1.1 本规程涵盖近红外光谱法用于液体和固体的定性分析。本实践是在假设大多数近红外定性分析将使用专门为该区域设计的仪器并配备计算机化数据处理算法的情况下编写的。然而，原则上，如果有合适的数据处理能力，该实践也适用于使用设计用于在紫外线（UV）、可见光和中红外（IR）区域操作的仪器处理液体样品。许多傅立叶变换红外（FTIR）（通常认为是中红外仪器）具有近红外能力，或至少具有扩展范围的分束器，允许操作到1。 2. μm；这一做法也适用于这些仪器的数据。 1.2 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。 ====意义和用途====== 4.1 近红外光谱技术是一种广泛应用的定量分析技术，它也越来越广泛地用于有机材料的鉴定，即定性分析。然而，总的来说，在近红外光谱区使用的定性分析概念不同于在中红外光谱区使用的定性分析概念- 红外光谱区，即近红外定性分析是指自动比较未知材料的光谱与已知材料的光谱以识别未知物质的过程。这种方法构成了一种库搜索方法，其中每个用户生成自己的库。 4.2 历史上，近红外光谱学与经典的UV-VIS-NIR仪器使用的方法类似于实践中描述的方法 E1252 被认为不是一种强有力的定性分析技术。虽然使用特定波长范围内吸收带的位置和强度来确认某些官能团的存在，但认为光谱的特异性不足以明确识别未知材料。 为了定性目的，开发了一些重要的近红外光谱库，但缺乏合适的数据处理设施严重限制了定性分析的范围。此外，早期的工作几乎完全局限于液体样品。 4.3 目前，通过分析单个吸收带的位置、强度和位置位移来推断未知材料结构的中红外程序通常不用于近红外。 4.4 随着专门的近红外仪器和用于处理数据的数学算法的发展，从迄今未使用的近红外光谱中获取大量信息成为可能。虽然本实践中描述的数学算法可以应用于任何区域的光谱数据，但本实践描述了其在近红外中的应用。 4.5 近红外光谱以所述方式应用于定性分析相对较新，该应用程序仍在不断发展。化学计量学方法在光谱学中的应用存在局限性，由于这些技术相对较新，因此这些局限性尚未全部定义。一些科学家关注的一个领域是低水平污染物的影响。任何分析方法都有其检测极限，近红外在这方面没有什么不同，但我们也不会期望它变得更糟。由于近红外波段相对较宽的特点使得污染物不太可能与任何测量波长重叠，因此问题只会是程度问题之一: 是否可以检测到给定量的污染物。用户必须意识到他可能遇到的污染物，并解释发生这种情况的可能性，可能是通过在训练集中包括故意污染的样本。

1.1 This practice covers the use of near-infrared (NIR) spectroscopy for the qualitative analysis of liquids and solids. The practice is written under the assumption that most NIR qualitative analyses will be performed with instruments designed specifically for this region and equipped with computerized data handling algorithms. In principle, however, the practice also applies to work with liquid samples using instruments designed for operation over the ultraviolet (UV), visible, and mid-infrared (IR) regions if suitable data handling capabilities are available. Many Fourier Transform Infrared (FTIR) (normally considered mid-IR instruments) have NIR capability, or at least extended-range beamsplitters that allow operation to 1.2 μm; this practice also applies to data from these instruments. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. ====== Significance And Use ====== 4.1 NIR spectroscopy is a widely used technique for quantitative analysis, and it is also becoming more widely used for the identification of organic materials, that is, qualitative analysis. In general, however, the concept of qualitative analysis as used in the NIR spectral region differs from that used in the mid-IR spectral region in that NIR qualitative analysis refers to the process of automated comparison of the spectra of unknown materials to the spectra of known materials in order to identify the unknown. This approach constitutes a library search method in which each user generates his own library. 4.2 Historically, NIR spectroscopy as practiced with classical UV-VIS-NIR instruments using methods similar to those described in Practice E1252 was not considered to be a strong technique for qualitative analysis. Although the positions and intensities of absorption bands in specific wavelength ranges were used to confirm the presence of certain functional groups, the spectra were not considered to be specific enough to allow unequivocal identification of unknown materials. A few important libraries of NIR spectra were developed for qualitative purposes, but the lack of suitable data handling facilities limited the scope of qualitative analysis severely. Furthermore, earlier work was limited almost entirely to liquid samples. 4.3 Currently, the mid-IR procedure of deducing the structure of an unknown material by method of analysis of the locations, strengths, and positional shifts of individual absorption bands is generally not used in the NIR. 4.4 With the development of specialized NIR instruments and mathematical algorithms for treating the data, it became possible to obtain a wealth of information from NIR spectra that had hitherto gone unused. While the mathematical algorithms described in this practice can be applied to spectral data in any region, this practice describes their application to the NIR. 4.5 The application of NIR spectroscopy to qualitative analysis in the manner described is relatively new, and procedures for this application are still evolving. The application of chemometric methods to spectroscopy has limitations, and the limitations are not all defined yet since the techniques are relatively new. One area of concern to some scientists is the effect of low-level contaminants. Any analytical methodology has its detection limits, and NIR is no different in this regard, but neither would we expect it to be any worse. Since the relatively broad character of NIR bands makes it unlikely that a contaminant would not overlap any of the measured wavelengths, the question would only be one of degree: whether a given amount of contaminant could be detected. The user must be aware of the probable contaminants he is liable to run into and account for the possibility of this occurring, perhaps by including deliberately contaminated samples in the training set.