University of Prince Edward Island, Department of Health Management, Atlantic Veterinary College, Charlottetown, PEI, C1A 4P3 Canada.
Appl Spectrosc. 2014;68(4):466-74. doi: 10.1366/12-06869.
A rapid, simple, and inexpensive method to measure the immunoglobulin G (IgG) concentrations in blood samples in human and veterinary medicine is highly desired. Infrared spectroscopy (coupled with chemometric manipulation of spectral data) has the advantages of simple sample preparation, rapid implementation of analysis, and low cost. Here a method that exploits infrared spectroscopy as the basis to measure IgG concentration in animal plasma samples is reported, with radial immunodiffusion (RID) used as the reference test method for partial least squares (PLS) calibration model development. Smoothed non-derivative and the second-order derivative spectra were used to develop calibration models. Various additional spectral preprocessing steps were evaluated to optimize the calibration models, and the possible benefits of using an internal standard (potassium thiocyanate [KSCN]) were investigated. Monte Carlo cross-validation was used to determine the optimal number of PLS factors, and an independent prediction set was used to test the predictive performances of provisional models. The effects of various preprocessing options (spectral smoothing, derivation, normalization, region selection, mean-centering, and standard deviation scaling) on quantification accuracy were investigated. The root mean squared error of prediction (RMSEP) for different combinations of spectra preprocessing steps was 394 ± 36 mg/dL for the non-derivative spectra and 427 ± 101 mg/dL for the second-order derivative spectra. Immunoglobulin G concentrations produced by the optimized PLS model for the non-derivative spectra (RMSEP = 352 mg/dL) were found to be stable with respect to different splits of the samples among the calibration, validation, and prediction sets. The precision of the Fourier transform infrared (FT-IR) method is found to be slightly superior to that of the RID method. The results of this work indicate that infrared spectroscopy is a promising technique for economically and rapidly determining the IgG concentrations of plasma and plasma-derived samples.
在人医和兽医领域，人们非常希望有一种快速、简单且廉价的方法来测量血液样本中的免疫球蛋白 G（IgG）浓度。红外光谱（与光谱数据的化学计量学处理相结合）具有样品制备简单、分析快速和成本低的优点。本文报道了一种利用红外光谱法测定动物血浆样品 IgG 浓度的方法，以放射免疫扩散（RID）作为偏最小二乘法（PLS）校准模型开发的参考测试方法。使用平滑非导数和二阶导数光谱来开发校准模型。评估了各种附加光谱预处理步骤，以优化校准模型，并研究了使用内标（硫氰酸钾 [KSCN]）的可能益处。蒙特卡罗交叉验证用于确定 PLS 因子的最佳数量，并使用独立预测集测试暂定模型的预测性能。研究了各种预处理选项（光谱平滑、导数、归一化、区域选择、均值中心化和标准差缩放）对定量准确性的影响。不同光谱预处理步骤组合的预测均方根误差（RMSEP）对于非导数光谱为 394±36mg/dL，对于二阶导数光谱为 427±101mg/dL。对于非导数光谱优化的 PLS 模型产生的免疫球蛋白 G 浓度，发现在校准、验证和预测集中对样品的不同划分是稳定的。傅里叶变换红外（FT-IR）方法的精度略优于 RID 方法。这项工作的结果表明，红外光谱是一种很有前途的技术，可以经济、快速地测定血浆和血浆衍生样品中的 IgG 浓度。
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