NIR spectroscopy

It has been developed a general strategy for the determination of pesticides in agrochemicals by Fourier transform near infrared (FT-NIR) spectroscopy. The methodology is based on previous extraction of the active principles through sonication with acetonitrile and direct determination by transmission measurements, using glass vials as measurement cells and univariate calibration at selected wavenumbers as a function of the pesticide to be analyzed. Chlorsulfuron, metamitron, iprodione, pirimicarb, procymidone and tricyclazole were used as test molecules and data obtained by FT-NIR for 20 samples containing one of these active principles compare well with those found by reference liquid chromatography (HPLC) procedures. In short, FT-NIR provides relative standard deviations between 0.04 and 0.7% and limit of detection values ranging from 0.004 to 0.17 mg g −1 with recovery values between 96.4 and 100.5%. On the other hand, FT-NIR offers a 10 times faster methodology than chromatography ones and an environmentally friendly alternative which reduces the reagent consumption to 1 mL acetonitrile per sample.

The accelerated transformation of three azithromycin pseudo-polymorphs (viz. the anhydrous, monohydrate (MH), and dihydrate (DH) forms) at a high temperature and moisture level was examined by near infrared spectroscopy (NIRS). The most marked spectral differences between the pseudo-polymorphs occurred in the 1800-2200 nm region, which corresponds to the first overtone for water. The qualitative analysis of the NIR spectra for the pseudo-polymorphs following storage in a stove at 608C at 100% relative humidity for 60 days suggests that the crystalline forms (viz. the MH and DH) are stable, whereas the amorphous (anhydrous) form evolves to the DH. This was confirmed by determining the amounts of water and DH present in anhydrous azithromycin and the MH by use of partial least-squares regression (PLSR). The method used to quantify the DH in MH samples was developed and validated in accordance with the standards of the International Conference of Harmonization (ICH) and the European Medicines Agency (EMEA) with a view to its subsequent application by the pharmaceutical industry. The limits of detection (LD) and quantitation (LQ) for the DH in MH provided by the NIRS method were consistent with those obtained by X-ray diffraction (XRD) methodology. This testifies to the accuracy of the proposed method.

The processing of polymers may be accompanied by oxidation and elimination reactions that affect the quality of the final product. In reactive processing, polymerisation occurs in the extruder or autoclave and the extent of reaction becomes an important process variable. The monitoring of these chemical changes in real-time so that processing may be optimised requires the use of analytical methods such as fibre-optic Near Infrared (NIR) spectroscopy. In this paper the requirements and limitations for this and related spectroscopic probes are described and novel approaches based on infrared emission and transient infrared transmission spectroscopy (TIRTS) are discussed. To cite this article: G.

The objectives of the study were to evaluate the use of visible/near infrared reflectance spectroscopy (Vis/NIRS) in measuring the quality characteristics of Tomato ‘Heatwave’ (Lycopersicum esculentum), and to establish the relationship between nondestructive Vis/NIR spectra and the major fruit physiological properties, including fruit firmness, soluble solids content (SSC) and acidity (pH). Intact tomato fruit were measured by reflectance (R) in 350–2500 nm range. The absorbance, calculated via log (1/R), was analyzed for the best calibration model of each characteristic, using principal component re-gression (PCR) and partial least square regression (PLS). The results showed excellent prediction performances that the standard error of prediction (SEP) of SSC (r=0.90) was 0.19 oBrix with three factors; the SEP of pH (r=0.83) was 0.09 with four factors; that of compression force (r=0.81) was 16.017 N with six factors; and that of puncture force (r=0.83) was 1.18 N with three factors...

Hydrogen is a renewable and non-polluting fuel. Its production from water using renewable energy is an attractive challenge. In this work we report some results on the preparation of titanium oxide TiO 2 thin films for environmental applications such as water photosplitting. TiO 2 thin films have been prepared by spin coating technique of sol precursor onto glass substrates. The deposited films were annealed at different temperatures in air. The X-ray diffraction (XRD) experiments show that the two well-known anatase and rutile phases were observed depending both on the conditions of deposition and on the temperature of annealing. The best conditions of crystallization were found to be around 400 C in air. The influence of the number of deposited layer on the crystalline quality of the films was investigated. The surface morphology of the deposited film was characterized by atomic force microscopy (AFM) and scanning electronic microscopy (SEM). The UVeViseNIR spectroscopy shows that the film exhibits a high transmission around 90%. The best layers were obtained when concentrated (HCl) was added to the sol solutions. The direct band gap of the films was found to be around 3.7 eV, and their refractive index was found to vary from 2 to 2.4. (A. Elfanaoui).

