Safwan M. Obeidat

Bulk modification of polymeric microfluidic devices

The surface properties of microfluidic devices play an important role in their flow behavior. We report here on an effective control of the surface chemistry and performance of polymeric microchips through a bulk modification route during the fabrication process. The new protocol is based on modification of the bulk microchip material by tailored copolymerization of monomers during atmospheric-pressure molding. A judicious addition of a modifier to the primary monomer solution thus imparts attractive properties to the plastic microchip substrate, including significant enhancement and/or modulation of the EOF (with flow velocities comparable to those of glass), a strong pH sensitivity and high stability. Carboxy, sulfo, and amino moieties have thus been introduced (through the incorporation of methylacrylic acid, 2-sulfoethyl-methacrylate and 2-aminoethyl-methacrylate monomers, respectively). A strong increase in the electroosmotic pumping compared to the native poly(methylmethacrylate)(PMMA) microchip (ca. electroosmotic mobility increases from 2.12 to 4.30 x 10(-4) cm(2) V(-1) s(-1)) is observed using a 6% methylacrylate (MAA) modified PMMA microchip. A 3% aminoethyl modified PMMA microchip exhibits a reversal of the electroosmotic mobility (for example, -5.6 x 10(-4) cm(2) V(-1) s(-1) at pH 3.0). The effects of the modifier loading and the pH on the EOF have been investigated for the MAA-modified PMMA chips. The bulk-modified devices exhibit reproducible and stable EOF behavior. The one step fabrication/modification protocol should further facilitate the widespread production of high-performance plastic microchip devices.

Application of multi-way data analysis on excitation-emission spectra for plant identification

The ability to distinguish among diets fed to Damascus goats using excitation-emission luminescence spectra was investigated. These diets consisted of Medicago sativa L. (alfalfa), Trifolium spp. (clover), Pistacia lentiscus, Phyllirea latifolia and Pinus brutia. The three-dimensional luminescence response surface from phosphate buffered saline (PBS) extracts of each material was analyzed using muti-way analysis chemometric tools (MPCA) and parallel factor analysis (PARAFAC). Using three principal components, the spectra from each diet material were distinguished. Additionally, fecal samples from goats fed diets of either alfalfa or clover hays were investigated. The application of MPCA and PARAFAC to these samples using models derived from the pre-digested diet materials was strongly suggestive of the utility of similarly derive training samples for the elucidation of botanical diet composition for animals.

A Multi-Source Portable Light Emitting Diode Spectrofluorometer

A portable luminescence spectrofluorometer weighing only 1.5 kg that uses multiple light emitting diodes (LEDs) as excitation sources was developed and evaluated. Excitation using a sequence of seven individual broad-band LED emission sources enabled the generation of excitation-emission spectra using a light weight (<1.5 kg) spectrometer. Limits of detection for rhodamine 6G, rhodamine B, and fluorescein were 2.9, 3.2, and 11.0 nM, respectively. Generation of excitation-emission matrices (EEMs) enabled the analysis of samples containing mixtures of rhodamine B and fluorescein. Buffered saline plant and animal feed extracts were also analyzed using this instrument. These samples included the woody plants Pistacia lentiscus (Evergreen pistache or Mastic) and Philyria latifolia, and the herbaceous species Medicago sativa (alfalfa), Trifolium spp. (clover), and a feed concentrate. Application of multi-way principal component analysis (MPCA) to the resulting three-dimensional data sets enabled discernment among these various diet constituents.

Use of Fluorometry to Differentiate Among Clipped Species in the Genera Astragalus, Oxytropis, and Pleuraphis

Abstract A rapid and reproducible method to determine botanical composition of forage is an ecological and economic goal for range animal ecologists. Multidimensional fluorometry previously demonstrated the possibility of a unique optical approach for accurately determining species composition of clipped and digested plant materials. Fluorometry may be used to detect toxic plants in standing crop as well as diets by using electronic transitions in chemical structures at wavelengths between 370 and 580 nm. Grass hay (genus Pleuraphis) and 6 clipped forbs (4 species of Astragalus and 2 species of Oxytropis) were examined. The resulting spectral signatures were evaluated for differences in the blue and green regions of the visible spectrum using Principal Component Analysis (PCA). This represents the first published data using chemometrics to differentiate among fluorophores from these plant extracts. It was possible to distinguish between the grass and forbs and among forbs. Further research will be required to evaluate these same plant species in mixed diets and fecal samples.

Photoluminescent Distinction Among Plant Life Forms Using Phosphate Buffered Saline Extract Solutions

Photoluminescence of plant extract solutions has been investigated for discrimination of plant life forms (grasses, forbs, and shrubs) using principal component analysis (PCA). Clippings from each of six plant species representing three different plant life forms potentially found in the diets of free-ranging herbivores in the Chihuahuan Desert of North America were investigated for possible discernment. These plants included Sporobolus flexuosus (mesa dropseed, a grass), Pleuraphis mutica (tobosa, a grass), Dimorphocarpa wislizenii (spectacle pod, a forb), Sphaeralcea incana (pale globemallow, a forb), Flourensia cernua leaves (tarbush, a shrub), and Atriplex canescens leaves and stems (fourwing saltbush, a shrub). Emission spectra (370–600 nm) from phosphate buffered saline (PBS) extract solutions (pH 2.2, 7.5 and 12.5) were recorded for each plant with excitation at 365 nm. Use of PBS minimized chlorophyll interference. Discernment among plant life forms within these plant species was achieved.

