Question

a) Horvat and co-workers used atomic absorption spectroscopy to determine the concentration of Hg in coal fly ash.22 Of particular interest to the authors was developing an appropriate procedure for digesting samples and releasing the Hg for analysis. As part of their study they tested several reagents for digesting samples. Their results using HNO3 and using a 1 + 3 mixture of HNO3 and HCl are shown here. All concentrations are given as ppb Hg sample.

HNO3: 161 165 160 167 166

1+3 HNO3–HCl: 159 145 140 147 143 156

Determine whether there is a significant difference between these methods at a = 0.05.

B) Mizutani, Yabuki and Asai developed an electrochemical method for analyzing l-malate.27 As part of their study they analyzed a series of beverages using both their method and a standard spectrophotometric procedure based on a clinical kit purchased from Boerhinger Scientific. The following table summarizes their results. All values are in ppm.

Sample	Electrode	spectrophotometric
Apple Juice 1	34	33.4
Apple Juice 2	22.6	28.4
Apple Juice 3	29.7	29.5
Apple Juice 4	24.9	24.8
Grape Juice 1	17.8	18.3
Grape Juice 2	14.8	15.4
Mixed fruit Juice	8.6	8.5
Mixed fruit Juice	31.4	31.9
White wine 1	10.8	11.5
White wine 2	17.3	17.6
White wine 3	15.7	15.4
White wine 4	18.4	18.3 Determine whether there is a significant difference between the methods at a = 0.05.