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Categories >> Sciences >> Chemistry >> Analytical Chemistry
 
 


 

 
 Organic Chemistry interview questions  Organic Chemistry Interview Questions (222)
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 Analytical Chemistry interview questions  Analytical Chemistry Interview Questions (846)
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Question
How to calculate LOD & LOQ in HPLC Validation Method
 Question Submitted By :: Analytical-Chemistry
I also faced this Question!!     Answer Posted By  
 
Answer
# 1
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)
 
Is This Answer Correct ?    176 Yes 17 No
Abdulkalim
 
Answer
# 2
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
 
Is This Answer Correct ?    108 Yes 15 No
M
 
 
 
Answer
# 3
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
 
Is This Answer Correct ?    41 Yes 9 No
Balaji
 
Answer
# 4
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
 
Is This Answer Correct ?    30 Yes 6 No
Sunil.madhukar Rao Kulkarni
 
Answer
# 5
Signal of noise ratio X 3 = LOD
LOD X 3.33 =LOQ
 
Is This Answer Correct ?    23 Yes 9 No
Ashutosh Kumar Srivastava
 
Answer
# 6
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
 
Is This Answer Correct ?    14 Yes 1 No
Bhupalreddy
 
Answer
# 7
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)
 
Is This Answer Correct ?    6 Yes 2 No
Rakesh P. Kotkar
 
Answer
# 8
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.
 
Is This Answer Correct ?    5 Yes 1 No
Dr.praveen Choubey
 
Answer
# 9
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
 
Is This Answer Correct ?    4 Yes 2 No
Nikhil Gandhi
 
Answer
# 10
Look at DIN ISO 32645 how to "really" calculate LOQ and
LOD. You need to perform a linearity test before !
Everyt5hing else is not very serious.
 
Is This Answer Correct ?    2 Yes 2 No
Guido
 

 
 
 
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