Abstract: A spectroscopic method was used for the quantitative analysis of sodium nitrite after solid phase extraction. The analytical wavelength was set at 472.5 nm, and the derivatization conditions were optimized as follows: pH 4.74, derivatization time 15 min, and derivatization reagent composition sodium nitrite:p-aminobenzenesulfonic acid:1-naphthol molar ratio of 1:3:3. Enrichment was accomplished using a nylon membrane with a loading volume of 10 mL. In the concentration range of 0.002–0.030 mg/L, the absorbance (y) had a quadratic relationship with nitrite concentration (x), expressed as y = ?268.76x2 + 14.55x + 0.03, with a correlation coefficient (R2) of 0.999, and the limit of detection (LOD) of the presented method was 1.29 μg/L. The method was applied to the detection of NaNO2 in tap water with spiked recoveries of 91.3%–114.0%, and relative standard deviations (RSDs) of 4.21%–7.90%. The results of this method for sodium nitrite in bacon agreed with those of ion chromatography, with standard deviations of 8.51% and 9.98% in parallel experiments on American-style and Shuanghui-branded bacons, respectively. This study has provided a rapid, sensitive, accurate and precise method for the determination of NaNO2 with high selectivity.

Key words: solid phase extraction combined with spectroscopy; solid phase extraction; ultraviolet-visible diffuse reflectance spectroscopy; NaNO2; rapid determination