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Table 2 Optimization of the chromatographic conditions for separation of a mixture of cetirizine, phenylpropanolamine and nimesulide by the proposed HPLC method

From: Simultaneous determination of cetirizine, phenyl propanolamine and nimesulide using third derivative spectrophotometry and high performance liquid chromatography in pharmaceutical preparations

Parameter No. of theoretical plates (N) Resolution (Rs) Tailing factor (T) Capacity factor (K’) Selectivity factor (α)
CTZ PPA NMS CTZ/NMS NMS/PPA CTZ PPA NMS CTZ PPA NMS CTZ/NMS NMS/PPA
PH of the mobile phase
 3 1330 979 1947 1.2 3.8 1.26 1.39 1.25 2.1 0.33 1.5 1.4 4.5
 4.6 1398 1246 1548 1.25 4.6 1.31 1.5 1.37 2.61 0.367 2.04 1.28 5.6
 6 2351 1248 1490 2.1 4.68 1.30 1.35 1.30 3.47 0.74 2.56 1.36 3.45
 7 2432 1794 2804 3.8 5.1 1.19 1.11 1.23 4.5 1.05 2.8 1.64 2.6
Conc. of phosphate buffer
 0.05 1947 1696 2497 1.1 4.1 1. 34 1.49 1.38 3.4 1.06 2.75 1.24 2.5
 0.1 2432 1794 2804 3.8 5.1 1. 19 1.11 1.23 4.5 1.05 2.8 1.64 2.6
 0.2 1146 1280 1855 1.9 3.66 1.23 1.52 1.36 3.4 0.58 2.05 1.7 3.55
Conc. of methanol (% v/v)
 50% 1513 1309 2133 2.1 4.1 2.07 0.99 1.32 4.78 1.1 3.4 1.4 3.3
 60% 2432 1794 2804 3.8 5.1 1.19 1.11 1.23 4.5 1.05 2.8 1.64 2.6
 70% 2396 1271 1496 0.5 3.8 2.22 1.9 1.32 2.47 1.02 2.3 1.07 2.25
 80% 1638 1229 1369 0.74 2.1 1.23 1.09 1.33 1.86 0.99 1.62 1.15 1.64
Type of organic modifier
 Methanol 2432 1794 2804 3.8 5.1 1.19 1.11 1.23 4.5 1.05 2.8 1.64 2.6
 Acetonitrile 2278 1374 1795 2.1 4.1 1.36 0.77 1.27 3.2 0.5 2.03 1.59 4.6
 n-Propanol 1920 900 1058 2.4 3.9 3.22 1.9 2.3 2.88 0.42 1.88 1.5 4.5
Flow rate (mL/min)
 0.8 1889 1123 2543 2.4 3.9 1.2 1.56 1.28 3.4 0.98 1.8 1.88 1.84
 1.0 2432 1794 2804 3.8 5.1 1.19 1.11 1.23 4.5 1.05 2.8 1.64 2.6
 1.2 2117 1247 2178 1.1 2.9 1.32 1.56 1.35 2.9 1.00 2.3 1.3 2.30
  1. Italic values indicate the optimum chromatographic conditions
  2. Number of theoretical plates (N) = \({5.54} \left( {\tfrac{{\text{tR}}}{{\text{Wh/2}}}} \right)^{2}\)
  3. Resolution (Rs) = \(\frac{{2\Delta {\text{t}}_{\text{R}} }}{{{\text{W}}_{1} + {\text{W}}_{2} }}\)
  4. Tailing factor (T) = \(\frac{{{\text{W}}_{0.05} }}{2f}\)
  5. Selectivity factor (relative retention) (α) = \(\frac{{\text{tR2} - \text{tm}}}{{\text{tR1} - \text{tm}}}\)
  6. Capacity factor (K’) = \(\frac{{\text{tR} - \text{tm}}}{{\text{tm}}}\)