scholarly journals Synthesis of 1,5-diphenylcarbazide-immobilized alginate/pectin films for colorimetric detection of Cr(VI)

2020 ◽  
Keyword(s):  
Detection Limit ◽  
Optimum Condition ◽  
Optical Sensor ◽  
Potential Application ◽  
Colorimetric Detection ◽  
Ion Pairs ◽  
Direct Determination ◽  
Violet Color ◽  
Sensitive Sensor

<p>An optical sensor for colorimetric detection of Cr(VI) has been synthesized by immobilizing 1,5-diphenylcarbazide (DPC) into alginate/pectin films. The addition of cationic surfactant (CTAB) was used to increase the effectiveness of DPC immobilization by forming hydrophobic-ion pairs. At optimum condition, the films has good selectivity for Cr(VI) compare to other interference metals. The formation of violet color in the films showed its potential application for visual colorimetric detection of Cr(VI). The developed films in this study was found to be simple, rapid and sensitive sensor for direct determination of Cr(VI) with detection limit as low as 0.233 mg L–1 and time response was 8 minutes.</p>

Direct Determination of Nickel in Catalytic-Cracking Feedstocks by Atomic-Absorption Spectrophotometry

1966 ◽  
Vol 20 (4) ◽  
pp. 212-213 ◽  
Author(s):  
J. D. Kerber
Keyword(s):  
Detection Limit ◽  
Atomic Absorption ◽  
Catalytic Cracking ◽  
Direct Determination ◽  
Atomic Absorption Spectrophotometry ◽  
Rapid Testing ◽  
Absorption Spectrophotometry ◽  
Determination Of Nickel ◽  
No Sample Preparation

Nickel in catalytic-cracking feedstocks is determined by atomic-absorption spectrophotometry with no sample preparation other than dilution in p–xylene. A modification of the method of additions permits rapid testing with a detection limit of 0.05 ppm Ni and a precision of 0.05 ppm.

scholarly journals THE METHOD DEVELOPMENT OF ANALYSIS Cd, Cu, Pb AND Zn IN SEA WATER BY ABSORPTIVE STRIPPING VOLTAMMETRY (ASV) IN THE PRESENCE OF CALCON AS COMPLEXING AGENT

2012 ◽  
Vol 12 (1) ◽  
pp. 20-27 ◽  
Author(s):  
Deswati Deswati ◽  
Hamzar Suyani ◽  
Safni Safni
Keyword(s):  
Optimum Condition ◽  
Method Development ◽  
Sea Water ◽  
Supporting Electrolyte ◽  
Direct Determination ◽  
Stripping Voltammetry ◽  
Complexing Agent ◽  
Relative Standard ◽  
Ultra Trace

A sensitive and selective absorptive stripping voltammetric (AdSV) method to determine Cd(II), Cu(II), Pb(II) and Zn(II) in sea water is proposed. The aim of this study was to get optimum condition for the determination of Cd(II), Cu(II), Pb(II) and Zn(II). Absorptive stripping voltammetry has been used for ultra trace determination of Cd(II), Cu(II), Pb(II) and Zn(II) using calcon as a complexing agent (ligand). In this case, the optimum conditions were reached at 0.1 M KCl supporting electrolyte, concentration of 0.5 mM calcon for Cd(II), Cu(II) 0.3 mM while 0.7 mM for Pb(II) and Zn(II), pH 6 for Cu(II) and pH 7 for Cd(II), Pb(II) and Zn(II), accumulation potential -0.5 V for Cu(II) and Pb(II) and -0.6 V for Cd(II) and Zn(II) and accumulation time 70 sec for Cd(II), 90 sec for Cu(II) and Pb (II) while 50 s for Zn(II). At the optimum condition the relative standard deviations were 7.80%, 4.25%, 8.70% and 0.86% for Cd(II), Cu(II), Pb(II) and Zn(II) respectively for eight replicates (n = 8) measurements of 10 μg/L Cd(II), Cu(II), Pb(II) and Zn(II). The method was applied for the direct determination of Cd(II), Cu(II), Pb(II) and Zn(II) in sea water around Bungus, Padang City. Concentration Cd(II), Cu(II), Pb(II) and Zn(II) in sample were 13.200 μg /L for Cd(II), 17.200 μg/L for Cu(II), 0.089 μg/L for Pb(II) and 62.000 μg/L for Zn(II) with recovery of 98.68%, 97.99%, 96.17% and 99.96% for Cd(II), Cu(II), Pb(II) and Zn(II), respectively.

