Lecture 3

Question 1

what is a batch analysis?

Answer 1

many specimens are grouped in the same analytical session aka being tested for the same one thing (glucose levels)

Question 2

what is carryover?

Answer 2

transport of a quantity of analyte or reagent from one specimen reaction into and contaminating the next one

Question 3

what is continuous flow analysis?

Answer 3

analysis where each specimen in a batch passes through the same continuous stream at the same rate and subjected to the same analytical reaction

Question 4

random access analysis is:
a) most common configuration of an automated analyzer
b) analysis is performed on a collection of specimens sequentially
c) each specimen is analyzed from a different selection of tests
d) all of the above

Answer 4

all of the above

Question 5

what are multiple and single channel analysis?

Answer 5

multiple: each specimen is tested for multiple things, thus a set of results is obtained (CBC)
single: each specimen is only tested for one analyte, and one test result per specimen

Question 6

single channel analysis is similar to ______, multiple channel analysis is similar to _______

Answer 6

batch analysis; random access analysis

Question 7

if the wavelength is long, the frequency will be ____ and if the wavelength is short, the frequency will be ______

Answer 7

low; high

Question 8

does 300nm or 1200nm have a higher energy?

Answer 8

300nm; has shorter wavelength higher frequency

Question 9

are UV waaves longer or shorter than visible waves? are they higher or lower?

Answer 9

shorter and higher energ

Question 10

T/F DNA and protein do not absorb UV light because they are uncoloured

Answer 10

F, they still do because of the molecular makeup

Question 11

spectrophotometer is a device that measures

Answer 11

the amount of light energy a solutuon absorbds/transmits

Question 12

T/F the amount of transmitted energy is always less than the amount of incident energy

Answer 12

T

Question 13

what formulas can be used for absorbance?

Answer 13

A = 2-log(%T)
A= -log(T in decimal)

Question 14

as absorbance increases, that means that transmittance ____

Answer 14

decreases; inverse relationship

Question 15

how would you calculate % transmittance if you were given absorbance?

Answer 15

%T = 100x 10^(-Abs)

Question 16

the wavelength at which any give solute exhibits the max abs usually provides the best
a) precision
b) accuracy
c) sensitivity
d) specificity
e) more than 1

Answer 16

e) sensetivity and specificity

Question 17

what is molar absorptivity?

Answer 17

how much light will be absorped by 1cm of a 1M solution

Question 18

T/F we always use the maximum absorbance wavelength for every method

Answer 18

F, we try but need to be mindful of interference

Question 19

what are the limitations of beers law?

Answer 19

1. incident light must be monochromatic
2. solvent absorption is insignificant compared to solute (colourless)
3. solute [] is within linear limits
4. no optical interferences (dust, crack)
5. calibrate and check for quality!

Question 20

T/F you should always force your line through zero

Answer 20

false! it would create a bias

Question 21

what are things to watch for when deciding what light source to use for a spec?

Answer 21

how much heat it puts off, the temperature it reaches, the stability of light source (no flicker)

Question 22

how is a light beam split into its component wavelengths in a spec?

Answer 22

prism, filter or gratings

Question 23

would filter, prism, grating be more precise?

Answer 23

diffraction grating

Question 23

what is the purpose of fiber optics?

Answer 23

to allow closer positioning within the spec to minimize the footprint of the instrument

Question 24

which of the following is not meant for spec in the UV region? a) quartz b) silicate glass c) specialized plastics d) fused silica cuvetttes

Answer 24

b) silicate glass

Question 25

what nm can silicate glasses be used for?

Answer 25

350-2000nm

Question 26

what do photodetectors do?

Answer 26

convert light energy into electrical signal to give a readable number

Question 27

what is a photomultiplier tube (PMT)?

Answer 27

example of most used photodetector that has a very rapid response time

Question 28

what is a linear photoiode array?

Answer 28

less popular detector, more simple version

Question 29

what is a band pass?

Answer 29

range of wavelength(s) transmitted by the monochromater for any desired wavelength

Question 30

would you want a band pass that is lower or higher?

Answer 30

you want a lower band pass because it gives you a more specific wavelength

Question 31

what is false regarding photometric accuracy? a) uses filters or solns w/ exact known abs at specific wavelength b) must be insensitive to bandpass or spec config c) ensures that spec is measuring abs accurately d) ensures that selected wavelength on spec corresponds to actual wavelength being transmitted

Answer 31

d) ensures that selected wavelength on spec corresponds to actual wavelength being transmitted

Question 32

what does photometric linearity ensure?

Answer 32

that it is following beers law; amount of energy absorbed vs instrument readout should be linear in the anticipated range

Question 33

which is not a common source of error in a spec relating to photometric linearity? a) keeping the lid closed when it runs b) faulty detector c) improper wavelength d) stray light

Answer 33

a) keeping the lid closed when it runs

Question 34

what is false regarding stray light? a) is any light that reaches the detector that did not go through the sample b) may increase with time due to aging of optical components and cause drift/trends c) has no effect on the standard curve linearity d) may falsely contribute to transmittance reading

Answer 34

c) has no effect on the standard curve linearity

Question 35

what are the 4 quality processes in spec?

Answer 35

1. wavelength accuracy 2. photometric accuracy 3. photometric linearity 4. stray light

Question 36

which of the following may cause interferences in spec? a) hemolysis b) icteric c) lipemia d) drugs e) all of the above

Answer 36

all of the above

Question 37

T/F if hemolysis is due to collection, this is an invitro interference

Answer 37

T

Question 38

what is a chemical interference in spec?

Answer 38

relative to [] of interferent, best to remove if possible (use wavelength for least interference)

Question 39

which of the following is not a corrective measure for spec interferences? a) blanks b) diluting the patient sample c) multiple wavelength readings d) kinetic methods

Answer 39

b) diluting the patient sample

Question 40

how and when are blanks used as corrective measures?

Answer 40

if you cant correct interference bc its invivo, use a specimen blank. this blanks colour of specimen off

Question 41

which is true regarding corrective methods? a) only done when need to b) done during every run c) multiple wavelength readings is done with every sample d) kinetic methods are used for critical samples

Answer 41

a) only done when need to

Question 42

how does multiple wavelength reading work? give an example

Answer 42

bichromatic measuring at two wavelengths or at a high peak away from other interferences e.g. bilirubin has 2 peaks, one with interference w/ hemolysis so you run on both, then only run on the one where bilirubin is only detected

Question 43

how does kinetic method work?

Answer 43

reading over time to choose optimum expression of analyte, see when/where it shows up

Question 44

give an example of a lab method that uses reflectance photometry

Answer 44

urine dipstick reading in machine

Question 45

T/F reflectance photometry is linear

Answer 45

F, needs math to relate [] to reflectance

Question 46

what is fluorimetry?

Answer 46

measurement of emitted light, accurate and very sensitive

Question 47

what is the stoke's shift?

Answer 47

difference in wavelength from excitation to emitted

Question 48

when does fluorescence occur?

Answer 48

when a molecule absorbs a photon of radiant energy at one wavelength and reemits photons of light at a longer less energy wavelength

Question 49

which of the following is true regarding components for fluorometers? a) DNA and Ab are commonly measured this way b) spectrofluorometers have 2 spectral monochromators c) higher energy emitted radiation passes through excitation monochromator to isolate the fluorescent peak d) may use filters to restrict wavelengths e) two or more of the above

Answer 49

e) everything is true!