Paddle Dissolution Method:

• In this method, the rotating shaft is fixed to a blade attached vertically at the end.
• This blade is meant to act as a stirrer to mix the drug being tested with the liquid inside the holding vessel.
• Typically, the drug is placed inside the holding vessel and once it settles at the bottom, the rotating shaft is switched on to begin mixing.
• The drug being tested is also frequently attached to a sinker to prevent the drug from attaching itself to the vessel walls and also to ensure the drug being tested remains positioned beneath the rotating shaft.
• This sinker is made from a non-reactive element to prevent it from reacting with the drug sample it holds.

Basket Dissolution Method

• In the basket dissolution method, a different apparatus is placed at the end of the rotating shaft. This apparatus is called a basket.
• It is cylindrical in shape and is constructed from non-reactive mesh to prevent any unwanted chemical reactions that may alter the final result.
• The pores in the mesh allow the dissolving drug to move from the basket into the holding vessel, creating a uniform solution.
• The drug being tested is first placed inside the basket that is firmly attached to the end of the rotating shaft.
• Once the drug is securely in place, the motor is switched on and the shaft begins rotating the basket inside the vessel.
• The sticky tablets containing HPMC or similar compounds as a binder are tested using a basket because tablet swells in water and may stick to the walls of the dissolution vessel.

Calibration and Validation of Models

• The pH scale is maintained to range from 0-14 or maybe 1-14, but neither is correct.
• The pH range does not have an upper nor lower bound.
• The pH is an indication of concentration of H+.
• For example, at a pH of zero the hydronium ion concentration is one molar, while at pH 14 the hydroxide ion concentration is one molar.
• Typically, the concentrations of H+ in water in most solutions fall between a range of 1 M (pH=0) and 10-14 M (pH=14).
• Hence a range of 0 to 14 provides sensible (but not absolute) “bookends” for the scale.

• Residue on ignition means the residue that left over on ignition, the residue may be of any kind i.e. sulphate, or TiO2 or some other metal contamination. Sulphated ash means the ash should be of the sulphate counterpart.
• The Residue on Ignition / Sulfated Ash test utilizes a procedure to measure the amount of residual substance not volatilized from a sample when the sample is ignited in the presence of sulfuric acid according to the process.
• This take a look at is typically used for determinative the content of inorganic impurities in AN organic substance.

• Sodium tartrate dihydrate is the volumetric standard for Karl Fischer titration. Under normal conditions, it is stable and non-hygroscopic.
• Sodium tartrate dihydrate has a stoichiometric water content of 15.66% and is mainly used for titer determination in volumetric.

Karl Fisher Titration

• Karl Fisher Titration is a method for the determination of moisture content. The technique was established by a chemist named Karl Fischer. It is based on a mixture which reacts with water and converts the water into a non-conductive chemical. Karl Fisher provides for the specific detection of water. There are two methods used to perform the Karl Fischer titration test.
  • Volumetric Karl Fischer
  • Coulometric Karl Fischer

Volumetric Karl Fischer

• In this method, the moisture determination is based on the amount, or volume, of reagent used to convert the water.
• Samples are dissolved in a solvent before the titration begins.
• A reagent is added until the water is removed.

Coulometric Karl Fischer

• In this method, the reagent and solvent are combined in the titration cell.
• When a sample is introduced into the titration cell and dissolved, reagent is released by the induction of an electrical current.
• The amount of current required to convert the water is the determinant of the amount of moisture.
• A Coulometric Karl Fischer instrument is often referred to as a coulometer.

• Organic Chemistry is the study of the structures, properties, and behaviours of compounds containing carbon-hydrogen bonds.
• Organic compounds are molecules composed of carbon and hydrogen, and may contain any number of other elements.
• Many organic compounds contain nitrogen, oxygen, halogens, phosphorus, silicon, and sulfur.

• Sodium (Na) Lamp is used in a polarimeter because it gives monochromatic light and also gives high-energy output. High sensitivity and S/N ratio.
• Line spectrum i.e. gives monochromatic light of 589nm.
• A polarimeter is a scientific instrument used to measure the angle of rotation caused by passing polarized light through an optically active substance.