Question { Reddy Labs, 111963 }

How to calculate LOD & LOQ in HPLC Validation Method

Answer

There are three different method indiated in ICH guidelines
for determination of LOD and LOQ.

1 Visual evaution method - For non instrument and sometimes
for instrumental also.

2 Slope Method:Based on residual standard deviation of the
response and
the slope
obtained will be calculated as:

Limit of Detection (LOD):
DL= 3(RESIDUAL SD/Slope)


Limit of quantification(LOQ):
DL=10(RESIDUAL SD/Slope)

3 Signal to noise ratio method
Limit of Detection (LOD):
S/N NLT 3

Limit of quantification(LOQ):
S/N NLT 10
Slope and S/N methods are more reliable
method for determination of LOD and LOQ value

Question { Archimedes, 11286 }

How we can analysed unknown sample by hplc....

Answer

first check the structure of the compound.identify the
chromophore groups(for UV Detector),refractive index status
(for RI Detector),reactive status with other chromophore
group compounds(Derivitation method for UV.then check the
solubility status of the compound.prepare a known
concentration solution.

In HPLC select a C18 Column which can serve better for the
polar and not polar compounds.select a buffer pH Oof +/-1
unit of pka value of the compound prepare a buffer mix with
some 20% of organic solvent to chnge the elution early
(based on polarity)

inject the prepared known concentration sample solution in
to above system by observing the chromatogram procced
further by altering buffer
pH,COLUMN,FLOW,TEMPERATURE,ORGANIC RATIO Sample size etc.

but to quantify the unknown concentration we need a known
concentration of standard.

Question { 29530 }

what is the difference between mcg
and ppm?

Answer

PPM:
This is a way of expressing very dilute concentrations of
substances. Just as per cent means out of a hundred, so
parts per million or ppm means out of a million. Usually
describes the concentration of something in water or soil.
One ppm is equivalent to 1 milligram of something per liter
of water (mg/l) or 1 milligram of something per kilogram
soil (mg/kg).

mcg:
mcg = microgram = 1/1000 of a mg (milligram) There are one
thousand micrograms in one milligram.

Hardly we can say there is no much difference between these
two.

Question { Macleods, 49190 }

how can we determine RRF value in HPLC FOR CALCULATION OF
IMPURITY ?

Answer

RRF-Relative responce factor with respect to analyte(standard)
why its required- due to impurity cost,availability and time
consumption of analysis etc we can not go for everytime
impurity by impurity calculation every time
so,that finding a factor for impurities with respect to
standard.by preparing few levels of(3+ levels)standard and
impurities concentrations(can prepare between +/- 50% of
specification level of known impurities and for standard
between +/- 50% of specification level of unknown
impurities).inject the above prepared solution in to
hplc,calculate slope for impurities and standard by using
respective concentrations and areas.

RRF=SLOPE OF IMPURITIES/SLOPE OF STANDARD

Question { Granules, 6894 }

void volume is depending on column or not? if yes how will
you depend?

Answer

Yes column dependant.

Why because:Total volume of mobile phase in a fully wet
packed column- the space between the particles of the
stationary phase plus the volume within the particles

So,based on length,internal diameter and particle size of
column it varies.

Question { Neuland, 7574 }

what is defferance between dipolemoment and polarity

Answer

Electronegativities, Bond Polarities and Dipole Moments -The
electrons on the most chemical bonds are unequally shared.
The reason of the inequality is that the atoms forming bond
have different ability to attract electrons.
Electronegativity is a measure of the relative attraction
that an atom has for the shared electrons in a bond. Bond
Polarity is a measure of inequality in the sharing of
bonding electrons. The Bond Polarity is a vector, pointing
from the atom with less electronegativity to the atom with
larger one. The separation of positive and negative charges
causes an electric dipole moment. If the vector sum of Bond
Polarities of a molecule is not zero, the molecule is said
having Dipole Moment.

Question { Rakshit Drugs, 17641 }

why we use polystyrene film for ftir calibration?

Answer

Most people are only using FTIR for identification, so
wavelength accuracy is most important.

A polystyrene film is an easy way to calibrate the entire
wavelength range of the instrument. The film produces
sharp absorbance bands at known wavelengths (or
frequencies) which can be used to verify that the
instrument's spectrum is accurate.

And also additionaly other than polystyrene we can use any
other reference material which is having known sharp
absorbence bands at different wavenumbers.

concept is calibrating the instrument against known
material and known results.

Question { 7083 }

what is mean by profiling of dissolution

Answer

Dissolution profile means
collecting samples at different time points while
performing dissolution with respect to the nature and type
of formulation(IR,SR,MR etc).

Dissolution profiling will help you to find the
discreminating power,samness with innovator sample and also
as reference during other investicational studies.

Dissolution profile comparison
1. For accepting product sameness under SUPAC-related
changes.
2. To waive bioequivalence requirements for lower strengths
of a dosage form.
3. To support waivers for other bioequivalence requirements.