scholarly journals A Novel Potentiometric Sensor for Determination of Neurotoxinβ-N-Oxalyl-L-α,β-Diaminopropionic Acid

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Omer Isildak ◽  
Furkan Saymaz ◽  
Ahmet Karadag ◽  
Nesrin Okumus Korkmaz ◽  
Azade Attar
Keyword(s):  
Response Time ◽  
Dynamic Range ◽  
High Sensitivity ◽  
Potentiometric Sensor ◽  
Membrane Sensor ◽  
Relative Standard ◽  
Selective Membrane ◽  
Continuous Work ◽  
Diaminopropionic Acid

A novel potentiometric sensor based on ionophore (Cd(NH2CH2CH2OCH2CH2OCH2CH2NH2)Ag3(CN)5) for the determination ofβ-N-oxalyl-l-α,β-diaminopropionic acid (ODAP) is developed. The ODAP-selective membrane sensor demonstrates high sensitivity and short response time. The detection limit of the ODAP-selective membrane sensor is about2×10-6 mol L-1and the response time is shorter than 6 s. The linear dynamic range of the ODAP-selective membrane sensor is between ODAP concentrations of1.0×10-2and1×10-6 mol L-1. The ODAP-selective membrane sensor exhibits good operational stability for at least one week in dry conditions at 4–6°C. It has a reproducible and stable response during continuous work for at least 10 h with a relative standard deviation of 0.28% (n= 18).

Atomic absorption determination of Hg (II), Cd (II), and As (III) in natural and waste water after preliminary group preconcentration

2019 ◽  
Vol 85 (2) ◽  
pp. 12-16
Author(s):  
I. V. Saunina ◽  
E. N. Gribanov ◽  
E. R. Oskotskaya
Keyword(s):  
Waste Water ◽  
Atomic Absorption ◽  
High Sensitivity ◽  
Distribution Coefficients ◽  
Neutral Medium ◽  
Atomic Absorption Determination ◽  
Absorption Determination ◽  
Relative Standard ◽  
Preliminary Group

The sorption of Hg (II), Cd (II), and As (III) by natural aluminosilicate is studied. It is shown that the mineral absorbs those toxicants in a rather wide pH range, quantitative extraction of analytes being achieved in a neutral or close to neutral medium (pH values range within 7.0 - 8.0; 6.3 - 7.5; 7.4 - 8.5 for Hg (II), As (III), and Cd (II), respectively). The effect of the time of phase contact on the degree of extraction of elements is shown. The sorption capacity of the mineral in optimal conditions of the medium acidity (0.06 mmol/g for mercury, 0.31 mmol/g for cadmium, and 0.52 mmol/g for arsenic) is determined. The distribution coefficients attain values of aboutnX 103-nX 104. A new combined method for determination of Hg (II), Cd (II), and As (III) in natural and waste water is developed and tested. The method consists in a preliminary group sorption concentration of the analytes by aluminosilicate, desorption of the analytes from the surface of the mineral and their subsequent atomic absorption determination. The correctness of the method is verified in analysis of spiked samples. The method is easy to use and exhibits high sensitivity, reproducibility and accuracy of analyte determination. The relative standard deviation does not exceed 0.13. Economic availability and possibility of using domestic sorption materials are the important advantages of the proposed procedure which can be used in the practice of laboratories monitoring the quality and safety of environmental objects.

Genetically Engineered Pores as Metal Ion Biosensors

1993 ◽  
Vol 330 ◽  
Author(s):  
John Kasianowicz ◽  
Barbara Walker ◽  
Musti Krishnasastry ◽  
Hagan Bayley
Keyword(s):  
Response Time ◽  
Lipid Bilayers ◽  
Metal Ion ◽  
Dynamic Range ◽  
Divalent Cations ◽  
High Sensitivity ◽  
Genetically Engineered ◽  
Great Promise ◽  
Lipid Bilayer Membranes ◽  
Time Dynamic

ABSTRACTWe are adapting proteins that form pores in lipid bilayers for use as components of biosensors. Specifically, we have produced genetically engineered variants of the α hemolysin (αHL) fromStaphylococcusaureus with properties that are sensitive to low concentrations of divalent cations. For example, the pore-forming activity of one mutant (αHL-H5: residues 130–134 inclusive replaced with histidine) is inhibited by Zn2+at concentrations as low as 1 μM, as judged by the reduction in its ability to lyse rabbit red blood cells and to increase the conductance of planar lipid bilayer membranes. When αHL-H5 is added to the aqueous phase bathing one side of a planar membrane, the subsequent addition of 100 μM Zn2+to either side blocks the pores that form. This result suggests that at least part of the mutated region lines the channel lumen. Ca2+and Mg2+do not block the channel and therefore the H5 mutation confers a degree of analyte specificity to the αHL pore. The results suggest that genetically engineered pores have great promise for the rapid and sensitive detection of metal cations and we discuss the merits and potential limitations for their use in this application. Specifically, we examine the issues of selectivity, sensitivity, response time, dynamic range and longevity. Some of these properties are interdependent. For example, the goals of high sensitivity and rapid response time can be in conflict.