A dense silica glass was prepared by consolidating a highly dispersed silicic acid powder (particle size o10 nm) with the Spark Plasma Sintering (SPS) technique. The glass was characterized by ellipsometry, transmission electron microscopy (TEM), infrared reflectance and transmittance spectroscopy, as well as by Raman, UV-Vis-NIR and solid-state nuclear magnetic resonance (NMR) spectroscopy. The prototypic sample showed a transmittance of about 63% compared to silica glass in the UV-Vis spectral range. Based on the results of infrared transmittance spectroscopy this lower transparency is due to the comparably high water content, which is about 40 times higher than that in silica glass. 1 H magic-angle spinning (MAS) NMR confirmed an increase in hydroxyl groups in the sample prepared by SPS relative to that of the conventional SiO 2 reference glass. Aside from the comparably high water content, we conclude from the similarity of the IR-reflectance and the 29 Si MAS NMR spectra of the SPS sample and the corresponding spectra of the conventionally prepared silica glass, that the short-and medium-range order is virtually the same in both materials. Raman spectroscopy, however, suggests that the number of three-and four-membered rings is significantly smaller in the SPS sample compared to the conventionally prepared sample. Based on these results we conclude that it is possible to prepare glasses by compacting amorphous powders by the SPS process. The SPS process may therefore enable the preparation of glasses with compositions inaccessible by conventional methods.

Soybean seed averages about 40% protein and is a dominant source of protein in animals and human foods. Increasing protein in soybeans is a goal in soybean breeding programs. Initial selection for protein among progeny from breeding populations is often based on non-destructive Near Infrared Reflectance (NIR) spectroscopy analysis of a 5 g or more seed sample in the F 3 or later generations. NIR spectroscopy analysis for protein on single F 2 seed would allow selection at the earliest possible time and improve selection efficiency for protein content; however this practice has not been evaluated. The objective of this study was to test effectiveness of NIR spectroscopy analysis of single F 2 seeds to select for increased protein content from two populations developed from high and average protein content parents. F 2 seeds from a single F 1 plant of each population showed a normal distribution with transgressive segregation for protein concentration. In both populations, F 3 seeds produced from plants from single F 2 seeds with either low or high protein content were analyzed for protein by NIR spectroscopy. Protein means and ranges of F 3 seed selected from high protein F 2 seeds were higher in protein than F 3 seed from low protein F 2 seeds which produced low means and ranges in protein content. This shows that analysis of single F 2 seed for protein content using NIR spectroscopy was effective in selecting for increased protein in the F 3 generation. Analysis of single F 2 seeds from breeding populations will improve breeding efficiency for protein in soybean breeding programs.

Richard Crocombe of Crocombe Spectroscopic Consulting surveys the use of portable spectrometers in pharmaceutical manufacturing, with an emphasis on vibrational spectroscopy. Ideal and typical features of portable spectrometers are reviewed, alongside explanation of why device characteristics and sample presentation are critical to obtaining meaningful results.

The methods used to quantify total alginate in brown algal tissue are time-consuming and may also be misleading, so faster and simpler methods for measuring alginate content would be beneficial in a variety of applications. This study reports on the use of near infra-red (NIR) analysis to monitor the alginate content of Laminaria hyperborea stipe during biodegradation. NIR reflectance spectra were recorded for 78 different freeze-dried samples of its stipe. The samples were collected during several biological degradation experiments and the total alginate content varied from 2.2 to 40.8% Na-alginate (w/w), determined by established methods based on ion exchange. Data analysis was performed using multivariate calibration methods in order to relate the spectral data to the alginate content. PLS2 analysis revealed some dependence on material type, probably reflecting differences in polyphenol content. In the end, a PLS1 model with 9 components was selected. The calculated model was validated both with internal data and with an external test set. Internal full cross validation explained 96.6% of the variance in alginate content. The external validation showed that the PLS1 model was able to predict the alginate concentration with a root mean square prediction accuracy of 2.1%.

