6Wang G F, Horita K, Satake M. Simultaneous spectrophotometric determination of nitrate and nftrfte in water and some vegetable samples by column preconcentration[J]. Microchemical Journal, 1998, 58 :162 -174.
7Zatar N A, Abu-Eid M A, Eid A F. Spectrophotometric determination of nitrite and nitrate using phosphomolybdenum blue complex[J]. Talanta, 1999, 50:819- 826.
8Guerrero,Benito,Calatayud. Flow-injection analysis spectrophotometric determination of nitrite arid nitrate in water samples by reaction with proflavin[J]. Talanta, 1996, 43:239 -246.
9Davis J, Mckeegan K J, Cardosi M F, et al. Evaluation of phenolic assays for the detection of nitrite[J]. Talanta,1999, 50: 105-112.
10Kazemzadeh, Ensafi. Simultaneous determination of nitrite and nitrate in various samples using flow-iEjection spectrophotometric detection[J]. Microchemical Journal, 2001, 69:159- 166.