Raman spectroscopy is an established analytical technique for determining molecular structure, whose major drawback is lack of sensitivity. Enhanced Raman scattering techniques, such as surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS), utilise nanoscale substrates to enhance the Raman signal through the interaction of surface charges with the incident electromagnetic radiation. Here, nanoparticle-based SERS was used to detect dipicolinic acid (DPA), a biomarker for bacterial spores. Whilst this has been demonstrated previously, the use of a different nanoparticle aggregation mechanism and the inclusion of an internal standard has enabled a SERS detection method to be developed that is quantitative to almost an order of magnitude lower than previously reported. Moreover, for the first time, a nanoparticle-based SERS method was applied to the detection of viable Bacillus spores. Investigations were made into the possibility of SERS enhancement using deep UV laser excitation at 244 nm using a novel boron nitride surface material. This semiconductor has a band gap of comparable magnitude to the laser excitation wavelength and therefore had the potential to impart a SERS enhancement via a chemical enhancement mechanism. Whilst initial results looked promising using Rhodamine 6G as a test analyte, it was not possible to demonstrate reproducibly and no enhancement was observed on other analytes that were tested. TERS was shown to be able to discriminate between glycosylated and non-glycosylated forms of protein molecules, based on the measurement of just a few molecules at a time. This was achieved even without control of the protein interaction with the TERS substrate. The vibrational peak positions in TERS experiments were shown to be highly dependent on the analyte’s orientation relative to the TERS tip, giving variable and complex spectral data. As such, the data processing and analysis methods had to be carefully considered in order to eliminate bias. Lastly, a novel SERS detector for high-performance liquid chromatography (HPLC) was built and tested. It was shown to be able to quantify purine bases from mixtures in tandem with, and in lower amounts than the conventionally used UV absorbance detection, even when the analyte peaks were co-eluting. This quantitative analysis is conducted on-line and in real-time, making it applicable to high throughput applications. Together the four research projects presented in this thesis make a significant contribution to the field of enhanced Raman scattering and promote its sensitivity and reproducibility as a quantitative analytical technique for the trace analysis of biomolecules.

Ce manuscrit traite de l'étude métrologique d'un spectromètre Terahertrz (THz), de la caractérisation et de la quantification de produits pulvérulents par spectroscopie THz. Le sujet a été orienté afin de fournir les études préliminaires nécessaires à une thématique visant la détection de pesticides sur les aliments, à savoir la caractérisation métrologique de l'appareil (études de répétabilité, sensibilité...) ainsi que la faisabilité de la quantification de produits et l'application de méthodes chimiométriques lors du prétraitement des spectres. La thèse est ordonnée autour de trois publications. La première publication consiste en une revue de littérature servant à faire le point sur les applications concrètes existant en spectroscopie THz. La seconde porte sur la première partie de notre travail, à savoir la caractérisation métrologique du spectromètre THz sur lequel nous avons effectué nos mesures. Enfin, la troisième porte sur l'aspect quantification de la spectroscopie THz et la possibilité d'appliquer les mêmes principes et techniques chimiométriques qu'en spectroscopie infrarouge. / This manuscript concerns the metrological study of a Terahertz (THz) spectrometer, the characterization and the quantification of powder products by THz spectroscopy. The subject has been aimed to give preliminary analysis to a wider thematic of pesticides detection on aliments, which implies the metrological characterization of the device (repeatability, sensitivity...) and the quantification feasibility of these products and the application of chemometrics methods for spectral pretreatment. The thesis is organized around three publications. The first publication is a literature review, which aims to list but a few of the concrete applications of THz spectroscopy. The second one concerns the metrological characterization of the THz spectrometer we worked on. Lastly, the third one deals with the quantification aspect of THz spectroscopy and the possibility of using the same principles and chemometrics techniques that are used in infrared spectroscopy.