Moisture content is an important parameter for lyophilized vaccines. Currently, Karl Fischer titration is widely used for moisture determination in routine analysis. However, this method is time-consuming, sample destructive and requires environment polluting reagents, as well as the results rely on the random samplings. In this study, near infrared spectroscopy was used as a fast, non-invasive and non-destructive method to determine the moisture content in lyophilized allergy vaccines. Five different vaccine products were investigated, which contained water in the range of 0.17-1.51% (w/w, KF). Different data pre-treatments, wavelength selection and partial least squares regression were applied to construct calibration models. Multi-products model and product-specific models were obtained, which show the possibility of NIR as a rapid method to discriminate whether moisture content fit into the specifications of a pharmaceutical company.

ABSTRACT During the ripening season, measurements were performed on 4 grape varieties (i.e. Cabernet Sauvignon, Merlot, Syrah and Carmenère). Spectral reflection measurements were performed on intact grapes using the Zeiss corona 45 VIS–NIR spectrophotometer. Thereafter, the concentration of extractable anthocyanins at pH equal to 1.0 (pH10) and 3.2 (pH32), the concentration of polyphenols (IPT), the concentration of sugars (OH) and the density were determined from the samples. Partial least squares analysis showed that prediction of PH10 and PH32 was possible for Syrah. For this variety, PH10 and PH32 increased during the season and changes in the spectral properties of the grapes could be linked to these parameters. For all other varieties, the parameters PH10 and PH32 remained fairly constant over time and the results showed that prediction was not possible. The prediction of IPT was not possible for all varieties. The prediction of OH and density was achieved accurately for all varieties. An important region for the prediction of OH and density was detected around 700 nm, corresponding to the red colour. The prediction of sugar is consequently, at least partially, feasible due to the co-occurring colour change from green to blue/red.

A espectroscopia no infravermelho próximo (NIRS) surge no campo das ciências florestais como método não destrutivo, rápido e preciso capaz de predizer propriedades tecnológicas da madeira. O objetivo deste trabalho foi aplicar a técnica NIRS para desenvolvimento de modelos de calibração para estimar as propriedades químicas e a densidade básica da madeira de Eucalyptus. Foram utilizados clones de Eucalyptus de três anos de idade, provenientes de plantios comerciais nas localidades de Cocais,

Novel synthetic methods of PANI functionalization are described. We investigated coupling of diazonium salt and electrophilic nitration of the aromatic ring, amine group protection by amide formation, nucleophilic reaction with activated aromatic moieties and nucleophilic addition of sulfite ions to the ring. The structure of the products and their properties were studied by FTIR, UV-vis spectroscopy and electrochemistry.

The aim of the present study was to investigate the feasibility of near infrared (NIR) spectroscopy for rapid assessment of the Bloom value, viscosity, pH and moisture content of commercial edible gelatines. NIR spectra from both dry gelatine samples and freshly made gels (matured for 30 min) were calibrated against the four parameters. The lowest prediction errors for Bloom value and pH were obtained from the gel spectra, while dry gelatine spectra provided the lowest prediction errors for viscosity and moisture content. However, all four parameters could be predicted from dry gelatine spectra with cross-validated correlation coefficients between 0.80 and 0.86. All calibration models gave correlation coefficients in the region 0.80-0.92. q

. The relationship between absorption in the near-infrared NIR spectral region and the target analytical parameter is frequently of the non-linear type. The origin of the non-linearity can be widely varied and difficult to identify. In some cases, the relationship between absorption and the analytical parameter of interest is intrinsically non-linear owing to the very chemical nature of the sample or analyte concerned. In this work, various multivariate calibration procedures were tested with a view to overcoming intrinsic non-linearity in NIR reflectance. An approach to solving the problem is suggested. Calibration was done, after transformation of spectra, by using linear and non-linear techniques. The linear calibration techniques Ž . Ž . Ž . used are partial least squares PLS regression with and without variable selection , linear PLS with X projection LP-PLS Ž . and stepwise polynomial principal component SWP-PC regression. Non-linear calibration methods included polynomial PLS Ž . Ž . PPLS and artificial neural networks ANNs . Results were compared on the basis of NIR spectra for ampicillin trihydrate samples, where the simultaneous presence of crystallization water and surface moisture gives rise to intrinsic non-linearity that affects the determination of the total water content in the sample. The best results were obtained by using the non-linear calibration techniques. q

We present a novel technique for wide dynamic range optical investigations. It is based on a fast-gated silicon singlephoton avalanche diode (SPAD) in time-correlated single-photon counting (TCSPC) setup. The SPAD is gated-ON and OFF in 500 ps so as to detect photons only within a given time interval. This technique is particularly useful in applications where a large amount of unnecessary photons precede or follow the optical signal to be detected, such as in time-resolved near infrared (NIR) spectroscopy, optical mammography, and optical molecular imaging. In particular, in time-resolved reflectance spectroscopy, it is desirable to minimize the source-detector separation to improve system performance. This leads to the saturation of the detection electronics because of the huge amount of "early" photons back scattered by superficial layers. Our setup is able to reject these photons and detect only "late" photons from the sample, thus allowing an increase in the dynamic range and the injected power. We acquired diffusive curves of two phantoms with 95 ps time resolution and 10 7 dynamic range with a measurement time three orders of magnitude shorter than what is currently possible with a standard TCPSC setup.

