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Figure 14 The following method was used to determine the levels of nicotine (1) in the urine of smokers. A 1.00 cm³ sample of urine was placed in a 12 cm' vial containing 0.7 g Na,CO, powder. After 5.00 µg of the internal standard 5-aminoquinoline (2) was injected, the vial was capped with a rubber septum. The vial was heated to 80°C for 20 minutes before an SPME needle was passed through the septum. The fibre was left in the headspace for 5 minutes. Then volatile substances were desorbed from the fibre at 250°C for 10 minutes in the GC injection port. During this time the column was held at 60°C while the analyte and intemal standard were trapped at the beginning of the column. The column temperature was then raised to 260°C at 25°C-min'. The eluate was monitored by El-MS with SIM at "/, 84 for nicotine and at "1, 144 for the internal standard. All values are averages of duplicate measurements. NH₂ 2 Calibration y = 0.0064x + 0.0222 R = 0.9956 A (nicotine) A (5-aminoquinoline) 50 100 150 250 Concentration (ug L) 1.6 1.4 1.2 R 1 0.8 0.6 0.4 0.2 0 0 200
Question 17: Consider the information in Figure 14. A urine sample from a non- smoking girl whose parents are heavy smokers had an average peak area ratio of 1.25. Find the nicotine concentration (ug.L-¹) in the sample. [Do not type in the unit.] Your answer