Usually we have them tear out this page from the manual. It is what you prefer
Name here
5/11/2020
Pre-Laboratory Assignment
1. What is the usable range of a P-1000 Rainin Pipetman?
The recommended volume range for a P-1000 Rainin Pipetman is 100-1000µL.
2. What is the difference between accuracy and precision?
Accuracy represents the relationship between the desired measurement and the actual
measurement taken. Precision, however, represents the consistency with which a given
measurement is taken. For example, you want to pipet 100 µL of water but instead you
have taken 5 measurements that all ended up being 80 µL of water. These measurements
are not accurate as none of them match your target measurement of 100 µL, however,
they are precise in that you are continually getting the same measurement.
3. What should 100 µL of water weigh?
100 µL of water should weigh 0.10 g.
4. What should 1000 µL of water weigh?
1000 µL of water should weigh 1.0 g.
Name: xxxxxxx
Date: 05/19/2020
Lab 1: Biochemistry Boot Camp
Introduction/Objectives
This experiment centered on learning the proper techniques with which to utilize pipets in
the lab setting. Through this lab an understanding of pipet types, pipet sizing, appropriate pipet
selection, and pipet usage was obtained. Additionally, calculations determining accuracy and
precision were learned for usage in checking pipet calibration.
Results for Part A were collected by pipetting 100µL of deionized water with a P-100 or
P-200 micro pipet onto a tared balance and recording the weight in grams. Results for Part B
were collected by pipetting both 1000µL and 100µL (independently) onto a tared balance and
recording the weight in grams. For each data set, data was analyzed through statistical
calculations that aided in the determination of precision and accuracy. These calculations
included average, percent error and mean deviation.
Procedure:
The procedure for this experiment was broken into two parts. The first part centered
around determining the precision of a P-100 or P-200 pipettor. To start a P-100 or P-200 pipettor
was acquired along with the appropriately sized tips. To ensure the correct size was chosen the
color of the tips were checked to see if they matched the color of the chosen pipet. The P-100 or
P-200 pipettor was then set to 100µL. Weighing paper or a weighing boat was placed onto the
balance, which was then tared to zero. 100µL of deionized (DI) water was draw up with the
micro pipet and dispensed onto the weighing paper or weighing boat. The weight of the DI water
was recorded in the lab notebook. This procedure was repeated twice more so that a total of three
recorded measurements had been taken for part one. Finally, with a clean pipet tip, 10, 20, 50,
and 75µL of DI water were drawn up independently, allowing their appearance to be observed in
the pipet tip.
The second part of this experiment focused on determining the precision of a P-1000
pipettor. First, a P-1000 pipettor and the appropriately sized tips were obtained. Again, the color
of the tips were checked to ensure they matched the color of the P-1000 pipet. Next, the P-1000
pipettor was set to 1000µL. Weighing paper or a weighing boat was placed onto the balance.
This balance was then tared to zero. Using the P-1000 pipettor, 1000µL of DI water was drawn
up and dispensed onto the weighing paper or weighing boat. The weight was recorded in the lab
notebook. This procedure was then repeated twice more so that a total of three recorded
measurements had been taken. The P-1000 pipettor was then set to 100µL. The procedure
utilized for the first part of this experiment, as described above, was then repeated three times,
however, the P-1000 micro pipet was used in place of the P-100 or P-200 micro pipet. For part
two a total of 6 measurements were recorded. Finally, with a clean pipet tip, 200, 500, and
750µL of DI water were drawn up independently, allowing their appearance to be observed in
the pipet tip. After both parts of the experiment were completed pipettors were put away.
1
Observations:
When pipetting in the lab good practice needs to be utilized to yield accurate results. For
this experiment it was important to work with cool water (1-20°C) as the density of water is
temperature dependent and working with water outside of this range could have negatively
impacted the results. Pipets needed to be pushed firmly down onto pipet tips to ensure the tip was
securely attached. When drawing up liquid, the plunger was pressed down to the first stop, the
pipet tip was then placed into the liquid, the plunger was slowly released, and the pipet tip was
drawn out of the liquid. After drawing up the liquid, the outer surface of the pipet tip was
overserved. If the tip had excess liquid on its surface this was wiped away using a kimwipe. If
there was an air bubble in the bottom of the pipet tip the measurement was discarded and redone
as air bubbles can negatively impact results. To expel liquid, the pipet tip was placed into the
receiving container, the plunger was pressed slowly down to the first stop, and then the plunger
was pushed to the second stop to ensure all liquid was blown out. The pipet was always straight
up when dispensing liquid, as it should be. If there was excess water remaining in the pipet tip
after a measurement was completed that tip was removed and replaced before taking further
measurements as this excess water could have negatively impacted results.
