The following quality control method was used to measure EDTA in blood using fortification and allowing the calculation of detection limit.

 

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(a) To measure accuracy and precision of the method, blood was fortified with EDTA to known levels. Accuracy = 100 x (mean value found known value)/(known value) Precision = 100 x (standard deviation / mean) = coefficient of variation For each of the three spike levels in the table below, find the precision and accuracy of the quality control samples. EDTA measurements (ng/mL) at three fortification levels Spike: 22.2 ng/mL 88.2 ng/mL 314 ng/mL Found: 33.3 322 19.5 305 23.9 282 20.8 329 20.8 276 For the fortification level of 22.2 ng/mL what is the percent precision? 4.0 52.8 X % For the fortification level of 22.2 ng/mL what is the percent accuracy? 4.0 6.58 X Check the number of significant figures.% For the fortification level of 88.2 ng/mL what is the percent precision? 4.0 37.6 X % 83.6 69.0 83.4 100.0 76.4 For the fortification level of 88.2 ng/mL what is the percent accuracy? 4.0 -6.49 X Check the number of significant figures.% For the fortification level of 314 ng/mL what is the percent precision? 4.0 17.5 X % For the fortification level of 314 ng/mL what is the percent accuracy? 4.0 -3.57 X Check the number of significant figures.% (b) Low concentrations of EDTA near the detection limit gave the following dimensionless instrument readings: 175, 104, 164, 193, 131, 189, 155, 133, 151, and 176. Ten blanks had a mean reading of 60.0. The slope of the calibration curve is 1.75 x 10⁹ M-¹. Estimate the signal detection limit for EDTA. 4.0 531 X What is the concentration detection limit? 4.0 269e-9 X M What is the lower limit of quantitation? 4.9 898e-9 X M (a) To measure accuracy and precision of the method, blood was fortified with EDTA to known levels. Accuracy = 100 x (mean value found known value)/(known value) Precision = 100 x (standard deviation / mean) = coefficient of variation For each of the three spike levels in the table below, find the precision and accuracy of the quality control samples. EDTA measurements (ng/mL) at three fortification levels Spike: 22.2 ng/mL 88.2 ng/mL 314 ng/mL Found: 33.3 322 19.5 305 23.9 282 20.8 329 20.8 276 For the fortification level of 22.2 ng/mL what is the percent precision? 4.0 52.8 X % For the fortification level of 22.2 ng/mL what is the percent accuracy? 4.0 6.58 X Check the number of significant figures.% For the fortification level of 88.2 ng/mL what is the percent precision? 4.0 37.6 X % 83.6 69.0 83.4 100.0 76.4 For the fortification level of 88.2 ng/mL what is the percent accuracy? 4.0 -6.49 X Check the number of significant figures.% For the fortification level of 314 ng/mL what is the percent precision? 4.0 17.5 X % For the fortification level of 314 ng/mL what is the percent accuracy? 4.0 -3.57 X Check the number of significant figures.% (b) Low concentrations of EDTA near the detection limit gave the following dimensionless instrument readings: 175, 104, 164, 193, 131, 189, 155, 133, 151, and 176. Ten blanks had a mean reading of 60.0. The slope of the calibration curve is 1.75 x 10⁹ M-¹. Estimate the signal detection limit for EDTA. 4.0 531 X What is the concentration detection limit? 4.0 269e-9 X M What is the lower limit of quantitation? 4.9 898e-9 X M

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a To measure accuracy and precision of the method blood was fortified with EDTA to known levels Accu... View the full answer