Alexei Volkov
Plastic pipettes are used to measure and transfer precise amounts of liquid in laboratories and other scientific applications. They come in various types, sizes, and materials, including glass and plastic. Serological pipettes, for example, are commonly used to measure liquids in milliliters (mL) and feature markings along their length to indicate different volumes. These markings typically start with the largest volume near the tip and decrease towards the upper opening. When reading the volume of liquid in a serological pipette, it is important to look at the bottom of the concave shape formed by the liquid (known as the meniscus) rather than across the top. To ensure accuracy, it is crucial to choose the correct size of pipette, use proper techniques for aspiration and dispensing, and maintain the equipment appropriately.
| Characteristics | Values |
|---|---|
| Purpose | To measure and transfer liquids without cross-contamination |
| Types | Serological, measuring stem, fine stem, mechanical pipette pump, digital micropipetter |
| Measurement units | Milliliters (mL), microliters (µL) |
| Measurement range | 0.5 mL to 50 mL |
| Reading measurements | Read from the bottom of the meniscus; each pipette type has a different reading method |
| Precision | Small volumes are challenging to measure accurately; calibration and proper technique are critical |
| Technique | Use a bulb or pipette filler to aspirate liquid; depress plunger to the first stop, immerse the tip, slowly release the plunger, and dispense liquid |
Explore related products
What You'll Learn
Serological pipettes have markings along their length
Serological pipettes are precision instruments used in laboratories to accurately measure and transfer liquid volumes. They are typically made of plastic or glass and can hold anywhere from less than 1 millilitre to 50 millilitres of liquid. They have markings along their length that indicate volume, allowing for precise measurement. These markings are usually indelible and comprehensible, etched or printed using permanent or enamel ink. The markings start near the end of the tip and increase in volume towards the upper opening.
When using a serological pipette, it is important to choose the correct size based on the volume of liquid you need to transfer. The pipette should be slightly larger than the total volume of liquid you plan to move. For example, if you need to transfer 45 millilitres of liquid, you should use a 50-millilitre pipette.
To use a serological pipette, you will need the pipette itself and a bulb or pipette filler to aspirate the liquid. Some pipettes have a bulb attached, while others require a separate bulb that fits over the upper opening. Attach the bulb or pipette filler if it isn't already, and then squeeze the bulb to release air from the pipette. Place the opposite end into the liquid, and use the pipette filler to gently draw the liquid up into the pipette. Ensure the liquid level is slightly above the desired volume mark. Adjust the liquid level to the exact volume needed by carefully releasing any excess liquid back into the original container.
Once you have reached the desired volume, position the pipette tip over the receiving vessel and gently press the pipette filler to release the liquid. To ensure a complete transfer, serological pipettes typically need to be blown out to remove the last drop of liquid. This can be done by creating a vacuum with a rubber bulb attached to the end opposite the tip or by using gravitational force or air pressure.
Enzymes' Power to Degrade Plastics
You may want to see also
Explore related products
Measure from the bottom of the meniscus
When using a pipette, it is important to select the correct size for the volume of liquid you are transferring. Serological pipettes, for example, can measure liquids in milliliters (mL) and have markings along their length to help you accurately gauge the amount of liquid. These markings usually read from the largest near the tip to the smallest near the upper opening.
When measuring the volume of a liquid with a pipette, you must consider the meniscus. The meniscus is the top of the liquid, which forms a concave or U-shaped curve inside the pipette. This curve is a result of surface tension and the adhesion capacity of the liquid to the wall of the container. To obtain an accurate reading, you should measure from the bottom of the meniscus, not the top. This is because the liquid in contact with the tube wall reads higher than at the center.
It is important to note that the meniscus must be considered in your reagent volume calculations. For a concave meniscus, read the volume from the bottom of the curve. For a convex meniscus, read from the top. To ensure accuracy, carefully fill the pipette and hold it steady, then carefully eyeball the liquid level directly, not from an angle.
Additionally, it is recommended to use a well-calibrated pipette with proper-fitting tips for precise measurements, especially when dealing with small volumes. Consistency in your technique is also crucial. While precision refers to consistency between multiple experiments, accuracy refers to matching the expected value as written on the pipette. Calibration may be necessary to achieve accuracy.
The Swingline 99: Is It All Metal or Plastic Fantastic?
You may want to see also
Explore related products
Use a well-calibrated pipette
To ensure accurate measurements, it is important to use a well-calibrated pipette. Calibration is the process of ensuring that your pipette is dispensing the correct volume of liquid. Even small variations in volume can have a significant impact on many industries, especially in laboratories, research, and manufacturing.
To calibrate a pipette, you will need the pipette itself, pipette tips, distilled water, a beaker, a thermometer, a balance, and weigh boats. It is important to ensure that the pipette tips are the correct ones that properly fit the pipette. Before beginning the calibration process, wipe down the pipette with ethanol to kill any contaminants and ensure that nothing is clogging the tip end of the pipette. Allow the pipettes to adjust to the calibration environment for at least an hour to minimize potential errors during calibration. Large changes in temperature, humidity, and atmospheric pressure can impact evaporation during calibration, leading to unreliable tests.
