a rapid, specific and accurate proton quantitative nuclear magnetic resonance spectroscopic (1h qnmr) and also a reversed phase derivatization hplc method have been developed to quantify a toxic, uv-visible inactive and non-volatile impurity n,n-dimethylamine hydrochloride (dma∙hcl) in metformin hydrochloride (mf∙hcl), an active pharmaceutical ingradient. the method is based on proton quantitat...

anzali international wetland is one of the most valuable water resources as registered in ramsar convention with an extent of about 150 km2 in the south caspian sea. this wetland, not only has ecological and biological importance for migratory birds and rare fish species, but also is used for farms to discharge into the caspian sea through this wetland. therefore its pollution control is very i...

background and aims: although dental caries is a preventable disease, it is still common and remains a public health problem. one of the potentially effective preventive measures is laser irradiation. raman spectroscopy is a powerful technique for studying the microcrystalline structure of dental enamel. the study assessed the chemical alterations occurring in enamel irradiated with er:yag or n...

ftr-raman spectra of human dental enamel, both laser-irradiated and untreated, are reported. spectra are compared with hydroxyapatite. it is evident that unlike the co2 laser, the nd/yag laser does not induce any chemical change in dental enamel.

h-point standard addition method (hpsam) was applied for the simultaneous determination of v(v) and fe(iii). the method is based on the complex formation of v(v) and fe(iii) with chromazurol s (cas) in acidic media and in the presence of cetyltrimethylammonium bromide (ctab) as a micellizing agent. acidic media and the presence of a micellar system improve selectivity and sensitivity. fe (iii) ...

fibers of poplar wood (populus nigra l.) were prepared and oven dried. afterwards, they were acetylated with acetic anhydride without a catalyst. acetylation was carried out for different durations at 120ºc. different weight percentage gains (wpgs) were achieved based on the operating conditions. acetylated fibers were exposed to varying levels of relative humidity to determine equilibrium mois...

introduction: the aim of this study was to in-vestigate the effect of irradiation duration and distance of light tip to prepared samples in two different light curing unites on the degree of conversion of resin composite. materials and methods: conventional halogen and blue light emitting diode (led) units were used for polymerization of an opalis resin com-posite. the conversion measurements w...

surface-enhanced raman spectroscopy (sers) is a promising tool in the analytical science because it provides good selectivity and sensitivity without the labeling process required by fluorescence detection. this technique consists of locating the target analyte on nanometer range of roughed au-nanoparticles. the presence of the metal nanoparticles provides a tremendous enhancement to the result...

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