8- trace elements in the teeth of archeological specimentprovides anthropologists with clus about the dite and diseases ofancient people . Porter et al (20020 measured the trace elementsstrontium from extracted teeth by atomic absorption spectroscopy. Aseries of solutions were preaperd, each containing 0.750 mg ofdissolved tooth enamel. Varying volumes of 100.0 ng/ml Sr stocksolution were added to each flask ,and each solution was diluted toa total constant volume of 10.0 ml The final result was a series offlasks containing the following concentration of added Sr.

flask Volume of Sr stock solut. added ,ml concent. of Sr afterdiluttion ng/ml Blank-concent signal

1 ? 0.00 28.0

2 ? 2.50 34.3

3 ? 5.00 42.8

4 ? 7.50 51.5

5 ? 10.0 58.6

a. suppose 5.00 mg of powdered tooth enamel is dissolved inultra- pure HNO3 and diluted to 10.0 ml in volumetric glasswear.What volume of this solution must be delivered to each flask , inorder to deliver 0.750 mg dissolved enamel to the flask? (showcalculations)

b. The Sr standards in the table above were made by deliveringvolume aliquote of a 100.0 ng/ml Sr stock solution to each 10.0 mlflask . complete the table above to show what volume of Sr stockwere added to each flask ,in order to produce the specificconcentrations of added Sr?(please show calculations)

c. What type of standardization is being performed here? why isthis type of standardization being used , rather that somealternative standardization?

d. Least -squares analysis of the data resulted in the plotshown , where y=3.136x+27.36 and R^2 =0.9973

calculate the concentration of Sr in flask.( show the plot from-10 -5 0 5 10)

e. calculate the Sr content in the original tooth enamel , inunits of ppm=micro gram Sr/g enamel. ( please show completecalculation)