Table 3.

Percent weight and moles of colistin on the surface of spray dried combination particles determined by X-ray photoelectron spectroscopy (n=3 or 4). Data is presented as mean ± standard deviation

Formulation	Percentage weight fraction of colistin		Percentage molar fraction of colistin
	Theoretical	Experimental	Theoretical	Experimental
Colistin alone	100.0	99.6 ± 0.6	100.0	99.2 ± 1.1
1:1 Col a -Tob b	69.0	88.6 ± 5.0	50.0	78.0 ± 7.3
1:5 Col-Tob	31.0	76.8 ± 1.3	16.7	59.7 ± 1.5
Tobramycin alone	0.0	0.0 ± 0.1	0.0	0.0 ± 0.0

^aCol – colistin

^bTob – tobramycin