What is the Noyes-Whitney equation?
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What is the Noyes-Whitney equation?
The Noyes-Whitney equation was developed by some physical chemists at the beginning of the 20th century to characterize of the process of solid dissolution [33, 34]. The equation is. d C d t = D S V h ( C s − C ) , (3)
What is the unit of dissolution?
The intrinsic dissolution rate (kg . m-2 . s) is the dissolution rate of a pure solute, normalized to the solute surface area, and actually decreases with time.
Will influence the rate of dissolution according to Noyes-Whitney equation?
According to Noyes-Whitney equation when particle size is reduced, the total effective surface area is increased and thereby dissolution rate is enhanced. Additionally, reduction of particle size reduces the diffusion layer thickness surrounding the drug particles and thereby increases concentration gradient (4,50).
How do you calculate the dissolution of a tablet?
Formula for determination of percentage of release of drug from in vitro dissolution testing
- Concentration of drug (µg/ml)= (slope × absorbance) ± intercept.
- Amount of drug = Concentration × Dissolution bath volume × dilution factor.
Why dissolution is performed on six units?
Six units are tested to provide the minimal statistical significance. *Mean & Standard deviation (SD)* of any in-process or finished product CQA represents *Accuracy & Precision* of any Statistically Contolled Stable Process or Method.
What units are usually used to express the solubility of a solute?
Usually, solubility is expressed in grams of solute per milliliters of solution. Solubility can be expressed in any mass unit per any volume unit. On solubility graphs, solubility is usually expressed in grams of solute per mL of solution.
What are the customary units of solubility on solubility curves?
Hence, the customary units of solubility on solubility curves is grams of solute 100g of water . Additional Information: Solubility can also be expressed as grams of solute per millilitres of solution or mass unit per any volume unit. It can also be expressed as moles of solute per litre of solution.
What is the dissolution rate constant?
The dissolution rate constant, k, of oxalic acid dihydrate depends on linear velocity, v (centimeters per second), by the following equation: k = (2.54 +/- 0.76) X 10(-4) v, where k is measured in centimeters per second.
Why do we use 900 ml in dissolution apparatus?
Most likely, the volume was lowered to 900mL to account for volume displacement from the product and stirring shaft. This gives some wiggle room in the test, so that the vessel doesn’t spill over during the dissolution.
Why do we take 900 ml in dissolution apparatus?
What is f1 value in dissolution?
Fit factors The factor, f1, is the average % difference over all time points in the amount of test brand dissolved as compared to the reference brand. The f1 value is 0 when the test and the reference profiles are identical and increases proportionally with the dissimilarity between the two profiles.
What units is solubility measured in?
The unit of solubility is generally in mg/L (milligrams per liter) or ppm (parts per million).
How is solubility expressed in units of measurement?
The solubility of the solute in the solvent to form a solution is expressed in the terms of grams of solute per milliliter of the solution. The solubility is expressed in any mass unit per any volume unit. Note: The molar solubility is the number of moles of solute dissolved in one liter of solution.
What are the customary standard units on the Y axis of the solubility curve?
The customary units of solubility on a solubility curve are grams of solute per one hundred grams of solvent on the Y-axis and degrees Celsius for temperature on the X-axis.
How do you read a solubility curve?
Now let’s take a closer look at how to read a solubility curve….Trace the solubility of a substance with increasing temperature.
- The curved line represents saturation.
- Below the curve, the solution is unsaturated.
- Above the curve the solution is supersaturated. This means there is more solute than the solution can hold.
