Quantitative Infrared Analysis of Solids in Potassium Bromide Using an Internal Standard

Evaluation of carboxymethylpullulan-AlCl3 as a coagulant for water treatment: A case study with kaolin

A reduction in the use of aluminum (Al)-based flocculants in the treatment of drinking water is considered essential for human health reasons. In this study, a novel composite flocculant, made of carboxymethylpullulan-AlCl₃ , is evaluated in a lab-scale, jar test system for the flocculation of kaolin. The results showed that the coagulation efficiency of carboxymethylpullulan-AlCl₃ was more effective in reducing turbidity than the solo use of carboxymethylpullulan or AlCl₃ . The optimum treatment conditions assessed by a response surface methodology were obtained at pH 6.50, 13.03 mg/L carboxymethylpullulan, and 94.87 mg/L AlCl₃ . Zeta potential measurements and photometric dispersion analysis demonstrated that AlCl₃ had a more significant influence on charge neutralization than carboxymethylpullulan, whilst carboxymethylpullulan facilitated absorption and the development of particle bridges. Thus, the composite flocculant possessed both advantages that enhanced flocculation, and decreased the dosage of AlCl₃ , thereby reducing the potential for secondary environment pollution. When 90 mg/L carboxymethylpullulan-AlCl₃ was added to the model kaolin suspension characterized by a turbidity of 50 nephelometric turbidity units, the zeta potential and the maximum flocculating activity were determined as -2.28 mV and 98.0%, respectively. The results provide insight into the development of an environment-friendly composite flocculant prepared from water-dissolved polysaccharide and inorganic flocculants. PRACTITIONER POINTS: A novel composite flocculant CMP-AlCl₃ was achieved by combining CMP and AlCl₃ for water treatment. The coagulation efficiency of CMP-AlCl₃ was more effective in reducing turbidity than the solo use of CMP or AlCl₃ . The flocculation efficiency and mechanism were investigated by Zeta potential analysis, surface morphology, electron microscopy, and coagulation.

Origins of the method of standard additions and of the use of an internal standard in quantitative instrumental chemical analyses

The origin of the method of standard additions (SAM) and of the use of internal standard (IS) in instrumental chemical analysis and their spread into other areas has been reviewed. Recorded applications of IS range from flame spectroscopy in 1877 through multiple techniques to current use in NMR and standard additions with isotopically labelled internal standards in hyphenated techniques. For SAM, applications stemmed from polarography in 1937 and spread to most instrumental methods. Some misconceptions on priorities are corrected.

Isolation, purification, structural elucidation and antimicrobial activities of kocumarin, a novel antibiotic isolated from actinobacterium Kocuria marina CMG S2 associated with the brown seaweed Pelvetia canaliculata

AIMS

Screening of seaweed-associated bacteria capable of producing antimicrobials.

METHODS AND RESULTS

Fifteen microbial strains, associated to the brown seaweed Pelvetia canaliculata (Linnaeus) attached to the rocks of Sonmiani Beach (Karachi, Pakistan), were screened. Crude extract filtrates of CMG S2 strain grew on Zobell marine agar (ZMA) had the most remarkable antimicrobial activity. Based on its phenotypic aspects (e.g. Gram-positive, microccoid form), biochemical characteristics (e.g. halotolerance) and genetic analyses, CMG S2 is identified as a putatively new Kocuria marina type strain belonging to the actinobacteria's class and micrococcaceae family. Thereby, the nucleotide sequence analysis of its full-length 16S ribosomal ribonucleic acid (rRNA) gene (GenBank accession number EU073966.1) displayed highest identity (i.e. 99%) and score (2630) with K. marina KMM 3905. Phylogenic trees analysis using the neighbor-joining method showed closest evolutionary distance of CMG S2 with KMM 3905 strain and K. carniphila (DC2201) specie. Interestingly, a unique ultraviolet (UV)-bioactive compound was purified from CMG S2 crude extracts by flash silica gel column and thin-layer chromatography (TLC) techniques. Its chemical structure was unraveled as 4-[(Z)-2 phenyl ethenyl] benzoic acid (PEBA, later named kocumarin) by nuclear magnetic resonance (NMR) spectroscopy techniques. Importantly, kocumarin demonstrated prominent and rapid growth inhibition against all tested fungi and pathogenic bacteria including methicillin-resistant Staphylococcus aureus (MRSA), with a minimal fungal inhibitory concentration (MFC) of 15-25μg/mL and a minimal (bacterial) inhibitory concentration (MIC) of 10-15μg/mL.

