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Standard Addition

  • Page ID
    281556
    1. A spectrophotometric method for the quantitative analysis of Pb2+ in blood yields an Ssamp of 0.193 when a 1.00 mL sample of blood is diluted to 5.00 mL. A second 1.00 mL sample of blood is spiked with 1.00 mL of a 1560-ppb Pb2+ external standard and diluted to 5.00 mL, yielding an Sspike of 0.419. What is the concentration of Pb2+ in the original sample of blood?

     

     

     

     

     

     

     

     

    1. An experiment looking for sodium content in blood serum uses a standard addition method. Each sample contained 25.00 mL of serum, a volume of 2.640 M NaCl standard and a total volume of 50.00 mL. The data below are obtained. What is the concentration of sodium in the sample?

    Graph_Sodium.png

     

     

     

     

     

     

     

     

     

    1. Sodium concentration may be determined by flame emission, but the flame emission is effected by a number of parameters including flow rates, temperatures and other variables that can be hard to control. To aid detection, lithium can be added as an internal standard. Using a constant 1000 ppm Li solution, the following response curve was constructed. If an unknown has a sodium to lithium intensity ratio of 0.0463, what is the concentration?

    Graph_LithiumInternalStandard.png

    Figure from Fundamentals of Analytical Chemistry by Skoog

     

     

     

     

     

     

     

    1. To test a glucometer, a spike recovery is carried out by measuring the amount of glucose in a sample of a patient’s blood before and after spiking it with a standard solution of glucose. Before spiking the sample the glucose level is 86.7 mg/100 mL and after spiking the sample it is 110.3 mg/100 mL. The spike is prepared by adding 10.0 μL of a 25 000 mg/100mL standard to a 10.0-mL portion of the blood. What is the spike recovery for this sample?

     

     

     

     

     

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