Operation & Calibration of Melting Point Apparatus

Operation & Calibration of Melting Point Apparatus SOP

Operation & Calibration of Melting Point Apparatus SOP

SOP on Operation & Calibration of Melting Point Apparatus

1.0 WHAT
This document details the procedure for the Operation of Melting Point Apparatus
2.0 WHY
It is the policy of  the written procedure will be followed for the Operation of Melting Point Apparatus and its use monitored in order to ensure that the operation is carried uniformly by any of the analyst so as to avoid any deviation from the procedure.
3.0 WHEN
This procedure is to be applied at the time of Operation of Melting Point Apparatus
Persons along with their responsibilities are given below:







To prepare the SOP and follow the SOP.


Section In Charge

To ensure implementation of SOP.


QA In Charge

To ensure implementation of SOP.



5.1.1 Powder the sample as fine as possible.

5.1.2 Dry it at a temperature if specified in the individual monograph.

5.1.3 Heat the bath until the temperature is about 10 below the expected melting temperature.

5.1.4 Continue the heating and note the temperature at which the column of the sample  collapse definitely against the side of the tube at any point, when melting may be considered to have  begun and note also the temperature at which the sample becomes liquid throughout as seen by the formation of a definite meniscus.

5.1.5  Record the reading of Melting point.

5.1.6  After observation remove the capillaries/ sample column from oil bath.

5.1.7  After completing the test switch off the instrument properly.


5.2.1  Clean the instrument with Clean Cloth

5.2.2  Remove the Silicon Oil frequently

5.3   Precaution:

5.3.1 Keep the instrument clean and Dust free.

5.3.2  Do not go to the over limit of temperature as prescribed.

5.3.2 All the knobs are very delicate and should be handled carefully.



6.1.1  Melting point apparatus is calibrated by taking the melting points of vanillin, acetanilide, sulphanilamide and caffeine anhydrous.

6.1.2  Using the standard calibrated thermometer the temperatures at which the materials start melting, & at which they completely melt, are read and recorded.

6.1.3  The melting points of these materials should fall within the given limits; then the instrument is calibrated.

 1. Vanillin 81 to 83 Deg. C
2. Acetanilide 114 to 116 Deg. C
3. Sulphanilamide 164.5 to 166.5 Deg. C
4. Anhydrous Caffeine 234 to 237 Deg.C


Quarterly or after any maintenance work.

Record the data on APPENDIX I Format       

FAQs on Operation and Calibration of Melting Point Apparatus

  1. What is the significance of the melting point determination in chemistry? The melting point determination is important in chemistry for identifying and characterizing solid compounds, assessing their purity, and determining their physical properties.
  2. How does impurity affect the melting point of a substance? Impurities in a substance can lower its melting point and broaden its melting range, making it more difficult to accurately determine the purity of the sample.
  3. What factors can influence the accuracy of melting point measurements? Factors such as sample preparation, heating rate, atmospheric pressure, and calibration of the apparatus can influence the accuracy of melting point measurements and should be carefully controlled.
  4. Can melting point apparatus be used to determine the boiling point of a liquid? No, melting point apparatus is specifically designed for determining the melting point of solid substances. Boiling point determinations require specialized equipment, such as a distillation apparatus or reflux setup.
  5. Is it necessary to calibrate the melting point apparatus regularly? Yes, regular calibration of the melting point apparatus is essential to ensure accurate temperature measurements and reliable melting point determinations. Calibration should be performed using certified reference materials and adjusted as needed to maintain accuracy.

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