scholarly journals New Spectrofluorimetric Method with Enhanced Sensitivity for Determination of Paroxetine in Dosage Forms and Plasma

2008 ◽  
Vol 3 ◽  
pp. ACI.S1053 ◽  
Author(s):  
Ibrahim A. Darwish ◽  
Sawsan M. Amer ◽  
Heba H. Abdine ◽  
Lama I. Al-Rayes
Keyword(s):  
High Sensitivity ◽  
Dosage Forms ◽  
Official Method ◽  
Factors Affecting ◽  
Pharmaceutical Tablets ◽  
Enhanced Sensitivity ◽  
Spectrofluorimetric Method ◽  
Relative Standard ◽  
Optimized Conditions

New simple spectrofluorimetric method with enhanced sensitivity has been developed and validated for the determination of the antidepressant paroxetine (PXT) in its dosage forms and plasma. The method was based on nucleophilic substitution reaction of PXT with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole in an alkaline medium (pH 8) to form a highly fluorescent derivative that was measured at 545 nm after excitation at 490 nm. The factors affecting the reaction was carefully studied and optimized. The kinetics of the reaction was investigated, and the reaction mechanism was presented. Under the optimized conditions, linear relationship with good correlation coefficient (0.9993) was found between the fluorescence intensity and PXT concentration in the range of 80-800 ng ml-1. The limits of detection and quantitation for the method were 25 and 77 ng ml-1, respectively. The precision of the method was satisfactory; the values of relative standard deviations did not exceed 3%. The proposed method was successfully applied to the determination of PXT in its pharmaceutical tablets with good accuracy; the recovery values were 100.2 ± 1.61%. The results obtained by the proposed method were comparable with those obtained by the official method. The proposed method is superior to the previously reported spectrofluorimetric method for determination of PXT in terms of its higher sensitivity and wider linear range. The high sensitivity of the method allowed its successful application to the analysis of PXT in spiked human plasma. The proposed method is practical and valuable for its routine application in quality control and clinical laboratories for analysis of PXT.

scholarly journals Determination of cyanide in bamboo shoots by microdiffusion combined with ion chromatography–pulsed amperometric detection

2018 ◽  
Vol 5 (4) ◽  
pp. 172128 ◽  
Author(s):  
Ming Ding ◽  
Kailiang Wang
Keyword(s):  
Ion Chromatography ◽  
Limit Of Detection ◽  
Correlation Coefficients ◽  
Amperometric Detection ◽  
High Sensitivity ◽  
Practical Method ◽  
Pulsed Amperometric Detection ◽  
Bamboo Shoots ◽  
Relative Standard

A practical method for the determination of cyanide in bamboo shoots has been developed using microdiffusion preparation integrated with ion chromatography–pulsed amperometric detection (IC-PAD). Cyanide was released from bamboo shoots after Conway cell microdiffusion, and then analysed by IC-PAD. In comparison with the previously reported methods, derivatization and ion-pairing agent addition were not required in this proposed microdiffusion combined with IC-PAD method. The microdiffusion parameters were optimized including hydrolysis systems, temperature, time, and so on. Under the optimum conditions, the linear range of the calibration curve for cyanide was 0.2–200.0 µg kg −1 with satisfactory correlation coefficients of 0.9996 and the limit of detection was 0.2 µg kg −1 ( S/N  = 3). The spiked recovery range was from 92.8 to 98.6%. The intra-day and inter-day relative standard deviations of cyanide were 2.7–14.9% and 3.0–18.3%, respectively. This method was proved to be convenient in operation with high sensitivity, precision and accuracy, and was successfully applied in the determination of cyanide in bamboo shoot samples.

