1,721,050 research outputs found
The effects of acid and alkaline solutions on cut marks and on the structure of bone: An experimental study on porcine ribs
No full textAmong taphonomical modifications during decomposition processes, little is known about the action of
high or low pH to human tissues and bones. Moreover, acid or basic solutions are seldom used to ease
decomposition and wrecking of the body. In this study a total of 60 samples of porcine bones on which
two cut marks were produced before the beginning of the experiment, were put in six different solutions
with different pH (1, 3, 5, 9, 12, 14) and analyzed every five days over a period of 70 days. Surveys were
carried out macroscopically, with stereomicroscopy and with light microscopy on thin sections. Only the
specimens exposed to extremely acid (12) pH showed evident modifications of the bone’s
structure, as witnessed by the analyses with stereomicroscopy as well. Many samples showed a detachment
of the periosteum; cut marks became soon unrecognizable with pH 14 but still detectable in all the
other samples. The information gained from the present study can be of great help in detecting the exposure
of human tissues to high or low environmental pH and in understanding the effects that these solutions
can exert on human bones
Analytical application of carbon nanotubes, fullerenes and nanodiamonds in nanomaterials-based chromatographic stationary phases: a review.
No full textAn overview of the most significative results so far attained in the application of carbon nanotubes,fullerenes and anodiamonds as chromatographic separation media is presented. In particular, the authors focus on their use in capillary and packed-column as chromatography, in high performance liquid chromatography and capillary electrochromatography, paying also attention to ecently developed stationary phases for fast chromatography and nanochromatography. The performance of the nanomaterials
is compared to that of planar and amorphous carbon sorbents and critically discussed in regard to retentive capability and selectivity. A wide part of this review is devoted to the most recent improvements achieved in terms of selectivity by use of functionalized nanotubes and by combination of carbon nanotubes with ionic liquids. Practical aspects of synthetic procedures in preparing novel stationary phases in relationship with their chromatographic behaviour are also commented
Self-assembled monolayer modified gold electrodes for traces Cu(II) determination
Full text linkd,l-Penicillamine and thiodimethylglyoxime (TDMG) self-assembled monolayers (SAMs) on gold electrode were prepared and characterized
by electrochemical measurements. The two sensors exhibit sensitive and selective response to Cu(II), both forming 2:1 complexes, the first one in
acetic buffer and the second one in ammonia buffer.
Copper determination at trace level (LOQ 0.2 and 0.3 microg/L for d,l-penicillamine and TDMG, respectively) is possible with both the electrodes
as verified in tap, spring and sea water. The influence on copper determination of most common ions present in natural waters and of organic matter
has been investigated. Accuracy was checked by recovery test on spiked samples
Voltammetric determination of inorganic As(III) and total inorganic As in natural waters.
Full text linkThe paper describes a voltammetric method for the determination of As(III) and total inorganic As at ppb and sub ppb level using cathodic
stripping voltammetry. This method is based on the formation of a copper-arsenic intermetallic at HDME during the preconcentration step.
Sodium dithionite is used for the reduction of As(V) to As(III). As(III) is then determined in HBr supporting electrolyte. Compared to the
procedures described in previous literature, the determination of total inorganic arsenic in such conditions needs shorter deposition times and
less amount of copper. Moreover, better linear response current versus concentration and peaks repeatability are obtained. In the described
working conditions LOQ for As(III) and As(V) are 0.010 and 0.020 ppb respectively, for a deposition time of 300 s. Standard deviation for
1 ppb arsenic concentration (n = 7) is 5%. The method was applied to thermal, spring and sea waters and accuracy was verified by a recovery
test on spiked samples. Total arsenic concentrations are in good agreement with those obtained in ICP-OES-HG
Carbon nanotubes: purification, functionalization and analytical application as stationary phases for chromatographic separations
No full textMulti-walled carbon nanotubes (MWCNTs) were studied as stationary phases for packed-column gas
chromatography (GC). At first, a preservative purification procedure based on HCl washings was
developed for removing the metallic impurities from the raw material. CNTs were covalently derivatized
with different functionalities and chromatographic separations have been undertaken on pristine, purified
and functionalized MWCNTs. Mixtures of analytes of different chemical classes were analyzed with
remarkably diverse results on the different stationary phases. On MWCNTs-COOH the best separation of
light alkanes has been obtained, whereas MWCNTs-RNH2 were particularly suitable for the analysis of
BTX, alcohols, esters and chloroaromatics, with results comparable or even better of those achieved on a
commercial sorbent usually employed for such applications. Commercial samples of distillates and paint
thinners were successfully analyzed by GC on columns packed with the derivatized CNTs
Determination of Pb2+ in natural waters with 2-mercaptobenzimidazole-5-sulfonate (MBIS) chemically modified gold electrode.
No full textThe preparation, characterization and analytical applications of gold electrodes modified with omegamercapto alkyl/aryl sulfonates are described. The devices resulted effective for the determination of free and labile Pb(II) in water samples by anodic stripping voltammetry (Edep =−600mV) and in particular
2-mercaptobenzimidazole-5-sulfonate (MBIS) offered the best performances with detection limit of 0.4microgL−1.
Quantitative stripping of Pb from the electrode surface during the anodic scan, is obtained using sodium citrate buffer (pH = 9.0) as supporting electrolyte. Natural waters were analysed by standard addition method with good recoveries (mean percentage = 97%); no fouling effects due to humic acids or other organic constituents were observed in the reported conditions
Prebiotic Photochemistry
No full textThe role of photochemistry in the synthesis of prebiotic compounds is briefly reviewed
ω-Thio nitrilotriacetic chemically modified gold electrode for iron determination in natural waters with different salinity
No full textThe preparation, characterization and analytical application of a chemically modified gold electrode (CME), based on ω-thio nitrilotriacetic acid derivative (N-[5-[[[[20-(acetylthio)-3,6,9-trioxaeicos-1-yl]oxo]carbonyl]amino]-1carboxypentyl]iminodiacetic acid) self-assembled monolayer (SAM), have been described. The electrode has been characterized by electrochemical techniques and tested for its response towards metallic ions, demonstrating to be effective for the determination of ionized iron at sub-μg/L level by differential pulse cathodic stripping voltammetry (DPCSV). The analytical response towards iron in natural water (tap water, marine water) and the interference of ions usually present and chelating agents (humic acids and EDTA as model ligand of high complexing capacity) have been evaluated
Electrochemistry of olanzapine and risperidone at carbon nanotubes modified gold electrode through classical and DFT approaches
Full text linkAmong the neuroleptics, atypical antipsychotics have received great attention in recent years, because of their peculiar pharmacological profile. Due to their widespread use, rapid, efficient and economical methods of analysis of these compounds in pharmaceutical formulations and biological fluids are required, and in this sense electrochemical techniques appear particularly attractive. Most of these compounds are reported to be electroactive but quantification at classic electrodes is often unsuitable due to electrode fouling and absence or reduced linearity between concentration and current intensity. A gold electrode modified with oxidized single walled carbon nanotubes has proved useful to overcome these problems.
A deep insight into the electrochemistry of these compounds is reported, with the aid of Mass Spectrometry and DFT (Density Functional Theory) calculation; in particular, a computational approach to the electrochemistry of these substances turned out to be really useful to the purpose. A voltammetric method
for the determination of risperidone and olanzapine, two widely used atypical antipsychotics, has also been setup
Chemical reaction networks as a model to describe UVC- and radiolytically-induced reactions of simple compounds
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