Trace determination of Ag(I) after reduction to Ag nanoparticles and sol–gel entrapment by alginic acid hydrogel

2018 ◽  
Vol 15 (12) ◽  
pp. 2675-2688
Author(s):  
Habibollah Eskandari ◽  
Marzieh Nodehi
Keyword(s):  
Ag Nanoparticles ◽  
Alginic Acid ◽  
Sol Gel ◽  
Trace Determination ◽  
Gel Entrapment

Sol-Gel-based SPME and GC–MS for Trace Determination of Geosmin in Water and Apple Juice Samples

2007 ◽  
Vol 66 (9-10) ◽  
pp. 779-783 ◽  
Author(s):  
Habib Bagheri ◽  
Ali Aghakhani ◽  
Ali Es-haghi
Keyword(s):  
Apple Juice ◽  
Sol Gel ◽  
Trace Determination

scholarly journals Interference-Free Biosensor Based on Screen-Printing Technology and Sol-Gel Immobilization for Determination of Acetaldehyde in Wine

2002 ◽  
Vol 85 (6) ◽  
pp. 1382-1389 ◽  
Author(s):  
Thierry Noguer ◽  
Anca Tencaliec ◽  
Carole Calas-Blanchard ◽  
Alina Avramescu ◽  
Jean-Louis Marty
Keyword(s):  
Screen Printing ◽  
Sol Gel ◽  
Carbon Electrodes ◽  
Wine Quality ◽  
Gel Entrapment ◽  
Highly Sensitive ◽  
Screen Printing Technology ◽  
Mediated Oxidation ◽  
Screen Printed

Abstract A monoenzymatic amperometric biosensor was developed for the detection of acetaldehyde. The sensor is based on the association of screen-printed carbon electrodes and aldehyde dehydrogenase immobilized by a sol-gel entrapment method. Modification of screen-printed carbon electrodes with Reinecke salt of Meldola's Blue (MBRS) resulted in highly sensitive and interference- free nicotinamide-adenine dinucleotide (NADH) detectors. Based on MBRS-mediated oxidation of NADH at –150 mV versus pseudo Ag/AgCl, acetaldehyde was determined in the range 10–260 μM, compatible with wine quality monitoring. The method of immobilization based on sol-gel entrapment was optimized to obtain the best compromise between sensitivity and operational stability. The sensor response was stable for 40 consecutive assays with methyltrimethoxysilane used as alkoxide precursor, thus allowing a possible calibration of the sensor before each measurement. The biosensors were used to analyze French wines. The method was validated with a commercially available enzymatic kit based on a standard spectrophotometric method.

Preparation, characterization and analytical application of an electrochemical laccase biosensor towards low level determination of isoprenaline in human serum samples

RSC Advances ◽  
2014 ◽  
Vol 4 (101) ◽  
pp. 57591-57599 ◽  
Author(s):  
P. Gopal ◽  
T. Madhusudana Reddy ◽  
C. Nagaraju ◽  
G. Narasimha
Keyword(s):  
Carbon Nanotubes ◽  
Human Serum ◽  
Multiwalled Carbon Nanotubes ◽  
Electrochemical Biosensor ◽  
Sol Gel ◽  
Analytical Application ◽  
Serum Samples ◽  
Multiwalled Carbon ◽  
Gel Entrapment

A novel electrochemical biosensor has been developed based on the immobilization of multiwalled carbon nanotubes (MWCNT) followed by sol–gel entrapment of laccase (Lac) enzyme on to the GCE.

Simultaneous Spectrophotometric Determination of Salbutamol by Coupling with Diazotized 4-Aminobenzoic acid

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Hind Hadi ◽  
Gufran Salim
Keyword(s):  
Pharmaceutical Preparations ◽  
Coupling Reaction ◽  
Dosage Forms ◽  
Water Soluble ◽  
Trace Determination ◽  
Aminobenzoic Acid ◽  
Optimum Conditions ◽  
Colored Product ◽  
Versus Concentration

A simple, rapid and sensitive spectrophotmetric method for trace determination of salbutamol (SAL) in aqueous solution and in pharmaceutical preparations is described. The method is based on the diazotization coupling reaction of the intended compound with 4-amino benzoic acid (ABA) in alkaline medium to form an intense orange, water soluble dye that is stable and shows maximum absorption at 410 nm. A graph of absorbance versus concentration indicates that Beer’s law is obeyed over the concentration range of 0.5-30 ppm, with a molar absorbtivity 3.76×104 L.mol-1 .cm-1 depending on the concentration of SAL. The optimum conditions and stability of the colored product have been investigated and the method was applied successfully to the determination of SAL in dosage forms.

Optimization of sol-gel based fibre-optic cholinesterase biosensor for the determination of organophosphorus pesticides

2000 ◽  
Vol 42 (7-8) ◽  
pp. 283-290 ◽  
Author(s):  
H.-C. Tsai ◽  
R.-A. Doong
Keyword(s):  
Fiber Optic ◽  
Ph Value ◽  
Rapid Determination ◽  
Organophosphorus Pesticides ◽  
Sol Gel ◽  
Neutral Red ◽  
Fluorescent Indicators ◽  
Low Leakage ◽  
Fiber Optic System

A sol-gel based fiber-optic biosensor with acetylcholinesterase as the biorecognition element has been developed for the rapid determination of organophosphorus pesticides. Nine fluorescent indicators, acridine, acridine orange, neutral red, DAPI, rhodamine B, fluorescein, umbelliferone, FITC on celite and FITC-dextran, have been examined to optimize the fiber-optic system. Results showed that acridine and FITCs were sensitive to the change of pH value caused by the enzyme-substrate catalysis reaction. However, the sensitivity of acridine was 260 times lower than that of FITCs. Higher toxicity of acridine to acetylcholinesterase than FITC was also observed. Moreover, the high-molecular-weight FITC-dextran showed low leakage rate when immobilizing using sol-gel technology, showing that the FITC-dextran was a suitable pH sensitive fluorescent indicator for the OPPs biosensor. The response of the fiber-optic biosensor to the substrate, acetylcholine, was highly reproducible (RSD=3.5%). A good linearity of acetylcholine in the range from 0.5 to 20 mM was also obtained (R2=0.98). Furthermore, a 30% inhibition can be achieved in 30min when 152 ppb paraoxon was added into the system. The results show the possibility for real-time determination of organophosphorus pesticides by using the biosensor developed in this study.

