【讨论】USP30-NF25分光光度鉴别检验《197》

197 SPECTROPHOTOMETRIC IDENTIFICATION TESTS
197 分光光度鉴别检验
Spectrophotometric tests contribute meaningfully toward the identification of many compendial chemical substances. The test procedures that follow are applicable to substances that absorb IR and/or UV radiation (see Spectrophotometry and Light-Scattering 851 ).
分光光度法检测对于很多药典化学物质的鉴别做出了意味深远的贡献。下面的这些步骤适用于那些吸收红外和/或者紫外线的物质（见分光光度测定法和光散射<851>）。

The IR absorption spectrum of a substance, compared with that obtained concomitantly for the corresponding USP Reference Standard, provides perhaps the most conclusive evidence of the identity of the substance that can be realized from any single test. The UV absorption spectrum, on the other hand, does not exhibit a high degree of specificity. Conformance with both IR absorption and UV absorption test specifications, as called for in a large proportion of compendial monographs, leaves little doubt, if any, regarding the identity of the specimen under examination.
一个物质的红外吸收光谱，在与从对应的USP标准品处获得的光谱图进行比较后，或许提供了从任何单一检验中所能获得的关于该物质的鉴别的最具决定性的证据。而另一方面，紫外吸收图谱则并未展示出高度的特异性。与红外吸收和紫外吸收检验标准的符合性，如在很大比例的药典专论中所要求的，用于供试样品的鉴别几乎不会导致任何质疑。

INFRARED ABSORPTION 红外吸收
Six methods are indicated for the preparation of previously dried test specimens and Reference Standards for analysis. The reference 197K in a monograph signifies that the substance under examination is mixed intimately with potassium bromide. The reference 197M in a monograph signifies that the substance under examination is finely ground and dispersed in mineral oil. The reference 197F in a monograph signifies that the substance under examination is suspended neat between suitable (for example, sodium chloride or potassium bromide) plates. The reference 197S signifies that a solution of designated concentration is prepared in the solvent specified in the individual monograph, and the solution is examined in 0.1-mm cells unless a different cell path length is specified in the individual monograph. The reference 197A signifies that the substance under examination is intimately in contact with an internal reflection element for attenuated total reflectance (ATR) analysis. The reference 197E signifies that the substance under examination is pressed as a thin sample against a suitable plate for IR microscopic analysis. The ATR 197A and the 197E techniques can be used as alternative methods for 197K , 197M , 197F , and 197S where testing is performed qualitatively and the Reference Standard spectra are similarly obtained.
六种方法用于已干燥的待检样品和对照品的前处理。在专论中提到<197K>意味着该待检物质与溴化钾充分混合。在专论中提到<197M>意味着该待检物质被精细地碾磨并分散于矿物油中。在专论中提到<197F>表示待检样品均匀地悬置于适当的（例如，氯化钠或溴化钾）压片板之间。在专论中提到<197S>表示使用具体专论中指定的溶剂中并按照指定的浓度配制了溶液，并且如果具体的专论中没有指定不同的单位通道长度，则该溶液在0.1-mm的单位中检测。提到<197A>意味着该待检物质紧密地接触用于衰减全反射（ATR）分析的内反射元件。提到<197E>表示该待检物质通过一个适当的压片挤压成薄片，用于红外显微分析使用。当检测为定性检测，并且标准品的光谱图用相似的方法获得，ATR<197A>和<197E> 的技术可以作为<197K>、<197M>、<197F>、<197S>的替代方法。

Record the spectra of the test specimen and the corresponding USP Reference Standard over the range from about 2.6 μm to 15 μm (3800 cm–1 to 650 cm–1) unless otherwise specified in the individual monograph. The IR absorption spectrum of the preparation of the test specimen, previously dried under conditions specified for the corresponding Reference Standard unless otherwise specified, or unless the Reference Standard is to be used without drying, exhibits maxima only at the same wavelengths as that of a similar preparation of the corresponding USP Reference Standard.
除非在具体的专论中另有规定，在从约2.6μm至15μm（3800 cm–1至650 cm–1）的光谱范围内记录供试样品和对应的USP标准品的光谱。除非有另外的规定或者该标准品使用前无需干燥，供试样品应在为对应标准品规定的条件下预先进行干燥。只有当对应USP标准品按照类似方法进行了前处理，且在同样波长的情况下，前处理后的供试样品的红外吸收图谱才能展示出最大值。

Differences that may be observed in the spectra so obtained sometimes are attributed to the presence of polymorphs, which are not always acceptable (see Procedure under Spectrophotometry and Light-Scattering 851 ). Unless otherwise directed in the individual monograph, therefore, continue as follows. If a difference appears in the IR spectra of the analyte and the standard, dissolve equal portions of the test specimen and the Reference Standard in equal volumes of a suitable solvent, evaporate the solution to dryness in similar containers under identical conditions, and repeat the test on the residues.
在这样得到的光谱中有可能观察到差异，这些差异有时候是由于同质异像体的存在，这种情况并非总是可以接受的（见分光光度测定法和光散射<851>中的步骤项的规定）。因此，如果在具体专论中没有其他规定，则继续进行下述操作。如果同一个差异同时出现在待分析物和标准品的光谱中，将同样份额的供试样品和标准品溶于同样体积的一种适当溶剂中，在完全相同的条件下使用近似的容器将溶液蒸发至干，并使用残渣重复进行该检验。

ULTRAVIOLET ABSORPTION紫外吸收
The reference 197U in a monograph signifies that a test solution and a Standard solution are examined spectrophotometrically, in 1-cm cells, over the spectral range from 200 to 400 nm unless otherwise specified in the individual monograph.
如果在具体的专论中没有其他的规定，在专论中提到<197U>意味着供试溶液和标准溶液在1-cm单位中，利用从200至400nm的光谱范围进行分光光度检测。

Dissolve a portion of the substance under examination in the designated Medium to obtain a test solution having the concentration specified in the monograph for Solution. Similarly prepare a Standard solution containing the corresponding USP Reference Standard.
将一份该供试物质溶于指定的媒介中，以得到供试溶液，该供试溶液的浓度是在该专论中溶液项下所规定的浓度。类似地配制含有对应USP标准品的标准溶液。

Record and compare the spectra concomitantly obtained for the test solution and the Standard solution. Calculate absorptivities and/or absorbance ratios where these criteria are included in an individual monograph. Unless otherwise specified, absorbances indicated for these calculations are those measured at the maximum absorbance at about the wavelength specified in the individual monograph. Where the absorbance is to be measured at about the specified wavelength other than that of maximum absorbance, the abbreviations (min) and (sh) are used to indicate a minimum and shoulder, respectively, in an absorption spectrum. The requirements are met if the UV absorption spectra of the test solution and the Standard solution exhibit maxima and minima at the same wavelengths and absorptivities and/or absorbance ratios are within specified limits.
记录并比较伴随地得到的供试溶液和标准溶液的光谱。计算吸收率和/或者吸光度比值，如果这些标准包含在某个具体的专论。如果没有其他的规定，这些计算中要求使用的吸光度需是在具体专论中规定的大概的波长、在最大吸光度条件下，所测得的那些值。如果该吸光度的测定要求在指定的大概的波长，而不是在最大吸光度条件下，使用缩写（min）和（sh）以在吸收光谱图中分别显示最大值和肩部。如果供试溶液和标准溶液在同样的波长显示了最大值和最小值，并且吸收率和/或吸光率比值在规定的限度内，即为达标。

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