The feasibility of Fourier transform infrared (FTIR)-imaging spectroscopy as a tool to discriminate samples from patients suffering from benign prostatic hyperplasia (BPH) and prostate cancer (CaP) samples in blood serum was investigated. Prostate cancer is known to be an age related disease, with the risk of developing the disease dramatically increasing in men past forty years old. Currently the PSA blood test is notoriously unreliable and is non specific for CaP thus leading to overtreatment of the disease. It is important therefore to develop diagnostic method that is non-invasive, reliable, and specific for CaP.In order to achieve the objective of establishing a robust protocol, which could be applied to a clinical study, obtaining optimal sample preparation for the FTIR analysis of serum smears, had to be achieved. A protocol was developed to prepare the serum samples prior to their FTIR analysis. First, the samples were centrifuged with ultrafiltration devices of different sizes to obtain several fractions which were then smeared to obtain thin films of serum. The spectra from the larger (>100 kDa components) and medium (containing the 10–100 kDa components) fractions were utilised for both a pilot and a clinical study, while the spectra from the smaller fractions (containing the 3–10 and <3 kDa components) were affected by fringing and could therefore not be used. A major novelty of this project involved the application of FTIR-imaging to the analysis of serum smears. The use of the Focal Plane Array detector system enabled the collection of a spectral image containing 16,384 spectra, on which a Quality Testing and pre-processing techniques were applied to select the “good spectra” and reject the spectra that failed the Quality Test. Several types of substrates were assessed to determine the most appropriate for the analysis of the smears and it was established that the spectra obtained from the serum smeared on CaF2 windows gave the most reproducible results. 5 BPH and 5 CaP samples were analysed for the pilot study following the developed protocol. While no clear separation was observed in the Principal Component Analysis (PCA) plots between the BPH and the cancerous samples, a trend emerged throughout the results, with the CaP samples clustering together and the BPH samples scattered around them. A larger clinical study was conducted with 60 BPH samples and 60 CaP samples. PCA was applied on the “good spectra” and while the over 100 kDa fraction did not show a clear separation between the two types of samples, the 10–100 kDa fraction showed a distinct classification between the BPH and CaP samples. An artificial neural network was then applied to create a model using patients from the database used for the PCA analysis to determine whether the discrimination between the two types of samples could be increased or highlight different classification trends. For the >100 kDa fraction, the sensitivity value was calculated to be 97.8% and the specificity value was calculated to be 44.3% while the sensitivity and the specificity value for the 10 to 100 kDa fraction were calculated to be 78.9% and 60% respectively. A complementary study using mass spectrometry was carried out on healthy and diseased samples to identify the components contained within the different fractions and determine whether they could be correlated with the components identified from the spectral features of the FTIR data. While no quantitative information was obtained from this study, the components found in the different fractions were identified, confirming the results of the FTIR studies.

Orientadores: Maria Izabel Maretti Silveira Bueno, Kenneth E. Collins / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-14T13:16:38Z (GMT). No. of bitstreams: 1 Goraieb_Karen_D.pdf: 3845502 bytes, checksum: a098a9a519d072aa7b424abbad188970 (MD5) Previous issue date: 2009 / Resumo: Um método para a análise qualitativa e quantitativa de Al em matrizes com alto teor de Si (aluminossilicatos, por exemplo) utilizando-se a Espectrometria de raios-X aliada aos métodos quimiométricos PCA (análise de componentes principais), e PLS 1 (regressão por mínimos quadrados parciais para uma variável) foi desenvolvido. As amostras estudadas neste projeto foram: amostras-padrão (misturas de Al2O3 e SiO2), fases estacionárias de SiO2 com camada de Al2O3 para cromatografia, cimento Portland e Zeólitos. Primeiro foi feita a otimização do método acerca do tempo de irradiação das amostras e com relação ao pré-tratamento a ser aplicado aos espectros antes da análise quimiométrica. Depois, com o PCA, foi possível observar que há uma tendência em separar as amostras-padrão conforme o