The control of gelato powder mixture production usually is carried out evaluating the gelato liquid phase. The rheological measurements from the present study were conduced on gelato unfrozen liquid phase in order to indirectly evaluate its rheological properties by FT-NIR spectroscopy applied on gelato powders. The calibration set was composed by samples obtained from different recipes having increasing percentage of thickeners, maintaining the proportions of the others compounds constant. After the NIR acquisitions the powders were mixed with warm milk, blended and than settled in order to obtain the unfrozen liquid phase needed for the rheological measurements. For each of the 60 tested recipes three batches with the same thickeners concentration were prepared. The flow curves were obtained with a rotational viscosimeter and were evaluated by using the Ostwald de Waele's equation and the goodness of fit was evaluated by the R 2 , which was above 0.95. Predictive models of rheological parameters were set up by means of PLS regressions in order to predict the apparent viscosity (g), the consistency coefficient (K) and the flow behaviour index (n) from spectral acquisitions. A high correlation of calibration was found between NIR spectra and apparent viscosity with R 2 of 0.943. A good correlation was also found between the NIR spectra and the consistency coefficient (K) and flow behaviour index (n), with a determination coefficient (R 2 ) of 0.895 and 0.874, respectively.

The effects of moisture on the morphology and mechanical properties of polyamides have been extensively studied by a number of researchers. However, the assessment of water content in the resins has been carried out by thermal or thermogravimetric methods, which are destructive. In the present work partial least-squares (PLS) calibration models based on near-infrared (NIR) spectroscopy were produced in order to predict the moisture content of nylon 6,6. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and the loss-on-drying (LOD) method were used as reference methods. TGA, LOD, DSC, and NIR analysis were performed in parallel, and the obtained data were used for multivariate calibration purposes. Data pretreatment techniques such as derivation and multiplicative scattering correction (MSC) successfully eliminated the baseline offset present in the raw spectra and compensated for differences in thickness and light scattering of the analyzed samples. Calibration models were validated by full cross validation with the help of a test set. A comparison of the prediction ability of PLS models based on pretreated data was also done. NIR spectroscopy is a rapid and nondestructive method for the determination of moisture in recycled nylon. The moisture content can be predicted with a RMSEP ϭ 0.05 wt %.

The insolubility of single-walled carbon nanotubes (SWNT) in either water or organic solvents has been a limitation for the practical application of this unique material. Recent studies have demonstrated that the suspendability of SWNT can be greatly enhanced by employing appropriate surfactants. Although the efficiency of anionic, cationic, and nonionic surfactants has been demonstrated to different extents, the exact mechanism by which carbon nanotubes and the different surfactants interact is still uncertain. To deepen the understanding of this interfacial phenomenon, we have investigated the effects of chemical modifications of the surface on the extent of nanotube-surfactant interaction. Such changes in the surface chemistry of the SWNT can be achieved by simply varying the pretreatment method, which can be acidic or basic. We have found that intrinsic surface properties such as the PZC (point of zero charge) are greatly affected by the purification method. That is, the electrical charge of the SWNT surface varies with the pH of the surrounding media. However, it has been found that during the adsorption of the anionic surfactant sodium dodecylbenzenesulfonate (NaDDBS) on SWNT Coulombic forces do not play a central role, but are overcome by the hydrophobic interactions between the surfactant tail and the nanotube walls. Only at pH values far from the PZC do the Coulombic forces become important. The hydrophobic forces between the surfactant tail and the nanotube determine the structure of the surfactant-stabilized nanotubes. In such a structure, each nanotube is covered by a monolayer of surfactant molecules in which the heads form a compact outer surface while the tails remain in contact with the nanotube walls. It is important to note that although the final configuration can be described as a cylindrical micelle with a nanotube in the center, the mechanism of formation of this structure does not proceed by incorporation of a nanotube into a micelle, but rather by a two-step adsorption that ends up in the formation of a surfactant monolayer.

