Interference in Na+ measurements on the Siemens RAPIDPoint® 500 after nortriptyline intoxication: a case report

Perchlorate interference with electrolyte analysis

“…Interestingly, in previous reports no effect of perchlorate on Na + or Cl − measurements of Siemens RAPIDPoint 405, RAPIDLab 405 and RAPIDLab 865 blood gas analyzers was mentioned [4,5]. Only a few substances were reported to interfere with Na + measurements on blood gas analyzers, such as benzalkonium heparin and nortriptyline [6,7]. The interference of nortriptyline was only observed for RAPIDPoint 500 and was specific for Na + [7].…”

“…Only a few substances were reported to interfere with Na + measurements on blood gas analyzers, such as benzalkonium heparin and nortriptyline [6,7]. The interference of nortriptyline was only observed for RAPIDPoint 500 and was specific for Na + [7]. The authors suggested that the Na + -selective ionophore in the membrane of the electrode was also susceptible to nortriptyline.…”