teor de Al em 3 subgrupos (alto, médio e baixo). Porém, para as amostras mais complexas, não se observou uma grande influência do Al nas separações dos subgrupos durante uma análise exploratória inicial, porém outras características importantes, tais como, grau de uso (para os zeólitos) e origem (para os cimentos) foram relevantes. Com o PLS 1 foi possível construir modelos de calibração e de validação cruzada para o Al nas amostras-padrão, nos cimentos e nos zeólitos com excelentes coeficientes de correlação de calibração e de validação cruzada ( 0,97), com baixos erros ( 2,21%). Também foi possível construir modelos de calibração e de validação cruzada simultaneamente para outros elementos presentes nas amostras estudadas tais como Si (nas amostras-padrão) e Ca (cimento). Neste caso, tanto as análises empregando PCA como PLS 1 utilizou-se de todo o espectro, incluindo a região de espalhamento da fonte de raios-X / Abstract: A qualitative and quantitative method for Al analysis with high content of Si, (e.g. aluminum-silicates) using X-ray spectrometry allied to the chemometric tools PCA and PLS 1 was developed. The studied samples in this project were: standard samples (a mixture of Al and Si oxides), stationary phases made by SiO2 with a layer of Al2O3 for chromatographic purposes, Portland cement and zeolites. First, the method optimization related to the "irradiation time" and "pre treatment to be employed to the spectra prior to chemometric analysis" was done. Then, using PCA, it is observed that there is a tendency to separate the standard samples according to their Al content in three subgroups (high, medium and low). However, for more complex samples, a high influence of Al in the observed separations was not observed during the initial exploratory analysis but other important information, such as, degree of use (for zeolites) and origin (for cements), was seen. With PLS 1, it was possible to construct the multivariate calibration and cross-validation models for Al in the standard samples, cement and zeolites with excellent calibration and cross-validation correlation coefficient ( 0.97) and with low errors ( 2.21). Also, the construction of multivariate calibration and cross-validation models for other elements present in the studied samples, like Si (for standard samples) and Ca (for cement) were possible. As for PCA analysis and for PLS 1, the whole spectral range, including the scattering portion from the X-ray source, was employed. / Doutorado / Quimica Analitica / Doutor em Ciências

Orientador: Ronei Jesus Poppi / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-14T14:16:59Z (GMT). No. of bitstreams: 1 Gallo_LucianaViviani_M.pdf: 1018650 bytes, checksum: 36599aa45a93a7d16c638ac0c60d6716 (MD5) Previous issue date: 2008 / Resumo: Neste trabalho foi desenvolvida uma metodologia analítica alternativa para a determinação de parâmetros de qualidade em bananas: pH, acidez titulável e Brix utilizando as espectroscopias no infravermelho médio e próximo em conjunto com calibração multivariada. A estratégia adotada foi obter os espectros na região do infravermelho próximo e médio do fruto e estabelecer um modelo de calibração multivariada, baseada no método dos mínimos quadrados parciais, para prever os diversos parâmetros. Foram utilizadas 54 amostras de banana, em diferentes estágios de maturação. Os espectros foram obtidos a partir da análise da polpa do fruto macerada, da solução obtida após a centrifugação da polpa, e pela técnica ¿Dry Extract Spectroscopy by infrared Absorption¿ (DESIR). Um total de 9 modelos foram propostos para a determinação dos parâmetros de qualidade e o melhor resultado para a determinação de pH foi na região do infravermelho médio utilizando a técnica DESIR, com erro médio de 1,32%. Já para a acidez, o melhor modelo obtido foi na região do infravermelho próximo utilizando DESIR, com erro relativo médio de 6,20%. O parâmetro brix apresentou melhores resultados na região do infravermelho médio através da análise da solução, com erro médio de 3,78%. Dessa maneira, a espectroscopia vibracional possibilita viabilizar a obtenção de maior número de informações sobre a qualidade da fruta, através da relação dos espectros com várias propriedades de interesse. / Abstract: banana quality parameters as pH, acidity and Brix by using infrared spectroscopy in the mid and near regions in conjunction with multivariate calibration. The strategy adopted was to obtain the fruit spectra in mid and near regions and to establish a multivariate calibration model, based on the partial least squares, to predict the several parameters. It was used 54 banana samples, in different stages of maturation. The spectra were