Lecture 1 - chemical techniques

Question 1

what is an analyte

Answer 1

the chemical/substance of interest to be detected in the test

Question 2

what measurable characteristics must analytes have

Answer 2

light emission

light absorbance

charge

Question 3

what must there be for a quantification of an analyte

Answer 3

predicatable relationship between the measureable effect and the amount of analyte

Question 4

what is accuracy

Answer 4

closeness of a results to the true value

Question 5

what is precision

Answer 5

closeness of repeated results

Question 6

what is sensitivity

Answer 6

smallest amount that can be accurately measured

Question 7

what is specificity

Answer 7

ability to measure only the analyte of interest

Question 8

what are the qualities of an analytical test

Answer 8

robustness - no interferences

ruggedness - consistency w small changes

time - how many can happen at the same time

cost - machines

Question 9

what is robustness

Answer 9

consistency in the presence of interferences

Question 10

what is ruggedness

Answer 10

consistency throughout small changes in conditions

Question 11

what is an immune complex

Answer 11

the specific reaction between an antibody and an antigen

antigen-antibody complex

Question 12

what does the amount of immune complex indicate in immunoassay

Answer 12

the amount of analyte in the sample

Question 13

what is a tracer

Answer 13

a radioactive isotope label on an assay component

Question 14

what are radioactive isotopes

Answer 14

unstable variants of atoms that spontaneously transform to a more stable state emitting energy

Question 15

what can radioactive isotopes be measured by

Answer 15

using a Geiger counter or scintillation counter

Question 16

what are common isotopes

Answer 16

iodine: I125, I131

tritium: 3H

Question 17

what does enzyme labes use

Answer 17

catalytic properties of enzymes to generate coloured, fluorescent
or luminescent compounds from the substrate

Question 18

what can single enzyme labels produce

Answer 18

many detectable product molecules which enhances assay sensitivity

Question 19

what are common enzyme labels

Answer 19

alkaline phosphatase

horseradish peroxidase

Question 20

why are coloured dyes used in lateral flow and pregnancy test

Answer 20

labels the specific antibody for the analyte

Question 21

what are colorimetric assays detected by

Answer 21

spectrophotometer

Question 22

what does a fluorphore do

Answer 22

absorbs light at one wavelength and reemits light at a longer wavelength

Question 23

what do lanthide chelates do

Answer 23

absorb light and then use that energy to emit fluorescence - can be detected with a fluorimeter

Question 24

what can break down a chemiluminescent substrate

Answer 24

enzymes such as adamantyl phosphate

Question 25

what detects light emission

Answer 25

luminometer

Question 26

why are immunoassays useful in a clinical lab

Answer 26

highly specific sensitive can be manufactured on a large scale can be automated

Question 27

what do labs use immunoassay for

Answer 27

hormones antibodies pregnancy urine albumin

Question 28

what is optical density measured by

Answer 28

passing a beam of white light through the mixture and measuring the amount of absorbance

Question 29

what happens in photometric assay

Answer 29

a reagent is added to the sample, resulting in a reaction that causes the mixture to undergo an optical change, which can be measured

Question 30

what is an example of photometric assays

Answer 30

bradford essay to measure protein concentration

Question 31

whats the difference between a photometer and a spectrophotometer

Answer 31

spectro uses light of a single wavelength, rather than white account

Question 32

why is absorbance an idea method in the lab

Answer 32

quick and easy cheap reproducible readily integrated into automation

Question 33

what is turbidimetry

Answer 33

measure of the cloudiness of a sample

Question 34

how is turbidimetry measured

Answer 34

light is passed through a sample and scattered or absorbed by solid particles in the suspension

Question 35

what does the amount of scattering in turbidimetry depend on

Answer 35

concentration of particles size of particles distribution of particles wavelength of light source

Question 36

does turbidimetry follow the Beer-Lamber Law

Answer 36

No

Question 37

what does ion selective electrodes compare

Answer 37

the electric potential generated across a membrane by specific ions (Eise) to a reference electrode (Eref)

Question 38

what is the principal of potentiometry

Answer 38

The strength of this net charge (ECell) is directly proportional to the concentration of the selected ion.