Pipette Testing Using Distilled Water - Precise Technical Solutions (2024)

You have a favorite pipette. Familiarity with the electronic interface makes its use second nature. Maybe your hand fits it just right, or the smoothness of the action makes it easy to use. Then, one day, your dispensed volume just feels “off”. You try pipetting the liquid again, and again it looks too low or too high. What can you do? Basic pipette testing verifies the accuracy – or inaccuracy – of your equipment.

Fortunately, you can perform basic pipette testing with a few pieces of lab equipment. Let’s get started.

Pipette Testing Using Distilled Water - Precise Technical Solutions (1)

Required Equipment

Collect the following equipment and supplies.

  • A weighing device. Balances offer more precision, but a digital scale can suffice for larger volume samples.
  • A weighing vessel, such as a beaker.
  • A steady and consistent pipette technique.
  • An environment with stable temperature and humidity.
  • A stable surface.
  • Distilled water.

Pipette Testing Preparations

Once you collect the needed items, start by setting up your weighing device on a stable surface in an environment with minimal temperature and humidity variations. If your scale or balance has a leveling bubble and internal calibration, utilize both now. Finally, set your weighing device to read grams.

With your scale or balance ready, place your weighing vessel on the weighing device and either “tare/zero” the unit or record the weight of the vessel to be subtracted from your overall weight later.

Pipette Testing Using Distilled Water - Precise Technical Solutions (2)

Pipette Testing Procedure

With all the preparations made, set the pipette’s volume to the middle of its range. Draw up a sample of water and dispense it into your weighing vessel. The elegance of this procedure lies in the near-perfect conversion of microliters of distilled water to grams of mass. This conversion involves nothing more than moving the decimal three (3) places. To go from grams to microliters, move the decimal to the right. To from go from microliters back to grams, move the decimal to the left.

For instance, fifty (50) microliters of water weighs 0.05 grams: a movement of the decimal from 50.0 three places to the left to 0.05. Similarly, .0485 grams of distilled water translates to 48.5 microliters of water: a movement of the decimal from 0.0485 three places to the right, to 48.5.

So, when you verify a pipette with a range of 10-100 microliters at 50 microliters and the balance reads 0.0487g, then your pipette dispensed 48.7 microliters. If your scale or balance does not have a zero or tare function, subtract the weight of the vessel from the total measured weight after dispensing the water. After verification at the mid-range, set the pipette’s range for its lowest and highest settings and repeat the procedure for the respective ranges.

Conclusion

While this method does not yield the precision results of more in-depth procedures, it provides you with a general idea of pipette performance and accuracy. With that in mind, let’s say you’ve figured out that your pipette is reading too far out of range to be used within your lab. What do you do now? Throw the pipette away and buy new?

Of course not! Send it to the professionals at Precise Technical Solutions. The diagnosis, repair, and calibration of lab instruments such as pipettes forms a core part of our team’s competencies. With a little time in our lab, our technicians will have your favorite pipette operating just like it did the day it was new.

Pipette Testing Using Distilled Water - Precise Technical Solutions (2024)

FAQs

How to check pipette accuracy and precision? ›

The most common way to check your pipette accuracy is by weighing water. The density of water is 1 g/mL. This means that every microliter (µL) should weigh exactly 0.001 g using a high-precision balance.

Why should the water used in calibration be distilled water? ›

Distilled water was used as the primary calibration medium for the refractometer because of the accuracy of the temperature measurement and the accuracy of the algorithm relating this temperature to the index of refraction.

Why water is used for pipette calibration? ›

Principle: Under a constant temperature and atmospheric pressure, the density of distilled water is constant. The volume of water can be determined by weighting dispensed water. The calibration of pipette is carried out by gravimetric method.

Why is it important to rinse the pipette with fresh distilled water between uses? ›

Answer and Explanation:

However, rinsing the burettes and pipettes with their respective rinsing solution is done more importantly to avoid any contamination or dilution of the solution to be filled in it later.

Why is rinsing with distilled water important? ›

Unparalleled Purity

Distilled water undergoes a rigorous purification process, removing nearly all minerals, impurities, and contaminants. This results in a neutral, uncontaminated medium. By using distilled water, we ensure that our cleaning solutions remain consistent, free from unpredictable mineral reactions.

Why do you allow the distilled water to stand for about 10 minutes before use? ›

Why do we need to let distilled water sit for a while before use in a lab experiment? It gets very tired from being distilled, and needs a bit of a rest.

Why is it important to test the distilled water before testing the solutions? ›

Distilled water testing ensures optimal purity and quality of the water. It exhibits the usability and purity of the water being used in critical experiments and testing procedures.

Why do we double distilled water? ›

Double distilled water: Distillation-DistillationH2O is the water obtained after two distillations. The water contains very low inorganic salts, organic matter, microorganisms, soluble gases and volatile impurities, and removes the heat source. Generally, it can be used for water for injections.

How to calibrate a pipette step by step? ›

Procedure:
  1. Obtain the pipette to be tested and a few milliliters of water. ...
  2. Set the pipette to the desired volume, determine how much that water should weigh. ...
  3. Draw water up into the tip again and eject it into the weight boat. ...
  4. Press “tare.”
  5. Repeat steps 3 and 4 about 10 times.

What is the most accurate method of pipette calibration? ›

Using the same tip(s), aspirate the nominal volume. With the tip(s) immersed 2 mm in liquid, hold the pipette vertically for 30 seconds then, with tip(s) immersed in liquid, dispense all remaining liquid from the tip(s). If liquid level does not drop and no air bubbles are present, continue with validation.

What to do if a pipette fails calibration? ›

If a pipette's accuracy falls outside the 99–101% range after calibration, stop using the pipette for accuracy-critical tasks. There may be arrangements available to service and recalibrate the pipette, either in-house or with a company specializing in calibration services.

What are the solutions used in pipette calibration? ›

To check the calibration of a pipette, you will need the pipette, pipette tips, distilled water, a beaker, a thermometer, a balance, and weigh boats. The balance needs to be specific to micrograms to calibrate micropipettes with a maximum of 1 µL. You won't need more than 5 mLs of water.

What is the accuracy and precision of volumetric pipette? ›

Volumetric pipettes are considered the most accurate, with the capacity to measure up to four significant figures. This makes them the pipette of choice for applications where accuracy is critical.

What is the accuracy and precision of a micropipette? ›

The accuracy of a micropipette decreases somewhat when micropipettes are set to deliver volumes close to the lowest values in their range. Precision provides information about reproducibility, without any reference to a standard. Precision reflects random errors that can never be entirely eliminated from a procedure.

How do you check for precision? ›

Precision is determined by standard deviation, which is how much and how often measurements differ from one another. If a standard deviation is high, then it suggests low precision. On the other hand, if a standard deviation is low, then it suggests high precision.

Where should you look to find the precision of the pipette so you know how many decimal places to record in the volume? ›

The precision is printed on the flask for reference. Micropipette are very precise tools for measuring extremely small volumes (less than one milliliter). The number of significant digits you get from a micropipette is printed on the pipette for your reference, but it is usually about 4 significant digits.

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