一种测定纸制品中可迁移性荧光增白剂含量的双波长紫外光谱方法

在现行GB/T 27741—2011的“可迁移性荧光增白剂的定量测定—紫外分光光度法”对纸制品进行萃取时，其中的残余木素会部分析出，对可迁移性荧光增白剂含量的光谱检测造成了干扰。据此，提出了一种双波长(305和348 nm)光谱的改进方法，旨在消除析出木素的干扰。它是基于可迁移性荧光增白剂在348 nm波长处有最大吸收，并且析出木素和荧光增白剂分别在波长305和348 nm的吸光度比值确定，因此可通过双波长光谱法扣除析出木素在348 nm处对荧光增白剂吸光度检测的干扰，从而实现对可迁移性荧光增白剂的准确定量检测。结果表明：双波长光谱法可有效地减少析出木素对可迁移性荧光增白剂吸光度检测的干扰，使定量检测的结果更为可观。方法的重复性检测的相对标准偏差为2.17%;定量检测限为16.9 mg·kg-1;回收率在98%～104%之间。与现行可迁移性荧光增白剂的定量测定的平行标准—液相色谱法相比，由于本方法具有简便、仪器及操作维护费用低等优点，因此更适合生产过程的产品质量控制和市售点对纸制品中可迁移性荧光增白剂含量的快速分析。

A Method for Determination of Migratable Fluorescent Whitening Agents in Paper Products by Dual-Wavelength UV Spectroscopy

The current national standard method GB/T 27741—2011, i. e., “quantitative determination of migratable fluorescent whitening agents-UV spectroscopy”, overestimates the migratable fluorescent whitening agents (FWA) in the paper based products because of the spectral interference of the leached lignin from the cellulose fibers. To minimize such interference, a spectroscopic method based on dual-wavelength (305 and 348 nm) measurement was proposed. It was observed that the dual-wavelength spectroscopy can effectively subtract the spectral absorption contributed by the leached lignin in the extraction medium, thus more accurately determination of migratable FWA can be performed. The results showed that the present method has a relative standard deviation of 2.17%, the quantitative detection limit of 16.9 mg·kg-1, and recovery of 98%～103%. Compared with the current alternative standard-HPLC method, the present method possesses advantages of low operation and maintenance costs, simple, and practical in application. Therefore, it is more suitable for the rapid determination of migratable FWA in the product quality control in the production process and sample examination in the commercial market.