Serum containing Na + gave a signal of 4.27 mv in an atomic emission analysis. 5.00 mL of 2.08 M NaCl were added to 95.0 mL of serum. The spiked serum gave a signal of 7.98 mV. How much Na + was in the original sample ( emission intensity in atomic emission analysis is directly propotional to the concentration of anlyte ) ? 2. Write a main protocal of spectrophotometric determination of iIron in industrial waste water using 1,10-Phenanthroline . 3. Why do we use Phenanthroline in question 2? 4. what is your standard sample? 5. Why do we add hydroxylamine hydrochloride in question 2?