Role of sodium sulphate as additive in mobile phase

[AA]

Chris,

Post up the conditions, I would love to try them. I have little doubt that freshly distilled THF would be better than stabilized, but as you point out, most (including me) would be unwilling to do that.

AA

[Chris Pohl]

AA,

I'm not sure which aminoglycosides you're interested in but I've taken these conditions from a recently developed method for Sisomicin and Netilmicin. The column used is the Acclaim PA (from Dionex) 2.1 x 150 mm. Temperature: 40°C. Eluent: 800mM HAc/NaAc (pH 5), 1mM sodium octanesulfonate, 1% acetonitrile (12.96 mL of 100% HAc, 47.12g NaAc, 10 mL acetonitrile, 10 mL 0.1M OSA Na to a final volume of 1.0 L). Flow rate: 0.25 mL per minute. IPAD detection at 0.05 volts versus a silver / silver chloride reference electrode (waveform below). 3 mm gold working electrode. Gasket thickness: 5 mil (0.127 mm). Post column addition of 0.5 molar sodium hydroxide at 0.25 mL per minute.

Waveform (time in seconds):
Time 0.00, 0.05 Volts
Time 0.20, 0.05 Volts (start integration)
Time 0.40, 0.05 Volts (stop integration)
Time 0.41, -2.0 Volts
Time 0.42, -2.0 Volts
Time 0.43, +0.6 Volts
Time 0.44, -0.1 Volts
Time 0.50, -0.1 Volts