Trifluoroacetic acid

Fluticasone propionate and salmeterol xinafoate powder were purchased from Discovery Fine Chemicals (Windborne, United Kingdom). Fisher Scientific supplied the dimethyl malonyl (Waltham, MA, USA). Methanol and dimethylformamide (DMF) were obtained from Tedia high purity solvent (Fairfield, USA). Alpha Chemika (Mumbai, India) supplied chloroform, acetonitrile HPLC grade, trifluoroacetic acid (TFA), and HPLC grade water. Diethyl ether, dimethyl sulfoxide (DMSO), potassium hydroxide (KOH), sodium hydroxide (NaOH), and sodium chloride (NaCl) were purchased from Labogens (Ahmedabad, Gujarat, India). Sigma (Pool, UK) provided the tyrosine amino acid and tetramethyl silane. All materials were used as supplied without any further purification.

FP, salmeterol xinafoate (SAL) and diethylene glycol were obtained from Sigma (Pool, UK). L-lysine and 2,5-furyl dichloride were purchased from Acros Organics (Geel, Belgium). Ethyl acetate, trifluoroacetic acid (TFA), dimethyl sulfoxide (DMSO), acetone, and acetonitrile were obtained from Alpha Chemika (Mumbai, India). Glycerin was obtained from Labchem (Zelienople, PA, USA). Additionally, potassium hydroxide (KOH) pellets were obtained from Riedel-de Haën (Seelze, Germany), while methyl alcohol, diethyl ether, and HPLC-grade water were purchased from Tedia High Purity Solvents (Fairfield, CT, USA).