Answer / abdulkalim

Based on standard deviation of the response and the slope
obtained will be calculated as:

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


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

Answer / m

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

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


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

3 Signal to noise ratio method

But residual standard deviation method is more reliable
method for determination of LOD and LOQ value

Answer / balaji

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

Answer / sunil.madhukar rao kulkarni

We can calculate LOD and LOQ values using linearity
graph,insted of sigma value STEYX can be considered for
more acuurate vale of LOD and LOQ

where STEYX : Standard error of the pridected Y-value for
each X in a regression

Final calulation given as below :

LOD = STEYX x 3/ Slope

LOQ = STEYX x 10 /Slope

Answer / ashutosh kumar srivastava

Signal of noise ratio X 3 = LOD
LOD X 3.33 =LOQ

Answer / bhupalreddy

Limit of Detection (LOD):
• Based on visual limitation
– Visual evaluation may be used for non-instrumental
methods but may also be used with instrumental methods.
– The detection limit is determined by the analysis
of samples with known concentrations of analyte and by
establishing the minimum level at which the analyte can be
reliably detected.
• Based on signal-to-noise
– This approach can only be applied to analytical
procedures which exhibit baseline noise.
– Determination of the signal-to-noise ratios is
performed by comparing measured signals from samples with
known low concentrations of analyte with those of blank
samples an establishing the minimum concentration at which
the analyte can be reliably detected. A signal-to-noise
ratio between 3 or 2:1 is generally considered acceptable
for estimating the detection limit.
• Based on the standard deviation of the response
and the slope
– The detection limit = 3.3 s / S
– Where s is the standard deviation of the response
and S is slope of the calibration curve.
– The estimate of S may be carried out in a variety
of ways, for example:
• Based on the standard deviation of the blank
• Based on the calibration curve


Limit of Quantification (LOQ):
• Based on visual limitation
– Visual evaluation may be used for non-instrumental
methods but may also be used with instrumental methods.
– The quantification limit is 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.
• Based on signal-to-noise
– This approach can only be applied to analytical
procedures which exhibit baseline noise.
– Determination of the signal-to-noise ratios is
performed by comparing measured signals from samples with
known low concentrations of analyte with those of blank
samples an establishing the minimum concentration at which
the analyte can be reliably quantified. A typical signal-to-
noise ratios is 10:1.
• Based on the standard deviation of the response
and the slope
– The quantification limit = 10s / S
– Where s is the standard deviation of the response
and S is slope of the calibration curve.
– The estimate of S may be carried out in a variety
of ways, for example:
• Based on the standard deviation of the blank
• Based on the calibration curve

Answer / dr.praveen choubey

by HPLC LOD @ LOQ calculated by S/N ratio that is the best
method.LOD s/N NLT 3 and LOQ S/N NLT 10 and also calculated
by visual evalution.

Answer / nikhil gandhi

Based on ICH Guideline there are many method given to
identify LOD and LOQ, but most useful method is slope and
residual standard deviation is used.

LOD : 3.3 X sigma/ Slope
LOQ : 10 X sigma/ Slope

Sigma : Residual Standard Deviation

Answer / rakesh p. kotkar

Based on standard deviation of the response and the slope
obtained will be calculated as:

Limit of Detection (LOD):
DL= 3.3(ASD/Slope)


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

Answer / pruthvi

why we have to take 3 for LOD and 10 for LOQ? why not other numbers?

How will decide to use HPLC OR GC for developing method for unkown compund

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