新型三维可调共聚焦激光诱导荧光检测器的研制与评价

共聚焦结构是激光诱导荧光检测器(LIFD)中使用最广泛的光路结构之一,增强光路系统同轴精度和降低系统杂散光是降低仪器基线噪声水平、提高其信噪比(S/N)的两种有效手段。采用精密三维反光镜调节架和模块化设计光路系统,研制了一种高效液相色谱用高精度共聚焦激光诱导荧光检测器,对异硫氰酸荧光素(fluorescein isothiocyanate, FITC)的检出限为1×10~12 mol/L。基线噪声与漂移较改进前降低了一个数量级,分别达到8.0×10~3 mV和1.4×10~3 mV/h,且稳定性好,5×10~9 mol/L FITC样品连续5次进样分析的峰面积和峰高相对标准偏差(RSD)均小于0.5%。进一步用FITC衍生化生物胺对研制的检测器进行评价,检出限(S/N=3)达到0.01～0.02 nmol/L。新研制的LIFD噪声低、稳定性好、灵敏度高,适用于生物、食品和环境样品中痕量物质的分析。

Development and evaluation of a novel three-dimensional adjustable confocal laser-induced fluorescence detector

Laser-induced fluorescence detector (LIFD) is one of the most sensitive detectors in analytical chemical files. Confocal optical configuration is widely used in LIFDs. Two effective approaches used to achieve the best signal to noise ratio (S/N) are increasing the confocal precision and minimizing the background noise. A novel three-dimensional adjustable confocal LIFD was developed, using a new three-dimensional adjustable supporter of reflector and modularized optical system. A detection limit (S/N = 3) of 1 x 10(-12) mol/L and a linear dynamic range of 3 orders of magnitude were obtained using fluorescein isothiocyanate (FITC) standard as the test sample. The noise level and drift levels were 8.0 x 10(-3) mV and 1.4 x 10(-3) mV/h, respectively, which were almost 10 times lower than before. And the stability of the LIFD was evaluated by five replicate injections of 5 x 10(-9) mol/L FITC, and the relative standard deviations (RSDs) of peak height and peak area were 0.38% and 0.41%, respectively. Further more, three biogenic amines, which were derivatized by FITC, were separated by high performance liquid chromatography (HPLC) and then detected by the novel LIFD. And the detection limits (S/N = 3) ranged 0.01 to 0.02 nmol/L, which were better than other methods. Therefore, the LIFD is highly sensitive, as well as shows a real low noise level and good reproducibility.