Kramer Kirsten E, Small Gary W
Optical Science and Technology Center and Department of Chemistry, University of Iowa, Iowa City, Iowa 52242, USA.
Appl Spectrosc. 2009 Feb;63(2):246-55. doi: 10.1366/000370209787392076.
Fourier transform near-infrared (NIR) transmission spectra are used for quantitative analysis of glucose for 17 sets of prediction data sampled as much as six months outside the timeframe of the corresponding calibration data. Aqueous samples containing physiological levels of glucose in a matrix of bovine serum albumin and triacetin are used to simulate clinical samples such as blood plasma. Background spectra of a single analyte-free matrix sample acquired during the instrumental warm-up period on the prediction day are used for calibration updating and for determining the optimal frequency response of a preprocessing infinite impulse response time-domain digital filter. By tuning the filter and the calibration model to the specific instrumental response associated with the prediction day, the calibration model is given enhanced ability to operate over time. This methodology is demonstrated in conjunction with partial least squares calibration models built with a spectral range of 4700-4300 cm(-1). By using a subset of the background spectra to evaluate the prediction performance of the updated model, projections can be made regarding the success of subsequent glucose predictions. If a threshold standard error of prediction (SEP) of 1.5 mM is used to establish successful model performance with the glucose samples, the corresponding threshold for the SEP of the background spectra is found to be 1.3 mM. For calibration updating in conjunction with digital filtering, SEP values of all 17 prediction sets collected over 3-178 days displaced from the calibration data are below 1.5 mM. In addition, the diagnostic based on the background spectra correctly assesses the prediction performance in 16 of the 17 cases.
傅里叶变换近红外（NIR）透射光谱用于对17组预测数据进行葡萄糖定量分析，这些预测数据是在相应校准数据的时间范围之外长达六个月采集的。含有生理水平葡萄糖的水溶液样本置于牛血清白蛋白和三醋精基质中，用于模拟临床样本，如血浆。在预测日仪器预热期间采集的单一无分析物基质样本的背景光谱用于校准更新以及确定预处理无限脉冲响应时域数字滤波器的最佳频率响应。通过将滤波器和校准模型调整到与预测日相关的特定仪器响应，校准模型的长期运行能力得到增强。结合在4700 - 4300 cm(-1)光谱范围内构建的偏最小二乘校准模型对该方法进行了验证。通过使用背景光谱的一个子集来评估更新模型的预测性能，可以对后续葡萄糖预测的成功与否进行预测。如果使用1.5 mM的预测标准误差（SEP）阈值来确定葡萄糖样本的模型性能成功，则发现背景光谱SEP的相应阈值为1.3 mM。对于结合数字滤波的校准更新，从校准数据起3 - 178天内收集的所有17个预测集的SEP值均低于1.5 mM。此外，基于背景光谱的诊断在17个案例中的16个中正确评估了预测性能。
