Select which of the following statements are true for high performance liquid chromatography (HPLC)Group of answer choicesHPLC often has an injector that only allows a fixed volume of sample (e.g. 10 μL) to be injected.There is no low-cost detector for HPLC that is as general, as sensitive, and with as large a relative range as the flame ionisation detector in gas chromatography.If the compounds in a normal phase HPLC analysis using a 50:50 vol/vol mixture of hexane: ethyl acetate were eluting too slowly, increasing the concentration of hexane would decrease the retention times of the analytes.The general elution problem in HPLC is solved by using rapid changes in temperature of the column and mobile phase.An HPLC column containing very small, uniform spherical packing material will have a higher column efficiency than a column with the particles of the same material that are larger and more irregular in size and shape.

True - HPLC often has an injector that only allows a fixed volume of sample (e.g. 10 μL) to be injected. This is to ensure precision and reproducibility in the analysis.

True - There is no low-cost detector for HPLC that is as general, as sensitive, and with as large a relative range as the flame ionisation detector in gas chromatography. Different detectors are used in HPLC depending on the nature of the compounds being analyzed.

False - In normal phase HPLC, the stationary phase is polar and the mobile phase is non-polar. If the compounds were eluting too slowly, you would want to increase the polarity of the mobile phase to decrease the retention times of the analytes. Therefore, you would increase the concentration of ethyl acetate, not hexane.

False - The general elution problem in HPLC is not solved by using rapid changes in temperature of the column and mobile phase. Instead, it is solved by using a gradient elution, where the composition of the mobile phase is changed during the separation process.

True - An HPLC column containing very small, uniform spherical packing material will have a higher column efficiency than a column with the particles of the same material that are larger and more irregular in size and shape. This is because smaller, uniform particles provide a larger surface area for interaction between the stationary phase and the analytes, leading to better separation.