Research laboratory

Measuring instruments

Instruments for measuring volume

MicropipetteZoomZoom
© Catherine Vamos

Micropipette

The micropipette is useful for very precise sampling of volumes from 0.5 to 5000 microliters. Its functioning is based on the action of a piston that can draw up or push volumes of air corresponding to the volume of liquid to be recovered. The volume to be drawn is adjusted with a thumb wheel. A whole range of pipettes exists, varying in volume and in precision.

  • P5000: pipets up to 5 ml of solution
  • P1000: pipets from 200 to 1000 µl of solution
  • P200: pipets from 20 to 200 µl
  • P20: pipets from 10 to 20 µl
  • P10: pipets from 0.5 to 10 µl
  • P2: pipets from 0.2 to 2 µl

To sample different solutions without changing the micropipette, a disposable tip, adapted to the micropipette according to the chosen volume, can be used. These tips must be as thin as possible, especially for small volumes, to ensure optimal precision.

Automatic pipetterZoomZoom
© Catherine Vamos

Automatic pipetter

The automatic pipetter is an electrical system that can draw up or release volumes from 1 to 100 milliliters in graduated glass (reusable) or plastic (disposable) pipettes. A rechargeable battery powers the bi-directional pump that can be controlled by two buttons, one to draw up the solution and the other one to release it from the pipette. It is therefore no longer necessary to draw up solutions by mouth; this is now prohibited in all laboratories for security reasons.

Instruments for measuring weights

Analytical balanceZoomZoom
© Nicole Catellier, Cinémanima

Analytical balance

The analytical balance is a precision instrument for measuring mass. Using this instrument, powders and solutions can be measured with remarkable precision reaching one ten-thousandth of a gram (0.0001 g). This instrument must always be installed on a flat, stable surface.

Two-pan balanceZoomZoom
© Catherine Vamos

Two-pan balance

The two-pan balance is an instrument for measuring mass. It is very often used to equilibrate two solutions before centrifugation. Thus, the volumes may be different but the weights will be identical. This instrument must be installed on a flat, stable surface.

Instruments for measuring concentration

Geiger-Müller counterZoomZoom
© Nicole Catellier, Cinémanima

Geiger-Müller counter

The Geiger-Müller counter is used to measure certain types of ionizing radiation (alpha, beta, or gamma particles, and X-rays) emitted by radioactive particles. The counter is made up of an aluminum cylinder filled with a rare gas at low pressure (10/76th of atmospheric pressure). When a charged (or radioactive) particle crosses the detector, it ionizes the gas contained in the cylinder. The ionization electrons are accelerated towards the central anode and undergo an important multiplication. The electrical impulse collected at the exit signals the passage of a particle in the counter. In the laboratory, the Geiger-Müller counter is used to detect radioactive contaminants that may have been left on the workbench.

Instruments for measuring time

TimerZoomZoom
© Catherine Vamos

Timer

A timer is indispensable to control time. It is often used to count down the time in reverse: the desired countdown (hours, minutes, seconds) can be programmed. At the end of each countdown, a characteristic ring sounds for 1 minute. Some timers can have several programming channels so that the time for several experiments can be controlled simultaneously. These timers come with a stand, a pocket clip and a magnet. They are easy to handle and can be taken anywhere without encumbering the researcher.

Instruments to measure the pH

PH meterZoomZoom
© Catherine Vamos

PH meter

The pH meter is an electrical instrument used to measure the pH (acidity-basicity) of an aqueous solution. It consists of an electronic case that displays the numerical value of the pH and two electrodes: a standard electrode with a constant, known pH (reference electrode) and another variable potential electrode (glass electrode) that can measure the pH. Its functioning is based on the ratio between the concentration of H3O+ ions and the difference in electrochemical potential that is established in the pH meter when it is immersed in the study solution. Before carrying out measurements, the pH meter must be calibrated with standardized solutions.