Melting Point Apparatus Calibration Report

🔬 Calibration of Melting Point Apparatus

1. Objective

To define the calibration procedure for the Melting Point Apparatus.

2. Scope of Procedure

2.1. Instrument Preparation and Setup

1. Ensure the instrument is placed on a surface free from vibration and away from the wall (at least 80 cm away).
2. Ensure the sample capillaries do not break or damage the sample holder while placing or removing them.
3. Disconnect the power supply before performing any service on the instrument.
4. Connect the instrument to the power supply.
5. Turn on the instrument by toggling the switch located at the front of the instrument.
6. Place a calibrated thermometer in the space designated on the top of the instrument.
7. Set the toggle switch on the front of the instrument to ‘L’ for temperatures up to 150∘C and to ‘H’ for temperatures greater than 150∘C.

2.2. Reference Standards

Use the following certified reference substances for calibration: | Substance | Melting Range (Certified) | | :— | :— | | A. Vanilline | 81∘C to 83∘C | | B. Acetanilide | 114∘C to 116∘C | | C. Sulphacetamide | 164∘C to 166.5∘C | | D. Caffeine | 234∘C to 237∘C |

2.3. Sample Preparation

1. The reference substance must be dried at 50∘C over Silica gel for 24 hours before use.
2. Fill the sample whose melting point is to be determined into a suitable glass capillary tube, sealed at one end.
3. Compact the sample in the capillary tube by gently tapping the tube on the bench. Fill additional material into the tube such that the height of the compacted sample in the tube is 4 to 6 mm.

3. Calibration Procedure

1. Start the heater of the instrument by turning the regulator knob on the front of the instrument.
2. Place the capillary tube with the sample in one of the sample holders provided on the top of the instrument when the temperature is about 10∘C below the expected melting point of the sample.
3. Observe the sample through the magnifying glass at the front of the instrument.
4. Note the temperature when the substance starts to melt (first drop of liquid) and record the temperature when the substance is completely melted (defined as the formation of a definite meniscus).
5. Record the observation on the calibration record.
6. Repeat the procedure for all other standards and record the observations in the calibration record.

4. Post-Calibration & Documentation

1. If the melting range for any of the standards does not fall within the prescribed range, repeat the determination for the standard. If a discrepancy is still observed, the instrument is considered to have failed calibration.
2. In case of failure, place a “Do-Not-Use” or “Out-of-Calibration” label on the instrument and arrange for servicing.
3. If the instrument passes calibration, affix a calibration sticker on the instrument.
4. Present the calibration record to the QC In-charge for review and place it in the appropriate files.