Internal Standard for Paracetamol Assay

[Merrin]

Hi everyone,

I have been developing an assay for paracetamol and it's metabolites (paracetamol sulphate and paracetamol glucuronide) and the method I have developed was based ona literature method (Journal of Pharmaceutical and Biomedical Analysis, 34 (2004) 585-593). The method uses a mobile phase of 0.1M KH2PO4, 1.5% isopropanol, 0.,1% THF - I recognize that this is an unusual mobile phase but it works really well for this separation. The flow rate is 0.8mL/min and the column is a 4.6 x 250mm c18 column.

The problem I am having is finding a suitable internal standard. The paracetamol is the last of the analytes to elute (24.5min) and I would be looking for an internal standard likely to elute after this. If anyone has any suggestions I would love to hear them!

Thanks.

Merrin

[Kazimierz]

Dear Merrin,

Please try 3-acetamidophenol acc. to

Karel Allegaert et al. (2005)
Intra- and interindividual variability of glucuronidation of paracetamol during repeated administration of propacetamol in neonates
Acta Paediatrica 94 (9), 1273–1279, 2005.

http://www.blackwell-synergy.com/doi/ab ... .tb02088.x