Multi-walled Carbon Nanotubes Reinforced into Hollow Fiber by Chitosan Sol-gel for Solid/Liquid Phase Microextraction of NSAIDs from Urine Prior to HPLC-DAD Analysis

2019 ◽  
Vol 20 (5) ◽  
pp. 390-400 ◽  
Author(s):  
Nabil N. AL-Hashimi ◽  
Amjad H. El-Sheikh ◽  
Rania F. Qawariq ◽  
Majed H. Shtaiwi ◽  
Rowan AlEjielat
Keyword(s):  
Carbon Nanotubes ◽  
Liquid Phase ◽  
Hollow Fiber ◽  
Sol Gel ◽  
Liquid Phase Microextraction ◽  
Extraction Device ◽  
Multi Walled Carbon Nanotubes ◽  
Solid Liquid ◽  
Walled Carbon Nanotubes

Background: The efficient analytical method for the analysis of nonsteroidal antiinflammatory drugs (NSAIDs) in a biological fluid is important for determining the toxicological aspects of such long-term used therapies. Methods: In the present work, multi-walled carbon nanotubes reinforced into a hollow fiber by chitosan sol-gel assisted-solid/ liquid phase microextraction (MWCNTs-HF-CA-SPME) method followed by the high-performance liquid chromatography-diode array detection (HPLC–DAD) was developed for the determination of three NSAIDs, ketoprofen, diclofenac, and ibuprofen in human urine samples. MWCNTs with various dimensions were characterized by various analytical techniques. The extraction device was prepared by immobilizing the MWCNTs in the pores of 2.5 cm microtube via chitosan sol-gel assisted technology while the lumen of the microtube was filled with few microliters of 1-octanol with two ends sealed. The extraction device was operated by direct immersion in the sample solution. Results: The main factors influencing the extraction efficiency of the selected NSAIDs have been examined. The method showed good linearity R2 ≥ 0.997 with RSDs from 1.1 to 12.3%. The limits of detection (LODs) were 2.633, 2.035 and 2.386 µg L-1, for ketoprofen, diclofenac, and ibuprofen, respectively. The developed method demonstrated a satisfactory result for the determination of selected drugs in patient urine samples and comparable results against reference methods. Conclusion: The method is simple, sensitive and can be considered as an alternative for clinical laboratory analysis of selected drugs.

Pitfalls and Solutions for the Trace Determination of Phthalates in Water Samples

2005 ◽  
Vol 61 (7-8) ◽  
pp. 365-370 ◽  
Author(s):  
Bart Tienpont ◽  
Frank David ◽  
Eric Dewulf ◽  
Pat Sandra
Keyword(s):  
Water Samples ◽  
Trace Determination

scholarly journals A Magnetic Nanocomposite Modifier for Improved Ultrasensitive Detection of Hexavalent Chromium in Water Samples

Chemosensors ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 189
Author(s):  
Nuša Hojnik ◽  
Olivija Plohl ◽  
Matjaž Finšgar
Keyword(s):  
Electron Microscopy ◽  
Analytical Performance ◽  
Magnetic Nanocomposite ◽  
Ex Situ ◽  
Trace Determination ◽  
Silica Layer ◽  
X Ray ◽  
Square Wave ◽  
Static Contact

In this work, different electrodes were employed for the determination of Cr(VI) by the cathodic square‑wave voltammetry (SWV) technique and the square-wave adsorptive stripping voltammetry (SWAdSV) technique in combination with diethylenetriaminepentaacetic acid. Using SWV, a comparison of the analytical performance of the bare glassy carbon electrode (GCE), ex situ electrodes (antimony-film—SbFE, copper-film—CuFE, and bismuth-film—BiFE), and the GCE modified with a new magnetic nanocomposite (MNC) material was performed. First, the MNC material was synthesized, i.e., MNPs@SiO2@Lys, where MNPs stands for magnetic maghemite nanoparticles, coated with a thin amorphous silica (SiO2) layer, which was additionally functionalized with derived lysine (Lys). The crystal structure of the prepared MNCs was confirmed by X-ray powder diffraction (XRD), while the morphology and nano-size of the MNCs were investigated by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), where TEM was additionally used to observe the MNP core and silica layer thickness. The presence of functional groups of the MNCs was investigated by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and surface analysis was performed by X-ray photoelectron spectroscopy (XPS). The hydrophilicity of the modified electrodes was also tested by static contact angle measurements. Then, MNPs@SiO2@Lys was applied onto the electrodes and used with the SWV and SWAdSV techniques. All electrodes tested with the SWV technique were effective for Cr(VI) trace determination. On the other hand, the SWAdSV technique was required for ultra-trace determination of Cr(VI). Using the SWAdSV technique, it was shown that a combination of ex situ BiFE with the deposited MNPs@SiO2@Lys resulted in excellent analytical performance (LOQ = 0.1 µg/L, a linear concentration range of 0.2–2.0 µg/L, significantly higher sensitivity compared to the SWV technique, an RSD representing reproducibility of 9.0%, and an average recovery of 98.5%). The applicability of the latter system was also demonstrated for the analysis of a real sample.

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