Question

the lithium concentration in serum taken from a patient being treated with lithium for manic-depressive illness was analyzed using flame emission spectroscopy. a sample of the serum gave a reading of 223 units for the intensity of the 671 nm red emission line. then, 1.00 ml of a 11.4 mm lithium standard was added to 9.00 ml of serum. this spiked serum gave an intensity reading of 565 units at the 671 nm emission line. what is the original concentration of li in the serum?

Answer 1

To determine the original concentration of lithium in the serum, we can use the concept of dilution. First, calculate the dilution factor by taking the ratio of the final volume to the initial volume. Next, set up a proportion using the dilution factor and solve for the original concentration of lithium in the serum.

Step-by-step explanation:

To determine the original concentration of lithium in the serum, we can use the concept of dilution. First, we need to calculate the dilution factor, which is the ratio of the final volume to the initial volume. In this case, the final volume is 10 ml (1 ml of standard + 9 ml of serum) and the initial volume is 9 ml. Therefore, the dilution factor is 10/9.

Next, we can use this dilution factor to calculate the original concentration of lithium in the serum. The intensity of the red emission line is directly proportional to the concentration of lithium. So, we can set up a proportion:

Intensity of standard/Original concentration of standard = Intensity of spiked serum/Original concentration of serum

Plugging in the given values, we have:

223/11.4 = 565/C

Solving for C, we get:

C = (565 * 11.4) / 223

C ≈ 28.85 mm

Therefore, the original concentration of lithium in the serum is approximately 28.85 mm.