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TitleUse of Micropippettor and Spectrophotometer
TagsLaboratories Scientific Techniques Absorbance Spectrophotometry Coefficient Of Variation
File Size117.9 KB
Total Pages6
Document Text Contents
Page 2

INTRODUCTION

The study of Cell and Molecular Biology involves a vast number of methods and

techniques as it studies the structural unit of the living system. Laboratory instruments are

devised to achieve accuracy and precision as it deals with up to microscopic level.

The micropipettor is one of the most commonly used instruments in science laboratories.

The micropipette is a Wisconsin invention developed through interactions among several people,

primarily inventor Warren Gilson and Henry Lardy, a professor of biochemistry at the University

of Wisconsin-Madison. Pipettes are used to accurately measure and dispense relatively small

volumes of liquid. A small volume micropipettor has a range of 0.5–10 mL, a mid range

micropipettor can handle 10-100 mL of liquid and a large volume micropipettor can measure up

to 100-1,000 mL. It is a precision instrument and should be handled with utmost care.

A Spectrophotometer is an instrument used to measure the intensity of wavelengths in a

spectrum of light compared with the intensity of light from a standard source. It has varied

applications in the qualitative analysis of sample purity, DNA and protein quantitation, cell

density measurements, and assays involving enzyme – catalyzed reactions. The most common

spectrophotometers are used in the UV(200 – 400nm) and visible regions of the spectrum(400 –

700nm), and some of these instruments also operate into the near-infrared region(700 – 900nm)

as well. The VIS and UV spetrophotometric techniques are used mainly on qualitative

determination of components present at low concentration. The IR measuring technique is

mainly used for qualitation. The spectrophotometer compares the intensity of the trensmitted

light with that of the incident light.

The objective of this experiment is to familiarize the students with the use of the

micropipettor and the spectrophotometer and to some of their applications in scientific research.

http://en.wikipedia.org/wiki/Infrared
http://en.wikipedia.org/wiki/Visible_spectrum
http://en.wikipedia.org/wiki/UV
http://en.wikipedia.org/wiki/Laboratories

Page 4

T he Standard Curve of A540 Versus the

Concentration of Bromphenol Blue

0.5, 0 .094

1, 0.274

2, 0.688

4, 1.073

8, 1.866

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 2 4 6 8 10

concentration (uL)

ab
so

rb
an

ce
(n

m
)

RESULTS AND DISCUSSION

There are two laboratory instruments commonly used in Cell and Molecular Biology

namely the micropipettor and spectrophotometer. In this experiment, the following results were

obtained:

Bromphenol Blue (μL) Absorbance (540nm)
0.5 0.094nm
1.0 0.274nm
2.0 0.688nm
4.0 1.073nm
8.0 1.866nm

Standard Deviation
SD = [N ∑X 2 – (∑X) 2 ]

N(N – 1)
= 0.70694

Mean: 0.799

Coefficient of Variation
CV = SD
Ave.
= 0.8845595596

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