Liquid Handling

Calculations3. Calculation of the standard deviation, necessary for the determination of coefficient of variation(x 1 - x – ) 2 + (x 2 - x – ) 2 + (x 3 - x – ) 2 + ... + (x n - x – ) 2s = Z ·n-1Technical Informations = 1.0032 ·(200.2 - 199.51) 2 + (199.6 - 199.51) 2 + (199.49 - 199.51) 2 + ... + (199.19 - 199.51) 29s = 1.0032 ·0.83939s = 0.3064. Calculation of the coefficient of variationCV [%] = s · 100V –CV [%] =0.306 · 100200.1514CV [%] = 0.153The result for the calculated example is:Results of the gravimetric testing:Tested volume (µl): 200.0000Mean volume (µl): 200.1514A [%] 0.076CV [%] 0.153A [%] specified* 0.600CV [%] specified* 0.200* Error limits specified by the manufacturer of instrument.See your operating manual for specifications.⇒ This pipette meets specifications.If the calculated values for Accuracy (A [%])and Coefficient of Variation (CV [%]) areless than or equal to the factory publishedspecifications, the instrument is calibratedto operate within specifications.Note:If there are no specifications for partialvolumes, the values A nominal [%] andCV nominal [%] which are related to thenominal volume V nominal must be converted.For a partial volume of 20 µl this means:A 20 µl [%] = V nominalV 20 µl· A nominal [%]A 20 µl [%] =A 20 µl [%] = 5%200 µl· 0.5%20 µlThe calculation of CV 20 µl is analog.What to do if the instrument isnot within the factory-specifiederror limits?1. Check whether all sections of theSOP are taken into account.2. Follow the troubleshootingguide in the operating manual forassistance.3. Adjust the calibration of theinstrument in accordance withthe operating manual.If despite these steps the instrumentstill does not meet the specifications,remove from service and contactBRAND for support.www.brand.de323