Results:
Note: Written results and calculations can be found on pgs. 35-36 of the lab manual under the
Analysis of Results section and on pgs. 4-6 in the lab notebook under the Results section as well
as in the results section below.
Part A: Precision of P-100 or P-200 Pipettor
Table 1-1: P-100/P-200 100µL Measurements
Measurement Number
Weight (g)
1
0.09g
2
0.09g
3
0.11g
Average Weight Calculation:
(0.09g + 0.09g + 0.11g) / 3 = 0.1g
Percent Error Calculation:
[ ( |0.1g – 0.1g | ) / 0.1g ] x 100% = 0%
Mean Deviation Calculation:
( | 0.09g – 0.1g | - | 0.09g – 0.1g | - | 0.11g – 0.1g| / 3 = 0.01 = 1x10-2
2
Part B: Precision of a P-1000 Pipettor
Table 1-2: P-1000 1000µL Measurements
Measurement Number
Weight (g)
1
0.99g
2
1.05g
3
0.97g
Average Weight Calculation:
(0.99g + 1.05g + 0.97g) / 3 = 1.0g
Percent Error Calculation:
[ ( | 1.0g – 1g | ) / 1g ] x 100% = 0%
Mean Deviation Calculation:
( | 0.99g – 1g | - | 1.05g – 1g | - | 0.97g – 1g| / 3 = 0.03 = 3x10-2
Table 1-3: P-1000 100µL Measurements
Measurement Number
Weight (G)
1
0.09g
2
0.08g
3
0.12g
Average Weight Calculation:
(0.09g + 0.08g + 0.12g) / 3 = 0.1g
Percent Error Calculation:
[ ( | 0.1g – 0.1g | ) / 0.1g ] x 100% = 0%
Mean Deviation Calculation:
( | 0.09g – 0.1g | - | 0.08g – 0.1g | - | 0.12g – 0.1g| / 3 = 0.02 = 2x10-2
3
Discussion:
Note: Discussion questions for Part C: Pipettors in the Lab are filled out on pgs. 36-37 of the lab
manual and Discussion section below. Additional Problem Set questions 6 and 7 can be found on
pgs. 7-8 of the lab notebook and in Discussion section below.
Part C: Pipettors in the Lab
1. Which of the two pipettors that you used was the more accurate? Explain.
Based on the analysis of results the P-100/P-200 and the P-1000 were equally accurate.
This conclusion comes from the percent error calculations which determined a 0% error
for each of the pipettors, meaning that both were very accurate, and one was not more
accurate than the other.
2. Which of the two pipettors that you used was the more precise? Explain
The P-100/P-200 pipettors were more precise than the P-1000 pipettor but only by an
extremely small margin. This conclusion comes from the mean deviation calculations of
measurements taken at or near the pipettors max value (i.e. 100µL for the P-100/P-200
and 1000µL for the P-1000.). The P-200/P-100 pipettors had a mean deviation of 1x10-2
which is just slightly lower than the P-1000 pipettor’s mean deviation of 3x10-2. It is
important to note that this margin may be so small that it is insignificant, meaning , if this
is the case, that neither pipettor is more precise than the other.
3. What are the take-home messages from this exercise? Give three specific things that you
learned from this lab.
a. It is very important to select the appropriately sized pipet for your desired
measurement (e.g. a P-100 or a P-200 for a 100µL measurement as opposed to a
P-1000)
b. The goal in taking any measurement is to be both accurate and precise. Mean
deviation is a measurement of precision, while percent error is a measurement of
accuracy
c. When taking measurements with a pipettor it is imperative to understand and
follow proper protocol, as even slight mistakes in your pipet measurements can
skew results dramatically.
4. Without checking the accuracy of a given Pipetman, would you predict that it is better to
use a P-200 or a P-1000 to pipet 100µL? Why?
