关键词: 亚硝酸盐；快速检测；酱腌菜；检测性能；贮存稳定性

Abstract: In order to improve the safety and efficiency of spectrophotometry in the determination of nitrite and its applicability to pickles, the spectrophotometric method specified in the Chinese national standard was modified by using three new diazo-coupling reagents: p-aminobenzene sulfonic acid/N-(1-naphthyl) ethylenediamine dihydrochloride (ASA-NED), p-aminoacetophenone/N-(1-naphthyl) ethylenediamine dihydrochloride (AAP-NED) and sulphanilamide/N-(1-naphthyl) ethylenediamine dihydrochloride (SN-NED) to replace the two-step reaction. For each diazo-coupling reagent, the operating conditions were optimized using an orthogonal array design, and the detection performance and storage stability of the diazo-coupling reagents were compared. The results showed that in the optimized ASA-NED, AAP-NED and SN-NED methods, succinic acid, tartaric acid, and malic acid respectively could replace concentrated hydrochloric acid as the acid medium, shortening the detection time by 5–14 min, and improving the safety and detection efficiency. The linear detection ranges of the ASA-NED, AAP-NED and SN-NED methods were 0.02–3, 0.02–3 and 0.02–3.4 μg/mL, and the detection limits were 0.82, 0.51 and 0.76 mg/kg respectively, compared to 1 mg/kg for the traditional method. The AAP-NED method had comparable anti-interference capacity to that of the traditional method, and the AAP-NED and SN-NED methods were more resistant to interference than the traditional method. When the levels of nitrite in 15 kinds of pickle were detected by the four methods, except for high iodine kelp samples, the accuracy decreased as follows: AAP-NED (96.01%–99.60%) > SN-NED (93.82%–96.24%) > traditional (88.61%–92.66%) > ASA-NED (84.04%–87.00%), and the relative standard deviation (RSD) values were all less than 5%. SN-NED at all temperatures investigated and AAP-NED only at 4 ℃ were stable for 40 days, having better detection applicability than ASA-NED. In conclusion, the efficiency and safety of spectrophotometry could be improved by using AAP-NED and SN-NED, which could be suitable for the rapid determination of nitrite in pickles.

Key words: nitrite; rapid detection; pickles; detection performance; storage stability