Laboratory Report: Determining Pipettor Accuracy and Percentage Error

This laboratory report details an experiment designed to assess the accuracy and precision of various pipettors (P-20, P-200, P-1000, and P-5000) commonly used in biochemistry. The report outlines the experimental procedures, including the correct use of pipettors, and the method for calculating percentage errors. The experiment involved dispensing deionized water using each pipette at specified volumes and weighing the dispensed water to determine the actual volume delivered. The collected data was then used to calculate the percentage error for each pipettor, revealing that all pipettes exhibited positive errors, with P-200 having the highest percentage error of 37.27% and P-5000 the lowest at 9.02%. The report includes sections on the materials and methods used, the results obtained, and a discussion of the findings, offering insights into the sources of error and the importance of accurate pipetting in biochemical experiments. The report concludes that determining the accuracy and precision of pipettes is essential for minimizing errors and improving experimental outcomes.

LABORATORY REPORT 1
LABORATORY REPORT
By Name
Course
Instructor
Institution
Location
Date

LABORATORY REPORT 2
Abstract
Pipettors are essential equipment in carrying out biochemistry experiments, determining their
accuracy and precision is very important to enable one to know the magnitude of the mistakes
which are committed during the experiment and come up with ways on how to reduce errors.
This report explains how to use the pipettors and skills on how to calculate the percentage
error in experiments. This aimed at enabling one to determine the accuracy and precision of
the pipettors. The following apparatus were used during the lab session Pipettes tips
Four pipettes, Deionized water, Balance and balance boats. During the experiment session
one was first required to know how to use the pipettors. Determining the precision of the
pipettors and record the data to be used in determine the percentage error. From the data
which was collected all the pipettes recorded a positive errors with P-200 recording the
highest percentage error of 37.27% and P-5000 recording the least percentage error of 9.02%.
Introduction
Pipettors are essential equipment in the field of Biochemistry; they are used in carrying out
various experiments which are aimed at studying different phenomena within the field of
Biochemistry. This report explains the skills which were gained during the lab session on
how to use pipettors and how to calculate the percentage errors of the equipment. The errors
committed in experiments can have adverse effects on the results obtained (Arneson, 2017, p.
78).
The objectives of this experiment were as follows:
To determine the percentage error of each pipette so that the magnitude of the mistakes
committed during the experiment can be known and dealt with.

LABORATORY REPORT 3
To develop skills on how to use pipettors, which was to make it easier and efficient to carry
out the biochemistry experiment.
Establishing the accuracy and precision of all the pipettes and also calculate their percentage
error because the errors committed in the experiments because they usually bring about
adverse effects on the results (Elkins, 2012, p. 236).
This experiment was aimed at measuring the accuracy and precision of pipettors. Accuracy is
the closeness of measured value to a known value or a standard value while precision refers
to the close relationship of two or more measurements to one another.
The procedures on how the experiment was to be carried out were followed which included
how to use the pipettes and how to determine the precision of each pipette. The following
materials were used in the experiment; Pipettes tips, four pipettes, i.e., p-20, p-200, p-1000
and p-5000, deionized water and balance and balance boats.
After the calculating the percentage error for all pipettes it was found out that P-200 had the
highest percentage error of 37.27% followed by P-20 which had the percentage error of 19.2
%.Pipette P-1000 recorded percentage error of 16.51% and P-500 recorded the least
percentage error of 9.02%.
This report contains the following sections; aims and objectives which explains why the
experiment was carried out. The methodology which discusses the procedures which were
followed during the experiment. The materials which list and explain the materials and
apparatus used and how they were used. The results which show the data which was recorded
and a well-calculated percentage error. The discussion which explains the findings of the
experiment and how the experiment can be improved.
Materials and methods

LABORATORY REPORT 4
The following materials and apparatus were used during the experiment;
Pipettes tips
Four pipettes i.e. p-20, p-200, p-1000 and p-5000
Deionized water
Balance and balance boats
How to use the pipettors.
Finding the stops
Hold tight the micropipette in your hand. Depress the plunger by use of your thumb, slowly
practice on how to depress the plunger and feel the two stops.
Move the plunger to the first stop in order to draw the sample fluid.
Lower the tip of the pipette into the sample fluid while keeping the plunger down and then
gradually release the plunger (Keel, 2013, p. 234). This should be down slowly to avoid the
pipette sucking liquid inside the shaft of the pipette then after filling, you should wait for one
second before removing the tip from the liquid.
Checking the tip of the pipette
First, check the amount of the fluid you have. Ensure that there are no air bubbles which are
trapped in the tip.in case there are air bubbles consider drawing the sample of water once
again. Ensure that the outside of the tip is completely dry (Lawn, 2013, p. 312).
Releasing the fluid from the pipette
First, lower the tip into the bottom of the tube. Depress the plunger slowly to the first stop
and then wait for one second before pushing the plunger to the second stop to remove the last

LABORATORY REPORT 5
bit of the fluid and ensure that there is no fluid left. While taking the pipette out of the tube
keep the plunger pushed down (Thomson, 2015, p. 245).
Ejecting the tip
By pushing the ejector button, eject the tip into the waste container of the pipette tips.
Determining the precision of the pipettors
To determine the precision of the pipettors, the following procedures were followed:
Select a pipette of your choice and then look for an appropriate pipette tip to attach to it.
The pipettors are then set to the following stated volumes; p-20=20μL, p200=200μL, p-
1000=1000μL, p-5000=5000μL.
Put the weighing boat O to the balance and then take the weight which is recorded to zero.
Take away the designated volume of the deionized water and then dispense it into the
weighing boat (Patnaik, 2014, p. 411).
Record the weight of water as observed on the weighing boat.
Repeat all these procedures twice more.
Repeat all the above procedures for all the pipettes and then record and tabulate all the
measurements that are obtained.
Results
The results for all the pipettes were observed, recorded and the tabulated as shown in the
tables below.

