The Volumetric Pipet and Pipetting Technique
TLDRThis video tutorial delves into the use of volumetric pipettes, precision instruments crafted from glass or plastic, designed for the accurate measurement of liquid volumes ranging from 1 to 100 milliliters. It explains the difference between 'to deliver' (TD) and 'to contain' (TC) calibrations, emphasizing the importance of cleanliness, the technique for rinsing the pipette with the liquid to be measured, and the precise method of filling, draining to the calibration mark, and ensuring the correct delivery of liquid into a receiving vessel. The guide underscores the necessity of following specific steps to ensure accurate and contamination-free liquid transfer, making it an essential resource for laboratory technicians and scientists aiming for precision in their experiments.
Takeaways
- 📃 Volumetric pipets are precise instruments made of glass or plastic, typically ranging from 1 to 100 milliliters, designed for accurate liquid measurements.
- 📄 They are calibrated to deliver or contain only one specific volume, with their specifications, including calibration temperature and volume, imprinted on the pipette itself.
- ✅ TD (to deliver) pipettes are calibrated to accurately deliver the specified volume of liquid, while TC (to contain) pipettes are designed to contain a specified volume without leaving any residue.
- 🔧 Before use, pipettes should be inspected for cleanliness. Water beads on the inner surface indicate the pipette is not clean and needs cleaning or replacing.
- 💰 The liquid to be pipetted should be poured into a beaker, ensuring sufficient quantity for filling the pipette and for rinsing it three times.
- 💦 A pipette bulb is used to draw up and rinse the pipette with the liquid to be measured, ensuring thorough internal coverage by rotating the pipette.
- ⤵️ To fill the pipette, liquid is drawn up to 2-3 cm above the graduation mark, then the excess is carefully released until the meniscus aligns with the calibration line.
- 📰 The pipette should be held vertically and wiped externally with lint-free tissue to remove any adhering liquid, preventing contamination.
- ⏰ After delivering the liquid into the receiving vessel, leave the pipette in place for an additional five seconds to ensure complete transfer of the specified volume.
- 📈 It's crucial not to blow or shake out the remaining liquid in the tip, as pipettes are calibrated to deliver the correct volume with this remainder considered.
Q & A
What are volumetric pipets typically made of?
-Volumetric pipets are usually made of glass or plastic.
What is the volume range of volumetric pipets?
-Volumetric pipets typically have a volume range between 1 and 100 milliliters.
Why are volumetric pipets used in laboratories?
-Volumetric pipets are used for accurate measurements of liquids, ensuring precise volume delivery in experiments and other scientific procedures.
How are volumetric pipets calibrated?
-Volumetric pipets are calibrated to deliver only one specific volume, with the specifications imprinted on the pipette itself.
What do the specifications on a volumetric pipet indicate?
-The specifications indicate the exact volume of liquid that will be transferred when the liquid is drawn up to the calibration line on the neck of the pipette, the temperature at which the calibration was made, and whether it is a TD or TC pipette.
What do TD and TC mean in the context of volumetric pipets?
-TD means the pipette is calibrated to accurately deliver the specified volume of liquid, while TC means the pipette is calibrated to contain a specified volume of liquid with no remainders.
How should one begin using a volumetric pipet?
-Before using a volumetric pipet, it should be inspected for cleanliness. If water beads up or collects on the inner surface, the pipette is not clean, and a cleaning procedure should be followed or a clean pipette should be obtained.
What is the procedure for rinsing a volumetric pipet?
-To rinse the pipette, pour the liquid to be pipetted into a beaker, ensuring there is sufficient liquid to fill the pipette and to rinse three times using a pipette bulb. Draw up a small quantity of the liquid to be pipetted and thoroughly rinse the entire interior surface by rolling the pipette horizontally.
How should you fill a volumetric pipet above the graduation mark?
-Using a pipette bulb, draw up the liquid to be pipetted and fill the pipette until it is about 2 to 3 centimeters above the graduation mark. Then, remove the bulb and quickly place your forefinger over the top of the pipette stem.
What steps should be taken to ensure accurate volume delivery?
-Tilt the pipette slightly from the vertical position and wipe the outside of the lower stem with lint-free tissue to remove any adhering liquid. Hold the pipette vertically with the tip touching the inner wall of a waste vessel, and slowly allow the liquid level to drop by slightly decreasing the finger pressure, halting further flow when the bottom of the meniscus coincides exactly with the top of the graduation mark.
How should you transfer the liquid to a receiving vessel?
-Move the pipette to the receiving vessel with the pipette held vertically and the pipette tip touching the wall. Allow the sample to drain freely once the liquid appears to be completely drained, and leave the pipette for an additional five seconds by counting to ten. Do not blow or shake out a small amount remaining in the tip, as the pipette is calibrated to deliver a specified volume with a small amount remaining.
Outlines
🧪 Volumetric Pipettes: Understanding Their Use and Calibration
Volumetric pipettes are precision tools made of glass or plastic, designed to measure specific volumes of liquid, ranging from 1 to 100 milliliters. They are calibrated to deliver ('TD') or contain ('TC') a precise volume of liquid. The calibration details, including the calibrated volume, temperature of calibration, and whether it's TD or TC, are imprinted on each pipette. The process of using a volumetric pipette involves inspecting it for cleanliness, ensuring no water beads are present inside. If it's not clean, a cleaning procedure is followed. The liquid for pipetting is placed into a beaker, and the pipette is rinsed with the liquid at least three times to coat its interior surface. After rinsing, the pipette is filled above the graduation mark, and the outside is wiped to avoid contamination. The liquid is then carefully dispensed into a receiving vessel until the meniscus aligns with the graduation mark. It's crucial not to blow or shake out the remaining liquid in the tip, as the pipette's calibration accounts for this remainder.
Mindmap
Keywords
💡Volumetric Pipets
💡Calibration
💡TD and TC Pipettes
💡Cleanliness
💡Rinsing
💡Meniscus
💡Graduation Mark
💡Air Bubbles
💡Contamination
💡Draining
💡Receiving Vessel
Highlights
Volumetric pipets are precision tools for accurate liquid measurement, available in glass or plastic.
Designed to deliver a specific volume between 1 and 100 milliliters.
Specifications such as volume, calibration temperature, and whether it's TD or TC are imprinted on the pipette.
TD pipettes are calibrated to accurately deliver a specified volume, while TC pipettes are calibrated to contain a specific volume.
Before use, pipettes must be inspected for cleanliness to ensure accurate measurement.
Rinsing the pipette with the liquid to be measured is crucial for preparation and accuracy.
The pipette bulb is used for drawing liquid above the graduation mark, then adjusted to align with the calibration line.
Proper technique involves tilting the pipette for outside wiping without contaminating the sample.
The liquid is drained into a receiving vessel with the pipette tip against the vessel wall to avoid splashes.
A specific volume is delivered by allowing a predetermined amount to remain in the tip, ensuring precision.
Counting for an additional five seconds after draining ensures complete delivery of the measured volume.
No blowing or shaking out the remaining liquid; the pipette design accounts for this residue.
Initial steps include pipette cleanliness inspection and thorough interior rinsing with the target liquid.
Filling the pipette involves careful handling to prevent air bubbles or foam formation.
Final steps ensure accuracy by wiping, draining to the calibration mark, and precise sample delivery.
Transcripts
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