A method of high sensitivity and in situ determination of trace cobalt(II) in water samples with salicyl fluorone

2014 ◽  
Vol 70 (7) ◽  
pp. 1182-1187 ◽  
Author(s):  
Zhe Chen ◽  
Hua Li
Keyword(s):  
Flow Injection ◽  
Water Samples ◽  
High Sensitivity ◽  
Basic Solution ◽  
Optimum Conditions ◽  
Cetylpyridinium Bromide ◽  
Test Conditions ◽  
Relative Standard

Based on the sensitive reaction of Co(II) and salicyl fluorone with the presence of cetylpyridinium bromide in basic solution, a new method of flow injection micelle-solubilized spectrophotometry was developed for the determination of cobalt. The reaction was monitored for the absorbance of Co(II) at 540 nm. The reagents, flow injection variables and effects of foreign ions were investigated and the optimum conditions were established. At the optimum test conditions, the developed method provides a linearity range of 3–40 μg L−1 with a detection limit of 0.1 μg L−1 at about 60 h−1 sampling frequency. Relative standard deviation of 0.91, 0.95 and 0.89% were obtained for the determination of 3, 15 and 30 μg L−1 Co(II) solution. The proposed method has been successfully applied for analysis of trace amounts of cobalt in water samples.

scholarly journals Self-Assembled Three-Dimensional Microporous rGO/PNT/Fe3O4 Hydrogel Sorbent for Magnetic Preconcentration of Multi-Residue Insecticides

2020 ◽  
Vol 10 (16) ◽  
pp. 5665 ◽  
Author(s):  
Sheng Wang ◽  
Xiuqin Li ◽  
Ming Li ◽  
Xianjiang Li ◽  
Xiaomin Li ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Solid Phase ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Magnetic Solid Phase Extraction ◽  
Interaction Force ◽  
Beneficial Effects ◽  
Reduced Graphene ◽  
Relative Standard ◽  
Magnetic Solid

The purpose of this work was to develop a highly selective, sensitive, and reliable method for multi-residual analysis. A three-dimensional microporous reduced graphene oxide/polypyrrole nanotube/magnetite hydrogel (3D-rGOPFH) composite was synthesized and utilized as a magnetic solid-phase extraction (MSPE) sorbent to preconcentrate thirteen insecticides, including five organophosphorus (isocarbophos, quinalphos, phorate, chlorpyrifos, and phosalone), two carbamates (pirimor and carbaryl), two triazoles (myclobutanil and diniconazole), two pyrethroids (lambda-cyhalothrin and bifenthrin), and two organochlorines (2, 4′-DDT and mirex), from vegetables, followed by gas chromatography-tandem mass spectrometry. This method exhibited several major advantages, including simultaneous enrichment of different types of insecticides, no matrix effect, high sensitivity, and ease of operation. This is ascribed to the beneficial effects of 3D-rGOPFH, including the large specific surface (237 m2 g−1), multiple adsorption interactions (hydrogen bonding, electrostatic, π–π stacking and hydrophobic interaction force), appropriate pore size distribution (1–10 nm), and the good paramagnetic property. Under the optimal conditions, the analytical figures of merit were obtained as: linear dynamic range of 0.1–100 ng g−1 with determination coefficients of 0.9975–0.9998; limit of detections of 0.006–0.03 ng g−1; and the intra-day and inter-day relative standard deviations were 2.8–7.1% and 3.5–8.8%, respectively. Recoveries were within the range of 79.2 to 109.4% for tomato, cucumber, and pakchoi samples at the fortification levels of 5, 25, and 50 ng g−1. This effective and robust method can be applied for determining multi-classes of insecticide residues in vegetables.

scholarly journals Determination of Ammonia and Aliphatic Amines in Food by Ion Chromatography with Double-Cell Bulk Acoustic Wave Detection

1998 ◽  
Vol 81 (5) ◽  
pp. 1099-1103 ◽  
Author(s):  
Shouzhuo Yao ◽  
Xiaorong Yang ◽  
Hong Zhang ◽  
Youtao Xie ◽  
Wanzhi Wei
Keyword(s):  
Acoustic Wave ◽  
Mobile Phase ◽  
Quartz Crystal ◽  
High Sensitivity ◽  
Aliphatic Amines ◽  
Bulk Acoustic Wave ◽  
Wave Detection ◽  
Relative Standard ◽  
Cured Meat

Abstract An ion chromatographic (IC) method with doublecell bulk acoustic wave (DCBAW) detection is described for determination of ammonia and low-molecular- mass aliphatic amines in food. A 9 MHz AT-cut quartz crystal is used as the resonator. This detection technique provides high sensitivity, good reproducibility, and wide work region. Its sensitivity is independent of background conductivity of the mobile phase in the range 10-2700 μS. Detection limits (peak = 3 δ) for NH4+, CH3NH3+ (CH3)2NH2+and (CH3)3NH+ were 0.02, 0.05, 0.13, and 0.6 μg/mL, respectively. Relative standard deviations for NH4+, CH3NH3+, (CH3)2NH2+, and (CH3)3NH+ were 0.7,1.0, 0.8, and 1.2%, respectively. For IC analysis, the analytical column is a Shim-pack IC-C1 column and the mobile phase is 2.0 mmol/L nitric acid solution at a flow rate of 1.5 mL/min. Detection with DCBAW was compared with series bulk acoustic wave and conventional conductivity. The method was applied to analyses of egg, fish, and cured meat