Once the pipette is prepared, you can begin the calibration process. First, aspirate the calibration volume by placing the tip of the pipette into the distilled water and releasing the button to aspirate the liquid. Make sure the tip is completely immersed during the entire aspiration process and that there are no bubbles in the tip. Next, dispense the liquid into the weigh boat on the scale. Place the tip against the bottom of the weigh boat and push the button to dispense the liquid. Keep the button pressed while lifting the tip away from the weigh boat.
Finally, calculate the accuracy of the pipette using the equation A = 100 x Vavg/V0, where A is the accuracy of the pipette, Vavg is the average calculated volume, and V0 is the value you set the pipette to dispense. Accuracy should fall within the range of 99-101%. If the pipette is properly calibrated, the calculated value should be very close to the actual value you set. For example, if you set the pipette to dispense 10 mL, and the average calculated volume is 10.019 mL, the accuracy would be 100.19%, which is within the acceptable range.
Wiremold Metal and Plastic Components: Are They Compatible?
You may want to see also
Explore related products
Use a safety bulb
Safety bulbs are used with pipettes to aid with proper pipetting techniques. They are used to draw up and dispense liquids. When using a safety bulb, it is important to follow the manufacturer's instructions. Here is a general guide on how to use a safety bulb with a plastic pipette:
Firstly, ensure the pipette is in good condition, checking for cracks or defects. Only use designated liquids with the pipette to avoid contamination or inaccurate measurements. It is recommended to use the pipette in a well-ventilated area, especially when working with hazardous materials or corrosive substances. In such cases, personal protective equipment (PPE) such as gloves and safety goggles should be worn.
To begin, squeeze the bulb lightly and connect it to the top of the pipette tip. Place the pipette tip into the liquid and slowly release the pressure on the bulb to draw up the liquid. Stop when the liquid reaches just above the desired measurement line. Quickly remove the bulb and use your thumb or index finger to cover the top of the pipette, preventing any liquid from escaping.
Now, slowly release your finger to allow a small amount of liquid to drain out until the curved surface of the liquid (the meniscus) reaches the target measurement line. Usually, the meniscus will be concave (shaped like a "U") for water-based liquids, and you want the bottom of the "U" to align with the measurement line.
Finally, carefully move the tip of the pipette into the receiving container and dispense the liquid. Always collect slightly more liquid than needed so that adjustments can be made easily.
Practice with non-hazardous liquids such as water or alcohol to improve your technique before working with more challenging substances.
Applying ZAGG Screen Protector: Easy Plastic Protection
You may want to see also
Explore related products
Choose the correct size pipette
To choose the correct size pipette, you need to consider the volume of liquid you are transferring. The pipette should be slightly larger than the total volume of liquid. For example, if you are transferring 45mL of liquid, you should use a 50mL pipette.
Serological pipettes have markings along their length to help you accurately gauge the amount of liquid. These markings usually read from the largest volume near the tip to the smallest near the upper opening. When measuring the volume, read from the bottom of the meniscus (the concave shape formed by the liquid) rather than across the top.
The type of liquid you are transferring is also important. For example, if you are working with viscous, corrosive, or volatile liquids, you may need a different type of pipette. Wide-orifice tips are better for viscous samples or those with many particulates, while gel-loading tips are tapered for use with electrophoresis gels. If you are working with fragile samples, such as macrophages or hepatocytes, you will also need to choose your pipette accordingly.
Other factors to consider when choosing a pipette include sterility, filter varieties, and vessel types. If you are working with sensitive reactions, such as polymerase chain reactions (PCR), you will need to choose pipette tips that are certified free of contaminants like DNA and DNase. Some manufacturers also design their pipette tips to work best with their own pipettes, so you may need to use the same brand for both to ensure accuracy.
Drilling Letters into Plastic: The Ultimate Guide
You may want to see also
Frequently asked questions
Plastic pipettes have markings along their length to help you measure the volume of liquid. The markings start from the largest volume near the tip to the smallest near the upper opening. Read the volume from the bottom of the meniscus, not across the top.
A meniscus is the concave shape that the top of the liquid forms inside the pipette.
First, push down the plunger until you feel the first "stop". This expels enough air from the pipette for an accurate measurement. Then, gently lower the pipette tip into the liquid. Slowly release the plunger to draw the liquid into the pipette.
Place the pipette tip into the container where you want to dispense the liquid. Slowly press down on the plunger all the way to the second stop to release the liquid. Before releasing the plunger, lift the pipette tip out of the liquid.
Choose the correct size of the pipette based on the volume of liquid you're transferring. It should be slightly larger than the total volume. Always use a well-calibrated pipette with proper-fitting tips to ensure accurate measurements.
