Analytical HPLC of daptomycin (A), daptomycin-TEG-maleimide (B), daptomycin-TEG-bisphosphonate (C), and dansyl-daptomycin-TEG-bisphosphonate (D). The analysis was performed with a Waters 600E system, using Alltech C18 5μ, 250×4.6 mm column coupled to a Waters 486 detector at 254 nm. Sample was eluted with a linear gradient of 20-70% CH3CN in water containing 0.1% CF3CO2H in 30 min with a flow rate of 1mL/min. The retention times for the peaks in A, B, C, and D were 18.3 min, 18.4 min, 15.5 min and 15.9 min, respectively.