obtained from the pulp fruit, of the solution obtained after pulp centrifugation and by technique Dry Extract Spectroscopy by Infrared Absorption (DESIR). A total of 9 models were proposed for the determination of the quality parameters and the best result for pH determination was in the mid infrared region using the DESIR technique, with mean error of 1.32%. For the acidity parameter, the best model was in the near infrared region using the DESIR technique, with mean error of 6.20%. The Brix model furnished the best result in the mid infrared region by using the solution obtained after pulp centrifugation, with mean error of 3.78%. In this way, the vibrational spectroscopy make possible to achieve large quantity of information about the fruit quality through the relationship between the spectra and several properties of interest. / Mestrado / Quimica Analitica / Mestre em Química

Orientadores: Roy Edward Bruns, Ieda Spacino Scarmínio / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-27T16:58:19Z (GMT). No. of bitstreams: 1 Passari_LiviaMariaZambroziGarcia_D.pdf: 4832842 bytes, checksum: 6cfad5327d02d0b0a32dff9178a76155 (MD5) Previous issue date: 2014 / Resumo: Neste trabalho foi estudada a planta Mikania laevigata Sch. Bip, uma vez que é utilizada na medicina alternativa para fazer xaropes e chás devido as suas propriedades terapêuticas. Foram avaliados os efeitos sazonais e da composição do solvente extrator, bem como as suas interações na qualidade e no rendimento dos extratos brutos e das frações neutras, orgânicas, básicas, polares e fibras. O modelo estatístico de mistura do tipo Centróide-Simplex com quatro componentes, etanol, acetona, clorofórmio e diclorometano, foi empregado para a extração dos metabólitos secundários e os resultados indicaram que os efeitos sazonais são evidentes para o rendimento dos extratos brutos e todas as frações. Por outro lado, os efeitos dos solventes são importantes e significativos para o extrato bruto e frações, exceto a fração polar. Métodos estatísticos multivariados e univariados foram empregados aos dados gravimétricos e aqueles obtidos por cromatografia líquida de alta eficiência com detecção por arranjo de diodos (CLAE-DAD) e cromatografia líquida de ultra-eficiência acoplada à espectrometria de massas com ionização por electrospray (CLUE-IES-EM). As análises das frações orgânicas permitiram estudar as quantidades relativas da cumarina, a principal substância química de ação farmacológica encontrada na Mikania, e também dos ácidos melilótico e o-cumárico, sendo este último o precursor biossintético da cumarina. A existência e medição das abundâncias relativas do ácido melilótico na planta Mikania laevigata não foi relatada anteriormente. As concentrações dos ácidos melilótico e o-cumárico foram altamente correlacionadas durante todo o ano. As maiores concentrações da cumarina foi obtida no verão, enquanto que para os ácidos o-cumárico e melilótico a maior abundância foi na primavera. O efeito do solvente também se mostrou significativo. No verão, etanol extraiu a maior quantidade de cumarina na planta. As maiores quantidades dos ácidos o-cumárico e melilótico foram extraídas por misturas contendo os solventes etanol e acetona em suas composições nas estações primavera e inverno / Abstract: In this work the secondary metabolites of the Mikania laevigata Sch. Bip plant have been studied since they are used in alternative medicine for making syrups and teas with reputed therapeutic advantages. We have evaluated seasonal and solvent composition effects as well as their interactions for crude extract and organic, neutral, basic, polar and fiber fraction yields. The Simplex-Centroid mixture design for the ethanol, dichloromethane, chloroform and acetone solvents has been applied to the extraction of the secondary metabolites, and the results indicate that significant seasonal effects exist for the crude extract and all the fraction yields. On the other hand, the solvent effects are seen to be significant for the crude extract and all the fractions except the polar one. Both univariate and multivariate statistical methods were applied to the gravimetric data and those obtained by RP-HPLC-DAD and both positive and negative modes of UPLC-MS analyses. Analyses the organic fraction of the M. laevigata plant allowed determining the relative quantities of coumarin, the principal active pharmacological substance in Mikania, o-coumaric acid, the coumarin biosynthesis precursor, and melilotic acid for each solvent composition of samples harvested in the four different seasons. The existence and measurement of the relative abundances of melilotic acid in Mikania laevigata have not been reported previously. o-coumaric and melilotic acids concentrations were strongly correlated during the year. Highest coumarin concentrations were encountered in the summer whereas its o-coumaric acid precursor as well as melilotic acid were most abundant in the spring. Also the solvent effects are seen to be significant. In summer, ethanol extracted the highest amount of coumarin from the plant. Highest amounts of o-coumaric and melilotic acids were extracted by mixtures containing both ethanol and acetone in the winter and spring / Doutorado / Quimica Analitica / Doutora em Ciências