. The goal of the presented study is two-fold. First, we want to emphasize the power of Near Infrared Reflectance NIR spectroscopy for discrimination between mayonnaise samples containing different vegetable oils. Secondly, we want to use our data to compare the performances of different classification procedures. The NIR spectra with 351 variables correspond to equally spaced wavelengths in the 1100-2500 nm area. Feature extraction both by automatic wavelength-selection and by Ž . projection onto principal components PCs is discussed. The discriminant methods considered are linear discriminant analy-Ž . Ž . Ä 4 sis LDA , quadratic discriminant analysis QDA and regression with categorical 0,1 -responses. A dataset containing 162 spectra of mayonnaise samples based on six different vegetable oils is analyzed. By LDA with authentic cross-validation Ž . PC-models re-estimated for each cross-validation segment , only one sample was misclassified. Classification by allocating Ž Ž . a sample according to the largest fitted value of a linear regression Discriminant-Partial least squares DPLS or Discrimi-Ž .. nant-Principal components regression DPCR is demonstrated sub-optimal compared to LDA of the corresponding PLS-or Ž PCR-scores. QDA significantly outperforms LDA for projections of the data onto subspaces of moderate size scores of 7-9 . Ž. PCs . Two automatic variable-selection procedures choose 16 and 26 wavelengths variables , respectively from the spectra. Based on the selected wavelengths, LDA gives considerably better classification than the regression approach. By reporting the performances of several feature extraction techniques in tandem with three of the most common classification methods, Ž . Ž we hope that the reader will notice two relevant aspects: 1 By using the DPLS and DPCR classification by 'dummy' re-. Ž . gressions one is exposed to a significant risk of obtaining sub-optimal classification results; 2 The automatic wavelength selections may give valuable information about what is actually causing a successful discrimination. Such knowledge can, for instance, be used to select the most suited filters for online applications of NIR. Besides, from demonstrating different classification strategies, our study clearly shows that classification methods with NIR spectra can be used to discriminate between mayonnaise samples of different oil types and fatty acid composition. q 1999 Elsevier Science B.V. All rights reserved.

The IQ Consortium reports on the current state of process analytical technology (PAT) for active pharmaceutical ingredient (API) development in branded pharmaceutical companies. The article uses an API process workflow (process steps from raw material identification through to finished API) to provide representative examples, including why and how the pharmaceutical industry uses PAT tools in API development. The use of PAT can improve R&D efficiency and minimize personnel hazards associated with sampling hazardous materials for in-process testing. Although not all steps or chemical processes are readily amenable to the use of the PAT toolbox, when appropriate, PAT enables reliable and rapid (real or near time) analyses of processes that may contain materials that are highly hazardous, transient, or heterogeneous. These measurements can provide significant data for developing process chemistry understanding, and they may include the detection of previously unknown reaction intermediates, mechanisms, or relationships between process variables. As the process becomes defined and understanding is gained through these measurements, the number of parameters suspected to be critical is reduced. As the process approaches the commercial manufacturing stage and the process design space is established, a simplification of the monitoring and control technology, as much as is practical, is desired. In many cases, this results in controls being either off-line, or if in situ control is required, the results from PAT are correlated with simple manufacturing measurements such as temperature and pressure.

—Near-infrared Spectroscopy (NIRS) is a spectroscopic method that uses the near infrared region of the electromagnetic spectrum (from about 800 nm to 2500 nm). Typical applications include pharmaceutical, medical diagnostics (including blood sugar and oximetery),food and agrochemical quality control, as well combustion research.

This paper proposes an analytical method for simultaneous near-infrared (NIR) spectrometric determination of ␣-linolenic and linoleic acid in eight types of edible vegetable oils and their blending. For this purpose, a combination of spectral wavelength selection by wavelet transform (WT) and elimination of uninformative variables (UVE) was proposed to obtain simple partial least square (PLS) models based on a small subset of wavelengths. WT was firstly utilized to compress full NIR spectra which contain 1413 redundant variables, and 42 wavelet approximate coefficients were obtained. UVE was then carried out to further select the informative variables. Finally, 27 and 19 wavelet approximate coefficients were selected by UVE for ␣-linolenic and linoleic acid, respectively. The selected variables were used as inputs of PLS model. Due to original spectra were compressed, and irrelevant variables were eliminated, more parsimonious and efficient model based on WT-UVE was obtained compared with the conventional PLS model with full spectra data. The coefficient of determination (r 2 ) and root mean square error prediction set (RMSEP) for prediction set were 0.9345 and 0.0123 for ␣-linolenic acid prediction by WT-UVE-PLS model. The r 2 and RMSEP were 0.9054, 0.0437 for linoleic acid prediction. The good performance showed a potential application using WT-UVE to select NIR effective variables. WT-UVE can both speed up the calculation and improve the predicted results. The results indicated that it was feasible to fast determine ␣-linolenic acid and linoleic acid content in edible oils using NIR spectroscopy.

