Hollow fiber-based liquid-liquid-liquid microextraction (HF-LLLME) followed by flow injection analysis and spectrophotometric detection was applied as a simple and sensitive quantitative method for the determination of nitrite in water and food samples. Flow injection system included a conventional HPLC system (without a chromatographic column) and spectrophotometric detector. First of all nitrite reacts with 4-aminobenzoicacid in acidic medium to form diazonium ion, which is coupled with 1-Naphtol in basic medium to form azo dyes, showing a maximum absorption at 517nm. The concentrations of these reagents were optimized. After adjusting the pH of the sample, the dye is extracted by HF-LLME. The extraction of nitrite was carried out using isoamyl benzoate as the organic phase for filling the pores of the hollow fiber wall, and 1 M NaOH solution as acceptor phase in the lumen of the fiber. The factors affecting the HF-LLLME including type of organic solvent, pH of donor phase, concentration of acceptor, salt effect, extraction temperature, extraction time, and stirring rate were investigated and the optimal extraction conditions were established. The interference of some anions and cations was also tested. With the consumption of 5 mL of sample solution, the enrichment factor was 402. The limit of detection was at 0.1 ?g/L. Inter- and intra-day precision was (RSD%) 2.3 and 4.8, respectively. Excellent linearity was found between 1 and 50 ?g/L. The method was successfully applied to the determination of nitrite in various water samples and food samples including tap water, Zayanderood water, potato, sausage, cucumber, and dill. the nitrite contents were also measured by Griess standard method. Then the results were compared and the good correspondence between them exhibit that the presence method could be competently used for determination of nitrite in food and environmental samples.