Direct Determination of Cadmium and Lead in Whole Blood by Potentiometric Stripping Analysis

1992 ◽  
Vol 38 (10) ◽  
pp. 1995-2001 ◽  
Author(s):  
P Ostapczuk
Keyword(s):  
Detection Limit ◽  
Blood Sample ◽  
Whole Blood ◽  
Deposition Time ◽  
Supporting Electrolyte ◽  
Direct Determination ◽  
Stripping Analysis ◽  
Lead And Cadmium ◽  
Potentiometric Stripping Analysis

Abstract The commercially available equipment for potentiometric stripping analysis (PSA) was tested for routine lead and cadmium determination in whole-blood samples. In contrast to anodic stripping voltammetry, PSA is not subject to background interferences from organic electroactive constituents in the sample or to the presence of dissolved oxygen (i.e., oxygen removal is not necessary). To determine lead and cadmium by PSA, it is sufficient to dilute the blood sample with an appropriate supporting electrolyte (0.5 mol/L HCl). The detection limit changes with deposition time and volume of blood sample used. For 1 mL of blood and a 1-min deposition time, the detection limit is 1 microgram/L for both elements. If the deposition time increases to 10 min, cadmium can be determined at its normal concentration in blood (the detection limit is improved to &lt; 0.1 microgram/L). Procedures for routine determination of lead and cadmium in whole blood are presented.

A Novel Ammonia Sensor Utilizing Cataluminescence on Nano-TiW3Cr2O14

2011 ◽  
Vol 694 ◽  
pp. 184-188 ◽  
Author(s):  
Kao Wen Zhou ◽  
Zi Qiao Zhang ◽  
Li Jing Xing ◽  
Xin Li ◽  
Chun Xue Fu
Keyword(s):  
Detection Limit ◽  
Flow Rate ◽  
Active Carbon ◽  
Room Temperature ◽  
High Selectivity ◽  
Direct Determination ◽  
Ammonia Sensor ◽  
On Line ◽  
Versus Concentration

A new sensor based on cataluminescence (CTL) produced on the surface of nanosized TiW3Cr2O14 was demonstrated for direct determination of ammonia in air. Trace ammonia was firstly absorbed on active carbon at room temperature to concentrate, then desorbed at 105°C to determine. The sensor showed high selectivity to ammonia at wavelength of 540 nm, satisfying activity at temperature of 275°C and good stability at air carrier flow rate of 115 ml/min. The linear range of CTL intensity versus concentration of ammonia was 1.0~50 mg/m3 (γ=0.9990), and the detection limit (3σ) was 0.5 mg/m3. The recovery of artificial sample was 97.45%—102.73% by this method. There was no response to benzene, SO2, CO and formaldehyde, and insignificant response to ethanol. This gas sensor allows on-line monitoring of ammonia in air.

A Rapid and Sensitive Ether Sensor Utilizing Thermal Desorption Coupled with Cataluminescence

2013 ◽  
Vol 641-642 ◽  
pp. 238-241 ◽  
Author(s):  
Zhi Gang Cui ◽  
Shao Tong Zhang ◽  
Jin Zhao ◽  
Kao Wen Zhou
Keyword(s):  
Detection Limit ◽  
Gas Sensor ◽  
Thermal Desorption ◽  
Flow Rate ◽  
Active Carbon ◽  
Room Temperature ◽  
High Selectivity ◽  
Direct Determination ◽  
Versus Concentration

A rapid and sensitive cataluminescence (CTL)-based gas sensor using nanosized Y2Zr1.5O6 as a probe was proposed for direct determination of ether in air. Trace ether was firstly absorbed on active carbon at room temperature to concentrate, then desorbed at 65°C to determine. The sensor showed high selectivity to ether at wavelength of 510nm, satisfying activity at temperature of 310°C and good stability at carrier flow rate of 110 ml/min. The linear range of CTL intensity versus concentration of ether was 2~100 mg/m3, and the detection limit (3σ) was 1.1 mg/m3. The recovery of artificial sample was 95.4%—106.7% by this method. The response to formaldehyde, benzene, NH3 and ethanol was insignificant, and there was no response to SO2, CO and acetone. The technique is a convenient and fast way of determining ether in air.

