What is the metastable zone width?

The Metastable Zone Width (MSZW) is the difference between the saturation temperature and the temperature at which crystals are detected under constant cooling rate.

How do you find your metastable zone?

The metastable zone width is defined as the zone between the solubility curve (clear points) and the metastable limit curve (cloud points) and provides essential information for developing well-controlled crystallization processes.

What is metastable state in crystallization?

A metastable state describes a phase in which an energy barrier must be surmounted before that phase can be transformed to one of lower free energy. While first- and second-order transitions are typically reversible by changing the temperature, transitions from a metastable to a more stable phase are not.

What is labile zone?

The nucleation range is also called the labile zone, while the growth range is known as the metastable zone. For crystal nucleation to occur, the experimenter must push the protein solution into the labile zone, which is also the region where fast growth of crystal nuclei occurs.

What is a solubility curve?

: a graphic representation of the variation with changing temperature of the solubility of a given substance in a given solvent.

What is the metastable limit?

The shape of the isotherm provides the definition for the metastable limit: it is the highest concentration NMSL/V at which the system remains dispersed and, more rigorously, the metastable limit is also the value of the concentration NMSL/V for which the NMSL value corresponds to a maximum in the chemical potential μ.

What are examples of metastable?

A ball resting in a hollow on a slope is a simple example of metastability. If the ball is only slightly pushed, it will settle back into its hollow, but a stronger push may start the ball rolling down the slope. Bowling pins show similar metastability by either merely wobbling for a moment or tipping over completely.

What is a metastable solution?

A metastable state is a state in which a solution exists at an energy level above the energy level of a stable state and if the solution gets a small amount of more energy, it can transit from metastable back to stable state. Therefore, the concentration of supersaturated solution exceeds the solubility.

What is seeding crystallization?

Crystal seeding is the process of adding homogeneous or heterogeneous crystals to a crystallising solution to nucleate and/or grow more crystals. This is achieved primarily by controlling the crystal size distribution and polymorphism of the crystals that are formed.

How does seeding initiate crystallization?

Seeding. Crystallization requires an initiation step. This can be spontaneous or can be done by adding a small amount of the pure compound (a seed crystal) to the saturated solution, or can be done by simply scratching the glass surface to create a seeding surface for crystal growth.

What are the 3 types of solubility?

Based on the concentration of solute dissolves in a solvent, solutes are categorized into highly soluble, sparingly soluble or insoluble.

How do you interpret a solubility curve?

Trace the solubility of a substance with increasing temperature.

  1. The curved line represents saturation.
  2. Below the curve, the solution is unsaturated.
  3. Above the curve the solution is supersaturated. This means there is more solute than the solution can hold.