National Institute of Laser Enhanced Science (NILES), Cairo University, Giza, Egypt.
Talanta. 2013 Apr 15;108:53-8. doi: 10.1016/j.talanta.2013.02.062. Epub 2013 Mar 7.
In most laser-based analytical methods, the reproducibility of quantitative measurements strongly depends on maintaining uniform and stable experimental conditions. For LIBS analysis this means that for accurate estimation of elemental concentration, using the calibration curves obtained from reference samples, the plasma parameters have to be kept as constant as possible. In addition, calcified tissues such as bone are normally less "tough" in their texture than many samples, especially metals. Thus, the ablation process could change the sample morphological features rapidly, and result in poor reproducibility statistics. In the present work, three artificial reference sample sets have been fabricated. These samples represent three different calcium based matrices, CaCO3 matrix, bone ash matrix and Ca hydroxyapatite matrix. A comparative study of UV (266 nm) and IR (1064 nm) LIBS for these three sets of samples has been performed under similar experimental conditions for the two systems (laser energy, spot size, repetition rate, irradiance, etc.) to examine the wavelength effect. The analytical results demonstrated that UV-LIBS has improved reproducibility, precision, stable plasma conditions, better linear fitting, and the reduction of matrix effects. Bone ash could be used as a suitable standard reference material for calcified tissue calibration using LIBS with a 266 nm excitation wavelength.
在大多数基于激光的分析方法中，定量测量的重现性强烈依赖于保持均匀和稳定的实验条件。对于 LIBS 分析，这意味着为了准确估计元素浓度，使用从参考样品获得的校准曲线，等离子体参数必须尽可能保持恒定。此外，像骨这样的钙化组织在质地方面通常比许多样品（尤其是金属）更“脆弱”。因此，消融过程可能会迅速改变样品的形态特征，导致重现性统计数据较差。在本工作中，制备了三组人工参考样品。这些样品代表三种不同的基于钙的基质，即 CaCO3 基质、骨灰基质和 Ca 羟基磷灰石基质。在两种系统（激光能量、光斑大小、重复率、辐照度等）下，对这三组样品进行了 266nm 的紫外（UV）和 1064nm 的红外（IR）LIBS 的比较研究，以检查波长效应。分析结果表明，UV-LIBS 具有提高的重现性、精度、稳定的等离子体条件、更好的线性拟合以及减少基质效应。对于使用 266nm 激发波长的 LIBS，骨灰可以用作钙化组织校准的合适标准参考物质。
