Instruction 1

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of an automatic pipette?

Measuring large volumes of liquid quickly and precisely.

Heating small volumes of liquid.

Separating different liquids.

Rapidly measuring small volumes of liquid. (correct)

What best describes the mechanism of an automatic pipette?

A piston with a spring that pulls liquid into a replaceable tip. (correct)

A pump system that dispenses liquid through a small opening.

A system of gears and filters that separate the components of liquid.

A gravity based system that dispenses liquid by pressure.

What is the purpose of the regulator on an automatic pipette?

To precisely limit the stroke of the piston to achieve a specific volume. (correct)

To control the temperature of the liquid being measured.

To filter the liquid before it enters the pipette tip.

To adjust the speed at which the liquid is drawn into tip.

What material is commonly used to make the tips of automatic pipettes?

Teflon or polyethylene. (A) Signup and view all the answers

Why is wetting the pipette tip recommended before pipetting?

To rinse the tip and account for viscous or density differences. (D) Signup and view all the answers

What is the recommended maximum angle of deviation when holding a pipette to reduce error?

20 degrees. (A) Signup and view all the answers

If the blue intake button is set to 100, what volume is being measured?

1000 µl. (A) Signup and view all the answers

If the yellow intake button is set to 010, what volume is being measured?

10 µl. (B) Signup and view all the answers

What is the minimum volume a pipette with a red intake button can measure?

0.5 µl. (D) Signup and view all the answers

Which of these is NOT an important feature of automatic pipettes?

They have a mechanism for measuring temperature of liquids. (B) Signup and view all the answers

What is the main reason for using an automatic pipette instead of other measuring devices, given the text?

To quickly measure small volumes of liquids. (C) Signup and view all the answers

What would be the direct consequence of using a pipette with an angle greater than 20 degrees from vertical while aspirating liquid?

The volume of liquid aspirated would be greater than the set amount. (D) Signup and view all the answers

If a pipette with a blue intake button is set to '010', what volume is being measured?

100µl (C) Signup and view all the answers

What is the purpose of rinsing the pipette tip with the liquid to be measured prior to aspiration?

To equilibrate the tip with the liquid, reducing errors. (C) Signup and view all the answers

If the red intake button on an automatic pipette displays '105', what would be the measured volume, in µl?

10.5 µl (A) Signup and view all the answers

Which of the following is NOT a typical feature of an automatic pipette, based on the information provided?

A built-in temperature control system. (D) Signup and view all the answers

According to the provided text, what is a unique characteristic of the tips used in automatic pipettes?

They are disposable and often made of polyethylene or Teflon. (A) Signup and view all the answers

What happens to the piston of an automatic pipette when the plunger is released after aspirating liquid?

It is pushed out by the spring, expelling the liquid. (A) Signup and view all the answers

Which setting on a yellow-coded pipette would measure the smallest volume?

001 (A) Signup and view all the answers

If a pipette is set to measure 100µl with a blue dial, based on the provided text, what would be the reading displayed on the volume scale?

010 (D) Signup and view all the answers

Study Notes

Exercise 1: Preparation of a Colored Saturated Sucrose Solution

Prepare a 1.5 ml test tube,
Pipette 405 µl of sucrose solution into the tube,
Pipette 95 µl of purple dye onto the surface,
Observe phase boundaries,
Mix by pipetting and vortexing,
Centrifuge in a benchtop microcentrifuge,
Divide into two equal tubes,
Note observations.

Exercise 2: Adding Small Volumes

Label a 1.5 ml tube,
Add 200 µl of sucrose solution,
Add 3 µl of green dye,
Add 3 µl of SDS detergent,
Mix.
Describe the procedure for adding small volumes using a pipette.

Exercise 3: Full Volume Transfer

Label a 1.5 ml tube,
Add 400 µl of sucrose, 10 µl of dye, and 10 µl of SDS detergent,
Mix,
Transfer solution to a 1.5 ml tube already containing 5 µl of dye,
Mix,
Observe and note if there's a risk of foaming.

Exercise 4: Performing a Serial 1:1 Dilution

Add 30 µl of sucrose solution to each of 8 tubes,
Add 30 µl of dye to the first tube,
Transfer 30 µl to the next tube, repeating until all tubes are filled,
Note the dilution level in each tube (1:1 dilution),
Add 2 µl of dye to each tube,
Specify the method for accurate dilutions (slow, controlled pipetting, consistent pressure).

Exercise 5: Centrifugation of Suspensions

Prepare a 1.5 ml tube containing 300 µl of suspension,
Add 50 µl of prepared solution,
Centrifuge at 12,000 xg for 5 minutes,
Pipette the liquid without disturbing the sediment,
Suspend sediment in 150 µl of solution.

Basic Principles of Working with an Electronic Analytical Balance

Analytical balances are precise instruments requiring specific handling & conditions,
Place on a stable, level surface,
Turn the balance on,
Use dry, clean containers for accurate measurements,
Close the door while weighing to avoid disturbance,
Perform operations smoothly to avoid destabilization,
Clean after usage and turn off.

Exercise 6: Weighing

Weigh a 1.5 ml tube on an electronic analytical balance, record the measurement,
Add 500 µl + 50 µl + 5 µl of water to the tube,
Weigh again,
Record results and conclusions,
Attempt volume estimation using a 1000µl pipette.

Automatic Pipettes

Automatic pipettes are used for quick measurement of small volumes (typically under 1 ml),
Mechanism includes a piston, spring, handle, regulator, replaceable tip,
Teflon or polyethylene tips are commonly used,
Regulator precisely controls piston movement, regulating volume,
Adjustment range is color-coded,
Some models have automatic tip removal,
Color-coded set points: Blue (100-1000 µl), Yellow (10-100 µl), Red (0.5-10 µl).

Pipetting Techniques

Wetting the tip: Rinse the tip with the liquid being measured, crucial for viscous liquids.
Holding the pipette: Hold upright, limiting angle to 20 degrees; avoid touching container walls.
Immersion depth: Adjust immersion depth based on volume: large-volume pipettes (1-5 ml) ~5-6 mm, smaller volume pipettes ~2-3 mm.
Operation: Use slow, even pressure when drawing/dispensing to avoid air bubbles.
Choosing the correct pipette: Select with a volume slightly larger than desired for accuracy.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz explores various laboratory techniques for preparing colored saturated sucrose solutions and performing dilutions. You'll learn the steps for adding small volumes, mixing solutions, and observing phase boundaries. Perfect for students in chemistry or biology labs.