A Pipetman’s given measurement will become more accurate the closer the desired
measurement is to the maximum measurement of the Pipetman. This means that a P-200
pipet should be used to measure 100µL as the P-200 will be closer to capacity (and so
more accurate) with a 100µL measurement than the P-1000 pipet. (Recall: a P-200
pipet’s max is 200µL while a P-1000 pipet’s max is 1000µL)
4
5. Is a Pipetman more like a serological pipet or a Mohr pipet? Why?
A Pipetman is more like a serological pipet as they are both graduated to include the
volume of the liquid all the way to the tip of the pipet. This means that they both express
the volumes all the way down to (and including) the tip. Mohr pipets are not graduated to
include the volume of the liquid all the way at the tip.
6. If you are trying to pipet an unknown liquid with a Pipetman and the liquid keeps running
out of the tip before you can transfer it, what are two possible reasons for this? What can
you do to remedy the situation?
The unknown liquid may be an organic solution which has low surface tension causing it
to run out of the tip before it can be transferred. To fix this one must prewet the tip with
the unknown liquid before drawing up the desired amount of the solution. Another
possibility is that the tip of the pipet may not be put on tightly enough, allowing the
unknown liquid to spill out. To remedy this, one can simply apply pressure to the tip to
tighten it.
7. How do you make 200mL of a 0.1M solution of a substance that has a molecular weight
of 121.1 g/mol?
To make 200mL of a 0.1M solution with the above substance you must add 2.42g of the
substance into 200mL of solvent (e.g. water) then mix until homogenized.
Calculations:
200mL x (1L/1000mL) = 0.2L
M = (mol/L)
0.1 M= (mol / 0.2L)
0.1M x 0.2L = (mol/0.2L) x 0.2L
0.02 = mol
0.02mol x (121.1g/mol) = 2.42g
8. If you take 10mL of the solution you made in Question 7, add 90mL of water, mix, and
then take 5mL of the mixture and bring it to 25mL, what will be the concentration of the
final solution in molars, milimolars, and micromolars?
Equations:
Df = (Final Volume/Initial Volume)
Cfinal = C1 / Df total
Calculations:
Df1 = (90mL + 10mL) / 10mL = 10
Df2 = (5mL + 20mL) / 5mL = 5
5
Df total = 10 x 5 = 50
Cfinal = 0.1M/50 = 2x10-3 M
Conversions:
2x10-3M x (1000 milimolars/1M) = 2 millimolar
2 millimolar x (1000 micromolar / 1 millimolar) = 2x103 micromolar
Answers:
2x10-3 molars
2 millimolar
2x10-3 micromolar
Additional Problem Set
6. Given stock solutions of glucose (1.0M), asparagine (100mM), and NaH2PO4 (50mM),
how much of each solution do you need to prepare 500mL of a reagent that contains 0.05M
glucose, 10mM asparagine, and 2mM NaH2PO4?
Glucose:
C1 = 1.0M
C2 = 0.05M
V1 = XmL
V2 = 500mL
C1V1 = C2V2
(1.0M)(V1) = (0.05M)(500mL)
[(1.0M)(V1)] / 1.0M] = (25M*mL) / 1.0M
V1 = 25mL of 1.0M glucose solution
Asparagine:
C1 = 100mM V1 = XmL
C2 = 10mM V2 = 500mL
C1V1 = C2V2
(100mM)(V1) = (10mM)(500mL)
[(100mM)(V1)] / 100mM] = (5000M*mL) / 100M
V1 = 50mL of 100mM asparagine solution
NaH2PO4:
C1 = 50mM
C2 = 2mM
V1 = XmL
V2 = 500mL
C1V1 = C2V2
(50mM)(V1) = (2mM)(500mL)
[(50mM)(V1)] / 50mM] = (1000M*mL) / 50M
V1 = 20mL of 50mM NaH2PO4 solution
6
7. Calculate the number of millimoles in 500mg of each of the following amino acids:
alanine (MW =89), leucine (MW = 131), tryptophan (MW = 204), cysteine (MW = 121), and
glutamic acid (MW = 147).
