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Whether the use of internal standard is mandatory as per usfda guidelines

Dear all

Could any one of you could clear me whether the usaged of internal standard is mandatory as per usfda guidelines in validating the method in LC/MS/MS

[quote=karthikeyan_j3]Dear all

Could any one of you could clear me whether the usaged of internal standard is mandatory as per usfda guidelines in validating the method in LC/MS/MS[/quote]

Not mendatory but recommended.

[quote=karthikeyan_j3]Dear all

Could any one of you could clear me whether the usaged of internal standard is mandatory as per usfda guidelines in validating the method in LC/MS/MS[/quote]

Not mandatory but recommended.

[quote=karthikeyan_j3]Dear all

Could any one of you could clear me whether the usaged of internal standard is mandatory as per usfda guidelines in validating the method in LC/MS/MS[/quote]

Internal standards are especially useful for analyses in which the quantity of sample analysed or the instrument response varies slightly from run to run for reasons that are difficult to control. For example, gas or liquid flow rates that vary by a few percent in a chromatography experiment could change the detector response. A calibration curve is only accurate for the one set of conditions under which it is obtained. However, the relative response of the detector to the analyse and standard is usually constant over a wide range of conditions. As long as the concentration of standard is known, the correct concentration of analyte can be derived. Internal standards are widely used in chromatography because the small quantity of sample solution injected into the chromatograph is not very reproducible in some experiments.

Internal standards are also desirable when sample loss can occur during sample preparation steps prior to analysis. If a known quantity of standard is added to the unknown prior to any manipulations, the ratio of standard to analyte remains constant because the same fraction of each is lost in any operation.

So it depends on method/ sample quanitity or sample preparation whether use the internal standard method or not, guidelines do not forced to do IS methods particulary and it is not mandotory anywhere.