Electrospun nanofibrous mercury filter: Efficient concentration and determination of trace mercury in water with high sensitivity and tunable dynamic range

2017 ◽  
Vol 982 ◽  
pp. 96-103 ◽  
Author(s):  
Huaming Wang ◽  
Wenyao Huang ◽  
Lin Tang ◽  
Ying Chen ◽  
Ying Zhang ◽  
...  
Keyword(s):  
Dynamic Range ◽  
High Sensitivity

scholarly journals A simple HPLC Method for the Determination of Caffeine Content in Tea and Coffee

2016 ◽  
Vol 9 ◽  
pp. 74-78 ◽  
Author(s):  
Prashanta Pokhrel ◽  
Suraj Shrestha ◽  
Som Kanta Rijal ◽  
Krishna Prasad Rai
Keyword(s):  
Dynamic Range ◽  
Hplc Method ◽  
Internal Diameter ◽  
Linear Dynamic Range ◽  
Uv Detector ◽  
Caffeine Content ◽  
Relative Standard ◽  
Validation Parameters ◽  
Correlation Coeffi

A simple HPLC-UV method was developed and validated for the determination of Caffeine content in tea and coffee samples of different local brands commercially available at Kathmandu and Kaski, Nepal. Water extracted caffeine was separated through c-18 column (ODS 5 μm, internal diameter 4.6 nm and length 150 mm) using methanol and water (40:60) as a mobile phase. The peak response time for caffeine was observed at 2.66 minutes using UV detector set at 275 nm. Method validation parameters viz. linearity, sensitivity (LOD & LOQ), repeatability and recovery were assessed for the detection of caffeine. Linear dynamic range was 2-10μg/ml with correlation coeffi cient (R2) of 0.9928. The LOQ and LOD were found to be 0.7 and 0.2μg/ml respectively. Relative standard deviation for retention time for intraday repeatability was 0.9 and for inter-day 1.63%. Recovery was measured by spiking blank tea samples and the results of recovery were greater than 97%. The validated method was fi nally adapted to determinate caffeine content in Nepalese tea and coffee samples. The average caffeine contents in tea and coffee were found in the range of (2.5-3.53) % and (1.17-1.34) % on dry basis respectively.

scholarly journals Determination of Atropine Sulfate in Human Urines by Capillary Electrophoresis Using Chemical Modified Electrode as Electrochemiluminescence Sensor

2011 ◽  
Vol 2011 ◽  
pp. 1-6
Author(s):  
Min Zhou ◽  
Juan Mi ◽  
Yujie Li ◽  
Huashan Zhang ◽  
Yanjun Fang
Keyword(s):  
Capillary Electrophoresis ◽  
Phosphate Buffer ◽  
Platinum Electrode ◽  
High Sensitivity ◽  
Atropine Sulfate ◽  
Sulfate Concentration ◽  
Electrokinetic Injection ◽  
Relative Standard ◽  
Optimized Conditions

A Ru(bpy)3 2+-based electrochemiluminescence (ECL) detection coupled with capillary electrophoresis (CE) was developed for the determination of atropine sulfate on the basis of an Eu-PB modified platinum electrode as the working electrode. The analyte was injected to separation capillary of 50 cm length (25 μm i.d., 360 μm o.d.) by electrokinetic injection for 10 s at 10 kV. Parameters related to the separation and detection were discussed and optimized. It was proved that 10 mM phosphate buffer at pH 8.0 could achieve the most favorable resolution, and the high sensitivity of detection was obtained by using the detection potential at 1.15 V and 5 mM Ru(bpy)3 2+in 80 mM phosphate buffer at pH 8.0 in the detection reservoir. Under the optimized conditions, the ECL peak area was in proportion to atropine sulfate concentration in the range from 0.08 to 20 μg⋅mL−1with a detection limit of 50 ng⋅mL−1(3σ). The relative standard derivations of migration time and peak area were 0.81 and 3.19%, respectively. The developed method was successfully applied to determine the levels of atropine sulfate in urine samples of patients with recoveries between 90.9 and 98.6%.

Sign in / Sign up

Export Citation Format

Share Document