Departamento de Química Analítica, Facultad de Ciencias, Universidad de Zaragoza, 50009-Zaragoza, Spain.
Analyst. 2010 Mar;135(3):564-9. doi: 10.1039/b919480k. Epub 2010 Jan 13.
Uncertainty in charge-coupled devices (CCDs) as UV-vis spectrophotometric detectors is studied here considering that it highly affects the limit of detection of analytical methods. Opposite to photomultiplier-type detectors (PMDs) and diode-array detectors (DADs), where uncertainty is mainly dependent on the photonic signal (shot noise), in CCD detectors uncertainty may come from both independent and dependent effects upon the photonic signal. Shot noise is specially important for high photonic signals in the detector (those for low absorbances) while the uncertainty that is independent of the signal is specially important for low photonic signals in the detector (those for high absorbances). That is, the main source of uncertainty is different depending on the value of the experimental measurement. On the other hand, temperature does not practically affect absorbance measurements, though it is very important for emission measurements (fluorescence, Raman, scattering, etc.). Mathematical equations for uncertainty are proposed with excellent fittings to the experimental data. The equation parameters can be experimentally determined from non-linear regression analysis and used to characterize spectrometers or to test their performance. In order to help buyers and users, some recommendations are finally given considering, among others, cooling, slit, attenuator or fiber optic assemblies.
电荷耦合器件 (CCD) 作为紫外-可见分光光度检测器的不确性在这里进行了研究，因为它会极大地影响分析方法的检测限。与光电倍增管型检测器 (PMD) 和二极管阵列检测器 (DAD) 不同，后者的不确性主要取决于光子信号（散粒噪声），而在 CCD 检测器中，不确性可能来自于光子信号的独立和依赖效应。对于检测器中的高光子信号（那些低吸光度的信号），散粒噪声特别重要，而对于检测器中的低光子信号（那些高吸光度的信号），与信号无关的不确性特别重要。也就是说，不确性的主要来源取决于实验测量值。另一方面，温度实际上不会影响吸光度测量，尽管它对发射测量（荧光、拉曼、散射等）非常重要。提出了用于不确性的数学方程，这些方程与实验数据拟合得非常好。方程参数可以通过非线性回归分析从实验中确定，并用于表征光谱仪或测试其性能。为了帮助购买者和使用者，最后还提出了一些建议，其中包括冷却、狭缝、衰减器或光纤组件等。
