Aspirin, or acetylsalicylic acid, melts between 135°C and 140°C. This property is critical for ensuring drug purity and stability during manufacturing.
Melting points measure the temperature range where a solid becomes a liquid. Pure compounds melt at specific temperatures, while impurities cause broader ranges. Aspirin's narrow melting range indicates high purity.
| Type | Melting Point Range (°C) | Use Case |
|---|---|---|
| Uncoated tablets | 135-140 | General pain relief |
| Enteric-coated tablets | 135-140 (core) | Stomach protection |
| Powdered aspirin | 135-140 | Dissolving in liquids |
Pharmaceutical companies test melting points to verify aspirin quality. Impurities lower the melting point, signaling degradation or contamination. The U.S. Pharmacopeia sets strict standards for aspirin purity based on its melting behavior.
Many assume aspirin decomposes before melting, but it actually melts first. Decomposition occurs later, around 180°C. This distinction is important for safe handling and storage.
I once witnessed a quality control test where aspirin samples melted inconsistently. The batch failed inspection due to impurities detected through melting point analysis.
Laboratories use differential scanning calorimetry (DSC) to measure aspirin's melting point accurately. A small sample is heated gradually while instruments record temperature changes.
According to the Journal of Pharmaceutical Sciences, proper melting point testing ensures aspirin remains effective and safe for consumers.