbing molecules

presence of the compound being measured.

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40
Q

The % T measured by commercial spectrophotometers is the ratio of the ______________ beam divided by the __________ beam.

A

sample transmitted

blank transmitted

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41
Q

As concentration of the sample increases, % T ___eases in a ______ manner.

A

Decr

logarithmic

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42
Q

Absorbance A is the amount of light _____.

A

absorbed

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43
Q

Absorbance can be measured directly by a spectrophotometer

T/F

A

F

It can not

44
Q

Absorbance can be mathematically derived from % T as follows:

From Beer’s law, absorbance is inversely proportional to the ______________

A

logarithm of the transmitted light.

45
Q

According to Beer’s law, absorbance is ______ proportional to concentration
A ∞ C
A = _____ x C
where _____ is constant

A

directly

e x b

e and b are

46
Q

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.

A

molar absorptivity

fraction ; specific wavelength

length

concentration

47
Q

Components of a Spectrophotometer: (1) A _______
(2)________
(3)A _____-
(4)________

A

Light Source
Monochromators

sample cell

photodetectors

48
Q

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.

A

incandescent tungsten or tungsten-iodide

deuterium-discharge; mercury-arc

49
Q

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 _______

A

Isolation of individual wavelengths

width of entrance and exit slits.

50
Q

Numerous devices are used for obtaining monochromatic light. The least expensive are ______ filters. You also have ______ filters, ______ and ________ etc

A

coloured-glass

interference

glass prisms

diffraction gratings

51
Q

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

A

round or square.

light path

52
Q

Cuvets with scratched optical surfaces will ________ and should be ______.

A

scatter light

discarded

53
Q

Inexpensive glass cuvets can be used for applications in the _____ range, but they ______ light in the UV region.

A

visible

absorb

54
Q

______ cuvets must, therefore, be used for applications requiring UV radiation.

A

Quartz

55
Q

Components of a Spectrophotometer

Photodetectors

The purpose of the detector is to ______________________

A

convert the transmitted radiant energy into an equivalent amount of electrical energy.

56
Q

Photodetectors

The least expensive of the devices is known as a _______ cell, or ________.

A

barrier-layer
Photocell

57
Q

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 ________

A

selenium

iron; thin

Transparent ; silver

light-sensitive material

highly conductive silver.

58
Q

Photodetectors

The produced current is not proportional to incident radiation.

T/F

A

F
It is

59
Q

Photodetectors

_____ signals are processed ______ to produce absorbance readings.

A

Digital

electronically

60
Q

flame photometry

The flame-emission photometer, which measures ______ by ______, was widely used to determine concentration of ___,___,___

A

light emitted

excited atoms

Na, K, or Li.

61
Q

With the development of ___________ for these analytes(Na,K,Li) , flame photometers are no longer routinely used in clinical chemistry laboratories.

A

ion selective electrodes

62
Q

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.

A

indicator
Reference
Liquid junction
Read-out Meter

63
Q

Potentiometric methods of analysis involve the _______ of electrical potential due to the activity of ________

A

direct measurement

free ions.

64
Q

Ion-selective electrodes (ISEs) are designed to be insensitive toward individual ions.

T/F

A

F

65
Q

(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.

A

silver; AgCl; HCl

special glass membrane

66
Q

special glass membrane

This membrane is only sensitive to _______ ions

A

hydrogen

67
Q

Glass membranes that are selectively sensitive to Hydrogen ions consist of specific quantities of _____,_____,____,____,or _____ oxides in ______

A

lithium, cesium, lanthanum, barium, or aluminum

silicate

68
Q

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 _______

A

test

Top

internal solution and the test solution

69
Q

The Reference Electrode

Reference electrodes generally consist of a ____ and its ____ in contact with a solution containing the same anion

A

metal; salt

70
Q

All reference electrodes must generate a _____________ potential.

A

stable electrical

71
Q

The reference electrode commonly used is the ______ electrode.

A

calomel

72
Q

Calomel, a paste of predominantly ________, is in direct contact with _________ in an electrolyte solution of ______.

