Jibran Iqbal

Determination of Tricyclazole Content in Paddy Rice by Surface Enhanced Raman Spectroscopy

An ultrasensitive method based on Surface enhanced Raman scattering (SERS) has been developed to determine content of a pesticide which is tricyclazole in paddy rice using sliver colloid as a substrate and pyridine as an internal standard. The peaks at 424 and 1035 cm(-1) in a SERS spectrum were selected as analytic and internal peaks, respectively, and their intensity ratio I(t)/I(p) was used to calculate the regression concentration of tricyclazole. The correlation between I(t)/I(p) and concentration showed significant linear relationship with a correlation coefficient of R(2)= 0.995 in a concentration range of 0.05 to 0.70 mg/L and the tricyclazole solution can be detected to be low as 0.002 mg/L by SERS. The method was applied to determine tricyclazole contents of 3 real rice samples with a standard addition method in order to eliminate interference of matrix. The errors of SERS measurements for the 3 samples were 0.0008 to 0.0246, 0.0013 to 0.0028, and 0.0129 to 0.0304 mg/kg, respectively, compared with the results obtained by high performance liquid chromatography method. This also showed a good reproducibility with low values of relative standard deviation (n= 3) for the 3 samples ranged from 3.63% to 4.64%.

Calibration transfer of near‐infrared spectra for extraction of informative components from spectra with canonical correlation analysis

A new calibration transfer method that applies canonical correlation analysis (CCA) to transfer the informative components extracted from a spectral dataset is proposed to reduce the interference of noise, background and non‐predicted properties. This method employs the partial least squares method to extract the informative components related to the predicted properties from the raw spectra and then corrects the informative components based on CCA. The performance of this algorithm was tested using three pairs of spectra batches: two pairs of corn spectra and one pair of tri‐component solvent spectra. The results showed that this method can significantly reduce prediction errors compared with CCA and piecewise direct standardization. Copyright

Sensitive determination of trace mercury by UV-visible diffuse reflectance spectroscopy after complexation and membrane filtration-enrichment.

A simple, sensitive and selective solid phase reflectometry method is proposed for the determination of trace mercury in aqueous samples. The complexation reagent dithizone was firstly injected into the properly buffered solution with vigorous stirring, which started a simultaneous formation of nanoparticles suspension of dithizone and its complexation reaction with the mercury(II) ions to make Hg-dithizone nanoparticles. After a definite time, the mixture was filtered with membrane, and then quantified directly on the surface of the membrane by using integrating sphere accessory of the UV-visible spectrophotometer. The quantitative analysis was carried out at a wavelength of 485 nm since it yielded the largest difference in diffuse reflectance spectra before and after reaction with mercury(II).A good linear correlation in the range of 0.2-4.0 μg/L with a squared correlation coefficient (R(2)) of 0.9944 and a detection limit of 0.12 μg/L were obtained. The accuracy of the method was evaluated by the analysis of spiked mercury(II) concentrations determined using this method along with those determined by the atomic fluorescence mercury vapourmeter and the results obtained were in good agreement. The proposed method was applied to the determination of mercury in tap water and river water samples with the recovery in an acceptable range (95.7-105.3%).

Micro near infrared spectroscopy (MicroNIRS) based on on-line enrichment: Determination of trace copper in water using glycidyl methacrylate-based monolithic material

A micro near infrared spectroscopy (MicroNIRS) technique based on monolithic column enrichment has been developed to detect low concentration metallic ions in water. Glycidyl methacrylate-ethylene dimethacrylate-iminodiacetic acid (GMA-EDMA-IDA) monolithic material was synthesized to construct an enrichment device, which can enrich metallic ions more efficiently than chelating resin materials such as D401. Cu(2+) solutions passed through the enrichment device and concentrated on the surface of the material, and then diffuse reflection NIR (DRNIR) spectra were measured by touching the NIR probe on the surface. The spectra were pretreated with multiplicative scatter correction (MSC) and the MSC-pretreated spectra showed high linear correlation to the Cu(2+) concentrations in spectral regions of 900-1350 nm, 1420-1480 nm and 1970-2050 nm for all concentration ranges. PLS models built with leave-one-out cross-validation also yielded good features. The mean relative error (MRE) of prediction was 10.0% in the 0.0001-0.0010 microg mL(-1) range. The concentration has low to ppb-level, but the MRE was not more than 10%, which was acceptable for trace analysis. The results revealed that the MicroNIRS technique enhanced the sensitivity of NIRS dramatically and widened the NIRS technique to micro and trace analysis field.

