In this article we will discuss about:- 1. Description of Glassware 2. Uses of Glassware 3. Care and Handling 4. Cleaning.
Description of Glassware:
Instruments and equipment are the most essential component of a medical laboratory.
It is quite important to get to know all the new instruments and equipment some of the equipment are given below:
Laboratory Glassware and Plastic Ware:
Earlier only glassware was used in laboratory but with recent advances several plastic wares made up of plastic are used now. Plastic wares are safer and cheaper than glassware’s but glassware has advantages like re-reusable. Now due to danger to infection of several fatal diseases like AIDS, Hepatitis Disposable plastic wares are preferable.
Selection of Glassware:
1. Heat Resistant
2. Free from soluble metal
Uses of Glassware:
1. Test Tubes:
They are used to heat and hold reagents for observing chemical reaction.
Type of Test-Tubes:
(a) Test tube- these are of uniform thickness & withstand mechanical & thermal shocks. Tubes with rim are preferred when reagent in a tube is directly heated on the flame with test-tube holder.
The commonly used test tubes are of following specification:
Outer Diameter x Length (mm):
(a) 10 × 75:
These are used for testing procedures as well as for centrifugation.
(b) 15 × 125:
These are used for most of the biochemistry tests.
(c) 18 × 150:
These are used for heating the reaction mixture directly on flame.
Centrifuge Tubes:
These are either graduated or plain & are available in the conical shape. The commonly used tubes are of the size 17 × 120 mm.
Folin-Wus̀ Tubes:
These tubes are mainly used for the determination of blood sugar by Folin-Wus̀ method. These are engraved at 12.5 & 25 ml.
Digestion Tubes:
These are calibrated at 35 & 50 ml and mainly used for the conversion of organic matter into inorganic matter by heating it in the presence of digestion mixture (50% sulfuric acid & selenium – dioxide).
2. Test Tubes Racks:
It is used to hold the test tube in the upright position. These are made of metal or plastics.
3. Test Tube Holder:
It is used during heating of the test tube.
4. Funnel:
It is used during filtration.
Volumetric Glassware:
It includes cylinders, pipettes, burette and volumetric flasks; it is used in measuring accurate volume of a liquid.
a. Dropping Bottle:
They permit the fluid to flow in a drop wise fashion.
Non-Volumetric Glassware:
1. Beaker:
It is used for heating liquid and for preparing reagent solution.
2. Petri Dishes:
It is used for the aerobic culture of microbes.
3. Stirring Rod:
It is used for dissolving the solute in preparing solution.
Care and Handling of Glassware:
Care of Glassware:
While working in a laboratory the technician must get acquainted with various types of glassware’s handled in the laboratory and use them appropriately.
Improper Use of Glassware may Lead to Breakage:
There are basically two types of glassware:
1. Borosilicate glassware
2. Soda-lime glassware
Borosilicate is heat and chemical resistant. It can also stand mechanical stress and will not break due to sudden change of temperature. While soda-lime glass, which is les resistant to mechanical shock and thermal shock. It is cheaper than borosilicate. It is easy to bend by heat.
Handling of Glassware:
Laboratory glassware is expensive proper care and handling reduces the risk of personal injury.
Some common type of care and handling are:
i. Never leave the glass wares in the absence of attendant when it is heated, it will crack and explode.
ii. Avoid scratching of glass in its daily use.
iii. Use heat resistant glass while preparing solution of acids and alkaline.
Cleaning of General Laboratory Glassware:
Cleaning of Glass Wares:
New:
1. Soak in 2% HCl for overnight to neutralize any alkali present.
2. Wash in running tap water.
3. Boil in any synthetic detergent for 30 minutes. Rinse well with tap water and finally in distilled water.
Used Glassware’s:
Boil in a detergent for 30 minute, clean thoroughly with brush rinse in tap water. Dry them in the hot air oven with the temperature not exceeding 80°C.
Potassium Dichromate:
(kMnO4) cleaning solution composition.
kMnO4 – 25gm
Water – 25ml
Conc. H2SO4 – 50ml
Preparation:
Dissolve 25gm. Potassium dichromate in 25ml of water. Add 50ml of conc. Sulphuric acid (slowly, always add acid to water) and cool store in a stopper bottle. Dissolve when it starts turning green.
Test Tubes:
1. Autoclave to remove infected material.
2. Boil in a detergent solution for 30 minute. Clean with brush.
3. Rinse in running water and finally with distilled water and place them in test tube rack upside down and dry them in an oven.
4. Cotton plugs them and sterilizes them in the hot air oven.
Pipettes:
1. Soak in cleaning solution for overnight
2. Wash in running tap water.
3. Rinse in distilled water.
4. Dry on suction pump using spirit or acetone.
5. To sterilize plug mouth piece with cotton wool, wrap in craft paper and sterilize in hot air oven for 1hr at 160°C.
Petri-Dishes:
1. Autoclave to remove infected material.
2. Wash in soapy water.
3. Rinse in running water, let dry.
Pasteur Pipette:
1. Soak in 3% Lysol for 1 hour.
2. Wash it same as test tubes.
Glass Slides:
New:
1. Boil in a detergent for 30 min.
2. Place in Dichromate solution for overnight.
3. Wash in running water.
4. Keep methylated spirit.
For using, take them out with a forceps and hold them only by the edge
Used Slides:
Wash it same as used glassware.
Infected:
Infected slides should be autoclave and clean as earlier as new reuse slides used for examination of acid fast bacilli or gram stain.
Infected Glassware:
Contaminated material may be disposed in paper or cardboard wrappers and incinerated. Autoclave the glassware that has been contaminated. After autoclave, wash and use the usual way.
Complete bacterial sterility can be achieved either by sterilizing them in the hot air oven or in an autoclave. Keep injection syringes separate from blood withdrawing syringes. Fresh syringes (sterilized) should be used for withdrawing blood for each patient. Before reusing them properly sterilize them. Needles used should be sharp and not with blunted ends.
According to WHO, for collection of blood sample use and throw syringes should be used. All glass syringes are preferred over glass and metal ones. Preferably keep size 5ml or more syringes for withdrawing blood.
Needles should be of size less than 21 (SWG). A needle with a smaller diameter would cause lysis of blood when used for blood withdrawing. Withdrawing needles should be at least an inch long.
New Syringes:
These are washed in the usual way dried with acetone. Wrap the plunger and the barrel in a paper and sterilize in hot air oven.
Used Syringes:
Immediately after use, wash them thoroughly with cold water (hot water will coagulate proteins and will make the syringes difficult to clean). Clean then thoroughly in a detergent, brush the barrel properly, rinse in tap water and then in distilled water. Rinse in acetone and let dry. Sterilize in hot air oven as mentioned above.