Cooperative Institute for Research in Environmental Sciences Univers. of

Curtis L Shellum

John William Birks

A post-column photochemical reaction method to improve the detection limits of compounds which absorb radiation in the range of 240 nm to 800 nm has been developed for high performance liquid chromatography (HPLC). Specifically, the limit of detection of HPLC has been reduced to a range of from about 0.5 pg to about 10 pg for a large class of organic compounds which promotes the formation of 'singlet oxygen'. These compounds transfer excitation energy to ground state oxygen, forming the excited singlet species, O.sub.2 (.sup.1 .DELTA.g). Singlet oxygens in turn react with a substituted furan such as 2,5-dimethylfuran (DMF) or 2,5-diphenylfuran (DPF). UV absorption or fluorescence is used to detect either the loss of the substituted furan or the appearance of the oxidation product of the substituted furan. The reaction is photocatalytic in nature and results in a large chemical amplication of the signal. Detection limits are improved by one to two orders of magnitude for a wide variety of UV-absorbing compounds.

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Curtis L Shellum