An unknown compound was analyzed by GC with octane (C3H13) and decane (C10H22). The adjusted retention times were 14.6 min for octane, and 31.6 min for decane. Calculate the retention index for the unknown if its adjusted retention time was 21.2 min.

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You are trying to separate a sample with 2 components: X and Y with GC. X has a lower boiling point than Y. Which one has a higher retention time? What is the most common way to increase retention of analytes in gas chromatography?

Substances A, B, C and D were found to have retention times of 8.3 min (A), 10.6 min (B), 12.4 min (C) and 13.5 min (D), respectively on an 15.0 cm long column. There was also an unretained species which appeared at 1.5 min. The widths of the peak bases were 0.90 min (A), 1.1 min (B), 1.3 min (C) and 0.80 min (D). Given this information listed above, please choose the most appropriate answer for the six questions listed below for the list of possible answers. Part A Calculate the capacity factor (k') for peak B and peak D. Part B. Calculate the resolution (R) between peaks B and D. Part C. What do the capacity factor and resolution tell you about the separation of peaks B and D on this column? Part D What are the theoretical plate number (N) for peaks Band D? Part E. What is the average plate height (H), based on the information in Part D and the column length listed above? Part F What would be the required length of a column to achieve a Rs of 2.07

The figure below shows a typical separation of several fat-soluble vitamins by HPLC. The x-axis is retention time in minutes.  From the graph try to estimate retention times for peaks 2 and 3. Retention time peak 2 = Retention time peak 3 = Assume that w1/2 is 0.15 minutes for peak 2 and 0.16 minutes for peak 3. Assume that tm is 2.00 minutes. How much time does gamma-tocopherol spend in the stationary phase? From tr and w1/2 find N for the peak that elutes first.  From tr and w1/2 find the resolution of peaks 2 and 3 Calculate α for these peaks. If the flow rate for the column is 1.2 mL/minute what is the retention volume for peak 4?

QUESTION 5 In a chromatographic separation using a polar stationary phase and a mobile phase composed of 60% hexane and 40% ethyl acetate, two compounds, benzene (peak A) and toluene (peak B), are eluted. The width of peak A at its base is 1.2 min, the width of peak B at its base is 1.3 min, and the retention time of peak A is 5.2 min and peak B is 3.5 min. What is the resolution (Rs) between these two peaks and is it acceptable? R = 1.36. It is not an acceptable resolution. R = 0.74. It is an acceptable resolution. R = 1.36. It is an acceptable resolution. R = 0.74. It is not an acceptable resolution.

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You must separate three different compounds with reversed phase HPLC. Compound 1 is an acid (pKa = 4.3), compound 2 is neutral compounds and compound 3 is a base (pKa = 9.6). As eluent, use 30/70 (v / v)% methanol / pH 3.0 formic acid buffer. The retention time and the top width at the base of the top for the three components are presented below. You can assume the dead time to 1.2 minutes in your calculations.Compound Retention time [minutes] Peak width [seconds] 1 10.1     282 5.0 143 6.1 17a) Calculate the efficiency (number of theoretical bases) for component 1.b) Calculate the selectivity and resolution between components 1 and 2.c) When you increase the pH of your eluent to pH 6, how will the retention be affected (increase, decreaseor unchanged) for the different associations (1, 2 and 3) ?, justify your answer.d) How retention factors are generally affected by an increase in the proportion organicallymobile phase solvents for reversed phase HPLC separations ?, justify your…

A 20-cm long packed column was used to perform the separation of A and B by LC. TRA=16.28 min, TR,B=17.50 min, WA=1.11 min, WB=1.19 min, tм=1.30 min. (a) Calculate the retention factor (k') for A and B. (b) Calculate the average number of theoretical plates and plate height.

What is the best Chromatography instrument for analysis of Soluble Protein molecules CG-FID GC-MS LC-MS IC-MS O IC-EC