Alanine:
500mg x (1g/1000mg) x (1mol/89g) x (1000mmol/1mol) = 5.62mmol alanine
Leucine:
500mg x (1g/1000mg) x (1mol/131g) x (1000mmol/1mol) = 3.82mmol leucine
Tryptophan:
500mg x (1g/1000mg) x (1mol/204g) x (1000mmol/1mol) = 2.45mmol tryptophan
Cysteine:
500mg x (1g/1000mg) x (1mol/121g) x (1000mmol/1mol) = 4.13mmol cysteine
Glutamic Acid:
500mg x (1g/1000mg) x (1mol/147g) x (1000mmol/1mol) = 3.40 mmol glutamic acid
Summary:
This experiment centered on learning the proper techniques with which to utilize pipets in
the lab setting. Through this lab an understanding of pipet types, pipet sizing, appropriate pipet
selection, and pipet usage was obtained. These objectives were achieved by learning about pipet
types and sizing, practicing how to determine the appropriate pipet size for a given measurement
and practicing pipet use by taking various measurements with different sized pipets.
Additionally, calculations determining accuracy and precision were learned for usage in
checking pipet calibration. This objective was achieved by calculating percent error (a
calculation related to accuracy) and mean deviation (a calculation related to precision) to
determine if a pipet was properly calibrated.
The results for Part A were collected by pipetting 100µL of deionized water with a P-100
or P-200 micro pipet onto a tared balance and recording the weight in grams. Results for Part B
were collected by pipetting both 1000µL and 100µL (independently) onto a tared balance and
recording the weight in grams. For each data set, data was analyzed through statistical
calculations that aided in the determination of precision and accuracy. These calculations
included average, percent error and mean deviation.
Results and analysis indicated that both the P-100/P-200 and P-1000 pipettors were
equally accurate, as they both had a percent error of 0% across all measurements. Additionally,
results and analysis indicate that that the P-100/P-200 pipettor was more precise as the P-100/P200 had a mean deviation slightly smaller than that of the P-1000. It is important to note that this
7
difference is so small that it may be insignificant, indicating that both pipettor types are equally
precise. Results reflect expectations in that, when taking measurements close to their maximum
(e.g. 100µL for the P-100/P-200 and 1000µL for the P-1000µL), both the P-100/P-200 and P1000 are equally (or almost equally) precise and accurate. This result made sense in that when
pipettors are used properly to take measurements close to their maximum values they tend
towards being both precise and accurate. However, our results also indicated that the P-1000 was
nearly as precise and accurate as the P-100/P-200 pipettor in taking 100µL measurements. This
result did not line up with expectations as the P-1000 pipettor should be less accurate in taking a
100µL measurement. This expectation comes from the knowledge that the 100µL measurement
is far from the maximum of a P-1000 but much closer to the maximums of a P-100 or P-200 and
the understanding that a pipettor is more accurate the closer the measurement is to it’s maximum
measurement value.
8
35
Biochemistry Boot Camp - Farrell/Taylor
Removed Wooll
Carolin
Name
Section
6119120
Lab partner(s)
Date
Analysis of Results
Experiment 1: Using Pipettors
Part A: Precision
1.
of P-100 or P-200
Record
the weight you measured for the three trials of 100 uL:
Weight 1 (r,) O. fla
(8,)
Weight
(0.09. + 6.09+
09
0.119
-
Weight 3 (c3) 0-11 &
2.
Average the three weights.
Average
3.
of three
Calculate the %
trials: O:la
error between the
average of the three trials
and the
true value:
% Error
avg weight - 0.100 g
0.1 g
X 100 =
0%
4. Calculate the mean deviation for the three trials:
Mean deviation
Part B: Precision
1. Record the weight you measured for the three trials of 1000 pL:
of P-1000 Pipettor
Weight 164) Q..99 g
LOS
Weight 3 (k.) O.0
Weight (32)
2.
Average the three weights.
Average of
D.19)
0.994
three trials: 1.O
0.019
36
Biochemistry Boot Camp - Farrell/Taylor
11.0g - 1.091x 10091.=
09.8.
1.09
Calculate the % error between the average of the three trials and the
true value:
% Error
4.
lavg weight 1.00 gl
=
X 100
696
Calculate the mean deviation for the three trials:
Mean deviation
5. Record the weight you measured
the P-1000:
$ 0.03
Weight
for the three trials of
Average
(6) 2.049 (0.044
%
Weight 2 (x,) Q-08Q_
10.19 - 0.1g
100 pL using
0123) 0.19
Weight 3 (x,) Q.120.
6.
Average the three weights.
Average of three trials: O1
7.
