Proswift rp 4h monolithic column

Mass data for CTD-labeled HIV-1 CA were obtained with a Waters LCT Premier time-of-flight mass spectrometer, operating in positive ion mode and using electrospray ionization. Sample introduction was via a Thermo Proswift RP-4H monolithic column (1 mm inner diameter, 50 mm length), using a 100 μl/min flow rate and a solvent gradient from 100% H₂O to 80% methanol/20% acetonitrile (with 0.1% trifluoroacetic acid and 0.2% formic acid) in 9 min. The multi-charged m/z spectrum was deconvolved using the MaxEnt I program. Mass data for NTD-labeled HIV-1 CA were obtained with a Thermo MSQ Plus single quadrupole mass spectrometer, also operating in positive ion mode and using electrospray ionization. Sample introduction was via a Thermo Acclaim Pepmap 300 C18 column (1.0 mm inner diameter and 150 mm in length), using a 0.2 ml/min flow rate and a solvent gradient from 88% water/12% acetonitrile to 34% water/66% acetonitrile (with 0.01% trifluoroacetic acid) in 22 min. The multi-charged m/z spectrum was deconvolved using the MagTran program. Expected and measured masses for NTD-labeled CA were 26695.8 Da and 26527 Da respectively. Expected and measured masses for CTD-labeled CA were 26282.85 Da and 26134 Da respectively. From these data, we infer isotopic enrichment levels of about 99.4% for both segmentally labeled products.