Common Interview Questions and Answers on Analytical Development
Q. What is Dissolution?
Dissolution rate may be defined as amount of drug substance that goes in the solution per unit time under standard conditions of liquid/solid interface, temperature and solvent composition. It can be considered as a specific type of certain heterogeneous reaction in which a mass transfer results as a net effect between escape and deposition of solute molecules at a solid surface.
Q. What is Biopharmaceutical Classification System (BCS)?
The BCS is a scientific framework for classifying drug substances based on their aqueous solubility and intestinal permeability.
Q. What are different types of dissolution apparatus?
- Apparatus I: Rotating basket
- Apparatus II: Paddle
- Apparatus III: Reciprocating cylinder
- Apparatus IV: Flow cell
Q. What is Discriminatory dissolution media and how you develop it?
Discrimination, in the dissolution world, is having a dissolution test which will show a difference between one formulation and another. Basically, that you will be able to discriminate between a drug that passes and one that fails.
Discriminatory dissolution Media is which are sufficiently sensitive to highlight differences between variable formulations or quantity.
A discriminatory media is one part of a discriminatory dissolution test. The media should be able to meet sink condition (dissolve 3+ times the amount of drug), be a biologically relevant pH, contain as little surfactants or other solubilizers as needed. To determine a good media, typically it is best to study several different pH media, determine a couple which best dissolve your drug.
If you haven’t met sink, test the good media from your first experiment and try each with varying concentrations of surfactant until you get the lowest amount of surfactant needed to reach sink. You can verify the media by trying various formulations of the drug in the media if you wish, and see if it is able to discriminate the difference between multiple formulations (such as different coating levels, compression, etc.).
Q. What do you mean by “Significant Change” during stability testing?
For an API: “significant change” is failure to meet the specification for any parameter
For a Finished Pharmaceutical Product (FPP): significant change is any of:
- Any degradation product exceeding its limit
- Failure in tests of appearance, physical attributes and functionality test, e.g. colour, hardness, pH
- > 5% change in assay from initial
- failure to pass dissolution testing for 12 dosage units (S2)
Q. What do you mean by chromatography?
Chromatography is an analytical method in which separation of components take place between two phases – a stationary phase and a mobile phase.
Related: Interview Questions and Answers on Chromatography
Q. What do you mean by HPLC?
HPLC means ‘high performance liquid chromatography or high pressure liquid chromatography’. Where high pressure is used to pass the target molecule with mobile phase through compacted or densely packed stationary phase.
Q. What is the principle of HPLC?
A sample is injected through the injector in a flow of mobile phase and travels through a stationary phase (column). The analytes in the sample mixture move with the flow of the mobile phase and interact with the solid support. The rate of movement relies on the affinity of the analytes toward the stationary phase. The strongly interacting analytes with the stationary phase travel gradually, while the less interacting compounds elute quickly.
Q. What do you mean by Gas chromatography?
Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds depending on the volatility of sample.
Q. What is the principle of Gas Chromatography?
Gas chromatography follows the principle of the partitioning of volatile compounds with the mobile phase (gaseous) and stationary phase (liquid or solid). The separation speed of molecules through the column is based on the affinity for the stationary phase; the molecules which are partitioned in the gas first come out, whereas the other eluted later.
Related: Pharma Quiz on Chromatography
Q. What do you mean by Retention Time (tR)?
Retention time is the time required by the analyte from injection to migrate from the column to the detector.
Q. What do you mean by system suitability?
System suitability is to prove that system is working perfectly before the analysis on HPLC, GC, TOC analyzer or any other system. It is required to done before every sample analysis.
Q. What do you mean by Analytical method validation?
Analytical method validation is a process used to prove through scientific study that the method is suitable for its intended use. Compendial methods have to be verified for suitability under actual conditions of use and for a particular formulation.
Q. What are the major parameters in Analytical method validation?
- Accuracy
- Precision
- Limits of Detection (LOD)
- Limits of Quantitation (LOQ)
Q. What is Precision?
The precision of an analytical procedure refers to the closeness of agreement between a series of measurements obtained from multiple sampling of the same homogeneous sample under the prescribed conditions.
Q. What is Robustness?
Refer to the ability of an analytical method to remain unaffected by small, but deliberate variations in method parameters and provides an indication of its reliability during normal usage.
Q. What is Limit of Detection (LOD)?
LOD is the lowest concentration of a substance that can be reliably detected but not necessarily quantified.
Q. Wat is Limit of Quantification (LOQ)?
LOQ is the lowest concentration of a substance that can be reliably detected and accurately quantified.
Related: Difference between LOD and LOQ
Q. What are the major equipment in analytical laboratory?
- Analytical Balance
- pH Meter
- IR Spectrophotometer
- UV Spectrophotometer
- HPLC
- GC
- TLC
- Dissolution test apparatus
- KF Titrator
- IR Moisture Balance
- Hot Plate
- Ultrasonic Bath etc.
Q. What are the most common human errors in Analytical laboratories?
- Data entry errors
- Calculation errors
- Sampling errors
- Interpretation errors
- Bias errors etc.
Q. What are the major stage of analytical method lifecycle?
- Method Development
- Method Validation
- Method Transfer
- Method Verification
- Routine Use
- Method Maintenance
- Method Retirement
Q. What is the requiremnt of cGMP regarding analytical test method?
The cGMP regulations [21 CFR 211.194(a)] require that test methods, which are used for assessing compliance of pharmaceutical products with established specifications, must meet proper standards of accuracy and reliability
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