Table 1: The factors and their levels investigated in robustness test.

Symbol FactorsMethod conditionLevels
+

Sorbent type
(Merck, #)
Al sheet
(1.05554)
Al sheet
(1.05554)
Al sheet
(1.05570)
Chamber typeTwin trough,
20 cm × 20 cm
Twin trough,
20 cm × 20 cm
Twin trough,
20 cm × 10 cm
Temperature of plate activation (°C)120130110
Extraction time (min)564
Distance of development (cm)7.58.07.0
Wavelength (nm)248250246
AnalystAAB