5) Lab instrumentation

Question 1

spectrophotometer

Answer 1

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

Question 2

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

Answer 2

electromagnetic radiation (EMR)

Question 3

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

Answer 3

Maxwell’s waves
photons

Question 4

Length of the electronic vector at max peak height

Answer 4

amplitude, A

Question 5

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

Answer 5

period (P)

Question 6

Number of oscillations of the waveform in a second

Answer 6

frequency, v

Question 7

Linear distance between any two equivalent points on successive waveforms.

Answer 7

Wavelength, λ

Question 8

visible light

Answer 8

380-750 nm

Question 9

white light

Answer 9

polychromatic light
all colors

Question 10

3 primary colors

Answer 10

red, blue, green

Question 11

photometry measures…

Answer 11

reflected light

Question 12

refractometry measures…

Answer 12

bent light

Question 13

nephelometry measures…

Answer 13

scattered light

Question 14

spectrophotometry measures…

Answer 14

transmitted and absorbed light

Question 15

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

Answer 15

100% T

Question 16

transmittance =

Answer 16

P/P0

Question 17

A =

Answer 17

A = abc = -log(T)

Question 18

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

Answer 18

%T
ABS

Question 19

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.

Answer 19

Lambert’s law

Question 20

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.

Answer 20

Beer’s law

Question 21

define variables in Beer’s law

Answer 21

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

Question 22

there is a deviation from the line when A approaches…

Answer 22

2

Question 23

spec methodologies generally account for …..

Answer 23

7% lipemia

Question 24

combines measuring scattered and forward light

Answer 24

nephelometry
turbidimetry

Question 25

5 components of spectrophotometer

Answer 25

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

Question 26

2 types of radiant energy source

Answer 26

- continuum (Tungsten) - line (mercury or sodium vapor)

Question 27

wavelength selector

Answer 27

Monochromators

Question 28

Wavelength in nanometers at peak light transmittance

Answer 28

nominal wavelength

Question 29

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

Answer 29

effective bandwidth

Question 30

Total range of wavelengths transmitted

Answer 30

bandpass

Question 31

different types of monochromators

Answer 31

Absorption filters Interference filters Prisms Grating monochromators Monochromator Slits

Question 32

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

Answer 32

types of photodetectors

Question 33

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.

Answer 33

Photomultiplier Tubes (PMT)

Question 34

sources of spec error

Answer 34

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

Question 35

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

Answer 35

Assessment of photometric accuracy

Question 36

Optical instrument used for visual identification of atomic emission lines

Answer 36

spectroscope

Question 37

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

Answer 37

colorimeter

Question 38

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

Answer 38

photometer

Question 39

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

Answer 39

spectrometer

Question 40

2 types of double beam specs

Answer 40

Double beam in space Double beam in time

Question 41

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

Answer 41

reflectometer

Question 42

a urine dipstick is a type of...

Answer 42

reflectometer

Question 43

2 types of reflectance

Answer 43

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

Question 44

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

Answer 44

atomic absorption spectroscopy (AAS)

Question 45

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

Answer 45

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

Question 46

components of AAS different from spec

Answer 46

hollow cathode lamp flame serving as cuvette measures atoms

Question 47

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

Answer 47

fluorometry

Question 48

high specificity and sensitivity

Answer 48

fluorometry

Question 49

fluorescence vs phosphorescence

Answer 49

single excited state triplet excited state

Question 50

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

Answer 50

fluorometers

Question 51

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

Answer 51

chemiluminescence

Question 52

Rayleigh theory Mie theory Rayleigh-Debye theory

Answer 52

nephelometry

Question 53

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

Answer 53

mass spectroscopy

Question 54

mass spec steps

Answer 54

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.

Question 55

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

Answer 55

types of mass spec