Can high-performance liquid chromatography (HPLC) effectively separate and quantify trace levels of multiple pesticide residues in complex food matrices?

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.

You run the chromatography system with paper as the stationary phase and 70% isopropanol as the mobile phase. You determine the Rf  of a polar analyte to be 0.40. If you use 100% isopropanol (a less polar solvent) instead of isopropanol as the mobile phase what would you expect to happen to the Rf  value? No value effect on Rf higher  lower could be higher or lower

thin layer chromatography: What would happen to the Rf value of a compound if you increased the polarity of the mobile phase while using a polar stationary phase?   please help me this question! Thank you a lot

QUESTION 3 What is one disadvantage of using column chromatography?     It is relatively ineffective at separating most organic compounds     The desired compound must be the ≥95% majority compound in the initial mixture for a column to be effective     It is only effective at separating room temperature gasses     It wastes a significant amount of solvent