Here is a student procedure to measure nicotine in urine. A 1.00-mL sample of biological fluid was placed in a 12-mL vial containing $\mathbf{0}\mathbf{.}\mathbf{7}\mathbf{}{\mathbf{gNa}}_{\mathbf{2}}{\mathbf{CO}}_{\mathbf{3}}$powder. After $\mathbf{5}\mathbf{.}\mathbf{00}\mathbf{\mu g}$of the internal standard 5 -aminoquinoline were injected, the vial was capped with a Teflon coated silicone rubber septum. The vial was heated to ${\mathbf{80}}^{\mathbf{°}}\mathbf{c}$for 20 min and then a solid-phase microextraction needle was passed through the septum and left in the headspace for 5.00min. The fiber was retracted and inserted into a gas chromatograph. Volatile substances were desorbed from the fiber at ${\mathbf{250}}^{\mathbf{°}}\mathbf{c}$for 9.5min in the injection port while the column was at ${\mathbf{60}}^{\mathbf{°}}\mathbf{c}$. The column temperature was then raised to ${\mathbf{250}}^{\mathbf{°}}\mathbf{c}$at ${\mathbf{25}}^{\mathbf{°}}\mathbf{c}\mathbf{/}\mathbf{min}$and eluate was monitored by electron ionization mass spectrometry with selected ion monitoring at m/z 84 for nicotine and m / z 144 for internal standard. Calibration data from replicate standard mixtures taken through the same procedure are given in the table.

(a) Why was the vial heated to ${\mathbf{80}}^{\mathbf{°}}\mathbf{c}$before and during extraction?

(b) Why was the chromatography column kept at ${\mathbf{60}}^{\mathbf{°}}\mathbf{C}$during thermal desorption of the extraction fiber?

(c) Suggest a structure for m / z 84 from nicotine. What is the m / z, 144 ion from the internal standard, 5 -aminoquinoline?

(d) Urine from an adult female nonsmoker had an area ratio m / z .84 / 144=0.51 and 0.53 in replicate determinations. Urine from a nonsmoking girl whose parents are heavy smokers had an area ratio 1.18 and 1.32.

Find the nicotine concentration $\left(\mathrm{\mu g}/L\right)$and its standard uncertainty in the urine of each person.

• chromatography is a technique for separating the components, or solutes, of a mixture based on the relative amounts of each solute distributed between a flowing fluid stream, known as the mobile phase, and a stationary phase that is contiguous.

• Aminoquinolines are quinoline compounds that are most known for their antimalarial properties. They can be classified into the following categories based on where the amino group is located: 4-Aminoquinoline. 8-Aminoquinoline.

• During daily smoking, normal peak blood nicotine concentrations vary from 19 to 50 ng/ml, with typical trough concentrations ranging from 10 to 37 ng/ml; each cigarette raises blood nicotine concentrations by 5–30 ng/ml, depending on how the cigarette is smoked.

(a)

The purpose for heating the vial to ${80}^{°}\mathrm{C}$before and throughout the extraction must be explained.

To explain why the vial was heated to ${80}^{°}\mathrm{C}$before and throughout the extraction.

The vial was heated to increase the vapor pressure of the analyte and the internal standard, allowing enough headspace in the gas phase to extract a significant amount with the microextraction fiber.

(b)

The reason for keeping the column temperature at ${60}^{°}\mathrm{C}$during the thermal desorption of the fibre extraction must be explained.

To explain why the temperature of the column was kept at ${60}^{°}\mathrm{C}$during the thermal desorption of the fibre extraction.

During the start of the column, the analyte and the internal standard would be cold trapped at ${60}^{°}\mathrm{C}$. Desorption from the fibre would take longer (in minutes), and chromatography should not commence until complete desorption has occurred. As a result, during the thermal desorption of the fibre extraction, the temperature of the column is kept at ${60}^{°}\mathrm{C}$.

(c)

A framework for m/z84 derived from nicotine and m/z144 It must be proposed that 5 -aminoquinoline be used.

As an example, m/z84 derived from nicotine and m/z144 5-aminoquinoline is a 5-aminoquinoline derivative.

For 5-aminoquinoline

$\mathrm{m}/\mathrm{z}144{\mathrm{ismolecularionC}}_9{\mathrm{H}}_8{\mathrm{NC}}_5{\mathrm{H}}_{10}{\mathrm{N}}_2^{+}$

(d)

Each person's nicotine content and standard uncertainty in urine must be estimated.

To calculate the nicotine concentration and standard uncertainty in each person's urine.

The nicotine concentration in each person's urine, as well as the standard uncertainty, is listed here. Non-smokers are${78}_{-}^{+}5\mathrm{\mu g}/\mathrm{L}$

It is for non-smokers who have smoking parents${192}_{-}^{+}6\mathrm{\mu g}/\mathrm{L}$

Least squares parameters are utilized in the block B16:C18 of the spreadsheet below. For two duplicate unknowns, the mean value of y is put in cell B24. In cell B25, put the number of duplicates. Cell B26 calculates the derived value of x, while cell B27 calculates the uncertainty.

The values for the unknowns are,

Non-smokers are ${78}_{-}^{+}5\mathrm{\mu g}/\mathrm{L}$

It is for non-smokers who have smoking parents ${192}_{-}^{+}6\mathrm{\mu g}/\mathrm{L}$

A graph with x and y is plotted, and the graph is presented below.