12-preparing assays - calibrations

3 major assay categories

qualitative, semi qualitative, quantitative

calibration frequency depends on

complexity of assay → quantitative is the most frequent

what is calibration

create relationship between input and output by telling instrument that x signal = y result

linear relationship

upper and lower limit to range due to limitations of tests n stuff

want to keep quantification within the linear range so theres a direct proportional relationship

beers law

Cunk = Aunk/Astd x C std

measures will be inaccurate at

high values → sample absorbs too much/too high concentration = detector can’t detect small changes

low values → too little of a value to read and can’t detect small changes

linearity limitations

can’t extrapolate

interpolation

determines value from within a range of known standard values (inside linear curve)

extrapolation

determines value from outside range of known standard values

how to determine values outside of linearity

dilutions if too high

spiking with known value if too low

spiking low sample rarely done because

not clinically significant at that amount or knowing value is low is enough for clinical decision