Pipetting Techniques and Calibration
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Questions and Answers

What is the primary reason for avoiding organic solvents when cleaning a pipette?

  • They are more effective than water for cleaning.
  • They may leave residues that enhance sample accuracy.
  • They can improve the performance of the pipette.
  • They can cause damage or corrosion to the pipette. (correct)

    • Why is it recommended to store pipettes vertically when not in use?

  • To avoid dust accumulation on the tips.
  • To prevent clogging of internal mechanisms.
  • To maintain their calibration and functionality. (correct)
  • To minimize the risk of breakage or damage.

    • What is a suitable practice to minimize cross-contamination in a laboratory setting?

  • Regularly cleaning pipettes with water only.
  • Using the same pipettes for all lab procedures.
  • Calibrating pipettes less frequently.
  • Having separate sets of pipettes for different applications. (correct)

    • What might cause unexpected results when using pipettes, even with proper technique?

    <p>The properties of the compounds in the solutions.</p> Signup and view all the answers

    What is a benefit of using low retention pipette tips?

    <p>They repel the sample being pipetted.</p> Signup and view all the answers

    What is the main purpose of pipettes in laboratory settings?

    <p>To dispense accurate and precise volumes of solutions</p> Signup and view all the answers

    What should be included in the central storage of pipette information?

    <p>Serial number and make of the pipette</p> Signup and view all the answers

    How often should pipettes be calibrated?

    <p>Regularly, in accordance with guidelines</p> Signup and view all the answers

    Which balance is required for calibrating pipettes dispensing volumes below 10 µL?

    <p>A 5 place balance</p> Signup and view all the answers

    What is the acceptable accuracy percentage for a pipette during calibration?

    <p>Within 3% of expected weight</p> Signup and view all the answers

    Which type of pipette is particularly useful for high-throughput assays?

    <p>Multi-channel pipettes</p> Signup and view all the answers

    Why might a regulatory authority wish to view pipette information?

    <p>To check the maintenance history and calibration details</p> Signup and view all the answers

    What is the primary benefit of using unique identifiers for pipettes?

    <p>Helps in tracking maintenance and calibration</p> Signup and view all the answers

    What should be done if droplets of liquid are found on the side of the pipette tip?

    <p>Touch the tip against the side of the receiving vessel.</p> Signup and view all the answers

    Which type of pipette is ideal for aspirating and dispensing biological samples like DNA and plasma?

    <p>Air displacement pipette with a filter.</p> Signup and view all the answers

    For which sample type should a positive displacement pipette be used?

    <p>Glycerol.</p> Signup and view all the answers

    What is the best technique for dispensing a liquid from a pipette?

    <p>Dispense against the side of the receiving vessel at a slight tilt.</p> Signup and view all the answers

    How should pipettes be cleaned if they get any sample on them?

    <p>With a soft cloth and water.</p> Signup and view all the answers

    What ensures consistent and reproducible results when pipetting?

    <p>Aspiring and dispensing at a slow and consistent speed.</p> Signup and view all the answers

    What is the ideal volume range for using a variable volume pipette to minimize inaccuracy?

    <p>50-100% of the pipette's max capacity</p> Signup and view all the answers

    Which type of pipette is recommended for handling volatile organic solvents?

    <p>Positive displacement pipette.</p> Signup and view all the answers

    What cleaning solution can be used for pipettes before use in a sterile environment?

    <p>Ethanol or IMS.</p> Signup and view all the answers

    What should you do if a pipette continues to fail calibration after initial checks?

    <p>Get a second person to perform the calibration</p> Signup and view all the answers

    Which scenario indicates the necessity of using pipette tips with built-in filters?

    <p>When the sample must remain sterile</p> Signup and view all the answers

    Why is it essential to use a pipette tip compatible with your pipette's make and model?

    <p>To prevent leakage during pipetting</p> Signup and view all the answers

    What is the consequence of using a pipette at its lowest volume limit?

    <p>Increased risk of inaccuracy</p> Signup and view all the answers

    What is the recommended action when a pipette tip is found to be damaged or leaking?

    <p>Replace it immediately</p> Signup and view all the answers

    What should be done if a pipette fails calibration despite cleaning and maintenance?

    <p>Send it to the manufacturer for repair</p> Signup and view all the answers

    What is one advantage of using racked pipette tips over loose tips?

    <p>Racked tips reduce contamination risk</p> Signup and view all the answers

    When is it acceptable to reuse the same pipette tip?

