傅里叶变换-红外光谱法快速测定面粉中滑石粉

Rapid Determination of Talc Powder in Flour by FT-IRS

提出了应用衰减全反射(ATR)傅里叶变换-红外光谱(FT-IRS)法快速检测面粉中混入的滑石粉,测定中采用中红外检测器。根据滑石粉的标准红外光谱图并为避免面粉的吸收干扰,选择滑石粉在3 674.96 cm-1及668.16 cm-1两处的特征吸收峰作为判定面粉中是否含有滑石粉的依据,并且其吸收强度随滑石粉含量的增加而增加。由于面粉中滑石粉质量分数低于0.5%和0.2%时,分别在上述两吸收峰波长处已不呈现吸收,方法中将1%(质量分数)作为滑石粉的检出限。此外,根据吸收峰的吸收强度可估算出滑石粉的含量。方法中选用的主要仪器工作条件为:①扫描范围为4 000～650 cm-1;②分辨率为8 cm-1;③扫描信号累加次数为32;④衰减全反射压力常数为100。

FT-IRS with attenuated total reflection（ATR） was applied to the rapid determination of talc powder illicitly mixed into flour.Medium IR detector was used in the analysis.By referring the standard IR spectra and considering the absorption interference of flour,2 of the 3 IR absorption peaks of talc powder,i.e.,the peaks at 3 674.96 cm-1 and 668.16 cm-1,were selected as the characteristic absorption peaks to determine whether talc powder was present or not in the sample.It was shown that when the content（w%） of talc powder in flour was lower than 0.5% or 0.2%,no absorption was found in the spectra at the 2 wavebands respectively.Value of 1%（w%） was taken as the detection limit.In addition,magnitude of absorption intensity at both the wavebands was increased with the increase of amounts of talc powder present,hence the content of talc powder in samples of flour could be estimated.Working conditions of the instrument were as follows： ① scanning range： 4 000-650 cm-1;② resolution： 8 cm-1;③ number of time of scanning signal accumulation： 32 and ④ pressure constant of ATR： 100.