嬰兒配方食品中碘與氯之檢驗方法探討

STUDIES ON THE ANALYTICAL METHOD OF IODINE AND CHLORINE IN INFANT FORMULA

嬰兒配方食品中碘標示含量約在30-76μg/100g範圍，若以滴定法、比色法等檢驗，感度及精確度皆不足以測定此微量之碘，因此採用氣相層析法及離子電極法測定；氣相層析法係將碘衍生化為2-碘丁酮（2-Iodobutanone），再以配有電子捕獲檢出器之氣相層析儀（GC-ECD）分析，於5～50 ng/ml間取六點所得之線性回歸方程式為 Y = -3605.66 + 3304.48X，相關係數為0.9994，添加回收率為89.61%，標準偏差為1.55，變異係數為1.73%，最低檢出量為50ng/g。離子電極法係以標準加入法測定，於20～200 ng/ml間取六點所得之線性回歸方程式為 Y = 35.30-58.79 logX，相關係數為0.9994，添加回收率為96.98～107.82%，標準偏差為1.61-2.34，變異係數為1.54～2.17%，最低檢出量為100 ng/g。嬰兒配方食品中氯標示含量約在285～703 mg/100g範圍，其含量以硝酸銀滴定法即可測定，添加回收率為100.18～100.70%，標準偏差為0.40～0.86 ，變異係數為0.40～0.86%，最低檢出量為7.5μg/g。此外，氯之含量亦可採用離子層析法測定，於1～10μg/ml間取七點所得之線性回歸方程式為 Y = -128784.45 + 413434.85 X，相關係數為0.9997，添加回收率為104.36～107.47%，標準偏差為0.66～2.18，變異係數為0.63～2.03%，最低檢出量為100 ng/g。

The level of iodine content in infant formula was between 30 and 70 μg/100g. The sensitivity of titration and colorimetric methods were not enough for the detection of trace amounts of iodine. Therefore gas chromatography and ion electrode methods were used to determine iodine. Iodine was derivertized to form 2-iodobutanone and analyzed by GC-ECD. Linear regression equation of six concentrations between 5 and 50 ng/ml was Y = - 3665.66+3304.48 X. Correlation coefficientwas 0.9994. The recovery of added iodine was 89.61%. Standard deviation was 1.55, coefficient of variation was 1.73%. The detection limit was 50 μg/g. Ionicelectrode method was conducted with standard addition method. Linear regression equqtion of six concentrations between 20 and 200 ng/ml was Y =35.30- 58.79 log X. Correlation coefficient was 0.9994. The recovery of added iodine was 96.98- 107.82%. Standarddeviation was 1.61- 2.34. Coefficient of variation was 1.54-2.17% .The detection limit was 100 μg/g. The level of chlorine content in infant formula was between 285 and 703 mg/100g. The chlorine content was determined by silver nitrate titration method. The recovery of added chlorine was 100.18-101.70%. Standard deviation was 0.40-0.86. Coefficient of variation was 0.40-0.86% .The detection limit was 7.5μg/g. Beside, chlorine content could also be determine by ion chlomatography. Linear regression equation of seven concentrations between 1 and 10 μg/ml was y= -128784.45+413434.85 X.Correlation coefficient was 0.9997. The recovery of added chlorine was 104.36-107.47%. Standard deviation was 0.66-2.18. Coefficient of variation was 0.63- 2.03. The detection limit was 100 μg/g.