1)why use benzophenon,uracil in hplc calibration. 2)why use sucrose in polarime

1)why use benzophenon,uracil in hplc calibration.
2)why use sucrose in polarimeter calibration.
3)what is S/N ratio, noise and drift in hplc
4)how we can find lod and loq in method validation

Question Posted / jignesh

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1)why use benzophenon,uracil in hplc calibration. 2)why use sucrose in polarimeter calibration. 3)..

Answer / sri krishna

1. URACIL & BENZOPHENONE are commonly available standards,
with simple mobile phase i.e acetonitrile & water they can
be separated, peak shape is good, retension time is very low.
2. Sucrose is optically active which shows linearity1. Very
Easily prepared, Has a fixed rotation value which can
calibrated with 10%, 20% and 30% sugar value, and remains
constant for those concentration for a little time only,
upto that we can have a very sharp reading calibration of
pure sugar, Mainly polarimeter is used sucrose quality
detection for calibration with pure sucrose is the best
deal, Its shows almost no Muta rotation,And last and
final...Its most cheap to figure out and get the calibration
done.
3. signal to noise ratio. where signal is the response of
the analyte and noise is the disturbance present in the base
line.drift is the slow increase/ decrease the base line.
4.LOD: BY 7.1. Based on Visual Evaluation
Visual evaluation may be used for non-instrumental methods
but may also be used with instrumental methods.
The quantitation limit is generally determined by the
analysis of samples with known concentrations of analyte and
by establishing the minimum level at which the analyte can
be quantified with acceptable accuracy and precision.
7.2. Based on Signal-to-Noise Approach
This approach can only be applied to analytical procedures
that exhibit baseline noise.
Determination of the signal-to-noise ratio is performed by
comparing measured signals from samples with known low
concentrations of analyte with those of blank samples and by
establishing the minimum concentration at which the analyte
can be reliably quantified. A typical signal-to-noise ratio
is 10:1.
7.3. Based on the Standard Deviation of the Response and the
Slope
The quantitation limit (QL) may be expressed as:
QL = 10 σ/S

where σ = the standard deviation of the response
S = the slope of the calibration curve