A novel method for quantitative determination of tea polysaccharide by resonance light scattering

A new method for the determination of tea polysaccharide (TPS) in green tea (Camellia sinensis) leaves has been developed. The method was based on the enhancement of resonance light scattering (RLS) of TPS in the presence of cetylpyridinium chloride (CPC)–NaOH system. Under the optimum conditions, the RLS intensity of CPC was greatly enhanced by adding TPS. The maximum peak of the enhanced RLS spectra was located at 484.02 nm. The enhanced RLS intensity was proportional to the concentration of TPS in the range of 2.0–20 μg/ml. It showed that the new method and phenol–sulfuric acid method give some equivalent results by measuring the standard compounds. The recoveries of the two methods were 96.39–103.7% (novel method) and 100.15–103.65% (phenol–sulfuric acid method), respectively. However, it showed that the two methods were different to some extent. The new method offered a limit of detection (LOD) of 0.047 μg/ml, whereas the phenol–sulfuric acid method gives a LOD of 1.54 μg/ml. Interfered experiment demonstrated that the new method had highly selectivity, and was more suitable for the determination of TPS than phenol–sulfuric method. Stability test showed that new method had good stability. Moreover, the proposed method owns the advantages of easy operation, rapidity and practicability, which suggested that the proposed method could be satisfactorily applied to the determination of TPS in green tea.

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► Based on tea polysaccharide (TPS) reaction with cetylpyridinium chloride under alkaline condition, RLS method was developed to determine TPS content and colorimetric method was compared with.
► The detection limits of two methods are 0.047 μg/ml (RLS) and 1.54 μg/ml (colorimetric), respectively.
► RLS method had higher selectivity and safer operation than colorimetric method. RLS method was more suitable for the determination of TPS than colorimetric method.