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Mercy CLS 5: Chemistry > 5) Lab instrumentation > Flashcards

5) Lab instrumentation Flashcards

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1
Q

spectrophotometer

A

instruments used to measure the “optical density” of a solution.

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2
Q

Interaction of ———– in the form of photons with matter provides the principal means of measuring analytes in biological fluids.

A

electromagnetic radiation (EMR)

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3
Q

EMR exists both as ———– and as streams of ——–

A

Maxwell’s waves
photons

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4
Q

Length of the electronic vector at max peak height

A

amplitude, A

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5
Q

Time in seconds required for the passage of successive maxima or minima through a fixed point in space

A

period (P)

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6
Q

Number of oscillations of the waveform in a second

A

frequency, v

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7
Q

Linear distance between any two equivalent points on successive waveforms.

A

Wavelength, λ

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8
Q

visible light

A

380-750 nm

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9
Q

white light

A

polychromatic light
all colors

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10
Q

3 primary colors

A

red, blue, green

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11
Q

photometry measures…

A

reflected light

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12
Q

refractometry measures…

A

bent light

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13
Q

nephelometry measures…

A

scattered light

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14
Q

spectrophotometry measures…

A

transmitted and absorbed light

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15
Q

spectrophotometer is set to read —— with the “blank”, negating any absorbance occurring due to solvent

A

100% T

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16
Q

transmittance =

A

P/P0

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17
Q

A =

A

A = abc = -log(T)

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18
Q

concentration vs —– is nonlinear
concentration vs —– is linear

A

%T
ABS

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19
Q

States that for parallel monochromatic radiation that passes through an absorber material of constant concentration, the radian power decreases logarithmically as the light path increases arithmetically.

A

Lambert’s law

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20
Q

States that for monochromatic radiation, absorbance is directly proportional to the light path, b, through the medium and the concentration, c, of the absorbing species.

A

Beer’s law

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21
Q

define variables in Beer’s law

A

A = absorbance
a = absorptivity (L g-1 cm-1)
b = cell length (1cm)
c = concentration (g/L)

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22
Q

there is a deviation from the line when A approaches…

A

2

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23
Q

spec methodologies generally account for …..

A

7% lipemia

24
Q

combines measuring scattered and forward light

A

nephelometry
turbidimetry

25
Q

5 components of spectrophotometer

A
  1. A stable source of radiant energy
  2. A device that isolates a specific region of the electromagnetic spectrum
  3. A sample holder
  4. A photo detector
  5. A read- out device
26
Q

2 types of radiant energy source

A
  • continuum (Tungsten)
  • line (mercury or sodium vapor)
27
Q

wavelength selector

A

Monochromators

28
Q

Wavelength in nanometers at peak light transmittance

A

nominal wavelength

29
Q

Range of wavelengths at a point halfway between the baseline and the peak.

A

effective bandwidth

30
Q

Total range of wavelengths transmitted

A

bandpass

31
Q

different types of monochromators

A

Absorption filters
Interference filters
Prisms
Grating monochromators
Monochromator Slits

32
Q

Photovoltaic or Barrier Layer Cell
Vacuum Phototubes
Silicon Diode Transducers
Multichannel Photon Transducers
Photodiode Arrays
Charge-Transfer Devices

A

types of photodetectors

33
Q

commonly used when radiant power is very low, which is characteristic of very low analyte concentrations.

Output signal amplified up to approximately one million times.

A

Photomultiplier Tubes (PMT)

34
Q

sources of spec error

A

lipemia
hemolysis
icterus
Temperature
pH
Standards and Standardization
Preparation of Solutions/Reagents
Clean cuvettes
Wavelength selection
Presence of Stray Light
Incorrect Blank Used
Clerical Errors

35
Q

——- is performed using glass filters or solutions that have known absorbance values for a specific wavelength.

A

Assessment of photometric accuracy

36
Q

Optical instrument used for visual identification of atomic emission lines

A

spectroscope

37
Q

User compares the observed color of the unknown sample to a standard or a series of colored standards of known concentrations

A

colorimeter

38
Q

Consists of a light source, monochromatic filter and photoelectric transducer, signal processor, and readout.

A

photometer

39
Q

An instrument that provides information about the intensity of radiation as a function of wavelength or frequency

A

spectrometer

40
Q

2 types of double beam specs

A

Double beam in space
Double beam in time

41
Q

A filter photometer that measures the quantity of light reflected by a liquid sample that has been dispensed onto a nonpolished surface.

A

reflectometer

42
Q

a urine dipstick is a type of…

A

reflectometer

43
Q

2 types of reflectance

A

Specular reflectance—Occurs on a polished surface (e.g., a mirror)
Diffuse reflectance—Occurs on nonpolished surfaces

44
Q

Used for quantitative analysis of metals such as arsenic, lead, copper, mercury, zinc, and aluminum.

A

atomic absorption spectroscopy (AAS)

45
Q

AAS measures the amount of EMR absorbed at a specific wavelength by elements ….

A

in their ground state (Go) with a zero-net charge

46
Q

components of AAS different from spec

A

hollow cathode lamp
flame serving as cuvette
measures atoms

47
Q

Based on an energy exchange process that occurs when valence shell electrons absorb EMR, become excited, and return to an energy level lower than their original level

A

fluorometry

48
Q

high specificity and sensitivity

A

fluorometry

49
Q

fluorescence vs phosphorescence

A

single excited state
triplet excited state

50
Q

Conventional design of ——— places the detector at a 90° angle to the polychromatic light source.

A

fluorometers

51
Q

Light is produced from a chemical or electrochemical reaction and not from electromagnetic energy stimulation of electrons, resulting in emission of photons.

A

chemiluminescence

52
Q

Rayleigh theory
Mie theory
Rayleigh-Debye theory

A

nephelometry

53
Q

Used to identify unknown compounds, determine concentrations of known substances, and study the molecular structure and chemical composition of organic and inorganic material

A

mass spectroscopy

54
Q

mass spec steps

A
  1. Atomization
  2. Conversion of a substantial fraction of the atoms to a stream of ions
  3. Separation of the ions on the basis of their mass-to-charge ratio (m/z)
  4. Counting the number of ions of each type or measuring current produced when the ions formed from the samples strike a transducer.
55
Q

Electrospray ionization (ESI)
Matrix-assisted laser desorption ionization (MALDI)
Surface-enhanced laser desorption ionization (SELDI)

A

types of mass spec

Mercy CLS 5: Chemistry (24 decks)

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