Stable-isotopically-labeled internal standards are commonly incorporated in methods for trace analysis that utilize mass spectrometric detection. They closely mimic the physicochemical properties of the analyte, but their signal is easily differentiable based on a change in molecular mass. To investigate the potential to transfer methods incorporating such internal standards for analysis by vacuum ultraviolet detection, a study was conducted to compare the spectral shape (from 125 to 240 nm) of stable-isotopically-labeled compounds with their non-labeled counterparts. Gas chromatography – vacuum ultraviolet spectroscopic analysis was performed for a series of benzene isotopologues, as well as for clinically- and environmentally-relevant standard compounds and their deuterated counterparts. The absorption characteristics of the benzene isotopologues were evaluated based on similarity (normalized spectra), as well as on their magnitude of absorption. In general, very minor differences in absorption spectra were observed; however, increasing degree of deuteration did generally increase the spectral difference between labeled and non-labeled analytes. Sum of squared residuals were used as quantitative measures to assess spectral similarity (and dissimilarity). Theoretical computation of absorption spectra for benzene using time-dependent density functional theory was also examined; though, further work is needed in this area to extend the analysis to isotopologue analysis.

稳定同位素标记的内部标准通常结合到利用质谱检测的痕量分析方法中。它们紧密模拟被分析物的物理化学性质，但是根据分子质量的变化，很容易区分它们的信号。为了研究将结合了此类内标物的方法通过真空紫外检测进行分析的潜力，进行了一项研究，以比较稳定同位素标记的化合物与未标记的对应物的光谱形状（125至240 nm）。气相色谱-真空紫外光谱分析是针对一系列苯同位素，以及与临床和环境相关的标准化合物及其氘代对应物进行的。基于相似度（归一化光谱）及其吸收幅度，评估了苯同位素的吸收特性。通常，在吸收光谱上观察到很小的差异。但是，氘化程度的提高通常确实会增加标记和未标记分析物之间的光谱差异。残差平方和被用作评估光谱相似度（和相异度）的定量方法。还研究了基于时间依赖性密度泛函理论的苯吸收光谱的理论计算；但是，在这一领域还需要进一步的工作，以将分析扩展到同位素同位素分析。在吸收光谱上观察到很小的差异；但是，氘化程度的提高通常确实会增加标记和未标记分析物之间的光谱差异。残差平方和被用作评估光谱相似度（和相异度）的定量方法。还研究了基于时间依赖性密度泛函理论的苯吸收光谱的理论计算；但是，在这一领域还需要进一步的工作，以将分析扩展到同位素同位素分析。在吸收光谱上观察到很小的差异；但是，氘化程度的提高通常确实会增加标记和未标记分析物之间的光谱差异。残差平方和被用作评估光谱相似度（和相异度）的定量方法。还研究了基于时间依赖性密度泛函理论的苯吸收光谱的理论计算；但是，在这一领域还需要进一步的工作，以将分析扩展到同位素同位素分析。还研究了基于时间依赖性密度泛函理论的苯吸收光谱的理论计算；但是，在这一领域还需要进一步的工作，以将分析扩展到同位素同位素分析。还研究了基于时间依赖性密度泛函理论的苯吸收光谱的理论计算；但是，在这一领域还需要进一步的工作，以将分析扩展到同位素同位素分析。