Determination of Zinc by Linear Calibration and Standard Addition Methods using AAS

Summary

This video outlines a detailed procedure for preparing zinc stock solutions and standards for atomic absorption spectroscopy (AAS). It begins with the preparation of a 1,000 PPM zinc stock solution, followed by dilutions to create 10 PPM and various standard concentrations ranging from 0.1 PPM to 0.5 PPM. The unknown water sample containing zinc is then prepared for analysis. After completing all preparations, the standards and samples are ready for zinc content analysis using AAS, ensuring precise results through careful pipetting and volumetric measurements.

Takeaways

• 😀 Weigh 0.44 g of Z (zinc salt) to start the preparation of the stock solution.
• 😀 Dissolve the zinc salt in distilled water using a stirrer until completely dissolved.
• 😀 Transfer the solution into a 100 ml volumetric flask and fill up to the mark with distilled water.
• 😀 The 1,000 PPM zinc solution is diluted to 10 PPM by adding 1 ml of stock solution into a 100 ml volumetric flask.
• 😀 Prepare zinc standards by performing dilutions: 0.1 PPM, 0.2 PPM, 0.3 PPM, 0.4 PPM, and 0.5 PPM.
• 😀 For 0.1 PPM, pipette 0.5 ml of stock solution into a 50 ml volumetric flask and make up to the mark with distilled water.
• 😀 Repeat the dilution process for 0.2, 0.3, 0.4, and 0.5 PPM using the same method.
• 😀 For sample B, containing zinc, pipette 10 ml of the unknown sample into a 50 ml volumetric flask and dilute with distilled water.
• 😀 For preparation of the 0.0 PPM standard, use 20 ml of unknown water sample B and dilute to 100 ml with distilled water.
• 😀 The final preparation for 0.25 PPM involves pipetting 2.5 ml of stock solution into a 100 ml volumetric flask and diluting with distilled water.
• 😀 The prepared standards are ready to be analyzed using Atomic Absorption Spectroscopy (AAS).

Q & A

What is the first step in preparing the zinc stock solution?

The first step is to weigh 0.44 g of zinc (Z).

How do you dissolve the zinc salt in water?

Add distilled water into a beaker and use a stirrer until the salt dissolves completely.

How do you transfer the dissolved zinc solution to the volumetric flask?

After dissolving the salt, transfer the solution into a 100 ml volumetric flask and add distilled water up to the 100 ml mark.

What is the purpose of diluting the stock solution to 10 PPM?

The purpose is to create a lower concentration of zinc for preparing calibration standards.

How do you dilute the 1,000 PPM stock solution to 10 PPM?

Pipette 1 ml of the 1,000 PPM stock solution into a 100 ml volumetric flask and fill it with distilled water.

What concentration of zinc is used for the standard solutions?

The standard solutions are prepared at concentrations of 0.1, 0.2, 0.3, 0.4, and 0.5 PPM.

How is the 0.1 PPM standard solution prepared?

Pipette 0.5 ml of the 10 PPM stock solution into a 50 ml volumetric flask and dilute it to the 50 ml mark with distilled water.

What should be done after preparing all the standard solutions?

After preparing the standards, they are ready to be analyzed using Atomic Absorption Spectroscopy.

How is the unknown water sample prepared for analysis?

Pipette 10 ml of the unknown water sample containing zinc into a 50 ml volumetric flask and make up to the 50 ml mark with distilled water.

How is the unknown sample diluted for the 0.25 PPM standard?

For the 0.25 PPM standard, pipette 2.5 ml of the 10 PPM stock solution into a 100 ml volumetric flask and dilute it with distilled water.