Practical Laboratory Instruments PDF

Practical Laboratory Instruments First Class Lab -4 Assist. Lec. Omar A. Mahmoud Assist. Lec. Hayder Ahmed Laboratory Balances Lab Balances are essential laboratory instruments that are widely used for weighing of various sub...

Practical Laboratory Instruments First Class Lab -4 Assist. Lec. Omar A. Mahmoud Assist. Lec. Hayder Ahmed Laboratory Balances Lab Balances are essential laboratory instruments that are widely used for weighing of various substances (powders, crystals and others) to prepare reagents, stains and culture media. Lab balances are required to weigh substances accurately and exactly within the needed range. They should be kept clean and in an area away from heavy things and open windows. Types of Balances in medical laboratory: 1. Rough balances (mechanical balances): They are several types, some of them use sliding scale some have a single pan or double pans. They are used for weighing substances do not need for accuracy. They do not require electricity or battery power. They are less expensive than analytical balances. They are used to:  Weigh large amounts of substance up to several kilo grams (Kg).  Not examined a high degree of accuracy. 2. Analytical balances (electronic balances): Analytical and electronic balances are the most popular balances used in medical laboratories to provide accuracy. They use an electron magnetic force. They require electricity or battery power. They are used to:  Weight small amounts of substance usually in mili gram (mg).  Examined a high degree of accuracy. 1 Practical Laboratory Instruments First Class Lab -4 Assist. Lec. Omar A. Mahmoud Assist. Lec. Hayder Ahmed Figure (1): Mechanical balances Figure (2): Analytical balances 2 Practical Laboratory Instruments First Class Lab -4 Assist. Lec. Omar A. Mahmoud Assist. Lec. Hayder Ahmed Uses and care of the balances 1. Read carefully the manufacturer’s information. 2. Always handle a balance with care. 3. Put the balance on a firm bench away from vibration, water, dust, moisture and direct sunlight. 4. Before starting to weigh, zero the balance. 5. Weigh the chemical substances in a weighing scoop or small beaker. Never put the chemicals directly on the balance pan. 6. Use small brush to remove any chemical may have been spilt on the balance. 7. A container of silica gel should be kept inside the analytical balance to remove any moisture present. Refrigerators Refrigerators are physical instrument used to preserving various laboratory samples (prevent the sample from growth of bacterial, fungal and molds). Also used in the medical laboratory to preserve some reagents, drugs and kits such as:  Pregnancy tests kits.  Rapid plasma reagent (RPR) test kits.  Blood grouping test kits (O – A – B – AB) & (Rh + –).  Liver test kits (like: hepatitis types).  Culture media (like: blood - macConkey - chocolate agar). 3 Practical Laboratory Instruments First Class Lab -4 Assist. Lec. Omar A. Mahmoud Assist. Lec. Hayder Ahmed Refrigerators are commonly set at a temperature of (2 to 8 °C). There are also found of deep freeze refrigerators with different temperature (0 °C to -273 °C) mostly used for research purposes. Note: When whole blood is preserved in refrigerators the temperature should be at (2 to 8 °C) to avoid damage of red blood cells. Figure (3): Refrigerators Deep freezers: are the testing equipment that are used to preserve and store food products, medical equipment, blood samples, medicines and injections, etc. for a long period of time. 4 Practical Laboratory Instruments First Class Lab -4 Assist. Lec. Omar A. Mahmoud Assist. Lec. Hayder Ahmed Figure (4): Types of deep Freezers 5