Callibration of Spectrophotometer.pptx

Callibration of Spectrophotometer.pptx

1. Calibration of Spectrophotometer Mr.Rahul G.Sawarkar M.Sc.SET.GATE Asst . Professor Department of Chemistry J.D.Patil Sangludkar Mahavidyalaya, Daryapur. ONLINE VALUE BASED COURSE ON “CHEMICAL HANDLING AND LABORATORY SAFeTY ” FOR UG AND PG STUDENTS OF CHEMISTRY Duration : 14 TH November 2022 TO – 5 TH December 2022 Guest Lecture on

2. Plan of Lecture Introduction Spectrophotometer Control of Wavelength Control of absorbance for Ultra-Violet Region Limit of stray Light Resolution Power Maintenance Precautions

3. Cuvette

4. Spectrophotometer calibration is a process in which a scientific instrument known as a spectrophotometer is calibrated to confirm that it is working properly. This is important, as it ensures that the measurements obtained with the instrument are accurate. Introduction

5. Introduction What is Calibration Calibration is the act of ensuring that a method or instrument used in measurement will produce accurate results. Calibration is performed using primary reference standard.

6. Need of Calibration When a specific time period is elapsed. When a Specific operating hours has elapsed. With a new Instrument. When observations appears questionable.

7. Procedure of Calibration Control of Wavelength Control of absorbance for Ultra-Violet Region Limit of stray Light Resolution Power Maintenance Precautions Abbreviations

8. Control of Wavelength Chemicals :- 1.4 M perchloric acid, Holmium perchlorate solution Step I :- Dissolve 1gm of holmium oxide in 1.4 M perchloric acid with the aid of heating on water bath,cool and dilute to 25ml with same solvent. Step II :- Record the spectrum holmium perchlorate solution from 200nm to 600nm using 1.4M perchloric acid as reference solution.

9. Sr.No . Maxima Wavelength (nm) Tolerance nm 1 241.15 nm 240.15 nm to 242.15nm 2 287.15 nm 286.15 nm to 288.15nm 3 361.5 nm 360.50 nm to 362.50 nm 5 536.3 nm 533.30 nm to 539.30 nm

10. Control of Absorbance Step I :- Weigh 57gm to 63 mg of potassium dichromate primary standard and transfer to 1000 ml Volumetric Flask. Dissolve in 0.005 M sulphuric Acid and make up to the mark with the same acid. Step II :- Measure the absorbance at 235 nm,313 nm and 350 nm using 0.005M sulphuric acid as reference.

11. Sr.No . Wavelength (nm) Absorbance E (1% 1cm) Maximum Tolerance 1 235 124.5 122.9 to 126.2 2 257 144.0 142.8 to 145.7 3 313 48.6 47.0 to 50.3 4 350 106.6 104.9 to 108.2 5 430 15.9 15.7 to 16.1

12. Acceptance criteria : Absorbance at 200nm should be Greater than 2.0 Limit of Stray Light Step I :- Prepare the solution of 1.2 % v/v potassium chloride and dissolve with 50 ml distilled water Step II :- Determine the absorbance using path length of 1 cm at 200 nm against purified water as blank.

13. When the instrument not produce calibrated results it should be labeled “FAULTY” and should be repaired by service engineer of instrument . Maintenance

14. Resolution Power

15. Precautions