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Frontiers of Optoelectronics

Front. Optoelectron.    2015, Vol. 8 Issue (1) : 57-61     DOI: 10.1007/s12200-013-0381-3
Quantitative determination of n-heptane and n-octane using terahertz time-domain spectroscopy with chemometrics methods
Honglei ZHAN1,Fangli QIN1,2,Wujun JIN1,Li’na GE1,Honglan LIU1,Kun ZHAO1,2,*()
1. Key Laboratory of Oil and Gas Terahertz Spectroscopy and Photoelectric Detection, CPCIF, Beijing 100723, China
2. Laboratory of Optic Sensing and Detecting Technology, China University of Petroleum, Beijing 102249, China
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This paper introduces the terahertz time-domain spectroscopy (THz-TDS) used for the quantitative detection of n-heptane volume ratios in 41 n-heptane and n-octane mixtures with the concentration range of 0-100% at the intervals of 2.5%. Among 41 samples, 33 were used for calibration and the remaining 8 for validation. Models of chemometrics methods, including partial least squares (PLS) and back propagation-artificial neural network (BP-ANN), were built between the THz-TDS and the n-heptane percentage. To evaluate the quality of the built models, we calculated the correlation coefficient (R) and root-mean-square errors (RMSE) of calibration and validation models. R and RMSE of two methods were close to 1 and 0 within acceptable levels, respectively, demonstrating that the combination of THz-TDS and chemometrics methods is a potential and promising tool for further quantitative detection of n-alkanes.

Keywords partial least squares (PLS)      terahertz time-domain spectroscopy (THz-TDS)      n-heptane      n-octane      back propagation-artificial neural network (BP-ANN)     
Corresponding Authors: Kun ZHAO   
Online First Date: 17 December 2013    Issue Date: 13 February 2015
 Cite this article:   
Honglei ZHAN,Fangli QIN,Wujun JIN, et al. Quantitative determination of n-heptane and n-octane using terahertz time-domain spectroscopy with chemometrics methods[J]. Front. Optoelectron., 2015, 8(1): 57-61.
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Honglei ZHAN
Fangli QIN
Wujun JIN
Li’na GE
Honglan LIU
Fig.1  Chart of the sample held in a quartz cell
Fig.2  THz-TDS of 41 n-heptane and n-octane mixtures at the intervals of 2.5%
Fig.3  Time delay versus n-heptane percentage of 20 selected samples
Fig.4  THz-FDS of 41 n-heptane and n-octane mixtures at the intervals of 2.5%
Fig.5  Predicted n-heptane percentage versus actual n-heptane percentage from PLS models
Fig.6  Predicted n-heptane percentage versus actual n-heptane percentage from BP-ANN models
calibration validation calibration validation
R 0.9973 0.9764 0.9999 0.9716
RMSE/% 2.217 6.714 0.0003 6.21
Tab.1  Errors of calibration and validation of two methods
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