Physics Notes

 Solution

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The Determination of the Charge to Mass Ratio of the Electron. A magnetic field produced by Helmholz coils is used to deflect electrons into circular paths whose radii are known. By knowing the energy of the electrons and the magnetic field strength, the ratio of the charge to mass (e/m) of the electron is determined.

The calculated (e/m) ratio is  1.7588196×10 

11

 Ckg 

−1

 .

How it calculated two different methods

I calculated Limit of Detection (LOD) and Limit of Quantification (LOQ) with results (Table1) obtained from HPLC (spiked muscle sample) . For this purpose, I used regression analysis and two formulas. But, I obtained two different results from these two formulas. In fact, we expect that these two results have to be same. What is the reason?

Formula 1.

LOD = 3,3X(SD of interception /slope)

LOQ =10X(SD of interception /slope)

Formula 2.

LOD= 3.3*(SE of interception / X Value1)

LOQ= 10*(SE of interception / X Value 1)

Table 1. The results of spiked muscle sample

Table 1 is attached.

Which formula is correct in order to use?