Cloud-point extraction. Traces of lead in drinking water cause adverse health effects. The micelle-forming surfactant Triton X-114 (plus the co-surfactant cetyltrimethylammonium bromide) and a crown ether ligand extract and preconcentrate Pb2+ for analysis by inductively coupled plasma-optical emission spectrometry. The hydrophobic metal complex is extracted into the hydrophobic interior of micelles formed by Triton X-114 (Figure 28-17). Surfactants and crown ether are added to 245 mL of acidified aqueous sample. After 30 min for extraction, the solution is heated and becomes cloudy as the micelles aggregate into a separate please containing essentially all Pb(II). The aqueous phase is then removed. The micellar phase is back-extracted with 5.0 ml. of aqueous citrate solution that complexes Pb(l) more tightly than the surfactants. All Pb(l) ends up in the aqueous phase. By what factor is Ph(t) preconcentrated in this procedure? preconcentration factor Drinking water with negligible lead content was fortified with 2.14 g Pb(IIYL. Triplicate measurements yielded a mean of 1.93 g PITYL and a standard deviation of 0.2 mg Pb(IIYL. Find the percent recovery of the spike percent recovery: Determine the 95% confidence interval for the spike recovery. Refer to the table of Student's values as needed. 95% confidence interval: ot Does the spike recovery differ from the expected value of 2.14 pg/L 12+ at the 95% confidence level? no Determine the 95% confidence interval for the spike recovery if results were the same for six measurements instead of three. Refer to the table of Student's / values as needed 95% confidence interval: + pt. If results were the same for six measurements instead of three, does the spike recovery differ from the expected value at the 95% confidence level yes no Cloud-point extraction. Traces of lead in drinking water cause adverse health effects. The micelle-forming surfactant Triton X-114 (plus the co-surfactant cetyltrimethylammonium bromide) and a crown ether ligand extract and preconcentrate Pb2+ for analysis by inductively coupled plasma-optical emission spectrometry. The hydrophobic metal complex is extracted into the hydrophobic interior of micelles formed by Triton X-114 (Figure 28-17). Surfactants and crown ether are added to 245 mL of acidified aqueous sample. After 30 min for extraction, the solution is heated and becomes cloudy as the micelles aggregate into a separate please containing essentially all Pb(II). The aqueous phase is then removed. The micellar phase is back-extracted with 5.0 ml. of aqueous citrate solution that complexes Pb(l) more tightly than the surfactants. All Pb(l) ends up in the aqueous phase. By what factor is Ph(t) preconcentrated in this procedure? preconcentration factor Drinking water with negligible lead content was fortified with 2.14 g Pb(IIYL. Triplicate measurements yielded a mean of 1.93 g PITYL and a standard deviation of 0.2 mg Pb(IIYL. Find the percent recovery of the spike percent recovery: Determine the 95% confidence interval for the spike recovery. Refer to the table of Student's values as needed. 95% confidence interval: ot Does the spike recovery differ from the expected value of 2.14 pg/L 12+ at the 95% confidence level? no Determine the 95% confidence interval for the spike recovery if results were the same for six measurements instead of three. Refer to the table of Student's / values as needed 95% confidence interval: + pt. If results were the same for six measurements instead of three, does the spike recovery differ from the expected value at the 95% confidence level yes no
