Math Problem Statement
An unknown compounds was separated into its 4 components using liquid chromatography. The experiment was run using a C-18 column with a length of 25 cm and a diameter of 0.46 cm. The solvent eluted at 16.5 seconds and the experiment was run using a flow rate of 1.2 mL/min. The table above shows the resulting chromatogram parameters
Compound 1 had a peak height of 0.072, an elution time of 120 seconds, and a peak width at base 28 s. Compound 2 had a peak height of 0.046, an elution time of 225 seconds, and a peak width at base 70 s. Compound 3 had a peak height of 0.061, an elution time of 310 seconds, and a peak width at base 55 s. Compound 4 had a peak height of 0.041, an elution time of 608 seconds, and a peak width at base 98 s.
Solution
We can analyze the chromatography experiment based on the provided data. Here's the step-by-step breakdown:
1. Dead Time ()
The dead time, , is the time the solvent takes to elute, which is given as 16.5 seconds.
2. Capacity Factor ()
The capacity factor for each compound is calculated using: where is the retention time (elution time).
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For Compound 1:
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For Compound 2:
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For Compound 3:
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For Compound 4:
3. Column Efficiency (Number of Theoretical Plates, )
The number of theoretical plates is calculated using: where is the peak width at the base.
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For Compound 1:
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For Compound 2:
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For Compound 3:
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For Compound 4:
4. Selectivity ()
The selectivity is calculated for consecutive peaks as:
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Between Compound 1 and 2:
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Between Compound 2 and 3:
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Between Compound 3 and 4:
5. Resolution ()
The resolution between peaks is calculated as: where is the difference in retention times between adjacent compounds, and is the average of the two base widths.
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Between Compound 1 and 2:
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Between Compound 2 and 3:
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Between Compound 3 and 4:
6. Peak Asymmetry (Optional)
If peak asymmetry data is needed, it would require additional information about the peak tailing factor.
Summary of Key Results:
- values:
- values:
- values:
- values:
Would you like detailed steps for any calculation, or additional analysis such as peak areas or interpretation of chromatographic performance?
5 Questions for Deeper Exploration:
- How does the selectivity influence the separation efficiency of the column?
- Why might Compound 2 have the lowest number of theoretical plates?
- Can we infer anything about the polarity of the compounds from their retention times?
- How would increasing the flow rate impact the resolution of the peaks?
- What other factors can affect the column efficiency in this experiment?
Tip:
Always ensure the column's performance metrics (like , ) meet the method's validation criteria to maintain accurate and reproducible separations.
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Math Problem Analysis
Mathematical Concepts
Chromatography
Retention Time
Capacity Factor
Column Efficiency
Selectivity
Resolution
Peak Asymmetry
Formulas
Capacity Factor (k') = (t_r - t_m) / t_m
Column Efficiency (N) = 16 * (t_r / w_b)^2
Selectivity (α) = k'_2 / k'_1
Resolution (R_s) = Δt_r / w_b
Theorems
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Suitable Grade Level
Undergraduate
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