A

mercurous chloride

metallic mercury

potassium chloride

73
Q

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.

A

indicator and reference

Slow

two dissimilar

Unequal

74
Q

In liquid junction

Electromotive force produced by the reference and indicator electrodes in the test solution is in the ______ range and read by

A

millivolt

75
Q

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

A

Nernst

ISE

76
Q

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.

A

physical interactions

stationary phase

77
Q

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 ______________

A

mobile ; gas or liquid

stationary; solid or liquid

mobile

column; stationary

separated components (eluate).

78
Q

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.

A

liquid-solid

sample; mobile

adsorptive sites

solid stationary

79
Q

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 _______

A

Fastest

Slowest

polar functional groups.

80
Q

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.

A

silica gel

alumina

charcoal

81
Q

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

A

liquid-liquid

organic

aqueous

82
Q

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

A

aqueous

organic

allowed to separate.

aqueous

organic

83
Q

Partition chromatography

The ratio of the concentration of the solute in the two liquids is known as the _____________

A

partition coefficient

84
Q

Partition chromatography is applicable to any substance that ____________________________

A

may be distributed between two liquid phases.

85
Q

partition chromatography works best with (ionic or non-ionic?) compounds

With reason

A

Non-ionic

Because ionic compounds are generally soluble only in water

86
Q

Modes of Separation: steric conclusion

Steric exclusion, a variation of _________ chromatography, is used to separate solute molecules on the basis of ________

A

liquid-solid

size and shape.

87
Q

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 ______.

A

porous material.

mobile

momentarily trapped

particles

88
Q

Modes of Separation: ION exchange chromatography

In ion-exchange chromatography, solute mixtures are separated by virtue of the ________________

A

magnitude and charge of ionic species.

89
Q

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 _________

A

resin

benzene, silicates, or cellulose

cation exchange resins or anion exchange resins.

90
Q

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.

A

remove interfering substances from a solution

concentrate dilute ion

separate mixtures

91
Q

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 ______________

A

sorbent

glass or plastic plate.

spot

closed container

saturated with solvent vapor.

92
Q

Thin-layer chromatography (TLC) is a variant of _____ chromatography.

A

column

93
Q

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.

A

capillary action

reaches a predetermined height

plate

94
Q

TLC

The distance a component migrates, compared with the distance the solvent front moves, is called the _______

A

retention factor, Rf

95
Q

TLC is most commonly used as a __________ screening test.

A

semiquantitative

96
Q

Chromatographic Procedures: High-Performance Liquid Chromatography

High-Performance liquid chromatography uses _____ for fast separations, controlled temperature, in-line detectors, and gradient elution techniques.

A

pressure

97
Q

High-Performance Liquid Chromatography

The basic components are:

1) ____
(2) _____
(3)_______
(4)______
(5)______

A

Pumps
Columns
Sample injectors
Detectors
Recorders

98
Q

High-Performance Liquid Chromatography

Pumps: A pump forces the ____ phase through the _____ at a much (lesser or greater?) velocity than that accomplished by ________ columns.

A

mobile

column

Greater

gravity-flow

99
Q

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.

A

stationary

stainless steel

sharper peaks

pressure

100
Q

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.

A

Small

mobile

automatic injection

101
Q

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.

A

electronic

concentration

102
Q

Spectrophotometers that detect absorbances of visible or UV light can be used as detectors

T/F

A

T

103
Q

High-Performance Liquid Chromatography

Recorders: The recorder is used to record ——- signal versus the time the __________, starting from the time of _______

A

detector

mobile phase passed through the instrument

sample injection.

104
Q

High-Performance Liquid Chromatography

The graph is called a _______.

The _______ is used to identify compounds when compared with _______ run under identical conditions.

A

chromatogram

retention time

standard retention times

105
Q

High-Performance Liquid Chromatography

Peak area is proportional to ________ of the compounds that produced the peaks.

A

concentration

House Clinical Pathology (45 decks)

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