Centrifuges, Balances, pH Meters, Spectrophotometers, Temperature-Controlled Equipment, Water & Reagents, and Maintenance

What is the purpose of preventive maintenance in laboratory equipment?

To ensure equipment is functioning properly at scheduled intervals, maximizing operational efficiency and reducing costs.

What should be logged when equipment malfunctions?

Information like error codes, frequency of malfunctions, hotline calls, reference numbers, and corrective actions taken.

What is centrifugation?

A process used to separate or concentrate materials suspended in a liquid medium based on particle size and density.

What is sedimentation in centrifugation?

The process where particles/cells in liquid suspension eventually settle at the bottom due to gravity.

What components do centrifuges typically consist of?

A head or rotor, carriers, a shield, a vertical shaft motor, and are enclosed within a metal covering.

What is the purpose of a centrifuge's braking system?

To quickly stop the centrifuge from spinning for safety and to prevent sample dispersion.

What type of samples can be separated using centrifugation?

Solids from suspensions, such as urinalysis sediment and serum/plasma from blood cells.

What determines the speed of centrifugation?

The centrifugal force, which is dependent on mass, radius, and speed.

What is the meaning of Relative Centrifugal Force (RCF)?

The comparison of centrifugal force relative to the speed and radius of the center of rotation.

What are the two common categories of rotors in centrifuges?

Swinging-bucket rotors and fixed-angle rotors.

What is an advantage of a swinging-bucket rotor?

Allows better separation due to longer distance of travel and easier withdrawal of supernatant.

How does an angle head type rotor differ from a swinging-bucket rotor?

Holds cups at a fixed angle, allowing for more rapid centrifugation and less disturbance of sediment.

What is the purpose of properly balancing a centrifuge?

To prevent excessive vibrations that can damage the centrifuge and ensure accurate results.

What is essential when using centrifuge tubes?

They must be capped to prevent aerosols and sample evaporation.

What are the general maintenance tasks for centrifuges, daily?

Inspect interior and exterior for spills and contamination.

What is the purpose of using a pH meter?

To detect the amount of hydrogen ions (H+) in a solution and record it on a pH scale.

What components make up a pH meter?

A glass electrode (probe), indicating electrode, and reference electrode.

What is the main function of the indicating electrode in a pH meter?

To measure the difference in electrical potential between itself and the reference electrode.

What is a spectrophotometer used for?

To measure the light transmitted by a solution to determine the concentration of light-absorbing substances.

What does Beer’s Law state?

The concentration of a substance is directly proportional to the amount of light absorbed or inversely proportional to the logarithm of transmitted light.

What are the main parts of a spectrophotometer?

Light source, entrance slit, monochromator, sample compartment, detector, and digital display.

What is the purpose of the detector in a spectrophotometer?

To detect the light transmitted through the specimen and convert it into an electrical signal.

What is the range of temperature a refrigerator typically operates at in a laboratory?

Usually set at 4°C +/- 2°C.

What is a critical care requirement for water baths in a lab?

Temperature must be monitored regularly due to evaporation.

What should be done if a fridge or freezer's temperature is out of range?

Initiate corrective action logs and move reagents or samples to an alternative storage.

What is the most pure form of laboratory water?

Type I reagent water, produced through distillation followed by deionization.

How is type II reagent water different from type I?

Used for general laboratory testing that does not require type I water, with a higher maximum colony count.

What contaminants might affect the purity of laboratory water?

Microbial, organic, inorganic, and particulate contamination.

What is a critical quality control requirement for laboratory water?

Regular testing, including microbial monitoring and measuring pH.

What are the maintenance steps for temperature-controlled equipment in laboratories?

Daily temperature recording, weekly chart replacements, and as-needed cleaning.

What potential laboratory error can occur if proper weighing procedures are not followed?

Mechanical errors due to defects, human errors, and contamination causing inaccurate measurements.

What types of balances are commonly used in laboratories?

Analytical and top-loading balances.

What is a benefit of using electronic balances over mechanical balances?

More precise, easier to use, and have fewer moving parts.

What is the main purpose of a tare on a balance?

To disregard the weight of the weighing container, allowing accurate measurement of the sample.

How can you maximize the accuracy of weight measurements with a balance?

Ensure it is level, free from vibrations, and clean before use.

What must be done with a pH meter's electrode when not in use?

Always store it in distilled water or pH 7 standard buffer.

What is the advantage of using hot plates in lab settings?

Used for heating liquids and have replaced Bunsen burners for increased safety.

What safety feature is critical for incinerators in the laboratory?

The loop should be inserted fully without glowing to ensure maximum destruction of microorganisms.