Laboratory Glassware

Laboratory Glassware

• General glassware:
  • Not calibrated to hold or measure exact volumes
  • Not recommended for critical measurements
  • Can be made of glass or plastic
• Types of general glassware:
  • Centrifuge tubes: designed to withstand centrifugation, have calibration marks, and a pointed bottom
  • Beakers: wide mouth, straight sides, and a pouring spout; used to estimate liquid amounts and mix and heat
  • Erlenmeyer flasks: used for holding and mixing liquids, have measurement marks, and a flat bottom with sloping sides
  • Cylinders: marked with calibrated volumes, but not for precise measurements
  • Bottles: hold various reagents, made of polypropylene or clear plastic, some may be brown to protect from light
• Volumetric glassware:
  • Made with a rigorous calibration process for accurate measurements
  • More expensive than general glassware
  • Used for critical measurements, with temperature calibration (usually 20°C) and TD/TC labels

Pipettes

• Types of pipettes:
  • Volumetric pipettes: used for accurate measurements
  • Graduated pipettes: not accurate enough for critical measurements
  • Automatic pipettes: designed to pick up and dispense preset volumes
• Proper pipetting technique:
  1. Select the correct size pipette
  2. Place the tip below the surface of the liquid
  3. Attach a pipette aid and draw the liquid up past the calibration mark
  4. Adjust the meniscus to the calibration mark
  5. Deliver the liquid by holding the pipette vertically
• Precautions:
  • Use a biological safety cabinet or fume hood when handling biohazardous materials
  • Use plastic pipettes when possible
  • Clean and disinfect pipettes after use

Centrifuges

• Types of centrifuges:
  • Fixed head centrifuges: blood separates in a slanted form
  • Horizontal head centrifuges: blood separates straight across
• RCF (relative centrifugal force) and g-forces:
  • 1000g for 10 minutes for blood centrifugation
  • 1000-1300g for gel-containing tubes
• Cytocentrifuge: used to concentrate cells in fluid specimens onto a microscope slide

Balances

• Analytical balance:
  • Very sensitive and accurate (0.0001g)
  • Used for chemical analysis
• Other types of balances:
  • Triple beam balance
  • Top-loading balance
• How to operate an electronic balance:
  1. Place the balance on a flat surface
  2. Press the "ON" button and wait for zeroes
  3. Place an empty container on the balance
  4. Press the "Tare" or "Zero" button
  5. Carefully add the substance to the container

Incubators and Water Baths

• Incubators:
  • Used to keep specimens at body temperatures (e.g., 37°C)
  • Examples: CO2 incubators, blood culture incubators
• Water baths:
  • Steel container filled with water and antibacterial agent
  • Used to maintain specimens at 37°C
  • Precautions: check equipment, add disinfectant, and avoid sodium azide

Electronic Cell Counters

• Analyze whole blood:
  • Count RBC, WBC, and platelets
  • Measure hemoglobin content and hematocrit
  • Perform automated differential count

Refrigerators and Freezers

• Laboratory refrigerators:
  • Maintain internal temperature between 2°C and 8°C
  • Used to store temperature-sensitive products
• Laboratory freezers:
  • Maintain internal temperature between -15°C and -25°C
  • Used to store blood, chemicals, and medical samples
• Ultra-low freezers:
  • Maintain internal temperature between -40°C and -86°C
  • Used for molecular testing specimens

Microscopes

• Compound microscope:
  • Used for many tasks (e.g., evaluating stained blood smears, examining urine sediment)
  • Has low power, high power, and oil immersion lenses
• Adjustment knobs:
  • Coarse adjustment for low power lens
  • Fine adjustment for high power and oil immersion lenses
• Care of the microscope:
  • Clean the microscope regularly
  • Avoid jarring the microscope
  • Use the coarse adjustment only with the low power lens

Automation and Safety

• Laboratory automation:

  • Coagulation instruments
  • Microbiology instruments
  • Blood type determination
  • Slide stainers

• Safety precautions:

  • Handle equipment with care
  • Avoid physical strain when working with equipment
  • Take regular breaks
  • Rotate tasks to avoid repetitive strain injuries### Autoclave and Sterilization

• Use thermal gloves and eye protection when removing containers from an autoclave.

• There are different types of autoclaves, including:

  • Dry heat autoclaves, which heat up to 150-160°C for 1 hour.
  • Moist heat autoclaves, which use boiling water for sterilization.
  • Ethylene Oxide autoclaves, which are used for devices and plastic containers that cannot withstand high-temperature steam sterilization.

pH Measurement

• A pH meter is an instrument used to measure the acidity or alkalinity of a solution.
• pH is measured on a scale of 0 to 14.
• A pH value less than 7 indicates acidity, while a value greater than 7 indicates alkalinity. A pH of 7 is neutral.
• The pH value expresses the degree of activity of an acid or base in terms of hydrogen ion concentration.
• pH = -log10 c, where c is the hydrogen ion concentration in moles per liter.

Laboratory Equipment and Materials

• A funnel is an object with a wide round opening at the top, sloping sides, and a narrow tube at the bottom, used for pouring liquids or powders into containers.
• Distilled water is water that has been processed to remove impurities.
• Deionized water is distilled water that has been further treated through cooling, condensation, and membrane filtration.
• Tap water is rarely used in laboratories due to the presence of organic and inorganic contaminants that may interfere with testing.

Normal Saline

• Normal saline is a mixture of salt and water with a salt concentration similar to that found in tears, blood, and other body fluids (0.9% saline).
• It is also known as an isotonic solution.