**5. Conclusion**

182 Multivariate Analysis in Management, Engineering and the Sciences

**R² = 0.9915**

**RMSECV=2.32 Fact=10**

**Figure 19.** PLS of RDX on travel baggage (TB) as substrate.

**R² = 0.9994**

**RMSECV=1.82**

**Fact=10**

**Figure 20.** PLS of PETN on Travel Baggage as substrate.


0

50

100

150

**Prediction Concentration**

200

250

300

**b**

0.9994 and 1.82 g/cm2, respectively.

**Prediction Concentration**

**a**

g/cm2, respectively.

spectral range was 1000-1600 cm-1. PLS shown below was that best results obtained. Figure 19 shows PLS plots of RDX deposited on TB. The best result was achieved using the spectral region of 1000-160 cm-1 and using mean centering as preprocessing. A total of 10 latent variables or factors were necessary to obtain a R2 and RMSECV equal to 0.9915 and 2.32

Figure 20 shows PLS of PETN deposited on TB. The best resulted was achieved using the spectral region of 1000-1600 cm-1 and using mean centering as preprocessing treatment. A total of 10 latent variables or factors were necessary to obtain a R2 and RMSECV equal to

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RDX on TB

PETN on TB

**True Concentrtion**

0 50 100 150 200 250 300

**True Concentration**

Raman and infrared vibrational techniques were used for the detection of highly energetic materials and chemical warfare agents simulants in different matrices such as pharmaceutical mix, commercials bottles and travel baggage. The analysis of the spectral data allows emphasizing certain results. Satisfactory results were found for the quantification of explosives with good values of R2cv, RMSECV. Reliable predictions obtained by remote sensing based on Raman spectroscopy at remote distance of 10 m employing 532 nm laser as excitation source. Remote Raman system using the appropriate chemometrics tools such as PLS, iPLS and siPLS promises to be a reliable technique for finding the existence of highly energetic material such as PETN deliberately hidden in matrices with similar chemical structures.

Partial Least Squares (PLS) calibration models reported limits of detection very low for white plastic in commercial beverage bottle solutions which was the best model. Due to the bottle material and commercial beverage product coloration, Malta was the worst model with reported limits of detection more elevated. Limits of Detection and Quantification for commercial bottles were compared in aqueous and mixtures. It is observed that limits of Detection were significantly lower for mixtures of TEP with the commercial product. Integration times were the same for both aqueous and commercial beverage bottle solutions (each normalized with respect to bottle material, color and thickness). Water does not transmit significant Raman signal, which would make limits of detection lower for aqueous solutions. However, commercial beverage bottles mixtures showed lower limits of detection than aqueous solution since the beverage solutions inside each bottle showed significant Raman signal and, therefore, increasing CWAS presence in the spectra.

PLS-DA model and discriminant analysis was done to detect TATP and 2,4-DNT traces in fluid air. The region of 600 to 7500 cm-1 was highly significant in the discrimination with p < 0.00001 and 100 % discrimination for two vectors for TATP and four vectors for 2,4-DNT. These results show the ability of the Chemometrics methods to discriminate between vapor phase explosive (2,4-DNT) and air.

Results obtained from principal component analysis to determine the presence of peroxides explosives such as TATP when they are in gas phase mixed with air shown be useful for distinction between TATP vapors and air. The principal component analysis from infrared spectral data used little PC for predict the variability of the spectral data, being the first two PC more important. PC1 loadings confirm the results from the PCA because it contained features from TATP spectrum. Other hand, the PLS model were shown chemometrics tool for quantify explosive such as RDX and PETN on substrate of the real world such as travel baggage.

In general, vibrational spectroscopy systems designed based on this work should be useful for National Defense and Security applications, for screening hazardous liquids in government installations, seaports and in public installations to improve defense against terrorist attacks.
