Fluorimetric Determination of p-Hydroxybenzoic Acid in Beer as α-Cyclodextrin Inclusion Complex

Abstract

The inclusion complex of p-hydroxyenzoic acid and α- and β-cyclodextrin has been studied by fluorescence spectroscopy. To describe quantitatively complex formation between α-cyclodextrin (α-CD) and p-hydroxybenzoic acid, an association constant of 967 ± 14 M⁻¹ at 21°C was obtained. The inclusion complex has been used to determine p-hydroxybenzoic acid in the range 0.15–1.00 mg L⁻¹ (RSD 4.5%, n = 8). Application of the method to determination of p-hydroxybenzoic acid in beer samples gave an endogenous content of 1.25 mg L⁻¹.

Keywords:

• α-cyclodextrin
• fluorimetry
• inclusion
• p-hydroxybenzoic acid

Notes

S_A=s_s/m (s_s is the standard deviation of the analytical signal, m is the slope of calibration graph).

^a for a signal-to-noise ratio=3.

^b for signal-to-noise ratio=10.