Determination of trace analytes based on diffuse reflectance spectroscopic techniques: development of a multichannel membrane filtration-enrichment device to improve repeatability

The determination of trace analytes based on membrane filtration-enrichment and diffuse reflectance spectroscopic techniques has gained increasing interest in the past decade due to its simplicity, rapidity and high sensitivity. However, poor repeatability primarily attributed to the differences of characteristics between membrane filters limits the development of this technique. In the current study, a simple and effective multichannel device is specially designed for the membrane filtration-enrichment process. The device is able to enrich six samples simultaneously on different positions of a membrane filter and allows the spectroscopic measurement of six samples with only one membrane filter. The proposed approach avoided the effects caused by the nonuniform membrane filters on the performance of the enrichment process. Accuracy and repeatability have been improved significantly for the subsequent on-line spectroscopic detection. A case study was carried out to assess this method utilizing the carcinogenic dye rhodamine B (RhB) as a model analyte. Under the optimal conditions, linearity of the calibration curve based on the Kubelka–Munk function was achieved in the concentration range of 2–30 μg L−1 with the correlation coefficient (R2) of 0.9924. Good repeatability was achieved with three average relative standard deviation (RSD) values of 3.6%, 3.8% and 3.8% corresponding to the solutions of 30, 10 and 5 μg L−1 RhB, respectively. The presented method was successfully employed to quantify RhB in soft drink and river water samples.

Simultaneous Enrichment and On-line Detection of Low-Concentration Copper, Cobalt, and Nickel Ions in Water by Near-Infrared Diffuse Reflectance Spectroscopy Combined with Chemometrics

Sensitive detection of heavy metal ions in water is of great importance considering the effects that heavy metals have on public health. A developed fluidized bed enrichment technique was used to concentrate and detect low concentrations of Cu2+, Co2+, and Ni2+ in water samples by near-IR diffuse reflectance (NIDR) spectroscopy (NIDRS) directly without using any chemicals or reagents. The NIDR spectra of adsorbent were measured on-line, and quantitative detection was achieved by applying a built partial least-squares chemometric model. Sensitivity and accuracy was improved significantly because large-volume mixture solutions were used in the enrichment process. Root mean square error of cross-validation values for Cu2+, Co2+, and Ni2+ were 0.29, 0.41, and 0.35 μg/mL, respectively, with mean relative error values in the acceptable range of 6.56-10.27%. This study confirms the potential application of fluidized bed enrichment combined with NIDRS and chemometrics for the simultaneous detection of trace heavy metal ions in water, with low relative error.

Vibrational spectroscopy of selective dental restorative materials

ABSTRACT Recently, significant advancement has occurred in vibrational (Fourier transform infrared [FTIR] and Raman) spectroscopy associated with dental materials. FTIR and Raman spectroscopies have emerged as significant breakthrough techniques and offer exciting new possibilities in the area of dental materials. These techniques have been used to obtain chemical images of formulations and allow researchers to find out the in situ structure of materials. This review summarizes the information obtained from these two techniques and their application in dental material sciences. The presented database of vibrational spectroscopy facilitated the appropriate identification of frequently used dental materials ranging from filling, obturating, adhesive, lining/luting materials, and prosthodontics materials. Spectral peaks that are related to these materials are discussed in detail, which provided crucial data in understanding the chemical structural properties. The application of vibrational spectroscopy allowed for a quick differential identification of typical dental materials composed of organic and inorganic compounds. From our study as well as the literature reviewed, it appeared that investigators uniformly confirmed the benefits of vibrational spectroscopy concerning identification of chemical functional groups of different chemical compositions. The diagnostic and prognostic tools based on these technologies have the potential to revolutionize our concepts leading to improve materials sciences and clinical application.

