How to measure the theoretical plate number of a liquid chromatography column?

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Recently, the peaks obtained in the liquid phase have not been of good quality – either they show tailing or their shape is too wide. After consulting, it is possible that the column efficiency has decreased; it is recommended to measure the number of theoretical plates to verify this. Some theoretical knowledge was found, as follows: The theoretical plate number (N) is used to quantitatively express the separation efficiency of a chromatography column (referred to as column efficiency). N depends on the type and properties of the stationary phase (particle size, particle size distribution, etc.), the packing condition, column length, the type and flow rate of the mobile phase, as well as the properties of the substance used to determine column efficiency. If the peak shape is symmetric and follows a normal distribution, N can be approximated as: N = (tR / σ)² = 16 * (tR / W)² = 5.54 * (tR / 1/2w)²; where W is the peak width ； σ: Half of the peak width at the inflection point of the curve, that is, half of the peak width at 0.607 times the peak height. When N is a constant, W varies proportionally with tR. On a multicomponent chromatogram, if the contents of each component are similar, the peaks that elute later become progressively wider while their peak heights gradually decrease. Calculating the theoretical number of plates using the half-width is more convenient and common than using the full width, as the half-width is easier to measure accurately, especially for peaks with slight tailing. N is proportional to the length of the column; the longer the column, the greater N is. When using N to denote column efficiency, the column length should be specified; if it is not specified, it refers to the number of theoretical plates when the column length is 1 meter. (Generally, the N value for HPLC columns is above 1000.) ) If the theoretical number of plates is calculated using the adjusted retention time (tR’), the resulting value is known as the effective theoretical number of plates (N_eff or Neff) = 16(tR’/W)2. How exactly is this value determined? I hope everyone will not hesitate to share their insights.