Benzophenone Lab Report

wavelength Percentage concentration (methanol: water) Peak H value (height equivalent to a theoretical plate) (mm)
230nm 80:20 Phenol 0.0373 Benzophenone 0.0196 Naphthalene 0.0164
235nm 80:20 Phenol 0.0327 Benzophenone 0.0203 Naphthalene 0.0147
260nm 80:20 Phenol 0.0318 Benzophenone 0.0202 Naphthalene 0.0146
Figure 11: table for the height equivalent of the theoretical plates.

It can be observed that the H values or height equivalent to a theoretical plate for phenol at the three wavelengths (230, 235, and 260nm) are all fairly similar, they are all around the 0.03mm mark (use of one significant figure), with all three H value being above 0.03mm. It can be seen in the results that the theoretical plate height decreases as the wavelength
plate height is calculated using the equation:
H = L/N
Plate height is normally reported in millimetres. The ability of a column to separate components of a mixture is improved by decreasing the plate height, so therefore an efficient column will have more theoretical plates with smaller plate heights than an inefficient column with less theoretical plates and larger plate heights. The smaller the plate height in the column, the narrower the bandwidths will be (17, Harris, 2010).
The height equivalent to a theoretical plate, as discussed above, is defined as the proportionality constant relating the length of the column and the number of theoretical plates. Thus, the defining equation of the height equivalent to a theoretical plate is as displayed above. In which N is the number of theoretical plates and L the length of the column (18, 2015). eluent phenol benzophenone naphthalene
Values for the peak area at 260nm, and concentration mixture of 90% methanol 10% water. 2520.496 2595.128 1751.678 2521.154 2595.098
The composition of the mobile phase effects the retention times of the components and the resolution between the components, because the more polar that the mobile phase is the longer the components will take to elute from the column, this then effects the resolution. The more polar the mobile phase the larger or greater the resolution will be, and the larger the resolution is the clearer the separation between the components is.
The best detection wavelength was 260nm, this is because at 260nm the wavelength contains the least amount, if any background noise, which give extra peaks. The signal varies with wavelength because of its ability to detect the peak of interest at its maxima, and higher wavelengths this is quantitatively better because of the peak heights, at higher wavelengths the peaks heights are