Determination of Water in Slurries by Fiber-Optic Raman Spectroscopy

1995 ◽  
Vol 49 (2) ◽  
pp. 220-223 ◽  
Author(s):  
Daniel R. Lombardi ◽  
Charles K. Mann ◽  
Thomas J. Vickers
Keyword(s):  
Raman Spectroscopy ◽  
Detection Limit ◽  
Raman Line ◽  
Sodium Nitrate ◽  
Fiber Optic ◽  
Direct Determination ◽  
Water Detection ◽  
Multichannel Detection ◽  
Remote Determination

We have examined the feasibility of the remote determination of water in a sodium nitrate matrix by fiber-optic Raman spectroscopy with multichannel detection. The direct determination based on the Raman line due to OH bending is shown to be possible but relatively insensitive. A determination based on the ratio of signals due to dissolved and solid nitrate is shown to provide a water detection limit of less than 1% for a measurement time of one minute.

scholarly journals Ratiometric Colorimetric Detection of Nitrite Realized by Stringing Nanozyme Catalysis and Diazotization Together

Biosensors ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 280
Author(s):  
Mengzhu Wang ◽  
Peng Liu ◽  
Hengjia Zhu ◽  
Bangxiang Liu ◽  
Xiangheng Niu
Keyword(s):  
Detection Limit ◽  
Signal Analysis ◽  
High Efficiency ◽  
Colorimetric Assay ◽  
Low Cost ◽  
Colorimetric Detection ◽  
Health It ◽  
Practical Applications ◽  
Higher Sensitivity

Due to the great threat posed by excessive nitrite in food and drinking water to human health, it calls for developing reliable, convenient, and low-cost methods for nitrite detection. Herein, we string nanozyme catalysis and diazotization together and develop a ratiometric colorimetric approach for sensing nitrite in food. First, hollow MnFeO (a mixture of Mn and Fe oxides with different oxidation states) derived from a Mn-Fe Prussian blue analogue is explored as an oxidase mimic with high efficiency in catalyzing the colorless 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation to blue TMBox, presenting a notable signal at 652 nm. Then, nitrite is able to trigger the diazotization of the product TMBox, not only decreasing the signal at 652 nm but also producing a new signal at 445 nm. Thus, the analyte-induced reverse changes of the two signals enable us to establish a ratiometric colorimetric assay for nitrite analysis. According to the above strategy, facile determination of nitrite in the range of 3.3–133.3 μM with good specificity was realized, providing a detection limit down to 0.2 μM. Compared with conventional single-signal analysis, our dual-signal ratiometric colorimetric mode was demonstrated to offer higher sensitivity, a lower detection limit, and better anti-interference ability against external detection environments. Practical applications of the approach in examining nitrite in food matrices were also verified.

Direct determination of sulfate conjugates of 17-oxosteroids in urine by liquid chromatography.

1986 ◽  
Vol 32 (5) ◽  
pp. 835-839 ◽  
Author(s):  
O Nishikaze ◽  
J Iwata
Keyword(s):  
Liquid Chromatography ◽  
Trichloroacetic Acid ◽  
Chromatographic Method ◽  
Ion Pairs ◽  
Direct Determination ◽  
Good Separation ◽  
Trichloroacetic Acid Solution ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic

Abstract We describe a new liquid-chromatographic method with fluorescence detection for direct simultaneous determination of four urinary sulfate conjugates of 17-oxosteroids (17OS), without use of solvolysis or enzymatic hydrolysis. The 17OS sulfates in urine samples are extracted with benzene as ion pairs in the presence of benzyltributylammonium chloride. These ion pairs are converted to hydrazones by use of dansyl hydrazine in trichloroacetic acid solution and then are separated by liquid chromatography. The proposed method, being simple and rapid, shows a good separation of 17OS sulfates and superior sensitivity, sufficient recovery, and good reproducibility.