Differentiating Among Plant Spectra by Combining pH Dependent Photoluminescence Spectroscopy with Multi-Way Principal Component Analysis (MPCA)

Photoluminescence spectroscopic probes offer the potential for differentiation among plant species in real-time. Spectral emission signatures (excitation at 365 nm) from three different pH (2.2, 7.5 and 12.5) phosphate buffered saline (PBS) extracts from two grasses, Sporobolus flexuosus (Thurb. ex Vasey) Rydb., (mesa dropseed), and Pleuraphis mutica Buckley (tobosa), two forbs, Dimorphocarpa wislizenii (Engelm.) Rollins (spectacle pod), and Sphaeralcea incana Torrey (pale globemallow), and leaves and twigs from two shrubs Flourensia cernua DC. (tarbush), and Atriplex canescens (Pursh) Nutt., (fourwing saltbush) were examined. Since pH has been shown to be pivotal in affecting extraction effi- ciency of other plant compounds pH seemed appropriate as an additional dimension within our multi-way principal com- ponent analysis (MPCA) to differentiate among six different plant species. In particular, MPCA allowed differentiation between Sporobolus and Pleuraphis that was not possible using only principal component analysis (PCA). This research suggests MPCA may be a more appropriate tool than PCA when attempting to discriminate among plant species.

Combination of ICP-OES, XRF and XRD techniques for analysis of several dental ceramics and their identification using chemometrics

In this paper dental ceramic samples from seven vendors were studied. The elemental composition for each type was investigated using the ICP-OES and the XRF. Assessment of the seven types of ceramic was also successfully achieved using the XRD spectral data and processed with Principal Component Analysis (PCA). Detecting possible adulteration in different mass percentages of ceramic was also possible by applying the XRD data for the adulterated samples to the original PCA model.

Patterns in Volatile Emission of Different Organs of Inula viscosa growing wild in Jordan

Abstract In the current investigation, Volatile Organic Compounds (VOCs) spontaneously emitted from the different organs of Inula viscosa growing wild in Jordan were extracted by Solid Phase Micro Extraction (SPME) method and then analyzed using GC-MS technique. Oxygenated monoterpenes dominated roots emission (52.39%) while sesquiterpene hydrocarbons were the main class of compounds detected in the emission of the stems (60.05%). Leaves emission was characterized with high monoterpenoids content (oxygenated 24.34%, hydrocarbons 30.06%). The emission of the fully expanded flowers and flowering organs (receptacles, petals and pistils) was rich in oxygenated monoterpenes (51.96%, 46.94%, 45.45% and 53.13%, respectively). Flowering buds at the pre-flowering stage were rich in oxygenated sesquiterpenoids (40.02%). Principle Component Analysis (PCA) and Cluster Analysis (CA) analysis revealed that the emission profiles of different I. viscosa organs were classified into three clusters based on their chemical composition. In addition, the hydrodistilled essential oils obtained from the fresh leaves, pre-flowering buds and fully expanded flowers were dominated by oxygenated sesquiterpenoids (69.63, 92.75 and 76.70%, respectively).

Uncovering Counterfeit Viagra and Cialis Using Portable Nir and Uv-Visible Spectroscopy Coupled with Multivariate Data Analysis : A Preliminary Study

In this study, two of the most common drugs (Cialis ® and Viagra ® ) that are subjected to adulteration were investigated. The investigation involved examining the above drugs using both portable NIR and UV-Visible spectroscopy. The obtained spectral data were analyzed using multivariate chemometric methods such as Principal Components Analysis (PCA) and Cluster Analysis (CA). Discriminating between the original and the counterfeit drugs was successfully demonstrated with no or little chemical pretreatment. Detection of counterfeit drugs from different sources was also possible.

Volatile Components Analysis, Total Phenolic, Flavonoid Contents, and Antioxidant Activity of Phlomis Species Collected from Jordan

Abstract In this study, the composition of the essential oil, flavonoid and phenolic contents, and the antioxidant activities of three Phlomis species from Jordan (P. viscosa Poiret., P. platystegia Post. and P. brachyodon Boiss.) were examined. The essential oil from fresh and air dried aerial parts of these Phlomis species was obtained by hydrodistillation and analyzed by GC-MS. Germacrene B, E-caryophyllene and γ-muuroleneas were the major constituents of the oil from P. viscosa, while viridiflorol, β-eudesmol, Linalool and γ-cadieneneas dominated in P. platystegia, and γ-muurolene, α-humulene, γ-himachalene and Linalool were the chief components of the oil from P. brachyodon. Comparatively, the different oils extracted from the air-dried parts of the three Phlomis species showed less content in monoterpene and sesquiterpene hydrocarbons and higher amounts of oxygenated monoterpenes and sesquiterpenes than the oils from the same fresh areal parts. The total phenol and flavonoid contents from crude fractions obtained from these three species were determined by using Folin-Ciocalteu and AlCl3 assays. And four biochemical assays, namely 1, 1-Diphenyl-2-picrylhydrazyl (|DPPH), 2,22 -azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS), hydrogen peroxide scavenging (hydroxyl) and ferrous ion chelating (FIC) were used to evaluate antioxidant activities. The butanol fractions from the different species showed the highest content of both total phenol and flavonoid, when compared to aqueous and methanol extracts. Similarly, the butanol fraction showed the highest antioxidant capacity among the other extracts, as revealed by DPPH free radical scavenging activity, ABTS free radical scavenging assay, Hydroxyl radical assay and ferrous ion chelating assays.