Strata x 33 m polymeric reversed phase

The Pen content of the bone samples (TP) was analysed by HPLC as described by Greis et al. [34 (link)], with several modifications (introduction of a solid phase extraction, shortened gradient in HPLC). A total of 100 mg of bone powder were hydrolysed with 1 ml of 6 N HCl at 110 °C for 18 h. After drying, 1 ml of 0.01 M heptafluorobutyric acid (HFBA) was added. The solution was filtered through syringe filters (Ø 25 mm and 0.45 µm pore diameter), and solid phase extraction was performed (Phenomenex, Strata-X 33 µm Polymeric Reversed Phase). The dried samples were dissolved in 200 µl of pyridoxine-HFBA buffer. A total of 50 µl of each sample were injected into the HPLC system. The stationary phase was a semi-preparative column (Onyx™ Monolithic Semi-PREP C18, 100 × 4.6 mm) by Phenomenex. A linear gradient of acetonitrile (eluent B) and 0.1% HFBA in HPLC water (eluent A) was used as mobile phase with a flow rate of 1 ml/min over a period of 37 min, an extinction/emission wavelength of 335/385 nm for detection of pentosidine. Pen was identified by its retention time. A pentosidine standard (pentosidine 0.03303 nmol/ml in 0.01 M HFBA, Cayman Chemical) was used to establish a calibration curve.

All radiosyntheses were carried out using anhydrous DMF (Aldrich) and MeOH (Aldrich or Acros). Cu(MeCN)₄OTf (Aldrich) was stored under argon. QMA cartridges (Sep-Pak Accell Plus QMA Carbonate Plus Light Cartridge) were obtained from Waters (Waters GmbH, Eschborn, Germany) and used without any preconditioning. RP-cartridges (Strata™-X 33 µm polymeric reversed phase, 200 mg/3 mL, tube) were from Phenomenex (Phenomenex Ltd., Aschaffenburg, Germany).
[¹⁸F]Fluoride was produced by the ¹⁸O(p,n)¹⁸F reaction by bombardment of enriched [¹⁸O]water with 16.5 MeV protons at the BC1710 cyclotron (The Japan Steel Works Ltd., Shinagawa, Japan) of the INM-5 (Forschungszentrum Jülich) or PETtrace 4 cyclotron (GE Healthcare, Uppsala, Sweden) at the IHB (Saint-Petersburg). If not otherwise noted, all radiolabeling experiments were carried out under ambient or synthetic air.
Standard deviations were calculated using standard formulae.