β-环糊精增敏中性红荧光猝灭法测定痕量亚硝酸根

Fluorescence quenching method for the determination of trace nitrite with neutral red by sensitizing effect of β-cyclodextrin

建立了β-环糊精(-βCD)和中性红(NR)形成包合物,增敏中性红荧光猝灭测定亚硝酸根的新方法。在酸性介质中,亚硝酸盐与中性红直接反应,生成不发荧光的亚硝胺,调节溶液pH至9.6,在适量的β-CD存在下,过量的NR与β-CD形成包合物,体系荧光强度大大增强,据此提出了荧光猝灭法测定痕量NO2-的新方法。该体系最大激发波长为451 nm,最大发射波长为576 nm,线性范围为4～160μg/L,检出限为1.58μg/L,RSD为1.2%。方法可直接用于不同水样中痕量亚硝酸根的测定。

In acidic medium,neutral red can directly reacts with nitrite to form a new compound with no fluorescence.But the protonated form（NRH＋） of the dye does not form an inclusion complex with β-cyclodextrin,only the neutral form（NR） can.After the pH of the solution is adjusted to 9.6 by adding NaOH,the fluorescence intensity of neutral form（NR） is largely enhanced because of the formation of inclusion complex.A new fluorescent spectrophotometry based on this principle has been developed to determine trace nitrite.Its maximum excitation wavelength is 451 nm,and the maximum emission wavelength is 576 nm.The linear range,detection limit and relative standard deviation were 4～160 μg/L,1.58 μg/L and 1.2%,respectively.This method has high sensitivity and selectivity.It has been used to determine nitrite in different water samples with satisfactory results.