SIGNIFICANCE AND IMPACT OF THE STUDY

Kocumarin represents a new promising natural antibiotic for in vivo and environmental applications.

Determination of Glucose in Plasma by Dry Film-based Fourier Transformed-Infrared Spectroscopy Coupled with Boosting Support Vector Regression

In the present study, a dry film-based Fourier transformed-infrared (FT-IR) spectroscopic technique, coupled with boosting support vector regression (BSVR), was employed for a blood glucose assay. Potassium thiocyanate (KSCN) was taken in the dry-film method as an internal standard to compensate for any film thickness variation. This technique circumvents interference from water absorption, and requires only 5 microl of a sample. Moving window partial least-squares regression (MWPLSR) was used for wavenumber interval selection before multivariate modeling. By using the BSVR modeling technique, glucose in plasma could be determined over a 0.4 - 20 mmol/l concentration range with satisfactory accuracy. The performance of the BSVR methodology was compared with that of conventional support vector regression (SVR) as well as partial-least squares (PLS). The results demonstrated that BSVR is an effective multivariate calibration tool, providing better performance than conventional PLS and SVR.

Calcium nutrition has a significant influence on wood formation in poplar

To test the effects of calcium on wood formation, Populus tremula x Populus tremuloides clones were supplied with Hoagland solution modified in its calcium contents. Energy-dispersive X-ray analysis (EDXA) revealed an increase in calcium in the phloem, the cambium and the xylem elongation zone with increasing Ca(2+) supply in the nutrient solution. Using light and electron microscopy, a strong impact was shown on the cambial and the elongation zones under calcium starvation. Using Fourier transform infrared (FTIR) spectroscopy on wood and bark cells formed under calcium starvation, we detected a reduction of some absorptions, such as carbonyl and methoxy groups from S-lignin. Also, a significant reduction in fiber length was detected with decreasing calcium supply in the nutrient solution. High-performance liquid chromatography (HPLC) analysis revealed a large increase in sugar concentrations in the leaves, but reduced concentrations in the bark under Ca(2+) deficiency. In conclusion, our results show a significant influence of calcium on the structure, chemistry and physiology of wood formation. Thus, efficient Ca(2+) supply has to be considered a decisive factor in wood formation.

Conversion in denture base polymers

The purpose of this investigation was to determine residual monomers, the insoluble gel fraction, and singly reacted dimethacrylate monomers in heat-polymerized, auto-polymerized conventional and pour-type denture base materials. Residual monomers were determined by HPLC analysis of tetrahydrofuran extracts of denture base polymers. The gel fraction was determined by gravimetric analysis of the nonextractable portion. The pendant methacrylate groups in the gel fraction were determined by quantitative IR (infrared) spectrometry. It was demonstrated that the heat-polymerized materials had the lowest content of residual monomers. Generally, the content of pendant methacrylate groups in the gel was dependent on the initial quantity of crosslinking agent in the monomer liquids. The gel fractions of the heat-polymerized materials were larger than the quantity of reacted monomers and were also dependent on the quantity of crosslinking agent. These findings showed that some of the linear prepolymer, poly(methyl methacrylate) (PMMA), had been incorporated into the crosslinked polymer system. The gel fraction of the auto-polymerized pour-type materials corresponded to the quantity of reacted monomers, whereas the conventional auto-polymerized materials took an intermediate position between pour type materials and heat-polymerized materials in this respect.