Orientador: Jarbas José Rodrigues Rohwedder / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-27T15:32:58Z (GMT). No. of bitstreams: 1 Santos_LiviaMartinsdos_D.pdf: 6212654 bytes, checksum: f20eb97ce2aae510654340b401468dd2 (MD5) Previous issue date: 2015 / Resumo: A contaminação de solos oriundos de derrames de compostos derivados do petróleo é um problema que representa riscos ao meio ambiente e a população. Dentre os constituintes do petróleo, os BTEX são os mais tóxicos. O uso da espectroscopia no infravermelho próximo (NIR) foi empregado como uma ferramenta analítica visando a determinação de BTEX em amostras de solo. À um espectrofotômetro construído no laboratório foi adaptado uma célula de medida, uma célula de amostra e uma válvula esfera responsável pela conexão entre essas duas células. Uma bomba de vácuo foi adaptada ao instrumento visando facilitar o enriquecimento da fase vapor dos hidrocarbonetos voláteis na célula de medida, a qual operou com uma pressão de 29,0 inHg abaixo da pressão do laboratório (APL). Os espectros obtidos da fase vapor contendo os hidrocarbonetos aromáticos apresentaram sobreposição de bandas de absorção. Desta forma, foi necessária a construção de modelos de calibração multivariados empregando Regressão por Mínimos Quadrados Parciais (PLS). Os resultados do melhor modelo de regressão obtidos a melhores condições experimentais mostraram que os valores de RMSECV foram de 12,4 mg kg-1, 47,3 mg kg-1, 72,4 mg kg-1 e 58,6 mg kg-1, respectivamente, para benzeno, tolueno, etilbenzeno e xilenos. Esses valores estão de acordo com os valores orientadores para solo da CETESB de 2005, com exceção para o benzeno que encontra-se acima do valor permitido. Para cada tipo de solo é necessário a construção de modelos de calibração, pois a composição do solo influencia na determinação dos hidrocarbonetos / Abstract: The contamination of soils due to petroleum compounds spills is a problem that represents risks to environment and population. Among petroleum constituents, the volatile aromatic hydrocarbons known as BTEX are toxic. This study aims to evaluate the use of near infrared spectroscopy as an analytical tool for determination of volatile hydrocarbons in soil samples. Spectra were obtained in a spectrophotometer built in the laboratory. It is also part of the instrument, a measuring cell with 540 mm of optical path, a sample cell and a valve which allows connection between the two cells. A vacuum pump was adapted to the instrument in order to facilitate enrichment of the vapor phase of the volatile hydrocarbons in the measuring cell, which operated at a pressure of 29.0 inHg below of the laboratory pressure (BLP). Spectra of the vapor phase containing aromatic hydrocarbons exhibited overlapping of absorption bands. Thus, it was necessary to construct multivariate calibration models using Partial Least Squares Regression (PLS). The results obtained for the calibration model provided values of RMSECV of 12.4 mg Kg¬-1, 47.3 mg Kg¬-1, 72.4 mg Kg¬-1 and 58.6 mg Kg¬-1 for benzene, toluene, ethylbenzene and xylenes, respectively. These values are in agreement with the 2005 CETESB guiding values for soil, except for benzene that is above the allowed value. For each type of soil, it was needed to build calibration models because soil composition affects the determination of hydrocarbons. The developed method is promising and may be used as a screening method to determine the occurrence of contamination in soils by BTEX / Doutorado / Quimica Analitica / Doutora em Ciências

Táto diplomová práca sa zaoberá klasifikáciou kovov pomocou spektroskopie laserom indukovanej plazmy (LIBS) a chemometrických metód. Práca poskytuje prehľad o štúdiách na danú tému. Sú vybrané tri široko používané chemometrické klasifikačné metódy: "Soft Independent Modeling of Class Analogy" (SIMCA), "Partial Least Squares Discriminant Analysis" (PLS-DA) a variácia umelých neurónových sietí (ANN), "Feedforward Multilayer Perceptron". Rôzne prístupy k prieskumovej analýze su tiež preskúmané. Metódy sú stručne opísané. Následne sú klasifikátory experimentálne porovnané.