    <p>When preparing a calibration line and moving up in concentration</p> Signup and view all the answers

    What should you do before immersing the pipette tip in the liquid?

    <p>Prime or pre-wet the tip with the solution you wish to transfer</p> Signup and view all the answers

    What is a key characteristic of positive displacement pipettes?

    <p>They maintain constant aspiration force regardless of sample properties</p> Signup and view all the answers

    How should the pipette tip be positioned in the liquid during aspiration?

    <p>Below the meniscus but away from the sides</p> Signup and view all the answers

    What is the purpose of depressing the plunger to the first stop position during liquid dispensing?

    <p>To ensure complete liquid transfer</p> Signup and view all the answers

    Why should you always change pipette tips when working with samples of unknown concentrations?

    <p>To prevent contamination between samples</p> Signup and view all the answers

    What technique should be avoided when pipetting to ensure accuracy?

    <p>Depressing the plunger quickly</p> Signup and view all the answers

    What is the main advantage of using an air displacement pipette?

    <p>It can dispense variable volumes with high precision</p> Signup and view all the answers

    Study Notes

    Pipetting Techniques

    • Pipettes are essential lab tools for dispensing liquids.
    • They are used to dispense precise volumes of solutions, critical for experiments.
    • Many types exist, ranging from 0.1µL to 100mL+, including repeater and multi-channel pipettes.
    • Accurate pipetting is crucial for high-throughput assays.

    Identifying Pipettes

    • Pipettes used in GLP/GCP need unique identifiers (e.g., area/assay number).
    • All pipette info (make, model, serial number, identifiers) should be centrally documented.
    • This includes service history, faults, and repairs.
    • Regulatory authorities may request this data during inspections.

    Calibrating Pipettes

    • Regular calibration is necessary, adhering to manufacturer guidelines.
    • Use lowest and highest volumes for calibration.
    • Water or radioactive solutions can be used for calibration.
    • Accuracy should be within 3% of expected values.
    • Precision should be within 2.5% of expected values.

    Choosing the Right Pipette

    • Select a pipette optimal for the specific volume.
    • Aim to use a pipette where the target volume is 50-100% of its maximum capacity.
    • Use of the optimal range of the pipette will minimize errors.

    Pipette Tips

    • Use compatible pipette tips for the pipette model.
    • Racked tips available in sterile and non-sterile, and some RNAse-free options.
    • Tips should be compatible with the pipette device.
    • Pipette tips with filters are helpful for sterile samples or sensitive applications.

    Air Displacement Pipettes

    • The plunger is depressed to both draw up and dispense a liquid.
    • First stop while held in air, to draw liquid.
    • First and second stops (blow-out) positions expel liquid.
    • Air displaced corresponds to the volume of liquid drawn up.

    Positive Displacement Pipettes

    • These work like syringes, without an air cushion.
    • Aspirating force is constant, regardless of the sample viscosity.
    • Suitable for viscous or high-density samples (e.g., glycerol, blood).

    Pipetting Technique

    • Prime or pre-wet the pipette tip with the sample to avoid contamination.
    • Submerge the tip completely in the solution, without pulling air into the pipette.
    • Aspirate by depressing plunger until a pre-determined volume is attained.
    • The pipette should be held vertically during aspiration, to ensure no air enters the tip.

    Pipette Selection by Sample Type

    • Air displacement pipettes are suitable for aqueous solutions.
    • Positive displacement pipettes are best for viscous or hazardous samples (e.g., radioactive materials).
    • Ensure that sample type is considered before selecting the pipette.

    Pipette Care

    • Clean spills with a soft cloth and water, or appropriate cleaning agent.
    • Do not use organic solvents for internal parts.
    • Store pipettes vertically when not in use.
    • Calibrate pipettes after disassembling or dropping incidents..

    Unexpected Results

    • Solutions' properties could affect pipette performance.
    • Materials like different plastics (e.g., low bind), glass, or salinized glass, can be used in vessels.
    • Replace or prime/wet pipette tips to eliminate stickiness.
    • Low-retention tips can reduce sample adhesion.

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    Description

    This quiz covers essential pipetting techniques, including the identification, calibration, and selection of various types of pipettes. Understanding these principles is crucial for conducting experiments accurately and efficiently in laboratory settings. Assess your knowledge on maintaining high precision in liquid dispensing and compliance with regulatory requirements.

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