Study On Fluorescence Analysis Of Nitrite

Nitrite widely exists in the environmental,water,food,industrial and physiological systems.It would react with decomposition products of protein in the human body and then generate carcinogenic compunds.It can also make normal hemoglobin oxidized and deactivated,and then lead to hypoxic and cause acute poisoning.Therefore,it has very important significance for the determination of nitrite.Due to high sensitivity,selectivity and low detection limits of fluorescence methods,it is widely used in the detection of nitrite.Three novel fluorescent analysis methods were studied for the determination of nitrite in this paper.?1?Determination of nitrite with 2,3-diamino-phenazine by fluorescence quenching methodFluorescence intensity?FI?of 2,3-diamino-phenazine is very weak under acidic conditions,and reaching the maximum value within the pH range of 6-8,which would decrease with the increasing of the pH.2,3-Diamino-phenazine could react with nitrite in acidic conditions,and FI of the product obtained is weak in the neutral conditions,thus it would be used to detect nitrite in a nuetral condition.FI of the system would enhanced under the addition of hexadecyl-trimethyl-ammonium-bromide?CTAB?.Therefore,a micellar enhanced fluorescence quenching method for the determination of nitrite established.Its optimum reaction conditions was list as follows: the concentrations of sulphuric acid and CTAB were 0.03mol/L and 2.0×10^-3mol/L,the reaction temperature was 50?,reaction time was 50 min,and the emission wavelength was 557 nm.FI was linear in the nitrite concentration range from 0.1×10^-6mol/L to 2.1×10^-6mol/L,and the detection limit was 9.8×10^-8mol/L.This method was used successfully to detect the content of nitrite in water sample and the recovery rate was between 100.5%¹01.5%.?2?Determination of nitrite with 4-amino-n-butyl-1,8-naphthalimide by fluorescence quenching methodFluorescence quenching was found in the reaction between 4-amino-n-butyl-1,8-naphthalimide and nitrite under acidic conditions.And FI was enhanced at the addition of CTAB.Thus a new determination method of nitrite with 4-amino-n-butyl-1,8-naphthalimide by fluorescence quenching was established.Its option reaction conditions ws listed as follows: the concentrations of hydrochloric acid and CTAB were 0.09mol/L and 3.0×10^-3mol/L,the reaction temperature was 60?,reaction time was 30 min,and the emission wavelength was 535 nm.The linearity range for the concentration of nitrite was 0.1¹.7×10-7mol/L and the detection limit was 7.1nmol/L.The recovery rate of the nitrite content in water sample was from 101.1% to 103.4%.?3?Determination of nitrite with 4-?4-methylpiperazinyl?-n-amino-1,8-naphthalimide by fluorescence increasing method.FI of 4-?4-methylpiperazinyl?-n-amino-1,8-naphthalimide increased substantially after the reaction with nitrite under the acidic conditions.Thus a new determination method of nitrite with 4-?4-methylpiperazinyl?-n-amino-1,8-naphthalimide by fluorescence increasing was established.Its option reaction conditions was listed as follows: the concentrations of hydrochloric acid was 0.03mol/L,the reaction temperature was 50?,reaction time was 40 min,and the emission wavelength was 535 nm.The linearity range for the concentration of nitrite was 0.1¹.3×10^-6mol/L and the limit of detection is 2.3×10^-8mol/L.This method was used successfully to detect the content of nitrite in water,yogurt and sausage samples,and their recovery rate were between 98.8%¹02.7%.