提出了原子吸收光谱法间接测定食品中甲醛含量的方法。甲醛与斐林溶液(含铜离子和酒石酸钾钠的碱性溶液)在沸水浴中反应30 min生成氧化亚铜沉淀,或与银氨溶液(含银离子的氨性溶液)在50 ℃水浴中反应15 min生成单质银沉淀。两种沉淀分别用6 mol·L-1盐酸溶液和6 mol·L-1硝酸溶液溶解,并用原子吸收光谱法测定反应中定量释出的铜量或银量,间接换算成甲醛含量。铜和银的质量浓度分别在7.000,6.000 mg·L-1以内与吸光度呈线性关系。在试样溶液中加入1.000 mg·L-1铜、银标准溶液并按所述方法进行分析,所得回收率在99.6%~101%之间(Cu)和81.9%~84.2%之间(Ag)。

A method for indirect determination of formaldehyde in food by AAS was proposed in this paper. Formaldehyde was reacted with Fehling′s solution (an alkaline solution containing Cu2+ ion and sodium potassium tartrate) in a boiling water bath for 30 min to give Cu2O precipitate; or with Tollen′s solution (an ammoniacal solution of Ag+ ion) in a water bath at 50 ℃ for 15 min to give elementary silver. The precipitate obtained was dissolved in 6 mol·L-1 HCl (for Cu2O) or 6 mol·L-1 HNO3 (for Ag), and determined by AAS. The amounts of Cu or Ag found were converted into contents of formaldehyde. Linear relationships between values of absorbance and mass concentration of Cu and Ag were obtained in ranges within 7.000 and 6.000 mg·L-1 respectively. Tests for accuracy were made by addition of standard solution to sample solutions at the concentration level of 1.000 mg·L-1 and analyzed by the proposed method, values of recovery found were in ranges of 99.6%-101% for Cu and 81.9%-84.2% for Ag.