Lignin and Lignin Based Materials for the Removal of Heavy Metals from Waste Water-An Overview

Abstract Water Pollution through heavy metals is the concerned issue as many industries like tanning, steel production and electroplating are the major contributors. Various toxic Heavy metals are a matter of concern as they have severe environmental and health effects. Most commonly, conventional methods are using to remove these heavy metals like precipitation, ion exchange, which are not economical and have disposal issues. Adsorption of heavy metals by different low-cost adsorbents seems to be the best option in wastewater treatment. Many agricultural by-products proved to be suitable as low-cost adsorbents for removing heavy metals efficiently in a minimum time. Lignin residues that involves both agricultural and wood residues and sometimes separated out from black liquor through precipitation have adsorption capacity and affinity comparable to other natural adsorbents. However, lignin as bio adsorbents have the advantage of less cost and gives efficient adsorption results. This study is a review of the recent literature on the use of natural lignin residues for heavy metals adsorption under different experimental scenarios.

Waste Moringa oleifera seed pods as green sorbent for efficient removal of toxic aquatic pollutants

In the present study, biosorption of chromium (Cr(VI)) ions and Naphthol blue black (NBB) dye using Moringa oleifera seed pods powder (MPP) as green biosorbent was investigated. Three different sizes of MPP viz. fine fraction (<53 μm), coarse fraction (>250 μm) and mixed fraction were investigated. The biosorbent was characterized by pHzpc, Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM) in order to get an insight of the surface charge, functional groups, and morphology of the biosorbent, respectively. The biosorption studies were conducted with Cr(VI) and NBB dye and different parameters, such as solution pH, contact time, initial concentration of the pollutant, adsorbent dosage and co-existing ions were examined. Experimental results revealed that the maximum removal of Cr(VI) and NBB dye was observed at pH 1 and 2, respectively and the equilibrium was achieved in ca. 180 min. The removal efficiency of Cr(VI) by fine, mixed and coarse fraction was 91.8, 74.9, 52.6%, respectively, whereas for NBB dye, the removal efficiency for the same fractions was 97.5, 33.6, 18.9%, respectively. The removal efficiency of Cr(VI) and NBB dye was influenced in the presence of competing ions. The biosorption isotherm and kinetic data were best correlated with Langmuir isotherm and pseudo-second order kinetic model, respectively. Column studies were also conducted with MPP by studying different flow rates and adsorbates concentrations to check the practical applicability of MPP in removing target metal and dye pollutants.

Ionic liquid as a potential solvent for preparation of collagen-alginate-hydroxyapatite beads as bone filler

Abstract In this study, collagen/alginate/hydroxyapatite beads having different proportions were prepared as bone fillers for the restoration of osteological defects. Ionic liquid was used to dissolve the collagen and subsequently the solution was mixed with sodium alginate solution. Hydroxyapatite was added in different proportions, with the rationale to enhance mechanical as well as biological properties. The prepared solutions were given characteristic bead shapes by dropwise addition into calcium chloride solution. The prepared beads were characterized using FTIR, XRD, TGA and SEM analysis. Microhardness testing was used to evaluate the mechanical properties. The prepared beads were investigated for water adsorption behavior to ascertain its ability for body fluid uptake and adjusted accordingly to the bone cavity. Drug loading and subsequently the antibacterial activity was investigated for the prepared beads. The biocompatibility was assessed using the hemolysis testing and cell proliferation assay. The prepared collagen-alginate-HA beads, having biocompatibility and good mechanical properties, have showed an option of promising biologically active bone fillers for bone regeneration.