8.1 Purity, formulations, and chromatography

• Chemical purity is the degree to which a substance is free from impurities.


  True
• Order the methods for determining purity from lowest to highest accuracy:

  1️⃣ Measuring melting/boiling points

  2️⃣ Paper chromatography

  3️⃣ TLC

  4️⃣ HPLC
• The presence of impurities can alter the properties and performance
• Match the property with the type of substance:

  Composition | ↔️ Single, well-defined chemical |

  Safety | ↔️ Well-understood, controlled |

  Properties | ↔️ Consistent, predictable |
• Pure substances have sharp, defined melting and boiling points.


  True
• Substances in paper chromatography separate based on solubility and affinity.

  True
• High-performance liquid chromatography uses a pump to force a liquid mobile phase through a column
• What factors determine the choice of a method for determining chemical purity?

  Precision and resources
• Impurities cause a range of melting and boiling points

  True
• TLC provides better resolution than paper chromatography


  True
• Using HPLC requires technical expertise


  True
• Inactive ingredients in formulations are called excipients
• What is a benefit of using liquid formulations?

  Rapid absorption
• What are the main ingredients in cream formulations?

  Active drug, emollients, emulsifiers
• Formulations often combine active ingredients with inactive excipients to enhance stability and user experience
• Why is high chemical purity essential in industries like pharmaceuticals?

  Safety and quality control
• What is the melting point of a substance?

  Temperature solid turns to liquid
• What is the accuracy of measuring melting and boiling points to determine purity?

  Relatively low
• In paper chromatography, substances separate based on solubility and affinity
• What stationary phase is used in thin-layer chromatography (TLC)?

  Silica gel
• What are two advantages of HPLC over other methods for determining purity?

  High resolution and quantification
• Pure substances have sharp, defined melting and boiling points.


  True
• Order the methods for determining chemical purity from lowest to highest accuracy:

  1️⃣ Measuring melting and boiling points

  2️⃣ Paper chromatography

  3️⃣ Thin-layer chromatography

  4️⃣ High-performance liquid chromatography
• Impurities in a substance cause a range of melting and boiling
• Match the chromatography method with its properties:

  Paper chromatography | ↔️ Low cost, moderate accuracy |

  Thin-layer chromatography | ↔️ Moderate cost, moderate accuracy |

  High-performance liquid chromatography | ↔️ High cost, high accuracy |
• Impurities in a substance can reduce its effectiveness and alter its properties
• What are the two phases used in paper chromatography?

  Stationary and mobile
• What is the purpose of a pump in HPLC?

  To force mobile phase
• Match the method with its characteristics:

  Measuring melting/boiling points ↔️ Low cost and simple use

  Paper chromatography ↔️ Moderate accuracy and ease

  TLC ↔️ Moderate cost and accuracy

  HPLC ↔️ High cost and accuracy
• Formulations stabilize products by preventing degradation


  True
• What are four common types of formulations mentioned in the study material?

  Tablets, creams, liquids, sprays
• Liquid formulations offer rapid absorption and are easy to swallow.


  True
• What does chemical purity refer to?

  Degree of freedom from impurities
• A pure substance has a single, well-defined chemical composition
• Pure substances have sharp and defined melting and boiling points.


  True
• Measuring melting and boiling points is a simple method for determining purity.


  True
• TLC is more accurate than paper chromatography for determining purity.


  True
• What is the melting point of a substance?

  Solid turns to liquid
• What effect do impurities have on melting and boiling points?

  Range of points
• What are the two phases used in paper chromatography?

  Stationary and mobile