Checking Pipette’s Accuracy and Precision

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educational contents this video is about

the mechanical pipette which is almost

the most important device inside any

laboratory procedure that deals with

liquid transfer the mechanical pipette

is used to transfer small volumes of


since laboratory procedures usually

involve small liquid volumes the pipette

has to be accurate

therefore a procedure to ensure the

accuracy of the perpetual is a must in

order to make sure that your pipette is

actually drawing and dispensing the

right volumes for accurate and reliable

results there are multiple methods to

check your pipette accuracy but in our

laboratory we follow the gravimetric

method provided by ISO


before you start determine the z factor

the Z factor is determined by measuring

the temperature and the atmospheric


they use the table provided by ISO to

locate the Z factor that matches your

temperature and atmospheric pressure

the Z factor is one point zero zero

three four because the temperature of

our laboratory is 23 degrees Celsius and

the atmospheric pressure is ninety five

Cola tasko

now we can start

put the flask on the balance

note it is recommended to have water in

the flask prior starting the procedure

blanket to prevent your flasks weight

from interfering with your measurements

put on a tip suitable to pipette to be


it is recommended to draw and dispense

multiple times to wet the tip before

using it then

draw a 100

percent of Pripet samin volume then

dispense it in the flask to measure its


record the weight on your notebook

repeat the same procedure 9 more times


after 10 measurements repeat the same

procedure with 50 percent and 10 percent

of the maximum volume multiply each

single measurement by the Z factor to

correct your measurements these are our

measurements multiplied by the z factor

calculate a systemic and random errors

using the corrected measurements again

these are our results and these are the

calculations for each volume

obtain the maximum permissible error

from ISO 8655 protocol

our pipette is good to go since all of

the results are below the maximum

permissible error