Gas Chromatography and Petroleum Analysis Practice Questions

Flashcards covering key multiple-choice concepts in gas chromatography, spectroscopy, physical testing of petroleum products, and laboratory safety.

What is the required ratio of $\text{O}_2:\text{H}_2$ in a Flame Ionization Detector (FID)?

$$0.2 - 0.5$$

What is the characteristic spectrum wavelength of $\text{S}_2^*$ in a Flame Photometric Detector (FPD)?

$$394\,\text{nm}$$

How does the response value of FPD sulfur change if the temperature of the detector increases?

It decreases

How is the response value of FPD to sulfur related to its quantity?

Exponentially

What is the maximum allowed vacuum degree of the SCD burner?

Less than $400\,\text{Torr}$

What does the peak capacity of a chromatographic column refer to?

The maximum number of peaks that can be arranged side by side in a column

What term specifically defines the process in chromatography where only some components enter the second GC for secondary separation?

Center cutting

What is the main purpose of headspace injection in gas chromatography?

To eliminate matrix interference in the sample

What devices are required to achieve temperature control for programmed temperature injection ports?

Both heating and refrigeration devices with components of small heat capacity

According to qualitative chromatography rules, what column type causes homogeneous components to appear according to their boiling point?

Weak polarity column

Which quantitative calculation method is affected when the flow rate of the mobile phase changes?

External standard method

Where does gas leakage mainly occur in gas chromatography?

Pipe joints

What is the most likely reason if a Thermal Conductivity Detector (TCD) cannot be adjusted back to zero after long-term use?

Contamination of the detector

If the baseline becomes unstable after prolonged use of an FID, what is the first recommended repair step?

Clean the nozzle

What is the most likely cause if peak elution time is normal but peak width is significantly larger?

Large amount of sample injected

What is the most likely cause if peak elution time is delayed and accompanied by a significant increase in peak width?

Decrease in the oven temperature

What is a possible reason for a sudden absence of peaks in a chromatograph equipped with TCD?

Breakage of TCD heating wires

What does split ratio generally refer to in gas chromatography?

Ratio of split gas flow rate to column flow rate

What is the common range of split ratio for split and splitless injection?

$$20 - 200$$

What type of stationary phase polarity is squalane?

Weak polarity

What is the maximum service temperature for a quartz capillary column coated with polyimide?

$$360\,^\circ\text{C}$$

What is the inner diameter of a wide-bore capillary column?

$$0.53\,\text{mm}$$

What is the typical output signal of a TCD detector?

Unbalanced voltage of Wheatstone bridge

Below what temperature should samples containing methanethiol (boiling point $6.2\,^\circ\text{C}$) be stored to prevent loss?

Below $4\,^\circ\text{C}$

To what standard atmospheric pressure are closed-cup flash point determination results corrected?

$$101.3\,\text{kPa}$$

What percentage of container volume should a sample fill when taken for open flash point determination?

$$85\% - 95\%$$

Which electrode is used as the indicator electrode in the potentiometric determination of thiol sulfur?

$\text{Ag}-\text{Ag}_2\text{S}$ electrode

Which reagent is required for removing hydrogen sulfide from a sample?

Cadmium sulfate

What standard titration solution is used in the ASTM D3242 method?

Potassium hydroxide alcohol solution

What is the bath operating temperature required for determining the gum content of aviation turbine fuel?

$$232 - 246\,^\circ\text{C}$$

How is dynamic viscosity obtained from measured kinematic viscosity?

By multiplying kinematic viscosity by the density of the liquid

At what angle should a test tube be tilted when observing the liquid level during condensation point measurement?

$$45^\circ$$

How many millimeters should the wick project into the lamp tube during kerosene smoke point testing?

$$6\,\text{mm}$$

Where should an operator stand when opening a high-pressure gas cylinder?

At the side

What is the correct order of toxicity among benzene, toluene, and xylene?

Benzene > Toluene > Xylene

What is the primary purpose of conducting a blank test in quantitative analysis?

To eliminate System Error

What is the main purpose of determining the octane number of gasoline?

To judge the antiknock property of Gasoline

At what temperature range should the crucible containing residue be burned into ash during petroleum product ash content determination?

$$775 \pm 25\,^\circ\text{C}$$

What are the chemical components of Karl Fischer reagent?

Iodine, $\text{SO}_2$, and Methanol

What is the required engine speed when analyzing gasoline octane number by the research method?

$$600 \pm 6\,\text{r/min}$$

What is the maximum allowed water content in carrier gas?

$$5\,\text{mg/kg}$$

What is the characteristic X-ray energy ($\text{K}_\alpha$) of sulfur?

$$2.3\,\text{keV}$$

What solution is used to clean instruments during atomic absorption analysis?

$$10\%\,\text{HNO}_3$$

What causes Lorentz broadening of atomic absorption spectral lines?

Collision of Atoms with other particles

What causes the 'surface effect' in ICP light sources?

The flame temperature is high at the surface but low at the center

Which lamp emits sharp linear light sources for atomic absorption analysis?

Hollow cathode lamp

How can mass spectrometric interference be eliminated in ICP-MS?

By selecting Non-interfering isotopes