Improvised explosive devices (IEDs) are charged devices often used by terrorists and criminals to create public panic. When the general public is targeted by an act of terrorism, people who are not injured or killed in the explosion remain in fear until the perpetrator(s) has been apprehended. Methods that can provide investigators and first responders with prompt investigative information are required in such cases. However, information is generally not provided quickly, in part because of time-consuming techniques employed in many forensic laboratories. As a result, case report turnaround time is longer. Direct analysis in real time - mass spectrometry (DART-MS) is a promising analytical technique that can address this challenge in the Forensic Science community by permitting rapid trace analysis of energetic materials. The builder of an IED will often charge the device with materials that are readily available. The most common materials employed in the construction of IEDs are black and smokeless powder. However, other materials may include ammonia- or peroxide-based materials such as common household detergents. Smokeless powder is a propellant that is readily available to civilians. They are typically used for reloading ammunition and are sold in large quantities each year in the United States. Some states have stricter regulations than others but typically a firearms license is all that’s required to possess smokeless powder. Smokeless powder is considered a low explosive which is capable of causing an explosion if a sufficient quantity is deflagrated inside a confined container. The most commonly employed confirmatory techniques for the analysis of smokeless powder are gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-mass spectrometry (LC-MS). These methods often require extensive and time-consuming sample preparation procedures to prepare the powders for analysis. In addition to lengthy sample preparation procedures, GC-MS and LC-MS often require chromatographic separations that can range anywhere from 5 to 30 minutes or longer per sample. Ion mobility spectrometry (IMS) is widely used for the field analysis of smokeless powder and can provide faster results in comparison to GC-MS or LC-MS. However, identification is limited to drift time and no structural information is provided unless coupled to a mass spectrometer. In an effort to accelerate the speed of collection and characterization of smokeless powder, an analytical approach that utilizes novel wire mesh coated with CarbopackTM X, dynamic headspace concentration and DART-MS was evaluated to determine if the approach could generate information rich chemical attribute signatures (CAS) for smokeless powder. CarbopackTM X is a graphitized carbon material that has been employed for the collection of various volatile and semi-volatile organic compounds. The goal of using CarbopackTM X coated wire mesh was to increase the collection efficiency of smokeless powder in comparison to traditional swabbing and swiping methods. DART is an ambient ionization technique that permits analysis of a variety of samples in seconds with minimal to no sample preparation and offers several advantages over conventional methods. Heating time, heating temperature and flow rate for dynamic headspace concentration were optimized using Hodgdon Lil’ Gun smokeless powder. DART-MS was compared to GC-MS and validated using the National Institute of Standards and Technology reference material 8107 (NIST RM 8107) smokeless powder standard. Additives and energetic materials from unburnt and burnt smokeless powders were rapidly and efficiently captured by the CarbopackTM X coated wire mesh and successfully detected and identified using DART-MS. The DART source temperature was evaluated with the goal of providing the most efficient desorption of the analytes adsorbed onto the wire mesh. For this to be a robust approach in forensic analysis, chemometric analysis employing predictive models was used to simplify the data and increase the confidence of assigning a mass spectrum to a particular powder. Predictive models were constructed using the machine learning techniques available in Analyze IQ Lab and evaluated for their performance in classifying three smokeless powders: Alliant Reloder 19, Hodgdon LEVERevolution and Winchester Ball 296. The models were able to accurately predict the presence or absence of these three powders from burnt residues with error rates that were less than 4%. This approach has demonstrated the capability of generating comparable data and sensitivity in a significantly shorter amount of time in comparison to GC-MS. In addition, DART-MS also permits the detection of targeted analytes that are not amenable to GC-MS. The speed and efficiency associated with both the sample preparation technique and DART-MS, and the ability to employ chemometric analysis to the generated data demonstrate an attractive and viable alternative to conventional techniques for smokeless powder analysis.

The selection of a representative sample is a delicate problem when drug seizures comprised of large number of units arrive at the Swedish National Forensic Centre (NFC). If deviating objects in the selected sample size are found, additional analyzes are required to investigate how representative the results are for the entire population. This generates further pressure on operational analysis flow. With the goal to provide a tool which forensic scientists at NFC can base their assessment of the representative nature of the selected sampling of large drug seizures on, this project investigated the possibilities of evaluating the level of homogeneity in drug seizures using near-infrared (NIR) hyperspectral imaging along with principal component analysis (PCA). A total of 27 sample groups (homogeneous, heterogeneous and seized sample groups) were analyzed and different predictive models were developed. The models were either based on quantifying the variation in NIR spectra or in PCA scores plots. It was shown that in the spectral range of 1300-2000 nm, using a pre-processing combination of area normalization, quadratic (second polynomial) detrending and mean centering, promising predictive abilities of the models in their evaluation of the level of homogeneity in drug seizures were achieved. A model where the approximated signal-dependent variation was related to the quotient of significant and noise explained variance given by PCA indicated most promising predictive abilities when quantifying the variation in NIR spectra. Similarly, a model where a rectangular area, defined by the maximum distances along PC1 and PC2, was related to the cumulative explained variance of the two PCs showed most promising predictive abilities when quantifying the variation in PCA scores plots. Different zones for which within sample groups are expected to appear based upon their degree of homogeneity could be established for both models. The two models differed in sensitivity. However, more comprehensive studies are required to evaluate the models applicability from an operational point-of-view.