Pipetman Lab Purpose:
To determine the accuracy and precision of the pipetman. Accuracy The ability to obtain data equal to a known value. Precision is ability to obtain consistent data.

Background:
A pipetman is a laboratory tool used in chemistry , biology and medicine to transport a measured volume of liquid. Pipetman come in many designs for many purposes and much different levels of accuracy and precision
. Pipetman come from in many varieties such as a single piece glass pipettes or a more complex adjustable or even electronic pipettes. Many pipette types work by creating a partial vacuum above the liquid­holding chamber and selectively releasing this vacuum to draw up and dispense liquid. The measurement of accuracy and precision varies greatly depending on the type of pipet that is being used.

Hypothesis:
In this experiment If each pipet is measured to test accuracy and precision than the one that is most likely to be the most precise and accurate is the pipetman that is P10. This is because P10 is the smallest and has a better chance of being more precise and accurate due to the less amount of water volume it takes up. Materials
:
­

Pipetman

­

p20

­

p1000

­

p200

­

p10

­

Distilled Water

­

Balance

­

Weighing Container

­

paper towels

Procedure:
First Set Pipetman to test volume this also means zero it out. Then Place distilled water into the weighing container to a depth of 3 mm.Place correct tip on corresponding Pipetman.Wet
Pipetman tip 5 times to reach equilibrium. After Change tip of Pipetman. Pre­wet tip once
Pipette the test volume Determine take mass Deliver water from Pipetman into the container
Record the mass. Repeat steps 5 ­10 five times. Then Repeat process for each Pipetman
Calculate the average volume for each Pipetman Use the formula below to calculate the average error Compare results to accuracy and precision specifications given in the user’s guide of the test Pipetmans. Data:

P 20 #20

P 1000 #4

P 200 #9

P 10 #22

Target
Volume

20uL x 3

750uL x 2

100uL x 2

10uL x 5

Trial 1

.06g

1.51g

0.19g

Trial 2

.06g

1.52g

.18g

.05g

.05g

Trial 3

.05g

1.51g

.20g

.05g

Trial 4

.06g

1.51g

.20g

.06g

Trial 5

.05g

1.51g

.20g

.06g

Average %
Error

1.12

0.837

5.05

11.7

Scale

Weight

Test 1

Test 2 Average Mass

100 grams

99.99

99.98

99.985

0.015

­0.01166666667

50 grams

50

50

50

0

10 grams

10

10.01

10.005

­0.05

Average % Total Average %
Error
Error

Conclusion:
In this experiment if the pipettmen is measured to test accuracy and precision than the one that has the most likely chance to be the most accurate and precise is p10. This is accurate because after doing multiple tests with each pipettmen p10 was the most consistent even when weights were used as seen in