Eom In-Yong, Dasgupta Purnendu K
Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, USA.
Talanta. 2006 Jun 15;69(4):906-13. doi: 10.1016/j.talanta.2005.11.033. Epub 2005 Dec 20.
A frequency-selective absorbance detection approach and its applications are described. First, a digital signal processor-lock-in amplifier (DSP-LIA)-based absorbance detector was evaluated. Compared to a simple operational amplifier (TL082CP)-based detector, the DSP-LIA-based detector showed lower noise levels, but the relative advantage was reduced under very low photocurrent levels (down to few nA). A 7cm pathlength flow cell with this commercial LIA-based detector exhibited excellent Beer's law linearity (r(2)=0.9999) and a noise level of 7 micro absorbance units (muAU). The limit of detection (LOD, S/N=3) for methyl orange (MO) was 7nM with this detector. Finally, as a more affordable alternative to an LIA, a balanced demodulator integrated circuit chip was used to fabricate a dual wavelength-frequency-selective LED-based absorbance detector. This device successfully compensated refractive index (RI) effect and turbidity effect in test flow systems. The LOD for MO with this system was 8nM.
描述了一种频率选择性吸光度检测方法及其应用。首先，对基于数字信号处理器锁相放大器（DSP-LIA）的吸光度检测器进行了评估。与基于简单运算放大器（TL082CP）的检测器相比，基于DSP-LIA的检测器显示出更低的噪声水平，但在非常低的光电流水平（低至几纳安）下，相对优势有所降低。使用这种基于商用LIA的检测器的7厘米光程流通池表现出出色的比尔定律线性（r(2)=0.9999）和7微吸光度单位（μAU）的噪声水平。使用该检测器时，甲基橙（MO）的检测限（LOD，S/N=3）为7 nM。最后，作为LIA的一种更经济实惠的替代方案，使用平衡解调器集成电路芯片制造了一种基于双波长频率选择性发光二极管的吸光度检测器。该装置成功地补偿了测试流动系统中的折射率（RI）效应和浊度效应。该系统对MO的LOD为8 nM。