LABORATORY REPORT 6
P-20
P-200
P-1000
P-5000
1000 μL
(1000)
5000 μL
(5000)
20μL
(20)
20 μL
(20)
0.0063 0.0230
0.0063 0.0235
0.0060 0.0240
0.0058 0.0243
0.0063 0.0244
20 μL
(20)
200 μL
(200)
0.0948 0.2750
0.0968 0.2748
0.0943 0.2742
0.0940 0.2743
0.0951 0.2744
200 μL
(200)
1000 μL
(1000)
0.3693 1.1650
0.3722 1.1672
0.3720 1.1647
0.3722 1.1637
0.3744 1.1650

LABORATORY REPORT 7
5.4380 1.6190
5.4501 1.6185
5.4709 1.6177
5.4244 1.6288
5.4711 1.6339
After all the results were recorded they were further analysed to determine the percentage
error of each pipette.
The percentage error was calculated by using the formula below,
Percentage error = [(Average weight-Expected weight of water)/ Expected weight of
water]*100
The percentage error for P-20.
The expected weight of water = 0.02g
The average weight of water = (0.0230 + 0.0235 +0.02340 + 0.0243 +0.0244) /5
= 0.02384g
% error = [(0.02384 - 0.02)/0.02] *100
= 19.2 %
The percentage error for P-200.
The expected weight of water = 0.2g
The average weight of water = (0.2750 +0.2748 +0.2742 +0.2743 +0.2744)/5
= 0.27454g
% error = [(0.27454 – 0.2)/0.2] *100

LABORATORY REPORT 8
= 37.27%
The percentage error for P-1000.
The expected weight of water = 1 g
The average weight of water = (1.1650 +1.1672 +1.1647 +1.1637 +1.1650) /5
= 1.16512g
% error = [(1.16512 -1)/1] *100
= 16.51%
The percentage error for P-5000.
The expected weight of water = 5 g
The average weight of water = (5.4380 + 5.4501 +5.4709 +5.4244 +5.4711)/5
=5.4509g
% error = [(5.4509 -5)/5]* 100
=9.02%
Discussions
From the results obtained it’s was clear that all the pipettes which were measured the weight
of water measured was more than the weight of water which was expected.
After the calculating the percentage error for all pipettes it was found out that P-200 had the
highest percentage error of 37.27% followed by P-20 which had the percentage error of 19.2

LABORATORY REPORT 9
%.Pipette P-1000 recorded percentage error of 16.51% and P-500 recorded the least
percentage error of 9.02%.
The percentage errors which were obtained indicated that the experiment for measuring the
accuracy and precision of P- 5000 was carried with the highest level accuracy and the
mistakes which were committed were very minimal as compared to other experiments
(Wilson, 2015, p. 356). Experiment for measuring the accuracy and precision for P-200
recorded the highest level number of mistakes which were committed as shown by the
highest percentage error.
Conclusion
In conclusion, the pipettors have been considered to be essential equipment by biochemist,
they are used in carrying out experiments within that field of biochemistry. It is very
important to determine the accuracy and precision of the pipettes in order to come up with
ways on how to reduce the mistakes committed during the experiments and improve the
expected results of the experiment (Webster, 2016, p. 12).
From the results which were recorded all the pipettes recorded a positive errors with P-200
recording the highest percentage error of 37.27% and P-5000 recording the least percentage
error of 9.02%.The percentage error which was obtained is equivalent to the mistakes which
were committed during the experiment.

LABORATORY REPORT 10
Bibliography
Arneson, W. L., 2017. Clinical Chemistry: A Laboratory Perspective. 2nd ed. Chicago: F.A.
Davis.
Elkins, K. M., 2012. Forensic DNA Biology: A Laboratory Manual. 2nd ed. Berlin:
Academic Press.
Keel, B. A., 2013. Handbook of the Laboratory Diagnosis and Treatment of Infertility. 2nd
ed. Texas: CRC Press.
Lawn, R. E., 2013. Measurement of Volume. 3rd ed. Chicago: Royal Society of Chemistry.
Patnaik, P., 2014. Dean's Analytical Chemistry Handbook. 4th ed. London: McGraw Hill
Professional.
Thomson, S., 2015. Standard Operating Procedures In Vitro Toxicology. 1st ed. Paris:
Springer Science & Business Media.
Webster, B. W., 2016. American Biotechnology Laboratory, Volume 23, Issues 6-13. 3rd ed.
Chicago: International Scientific Communications, 2005.

LABORATORY REPORT 11
Wilson, K., 2015. Principles and Techniques of Practical Biochemistry. 1st ed. London:
Cambridge University Press.