scholarly journals Mesoporous Silica-gold Films for Straightforward, Highly Reproducible Monitoring of Mercury Traces in Water

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 35 ◽  
Author(s):  
Anna Mutschler ◽  
Vivian Stock ◽  
Lena Ebert ◽  
Emma Björk ◽  
Kerstin Leopold ◽  
...  

Trace-level detection of mercury in waters is connected with several complications including complex multistep analysis routines, applying additional, harmful reagents increasing the risk of contamination, and the need for expensive analysis equipment. Here, we present a straightforward reagent-free approach for mercury trace determination using a novel thin film sampling stick for passive sampling based on gold nanoparticles. The nanoparticles supported on a silicon wafer and further covered with a thin layer of mesoporous silica. The mesoporous silica layer is acting as a protection layer preventing gold desorption upon exposure to water. The gold nanoparticles are created by thermal treatment of a homogenous gold layer on silicon wafer prepared by vacuum evaporation. This gold-covered substrate is subsequently covered by a layer of mesoporous silica through dip-coating. Dissolved mercury ions are extracted from a water sample, e.g., river water, by incorporation into the gold matrix in a diffusion-controlled manner. Thus, the amount of mercury accumulated during sampling depends on the mercury concentration of the water sample, the accumulation time, as well as the size of the substrate. Therefore, the experimental conditions can be chosen to fit any given mercury concentration level without loss of sensitivity. Determination of the mercury amount collected on the stick is performed after thermal desorption of mercury in the gas phase using atomic fluorescence spectrometry. Furthermore, the substrates can be re-used several tens of times without any loss of performance, and the batch-to-batch variations are minimal. Therefore, the nanogold-mesoporous silica sampling substrates allow for highly sensitive, simple, and reagent-free determination of mercury trace concentrations in waters, which should also be applicable for on-site analysis. Successful validation of the method was shown by measurement of mercury concentration in the certified reference material ORMS-5, a river water.

2014 ◽  
Vol 6 (4) ◽  
pp. 1254 ◽  
Author(s):  
J. S. Crosby ◽  
J. Z. James ◽  
D. Lucas ◽  
C. P. Koshland

2002 ◽  
Vol 67 (10) ◽  
pp. 661-667 ◽  
Author(s):  
Snezana Mitic ◽  
Valentina Zivanovic

Akinetic method for the determination of phenol is proposed. The method is based on the inhibiting effect of phenol on the Mn(II) catalysis of the oxidation of malachite green with potassium periodate. The reaction rate was followed spectrophotometrically at 615 nm. Kinetic expression for the reaction in the presence and absence of phenol are postulated. The optimal experimental conditions for the determination of phenol were established and phenol was determined in concentrations from 30.0 to 188.0 ng/cm3 with a relative standard deviation of 5.5%. The lower detecton limit is 7.8 ng/cm3. The effects of certain foreign ions upon the reaction rate were determined for the assessment of the selectivity of the method. The method was applied for the determination of phenol in tap and river water.


2008 ◽  
Vol 59 (7) ◽  
Author(s):  
S. S. Mitic ◽  
V. V. Zivanovic ◽  
G. Z. Miletic ◽  
D. A. Kostic ◽  
I. D. Rasic

A kinetic method for the determination of dinitrophenol is proposed. The method is based on the inhibiting effect of 2,4-dinitrophenol on the Mn(II) catalysis of the oxidation of malachite green with potassium periodate. The reaction was monitored spectrophotometrically at 615 nm. Kinetic expressions for the reaction are postulated. The optimal experimental conditions for the determination of 2,4-dinitrophenol were established and 2,4-dinitrophenol was determined in concentrations from 0.092-0.92 mg . mL-1 with relative standard error of 5.9 %. Detection limit is 0.014 mg . mL-1. The selectivity of the method is appropriate. The method was applied for the determination of dinitrophenol in urine and river water.


Author(s):  
Franciele de Matos Morawski ◽  
Brenda Borges Xavier ◽  
Anike Hübner Virgili ◽  
Karine dos Santos Caetano ◽  
Eliana Weber de Menezes ◽  
...  

NANO ◽  
2013 ◽  
Vol 08 (04) ◽  
pp. 1350037 ◽  
Author(s):  
RUIYONG WANG ◽  
SHUMIN FAN ◽  
RUIQIANG WANG ◽  
RUI WANG ◽  
HUANJING DOU ◽  
...  

A sensitive and selective colorimetric biosensor for determination of gentamicin, amikacin and tobramycin was proposed with the unmodified gold nanoparticles (GNPs) as the sensing element. Gentamicin, amikacin and tobramycin can rapidly induce the aggregation of gold nanoparticles and is accompanied by a color change from red to blue. The concentration of gentamicin, amikacin and tobramycin can be determined by using UV-Vis spectrometer. The experimental parameters were optimized with regard to pH, incubation time and the concentration of the GNPs. Under optimal experimental conditions, the linear range of the colorimetric sensor for gentamicin/amikacin/tobramycin were 2.67–33.93 ng mL-1, 13.33–66.67 ng mL-1 and 20–180 ng mL-1, respectively. The corresponding limit of detection (3σ) was 0.354 ng mL-1, 0.999 ng mL-1 and 0.579 ng mL-1, respectively. This assay was simple and used to detect aminoglycoside antibiotics in milk and medicine products.


2013 ◽  
Vol 699 ◽  
pp. 3-6
Author(s):  
Qing Shan Pan ◽  
Wei Liu ◽  
He Ping Yan ◽  
Bo Zhou ◽  
Bao Sen Wang ◽  
...  

Using sulfhydryl cotton for preconcentration of arsenic in Radix aucklandiae and determination of the arsenic by hydride generation-atomic fluorescence spectrometry. The samples were pretreated by high pressure digest. The experimental conditions such as negative high-voltage of instrument, preconcentration conditions and separation conditions of arsenic were studied and optimized. There was a good linear relationship between the fluorescence intensity and arsenic concentration in the range of 0-10μg/L with a correlation coefficient of 0.9997, while the detection limits was 0.06μg/L, and the relative standard deviation was 1.7% .The content of arsenic in the samples was 68.9-252.3µg/kg and the recovery was 90.0-95.0%.


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