calibration curve and LoQ

[gkoksal]

Hi

for a new analysis,first calibration curve is plotted, 0,25-30 ppm range,
then LOD and LoQ are calculated by analysing blank sample (including anaylte naturally).
second calibration curve is plotted for LoD(2ppm)-30ppm.
then ı use last calibration curve to calculate samples. this way is correct,isnt it?
because when ı use last calibration curve to calculate LOD and LoQ by the same way, ı acquire different LOD and LoQ results

[shahi.hardeep]

It seemed you are using linear method to calculate the LOD and LOQ.There are 2 other methods to determine the LOQ and LOD.In the linear method though if your LOD and LOQ is the part of your Calibration curve standard then the results will be fine as long the higher concentration is close to LOQ.