Basic instruments /
PRACTICAL 1 BASIC INSTRUMENTS / Equipment used in
Biochemical Laboratories
EQUIPMENT USED IN and important working tips
BIOCHEMICAL
LABORATORIES AND
IMPORTANT WORKING
TIPS
Structure
1.1 Introduction
1.2 Basic Instruments/Equipment in Biochemical Laboratories
1.3 Safety in the Laboratory
1.4 Basic Calculations
1.1 INTRODUCTION
The first practical in this manual will orient you to the various equipment, apparatuses
you will need while working in the biochemistry laboratory. You must familiarize
yourself with these equipment as you would be using them quite often during your
course of laboratory work. Further, there are certain rules, regulations and safety
measures which need to be practiced while working in a laboratory. These points are
also highlighted in this practical. Some basic calculations are also given at the end of
the unit to help you with your calculations.
Objectives
After going through this practical you should be able to:
recognize the various equipment and appratuse available in a biochemistry
laboratory,
describe the working of each of these instruments/apparatuses, and
practice the general and safety measures recommended for working in
a laboratory.
1.2 BASIC INSTRUMENTS/ EQUIPMENT USED IN
BIOCHEMICAL LABORATORIES
A brief description of the equipment and apparatus used in a biochemical laboratory
is presented in this section.
1) pH meter: The pH of a solution, we know, measures the degree of acidity or
alkalinity relative to the ionization of water sample. A pH meter is a sophisticated
voltmeter capable of reading small millivolt changes from the pH electrode
system. It is an electric device that measures pH using an electrochemical cell.
The function of the pH meter is to measure the potential difference ( in mV)
between the electrodes and convert it to a pH display. Figure 1.1 illustrates
both the ordinary and the digital display pH meter for measurement of pH. You
will use them when you prepare the buffers in the laboratory.
90
Nutritional
Biochemistry
pH meter Digital pH meter
Figure 1.1: pH meters
2) Cyclomixer: This is an electrical mixer as illustrated in Figure 1.2 used for mixing
the contents of a test tube. The speed of the mixer can be adjusted to your
requirement. This is an integral part of all your calorimetric experiments and you
will be mixing the contents of your tubes with this equipment.
Figure 1.2: The cyclomixer
3) Single Pan Balance: This is a very sensitive balance used for weighing quantities
less than 10 grams. It accurately weighs quantities up to 0.1 mg. Figure 1.3
illustrates the single pan balance.
Figure 1.3: Single pan balance
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4) Electronic Digital Balance: Look at Figure 1.4. This is an ordinary electronic Basic instruments /
balance with digital display and can weigh substances from 10 mg to 100 g. Equipment used in
Biochemical Laboratories
and important working tips
Figure 1.4: Electron digital balance
5) Autodispensor: Look at Figure 1.5 which illustrates the autodispensor. This is
used to transfer accurate quantities of liquids that are difficult to pipette like
concentrated acids, alkalis, etc. You will also use this for transferring some
solution to your flask.
Figure 1.5: Autodispensor
6) Water Bath with Shaker: Figure 1.6 illustrates an electric water bath with a
shaker that can hold test tubes as well as conical flasks. When on a non-shake
mode, it acts as a simple water bath with the facility to hold the conical flasks and
test tubes in place and prevent them from spilling. When shaking and heating is
required, the shaker is switched on.
Figure 1.6: Water bath with shaker
7) Centrifuge: Centrifuge is an apparatus consisting essentially of a compartment
spun about a central axis to separate contained materials of different
specific gravities, or to separate colloidal particles suspended in a liquid. 110
Nutritional Figure 1.7 illustrates a centrifuge. This is a table top centrifuge for centrifuging liquids
Biochemistry for day to day tests. Very often it is used in the laboratories for centrifuging
blood to get serum or plasma.
Figure 1.7: Centrifuge
8) Dessicator: A dessicator is used to prevent an item from absorbing moisture. It is
able to accomplish this because of a chemical, known as the dessicant, is housed
within the container. This chemical, normally sodium sulfate, is extremely
hygroscopic and will readily absorb water from the air. Figure 1.8 illustrates a
dessicator used to keep salts that absorb atmospheric humidity. It prevents chemicals
from absorbing moisture from air.
Figure 1.8: Dessicator
9) Colorimeter: Colorimeter is an instrument for measuring the colour or colour
intensity of a solution. It is an instrument that measures the concentration of a
known constituent of a solution by comparison with colours of standard solutions
of that constituent. Figure 1.9 illustrates a colorimeter.
Figure 1.9: Calorimeter
10) Spectrophotometer: The spectrophotometer, a key instrument today in biomedical
laboratories, was invented in 1939 by the American chemist Arnold O. Beckman
(1900-2004). It is a device which measures the amount of light absorbed by a
substance. For example, vitamin A absorbs ultraviolet light so that a
spectrophotometer can measure within minutes with almost perfect accuracy the
amount of vitamin A in a given food. Figure 1.10 illustrates two types of
spectrophotometers one in which measurements can be made only in the visible
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spectrum and the other which can measure both in the visible and ultra violet spectral Basic instruments /
range. Equipment used in
Biochemical Laboratories
and important working tips
Visible range With Visible and UV range
Figure 1.10: Spectrophotometer
11) Oven: Oven is a general term used to describe a chamber or enclosed compartment
for heating, baking, or roasting food, as in a stove, or for firing, baking, hardening,
or drying objects, as in a kiln in a laboratory. Figure 1.11 illustrates the oven.