Calculate the
% Error
% error
between the average of the three trials and
the
avg weight - 0.100 gI
8. Calculate the mean deviation for the three trials:
Mean deviation
Part C:
Pipettors
in the Lab
1.
Which of the two
2-1001P-200
=
pipettors
that you used was the more accurate?
p- 1000
wer t
2. Which of the two pipettors that you used was the more precise? Explain.
Thu P-2001p-1oo pipth ot wao mon pritiot pus onul
3. What
are the take-home messages from this exercise?
cific things that
you learned from this lab.
2)Th coGr in taking ang
P-1000 mecun
Give three spe
15 to
loo th
37
Biochemistry Boot Camp • Farrell/Taylor
4. Without checking the accuracy of a given Pipetman, would you
dict that it is better to use a P-200 or P-1000 to pipet 100 pL? Why?
pre-
200 wiu bi
pipui. Inok: p-200
mhox is 2001A, p-1000 moxis 1000 LA.
5.
Is a Pipetman more like a serological pipet or a Mohr pipet? Why?
A pipumon is mave lin & Sioutua pipc
'to
The
and
inaudug) the tip.
6. If you are trying to pipet an unknown liquid with a Pipetman and the
liquid keeps running out of the tip before you can transfer it, what are
two possible reasons for this? What can you do to remedy the situation?
Tha
To Fix this you
pipes
fightin
To
7.
How do you make 200 mL of a 0.1-M solution of a substance that has
molecular weight of 121.1g/mol? To make
WOme of
a dim
.02 mot x 121.1g: 2.420
mot
8.
If you take 10mL of the solution you made in Question 7, add 90mL of
water, mix, and then take 5 mL of the mixture and bring it to 25mL, what
will be the concentration of the final solution in
micromolars?
= 10
2x10 m x
molars, millimolars, and
38
Biochemistry Boot Camp - Farrell/Taylor
Name removed
Note: Wrong type of notebook
5119120
Date
use piptars of vanious Situs AsJuionalu
Materials:
100- 61
1. Obtain
P. 100
S. hepccd Stops
la.
3-4 two mortimo.
10, 20. 80 cn0 7S ut
this
Name
Date needed
3. Pu
2-4 twiu moreal
Chick
Name
Date Needed
COOL
Hu
bubble
Name
Date needed
(
ls
P- 200 Pipdt
cision ot P-100 m
CH
me
hi (A
r.
0.09
0.1
Avaa
t
0.0
a + 0.09
+O-Ie
yyo
X100%o
O
0
Meen Deiauion
1 .09
)+1009-0ial * 10i01) = 001
Lx10
Name
Date needed
(sus
recsin a
Uom
C r emen
mes
. 0S9
0.q
(
99
+ 1.05
rio'
1.0 - 1.09
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u ftuon
1099-10 *1ia
a) * 10.97a- 1.0a
0.03- 3x
Name
Date needed
hw
ricaun
O
o
B-2: P100
Umcn
h(
mecsurmen+ ho
0.
3
0.12
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6,09a + 0.08a +0.12) = 0.
e
o
X 100%
mecn-Deiain
10.094-0.la +10.08-0ig) *101
0K)=0.02 = 2x10
Name
Date needed
Disrussion
A Iuinau Piobum
:
to. Gweose
XmoCVCaVa
1.0m
Ca= 0.0SmV2= S00m
1.omMh(V,)
3C0mLY0.02m
iOm
1.em
2Smlof 1.0n auueosc souin
CVe Ca2
100M-V=Xml
V2 = S00mu
(2:10m
(1mmiV) = (10mm) 800mt
160m
100m
20ml et 1mm. Aesua
n
Nalz POy
Z,z 80mnV,izXmi
V2z E00mi
2 Im
8mm) )
(2mm)
C
Cn
a
200 m
S0mm
20 mt ol Smm NakP04 Souin
Name
Date needed
Disuussion *
Alaninu
Imol 10 0m d =
500mg x 19
mme
Imsia euan in
9
(autona
10se
oronan
mol
1mmoi
3ie
I mol
Imalx 100mmol
201
(yskin
432mmcl
2.45 mmol
ImolIngoiophar
mmot z 4.13 mmol
Lmot
10004121(
uami Aea
500md X 19
1000
Imal 100mm = 2.40 mmo
0
Lmat