Table 2.

Comparative analysis of macro- and microanalytical tools for the separation of VOCs.

Feature	Conventional GC Columns [212,214]	µGC Columns [229,240]	Microfluidic Channels [253,261,262]
Typology	Capillary	Capillary Chip based	Chip based
Geometry 1	10–100 m (L) 0.18–0.53 mm ($\varnothing$)	1–3 m (L) 50–500 µm (W) 50–800 µm (H)	1–5 cm (L) 2–4 mm (W) 50–500 µm (H)
Selectivity 2	$\uparrow$ L  ;  $\downarrow \varnothing$	$\uparrow$ L  ;  $\uparrow$ H/W	$\uparrow$ L  ;  $\uparrow \uparrow$ W/H
Layout	Circular spiral	Serpentine Circular spiral Square spiral Wavy Zigzag Radiator	Straight
Cross section	Circular	Square Trapezoidal Semicircular Circular	Square Circular
Coating materials	Polymeric films (PDMS) Inorganic sorbents (silica, Al2O3)	Polymeric films (PDMS) Carbon–polymer hybrids Inorganic sorbents (silica, Al2O3)	Polymeric films (Parylene) Pure metals (Au) Metal oxides (ZnO)

¹ Length (L), width (W), height (H), and diameter ($\varnothing$). ² General premises to increase the selectivity or segregation power of each analytical solution.