Figure 1.11: Oven
Other than the apparatuses described above many other equipment and glassware are
used for analysis and estimations in a biochemistry laboratory. These equipment include:
a) Volumetric flasks
A volumetric flask is used to make up a solution of fixed volume very accurately. It
is calibrated to contain a particular volume of water at 20°C when the bottom of
the meniscus is adjusted to the centre of the line marked on the neck of the flask.
b) Burette
A burette is a vertical cylindrical piece of laboratory glassware with a volumetric
graduation on its full length and a precision tap, or stopcock, on the bottom. It is
used to dispense known amounts of a liquid reagent in a titration experiment.
c) Pipette
Pipettes are used to deliver a known volume of liquid from one container to
another. They are precision instruments of measurement and are marked with bold,
legible markings.
Pipettes are of many types but very often we will be using two types:
i) Graduated
ii) Volumetric or transfer 130
Nutritional Graduated pipettes can measure variable volumes whereas volumetric pipettes are
Biochemistry for transferring one fixed volume.
d) Conical flask
Conical flask is a piece of chemistry laboratory equipment, a container often made
of glass, which has a narrow cylindrical mouth and a cone-shaped main body that
ends in a wide, flat bottom. It may also have a smaller straight tube-shaped opening
from the side of the cylindrical part, where tubes can be attached. Conical flasks,
you will be commonly using for titrating an analyte with the titrant which is added
from a burette. What is titration? We shall learn about this later in Practical 2.
Conical flasks come in different sizes such as a 100 ml conical flask or a 250 ml
conical flask.
e) Measuring cylinder
It is used for measuring those reagents which need not be added in very accurate
volumes. Strong acids and alkalis are added with the help of a measuring
cylinder. Never suck any strong acid or alkali in a pipette. Use a rubber bulb, a
measuring cylinder or an autopipette.
f) Beaker
It is used for storing a liquid to be used in a reaction and for dissolving a substance
in a solvent to make its solution. A beaker should never be used for a titration in the
absence of a magnetic stirrer.
Having gone through the description of different apparatuses and equipments, presented
in this section, we hope you find yourself now better equipped to work in the laboratory.
Next, we would also like to bring to your notice some important points/precautions which
should be strictly adhered to while working in any laboratory. Read these points in the
next section.
1.3 SAFETY IN THE LABORATORY
You should be aware of the rules/regulations and the procedures before undertaking any
practical work in the laboratory. Much thought has been given to the safety aspects of
the practical work and the laboratory. Nevertheless your own safety and that of your
colleagues depends on your actions. So, work carefully and if you encounter any situation
where you consider you are at risk inform the laboratory assisstant or the counsellor in
your laboratory immediately.
General protection
You are required to wear a laboratory coat at all times in the laboratory. It is sensible
to buy one of good quality and to launder it regularly and repair it when necessary.
Never wear your laboratory coat anywhere outside the laboratory area.
Safe conduct
Avoid cluttering your bench space and the corridors between benches with coats and
bags. Undertake your work without haste and do not take risks to complete a task
quickly.
Take care:
a) When handling hot ovens.
b) Using a scalpel, particularly when fitting a new blade.
c) When fitting a rubber bulb to a glass pipette or the pipette to a filler.
d) Using electrical apparatus: particularly when inserting or removing a plug and when
14 using wet conditions on the bench. Remember that water is a good electrical conductor.
e) Never pipette liquids by mouth, always use a pipette filler. Basic instruments /
f) Never use any piece of laboratory apparatus such as a beaker for drinking: remember Equipment used in
that eating (even sweets), drinking and smoking within a laboratory are Biochemical Laboratories
strictly forbidden. and important working tips
g) Never distract the attention of anyone working with chemicals or delicate glass
apparatus or with a bunsen burner.
h) Extinguish any bunsen burner when it is not in use; or if required for aseptic conditions,
set the flame so that it can be easily seen.
Look up the Do’s and Don’t’s Section presented next for some handy advice.
Do’s and Don’ts
1) Always wear a lab coat when working a laboratory.
2) Ensure that no harm is caused to yourself or the people working aroundyou.
3) Keep your working table neat and avoid clutter.
4) Clean all spills immediately.
5) Clear all reagent bottles after use.
6) While heating test tubes on a flame, hold the mouth of the test tube in a
direction that is away from yourself.
7) Do not discard acids, alkali or left over reagents in the sink. Check with the
lab staff for safe disposal of these reagents.
8) If you spill any acid or alkali on your hands or body, immediately wash the
area in running water and immediately get help.
9) Do not pipette chemicals like strong acids, alkalis or reagents with strong
odour. Use an auto pipettes or dispenser for this purpose.
10) Clean your glassware before leaving the laboratory. Check if the gas is
switched off.
Adopt the sensible habit of washing your hands carefully after each practical
session. Enjoy your practical work safely. If you should feel ill during a practical
always inform the Counsellor.
Make sure you know what to do if things go wrong
In the event of any incident, or if you observe any practice that is potentially
unsafe, inform the person in charge of the laboratory immediately. Report any
cut, minor accident, or spillage of any materials to the lab assisstant or counsellor.
Please ensure that there is a first aid box in the laboratory. Remember the locations
of the first aid box.
1.4 BASIC CALCULATIONS
Some basic mathematical formulas and conversion factors are given herewith to help
you in your calculations during the practical work.
A molar solution contains the relative molecular mass (mole) of a substance (in
grams) in 1 litre of solution. For example, a molar solution of sodium chloride contains
58.5 g NaCl in 1 litre, because the molecular mass (one mole) of NaCl is 58.5 (Na
atomic mass 23 + Cl atomic mass 35.5).
1 millilitre (ml) is one thousandth (10-3) of a litre
1 microlitre (µl) is one millionth (10-6) of a litre
1 milligram (mg) is one thousandth (10-3) of a gram
1 microgram (µg) is one millionth (10-6) of a gram
The term “parts per million” (ppm) is no longer used; it is equivalent to µg/ml
With this we end our study of this practical. 150