A new method is developed to maintain the on-line robustness of multivariate calibrations against unknown influence factors, especially in the case of spectroscopy. This method is based on the use of the calibration database and the periodical on-line reference measurements with their corresponding spectra to compute an orthogonal correction. The spectra that would have been obtained in the absence of influence factor occurrence are estimated from the calibration database using the reference measurements and a kernel function. The difference between the estimated and the on-line spectra is used to compute an orthogonal projection correction of the calibration database that is used for recalibration. The originality of this method is its capability to handle different kinds of perturbations (chemical, physical, and environmental) using the original calibration database. This method was applied for on-line monitoring of alcoholic wine fermentation in the presence of temperature variations as the influence factor, where it showed a good performance for temperature variation and batch effects. Also, this method provides an on-line diagnosis tool for the spectral causes of robustness problems thus providing a basis to better understand the process in order to perform adjustments, if necessary, at an earlier stage. D

Here, we describe a combination approach using Two Calibration-Free Methods with reflectance nearinfrared (TCFM-NIR), which involves detecting end-points for active pharmaceutical ingredients (APIs) blending by simultaneously monitoring specific NIR peak intensity of APIs and calculating moving block standard deviation (MBSD). After determining the specific NIR peak range of nicaldipine hydrochloride, conditions for TCFM-NIR were established by monitoring the differential intensity of the second peak (1136 nm) while MBSD was calculated from the NIR peak intensity between 1100 and 1150 nm. In comparison with the validated reference method of UV-VIS spectroscopy, which is particularly destructive, TCFM-NIR was found to be useful in detecting end-points for blending of nicaldipine hydrochloride. TCFM-NIR monitors two important factors for estimation of blend uniformity: API concentration, using specific NIR peak intensity for APIs, and blend homogeneity, using MBSD. Also, the conditions of TCFM-NIR were confirmed to be adequate by using Partial Least Square (PLS). Further, simultaneously monitoring these two blend uniformity factors is more useful in preventing estimation errors for nondestructive monitoring of blend homogeneity than monitoring only one factor, as with NIR spectroscopy.

In recent years, near-infrared (NIR) spectroscopy has gained wide acceptance in different fields by virtue of its advantages over other analytical techniques, the most salient of which is its ability to record spectra for solid and liquid samples with no prior manipulation. Also, developments in instrumentation have resulted in the manufacture of spectrophotometers capable of quickly providing spectra that are flexible enough for use in different situations; thus, portable equipment can record spectra on site or even at production lines. This article discusses the features of NIR spectroscopy that have driven forward its dramatic development in a wide range of analytical fields in the last few years. #

This thesis contains a systematic study of the dispersion of pristine HiPco Single Walled Carbon Nanotubes (SWNTs) in a series of organic solvents. A double beamed UV-Vis-NIR absorption spectrometer coupled with an integrating sphere was employed to demonstrate the dispersibility of SWNTs in different solvents. Raman Spectroscopy and Atomic Force Microscopy (AFM) were used to confirm the debundling and exfoliation of SWNTs aggregates. An investigation of the solubility of SWNTs in four chlorinated aromatic solvents demonstrated that the similarity in structure between solvent molecules and nanotube sidewall is not a dominant factor to obtain stable SWNT solutions. A comparative study of the solubility of SWNTs between the aromatic solvents and other reported solvents was then conducted, in terms of the solvent solubility parameters, including Hildebrand and Hansen solubility parameters. Although the established correlation between extinction/absorption coefficients as a function of Hildebrand/Hansen solubility parameters indicated there may be a selective debundling of metallic and semiconducting SWNTs in different solvents, this was not confirmed by a detailed Raman investigation. A further study of the dispersion limit of SWNTs in different solvents as a function of the solvent solubility parameters was carried out. Good agreement with literature is demonstrated here in terms of Hildebrand parameters, but not in terms of the Hansen solubility parameters. It has been demonstrated that the degree of dispersion is critically dependent on sample preparation conditions, in particular sonication. Finally, the effect of sonication parameters and solvent properties ii during the dispersion of SWNTs was investigated. The results indicated that the sonication process is closely dependent on many of the physical parameters of the solvent, including vapour pressure, viscosity, surface tension, density and molecular weight. Longer sonication time and higher sonication power help debundling SWNTs in organic solvents but significantly damage the nanotubes. The choice of solvent should be guided by minimisation of sonication requirements. iii DECLARATION

