Rapid determination of sulfonated naphthalenes and their formaldehyde condensates in aqueous environmental samples using synchronous excitation fluorimetry

Sulfonated naphthalenes and their formaldehyde condensates (SNFC) were dete rmined in aqueous environmental samples by spectrofluorimetry. A clean-up s tep using n-hexane to extract possibly interfering nonpolar compounds such as naphthalene is the only preparatory procedure. Synchronous excitation mo de with a Delta lambda of 105 nm allows the determination of SNFC in enviro nmental samples without additional clean-up or analyte enrichment. Interfer ences by humic acids and nitrate occurred only at concentrations higher tha n 1 mg C L-1 and 10 mg NO3- L-1, respectively. The limit of detection was 0 .2 mug L-1, the average recovery was 104% and the confidence interval (95% certainty) was 24%. The response factor for the quantitative determination of total SNFC, depending on the distribution of the different SNFC componen ts, was validated for groundwater from two field sites using an HPLC-FD (fl uorescence detection) method as a reference method.