An analytical experiment yields a calibration curve which has a linear least squ

Question

An analytical experiment yields a calibration curve which has a linear least squares fit of

S = 1.25CPb + 0.06

with

S = relative instrument signal

CPb = lead concentration (in ppb)

When a blank sample (CPb = 0.0 ppb) was analyzed 25 times, the mean analytical signal was found to be 0.12 with a standard deviation of 0.019. Based on the above calibration equation and experimental results:

a) What is the calibration sensitivity?

b) What is the signal limit of detection for this method?

c) What is the limit of detection in concentration units for this method?

d) If the signal measured for a particular sample is S= 205+17, what is the lead concentration?

Please do include the formulas

Explanation / Answer

a) Calibration Sensitivity = Slope of the Calibration Curve

Calibration Sensitivity = 1.25

b) Signal limit of detection for this method = 3 x Stadard Deviation

Signal limit of detection for this method = 3 x 0.019 = 0.057

c) Limit of detection in concentration units for this method = 10 x 0.019 = 0.19

d) Lead Concentration = 205 / 1.25 = 160 ppb

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