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(a) What types of solutes are typically separated with a poly(dimethylsiloxane)-coated open tubular column?

(b) What types of solutes are typically separated with a poly(ethylene glycol)-coated open tubular column?

(c) What types of solutes are typically separated with a porous-layer open tubular column?

Short Answer

Expert verified

(a.)

Selecting a liquid stationary phase depends on the rule "like dissolves like". This signifies that the Polarity of the column must be the same as that of the solute

(b.) Solutes that are typically separated with a poly(dimethylsiloxane)-coated open tubular column are the following (based on Table 24-1)

(c.) Porous-layer columns contain porous solid particles with large surface area that adhere to the column wall. The highly retentive surface of the particles serve as the active stationary phase. Solutes that are typically separated with a porous-layer open tubular column areHe,Ar2O2,N2,CH4andCO. Furthermore, porous polymers, high-surface-area carbon , and alumina (Al2O3)can separate hydrocarbons in gas-solid adsorption chromatography.

Step by step solution

01

To find the types of solutes are typically separated with a poly(dimethylsiloxane)-coated open tubular column 

(a)

Selecting a liquid stationary phase depends on the rule "like dissolves like". This signifies that the Polarity of the column must be the same as that of the solute

02

find the types of solutes are typically separated with a poly(ethylene glycol)-coated open tubular column

03

Step 3: types of solutes are typically separated with a porous-layer open tubular column

(C)

Porous-layer columns contain porous solid particles with large surface area that adhere to the column wall. The highly retentive surface of the particles serve as the active stationary phase. Solutes that are typically separated with a porous-layer open tubular column areHe,Ar2O2,N2,CH4andCO. Furthermore, porous polymers, high-surface-area carbon , and alumina (Al2O3)can separate hydrocarbons in gas-solid adsorption chromatography.

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Most popular questions from this chapter

Nitric oxide (NO) is a cell-signaling agent in physiologic processes including vasodilation, inhibition of clotting, and inflammation. A sensitive chromatography-mass spectrometry method was developed to measure two of its metabolites, nitrite(NO-2)and nitrat(NO3),in biological fluids. Internal standards,NO-152and15NO-3, were added to the fluid at concentrations of 80.0 and, respectively.Natural14NO-2and14NO-3plus the internal standards were then converted to volatile derivatives:

Because biological fluids are so complex, the derivatives were first isolated by high-performance liquid chromatography. For quantitative analysis, liquid chromatography peaks corresponding to the two products were injected into a gas chromatograph, ionized by negative ion chemical ionization (giving major peaks forNO-2andNO3-and the products measured by selected ion monitoring. Results are shown in the figure on the next page. If the internal standards undergo the same reactions and same separations at the same rate as theN14analytes, then the concentrations of analytes are simply[14NOx-]=[15NOx-](R-Rblank)

where R is the measured peak area ratio(m/z46/47fornitriteandm/z62/63fornitrite)for nitrite andfor nitrate) andRblankis the measured ratio of peak areas in a blank prepared from the same buffers and reagents with no added nitrite or nitrate. The ratios of peak areas areand. The ratios for the blank werem/z46/47=0.062andm/z62/63=0.058. Find the concentrations of nitrite and nitrate in the urine.


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 0.7gNa2CO3powder. After 5.00μ²µof the internal standard 5 -aminoquinoline were injected, the vial was capped with a Teflon coated silicone rubber septum. The vial was heated to 80°cfor 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 250°cfor 9.5min in the injection port while the column was at 60°c. The column temperature was then raised to 250°cat 25°c/minand 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 80°cbefore and during extraction?

(b) Why was the chromatography column kept at 60°Cduring 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 (μ²µ/L)and its standard uncertainty in the urine of each person.

3. (a) What are the advantages and disadvantages of using a narrower open tubular column?

(b) What are the advantages and disadvantages of using a longer open tubular column?

(c) What are the advantages and disadvantages of using a thicker film of stationary phase?

This problem reviews concepts from Chapter 23 using

Figure 24-7.

(a) Calculate the number of theoretical plates (N in Equation 23-30)

and the plate height (H) for CO.

(b) Find the resolution (Equation 23-23) between argon and oxygen.

This problem reviews concepts from Chapter 23. An unretained solute passes through a chromatography column in 3.7 min and analyte requires 8.4 min.

(a) Find the adjusted retention time and retention factor for the analyte.

(b) Find the phase ratio b for a 0.32-mm-diameter column with a 1.0-mm-thick film of stationary phase.

(c) Find the partition coefficient for the analyte.

(d) Determine the retention time on a similar length of 0.32-mm diameter column with a 0.5-mm-thick film of the same stationary phase at the same temperature.

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