Determining retained properties and durability are among the most important tasks when evaluating the possibility of mechanical recycling of plastic waste. In this investigation, profiles made of rigid PVC have been studied after various numbers of repeated extrusions to gain knowledge about the changes of properties and durability after conventional processing. New indoor profiles of PVC were re-extruded, from one to five times without adding new additives. The material was characterised after each extrusion using measurements of colour, degree of gelation, stress-strain at break and UV-Vis-NIR spectroscopy. The durability of the material was evaluated by accelerated ageing in ventilated heat ovens with low laminar airflow, at various temperatures. Changes in elongation at break, colour and chemical characteristics, depending on degradation, were measured and compared for the material after each extraction and various periods of ageing time. The material showed an improvement of mechanical properties after the second extrusion. This is explained by an increase in the degree of gelation of the PVC material. The main colour change due to repeated extrusion was yellowing (Áb). In accelerated heat ageing, the main colour change was towards red (Áa) and a change in greyness (ÁL) as a result of thermal dehydrochlorination. The activation energies of the degradation were also determined for the material after each re-extrusion and were found to decrease with an increasing number of extrusions. The estimated lifetime for indoor use at room temperature for the material after five extrusions was one-third of the lifetime of the material extruded only once. Despite this finding, a long lifetime can be expected even for the material subjected to five consecutive extrusions, making the material suitable for mechanical recycling. #

Organic soils represent a substantial pool of carbon in Denmark. The need for carbon stock assessment calls for more rapid and effective mapping methods to be developed. The aim of this study was to compare traditional soil mapping with maps produced from the results of a mobile VIS/NIR system and to evaluate the ability to estimate TOC and map the area of organic soils. The Veris mobile VIS/NIR spectroscopy system was compared to traditional manual sampling. The system is developed for in-situ near surface measurements of soil carbon content. It measures diffuse reflectance in the 350 nm-2200 nm region. The system consists of two spectrophotometers mounted on a toolbar and pulled by a tractor. Optical measurements are made through a sapphire window at the bottom of the shank. The shank was pulled at a depth of 5-7 cm at a speed of 4-5 km/hr. 20-25 spectra per second with 8 nm resolution were acquired by the spectrometers. Measurements were made on 10-12 m spaced transects. The syst...

The aim of the present study was first to develop a robust near infrared (NIR) calibration model able to determine the acetaminophen content of a low-dose syrup formulation (2%, w/v). Therefore, variability sources such as production campaigns, batches, API concentration, syrup basis, operators and sample temperatures were introduced in the calibration set. A prediction model was then built using partial least square (PLS) regression. First derivative followed by standard normal variate (SNV) were chosen as signal pre-processing. Based on the random subsets cross-validation, 4 PLS factors were selected for the prediction model. The method was then validated for an API concentration ranging from 16 to 24 mg/mL (1.6-2.4%, w/v) using an external validation set. The 0.26 mg/mL RMSEP suggested the global accuracy of the model. The accuracy profile obtained from the validation results, based on tolerance intervals, confirmed the adequate accuracy of the results generated by the method all over the investigated API concentration range. Finally, the NIR model was used to monitor in real time the API concentration while mixing syrups containing various amounts of API, a good agreement was found between the NIR method and the theoretical concentrations.

