Constant-energy synchronous luminescence (CESL) offers significant improvements in selectivity and sensitivity compared to the more conventional constant-wavelength synchronous luminescence (CWSL) technique. Despite this consideration, practical problems can be encountered that have not been reported in the literature. This paper offers an explanation of these technical issues—why they occur and how they can be avoided—and the method optimized to take full advantage of this powerful technique. Polycyclic aromatic hydrocarbons (PAHs) were selected for demonstrating all our conclusions, because of their carcinogenic activity; 16 of them appear in the EPA (Environmental Protection Agency) list as PAHs for which it is necessary to develop efficient methods for their precise and accurate quantification at low levels. The technique can be applied to other complex fluorescent mixtures.

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