scholarly journals Occurrence of 222Rn and 226,228Ra in underground water and 222Rn in soil and their mutual correlations for underground water supplies in southern Greater Poland

2021 ◽  
Author(s):  
Henryk Bem ◽  
Magdalena Długosz-Lisiecka ◽  
Daria Mazurek-Rudnicka ◽  
Piotr Szajerski
Keyword(s):  
Detection Limit ◽  
Water Supply ◽  
Water Samples ◽  
Scintillation Counter ◽  
Direct Determination ◽  
Underground Water ◽  
Soil Gas ◽  
Human Consumption ◽  
Council Directive

AbstractEuropean Union Council Directive 2013/51/EURATOM recently sets out so-called indicator parameters for: radon, tritium and indicative dose of water intended for human consumption. The aim of this research was to elaborate an effective procedure for determination of radon and radium 226,228Ra isotopes (which are potentially the main contributors to the internal dose from drinking and cooking water) and to find the possible relationships between these radionuclides in underground water reservoirs and 222Rn concentration in the soil gas in their vicinity. The research was performed by applying a non-volatile and water-immiscible scintillation cocktail based on a pure diisopropylnaphthalene (Ultima Gold F: UGF), which allow for efficient radon extraction from 0.5 dm3 of water samples to 20 cm3 of scintillation phase and its direct determination with a detection limit of 5 × 10–3 Bq dm−3. The further preliminary concentration of 3 dm3 of crude water samples by evaporation to 0.5 dm3 samples led to the removal of all unsupported 222Rn activity and allowed the 226Ra determination via equivalent 222Rn detection after one-month samples storage using a low-background Triathler liquid scintillation counter in the α/β separation counting mode. Together with determination of 226Ra isotope in water samples, the simultaneous measurements of 228Ra and 222Rn radionuclides concentrations in water as well as 222Rn activity in the soil gas around the water supply sites were performed. The achieved limit of 226Ra detection was at a very low level of 10–3 Bq dm−3. The measured values of 226Ra concentration in 50 public underground water supply units for the Kalisz district of Poland were relatively low and ranged from below detection limit to 28.5 × 10–3 Bq dm−3 with arithmetic mean and median values of 12.9 and 12.2 × 10–3 Bq dm−3, respectively. Weak correlations were observed between activity concentrations of 226Ra and 222Rn in the crude water samples (R2 = 0.31) and 222Rn in water and its concentration in the nearby soil gas (R2 = 0.48).

scholarly journals The determination of N-methylcarbamate pesticides using enzyme immunoassays with chemiluminescent detection

2004 ◽  
Vol 22 (SI - Chem. Reactions in Foods V) ◽  
pp. S280-S282 ◽  
Author(s):  
B. Mičková ◽  
P. Rauch ◽  
A. Montoya ◽  
E. Ferri ◽  
F. Fini ◽  
...  
Keyword(s):  
Detection Limit ◽  
Matrix Effects ◽  
Colorimetric Detection ◽  
Fruit Juices ◽  
Analytical Performance ◽  
Experimental Comparison ◽  
Enzyme Immunoassays ◽  
Chemiluminescent Detection ◽  
Concentration Levels

In the present work, enzyme-linked immunosorbent assays (ELISAs) with chemiluminescent detection for the determination of carbofuran, carbaryl and methiocarb were developed and the analytical parameters of these assays were compared with those of ELISAs with colorimetric detection. The sensitivity of immunochemical methods was expressed as detection limit, linear working range, and I<sub>50</sub> value. In comparison with colorimetric ELISA, the ability of the chemiluminescent reagents to detect lower concentrations of HRP allowed to decrease the optimal antibody and conjugate concentrations and to reach better analytical parameters. The experimental comparison of the analytical performance of the ELISAs was carried out by analysing simply diluted fruit juices, spiked at different concentration levels with the above mentioned pesticides. Recovery values for both ELISAs were around 100% and no matrix effects were observed when fruit juices were diluted 1:20 or more.

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