Method In Clinical Chemistry Flashcards by Iseoluwa Ojo

Centrifugation

This is a basic ______ technique

separation

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

centrifugal

solid; liquid

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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

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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

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A tachometer which indicates _____

speed

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

mass, speed, and radius

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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).

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

RCF = ___

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

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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

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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

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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

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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

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Balancing the centrifuge load is mot important .

T/F

It is critical!

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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

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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

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

even

opposition

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

aerosol Closed

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

tachometer

strobe light.

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

speed verification

aerosol

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_______ agencies require periodic verification of centrifuge speeds.

Accreditation

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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

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spectrometry (including ______,_______ and __________ )

luminescence (including ________,_______, and _________ )

spectrophotometry, atomic absorption, and mass spectrometry

fluorescence, chemiluminescence, and nephelometry

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electroanalytic methods (including ___________,_______, and __________ )

chromatography (including _____,_____, and ________ )

electrophoresis, potentiometry, and amperometry

gas, liquid, and thin-layer

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SPECTROPHOTOMETERS AND PHOTOMETERS measure __________ passing through a _________.

electromagnetic radiation

solution

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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.

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

(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

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