开放式灰化·氟电极法测定食品中微量氟

Determination of the trace fluoride in food with the open type ashing-fluoride selective electrode

本文建立了开放式灰化·氟电极测定食品中微量氟的方法。利用开放式灰化炉以炭化和灰化面粉、大米等食品,采用5ml 0.12mol/L的Mg(NO_3)_2和0.5ml 0.25mol/L的NaOH溶液作氟保护剂,在300℃炭化1h,继而在600℃灰化1h,所得灰分以0.5mol儿HCIO_4浸泡溶解20min后用氟电极测定氟含量。回收率为96.8%,SD为0.016,CV为3.9%,经统计检验,空白值(0.51μg)显著低于茂福炉灰化时的空白值(1.36μg)。

In this paper, a method of determining the trace fluoride in food with the process of the open type ashing—fluoride selective electrode is introduced. The sample of the food (flour, rice etc.) was carbonized and ashed with the open type ashing—roaster. Magnesium nitriate and sodium hydroxide were used as the protective agent of fluoride. The sample was carbonized at 300℃ for 1 hour and then ashed at 600℃ for 1 hour, before the ash of the sample was soaked and dissolved in 5 ml of 0.5 mol/L HClO_4 solution for 20 min. Then, the fluoride contents in the sample were determined with the fluoride selective electrode. In this way, the rate of recovery is 96.8%, the SD is 0.016, and the CV is 3.9%. Tested with statistics, the blank value (0.51μg) is significantly lower than that (1.36μg)obtained from ashing with Maofu—roaster.