Advances in laboratory instrumentation and chemometrics provide alternatives to traditional methods of conducting soil chemical analysis. One of these is infrared diffuse reflectance spectroscopy in the near-infrared spectral range (NIRS). Herein we report the results of a multinational study to develop useful calibrations associating NIRS spectra with laboratory-measured results for total soil carbon (C), total soil nitrogen (N), δ13C, and δ15N from a single soil site in Mexico subjected to zero- and conventional-tillage regimens with and without crop residues and crop rotations of maize and wheat across 16 years. Modified partial least squares regression (MPLS) was used to obtain useful NIR predictions for total soil C and N, with ratio performance deviation (RPD) values of 6.8 and 2.6, respectively. Corresponding multiple correlation coefficients (RSQs) for C and N were 0.98 and 0.85, with standard errors of prediction (SEPs) of ±0.45 g C kg–1 and ±0.09g Nkg–1, respectively. The generation of δ15N and δ13C models produced different NIR recordings in soils with and without crop residues. Application of discriminant partial least squares (DPLS) statistics to the NIR spectral data allowed us to discriminate soils with and without residues. The prediction confidence for stable isotopes was 90% (internal validation) and 94% (external validation). Modified partial least squares regression was used to estimate δ15N and δ13C. Ratio performance deviation, RSQ, and SEP values obtained for δ13C and δ15N were 2.44 and 3.57, 0.83 and 0.81, ±0.5‰ (parts per thousand) and ±0.45‰ in soils with residues and 2.5 and 3.8, 0.93 and 0.92, and ±0.2‰ and ±0.23‰ in soils without residues, respectively. Overall, results obtained with NIRS were comparable to those obtained using conventional analytical methods, a finding that has wide relevance to agricultural soils and environmental studies in tropical locations. However, further testing is necessary to confirm that the calibration models are neither site nor instrument specific.

This paper reports a first attempt to develop a simple, quantitative, non-destructive and inexpensive methodology to characterise the mineral composition of soil using diffuse reflectance spectroscopy (DRS). Although there are studies that qualitatively characterise soil minerals using DRS, few studies quantify their composition in soil. Our aims were to: (i) design an experiment that may be used to model mineral-organic mixes as a function of their ultra violet (UV), visible (vis) and near infrared (NIR) diffuse reflectance spectra and (ii) use these models to predict the mineral-organic composition of independent test mixes. Our experiments used a three-factor simplex lattice design with three levels, corresponding to kaolinite (K), illite (I) and smectite (S). To this simplex we added two levels of goethite (G) and two levels of a 50/50 mix of humic and fulvic acids (H-F). Finally we added 3 levels of quartz (Q) to the mixes. We modelled the data using the partial least squares regression 1 algorithm (PLSR1) and made predictions using bootstrap aggregation-PLSR (or bagging-PLSR). The numbers of factors in the PLSR models were selected by leave-one-out cross-validation. These models were independently tested using mixes that we made up to roughly represent the mineral-organic composition of common Australian soils. Predictions of the amount of K, I and S in the test mixes were accurate (RMSE = 3.6, 3.4 and 3.4%, respectively). Predictions of goethite and the H-F mix were biased. Predictions of Q were very poor as quartz does not have a spectral response in the UV-vis-NIR. A principal components analysis (PCA) was used to compare the spectra of these test mixes with those of corresponding Australian soils. In future work we plan to expand our spectral library and improve the experimental design and our models.

An automated Fourier Transform Spectroscopic (FTS) solar observatory was established in Darwin, Australia in August 2005. The laboratory is part of the Total Carbon Column Observing Network, and measures atmospheric column abundances of CO 2 and O 2 and other gases. Measured CO 2 columns were calibrated against integrated aircraft profiles obtained during the TWP-ICE campaign in January-February 2006, and show good agreement with calibrations for a similar instrument in Park Falls, Wisconsin. A clearsky low airmass relative precision of 0.1% is demonstrated in the CO 2 and O 2 retrieved column-averaged volume mixing ratios. The 1% negative bias in the FTS X CO 2 relative to the World Meteorological Organization (WMO) calibrated in situ scale is within the uncertainties of the NIR spectroscopy and analysis.

The purpose of this paper is to describe the patterns of ground stone celt production in pre-contact southwestern British Columbia ( BP-AD ) and to offer hypotheses to explain those patterns derived from Coast and Interior Salish ethnographies. The mineralogy of celt production debris and celts was determined using a portable near-infrared spectrometer, and the resulting data mapped using GIS. The spatial distribution of such artifacts clearly indicates that celt production was a highly localized activity in a few centers along the Fraser River, with very little evidence of celt production anywhere else in the Salish British Columbia. Based on this evidence, it is clear that celts were exported in large numbers from very few communities and supplied a market of many hundreds of communities. The patterns evident in such data provide further resolution to the directionality and volume of exchange between celt producing and celt receiving communities. A number of avenues for increasing the volume of production of nephrite celts are explored against the archaeological record. I suggest that elites in nephrite source areas were well-positioned to sponsor or intensify the production of stone celts for export to distant exchange partners.