4. immunoassay and lab selection

Question 1

list the different assay types

Answer 1

• colourimetric (colour change)
• turbidometric (cloudiness)
• fluorometric (light excitement)
• immunoasssay (antibody/RIA/ELISA)

Question 2

describe the interpretation of colourimetry assay results

Answer 2

• chemical composition of a solution can affect colour
• as a chemicl reaction progresses the degree of colour change can be related to the concentration of the substrate
• absorbance of light of a specific wavelength for the colour of interest can be used in a calculation for concentration of the substrate
• what is being measured must first be limiting

Question 3

describe how immunoassay testing works

Answer 3

several components:
- antibodies (poly or monoclonal) react with hormone in species of interest
- tracer (enzyme/radioactive tag) attaches to molecule or antibody
- detection systmes looks for changes in light, colour or radiation
- separation of tracer signal that has reacted with hormone separated from that which it hasnt

Question 4

list immunoassay detection systems

Answer 4

• RIA (radiation)
• ELISA
• chemiluminescence

Question 5

how do we know if a test is valid

Answer 5

• precision
• accuracy

Question 6

what are the pros and cons of reference lab vs in clinic lab

Answer 6

ref lab
- quality assurance and QC taken care of
- daily or more frequent QC
- may be slower to get results (next day)
- using validated precise and accurate methods
- may be inspected annually if accredited

in clinic
- validation check responsibility on clinic
- may be less precise or accurate
- QC responsibility on clinic
- have to interpret. spot errors and understand what results mean yourself
- quicker
- may be more expensive for client

Question 7

what are the rules for sample shipping

Answer 7

• sample volume must be less than 50 ml
• that packaging must consist of 3 components: primary recepticle (tube), secondary packaging (plastic bag plus absorbant material if liqiuid) and outer packaging (envelope, box etc)
• the smallest external dimesnion of the outer packaging shall not be less than 100mm x 100mm
• the completed package shall be capable of successfully passing a 1.2 m drop test
• the primary receptacle must be leak proof
• the secondary packaging shall be leak proof
• if multiple fragile receptacles are placed in a single secondary package, they shall be either individually wrapped or seperate to prevent contact between them
• absorbent material shall be placed between the primary receptables and the secondary receptacles and it shall be in quantity sufficient to absorb the entire contents of the primary receptacle so the relase of liquid substance will not compromise the integrity of the outer packaging
• the primary receptacle or secondary packaging shall be capable of withstanding wihtout leakage an internal pressure of 95kPa
• paperwork needs to accompany and must include who you are, contact details/where results are to be sent, address/contact for invoicing, what tests are needed, animal id detail, animal species, age and breed, sample type, client id, dates samples taken and posted, case hx