Graphitic-Phase C3N4 Nanosheets Combined with MnO2 Nanosheets for Sensitive Fluorescence Quenching Detection of Parathion-Methyl

Abstract In this study, we have developed a sensitive approach to measure organophosphorus pesticides (OPs) using graphitic-phase C3N4 nanosheets (g-C3N4) combined with a nanomaterial-based quencher MnO2 nanosheets (MnO2 NS). Because MnO2 NS could quench the fluorescence of g-C3N4 via the inner-filter effect (IFE), the enzymatic hydrolysate (thiocholine, TCh) can efficiently trigger the decomposition of MnO2 nanosheets in the presence of acetylcholinesterase (AChE) and acetylthiocholine, resulting in the fluorescence recovery of g-C3N4. OPs, as inhibitors for AChE activity, can prevent the generation of TCh and decomposition of MnO2 nanosheets, accompanied by fluorescence quenching again. So the AChE-ATCh-MnO2-g-C3N4 system can be utilized to detect OPs quantitatively based on the g-C3N4 fluorescence. Under the optimum conditions, the linear range for the determination of parathion-methyl (PM) and 2,2-dichlorovinyl dimethyl phosphate (DDVP) were found in the range of 0.1-2.1 ng/mL with a limit of detection of 0.069 ng/mL, and 0.5-16 ng/mL with a limit of detection of 0.069 ng/mL, respectively. Finally, this method was exploited for the monitoring of PM in real samples. The advantages of the assay are user-friendly, easy-to-ease, cost-effective compared to sophisticated analytical instruments.

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Pitfalls in the Immunochemical Determination of β‑Lactam Antibiotics in Water

Antibiotics ◽

10.3390/antibiotics10030298 ◽

2021 ◽

Vol 10 (3) ◽

pp. 298

Author(s):

Alexander Ecke ◽

Rudolf J. Schneider

Keyword(s):

Limit Of Detection ◽

Cost Effective ◽

Enzyme Linked Immunosorbent Assay ◽

Degree Of Hydrolysis ◽

Site Analysis ◽

Antibody Recognition ◽

Immunochemical Determination ◽

Key Factor ◽

Lactam Ring

Contamination of waters with pharmaceuticals is an alarming problem as it may support the evolution of antimicrobial resistance. Therefore, fast and cost-effective analytical methods for potential on-site analysis are desired in order to control the water quality and assure the safety of its use as a source of drinking water. Antibody-based methods, such as the enzyme-linked immunosorbent assay (ELISA), can be helpful in this regard but can also have certain pitfalls in store, depending on the analyte. As shown here for the class of β-lactam antibiotics, hydrolysis of the β‑lactam ring is a key factor in the immunochemical analysis as it influences antibody recognition. With the antibody used in this study, the limit of detection (LOD) in the immunoassay could be significantly reduced by hydrolysis for the five tested penicillins, with the lowest LOD for carbenicillin (0.2 nmol/L) and the greatest impact on penicillins G and V (reduction by 85%). In addition to enhanced quantification, our strategy also provides access to information about the degree of hydrolysis in water samples as shown for the most abundant penicillin amoxicillin.

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Immobilization-Free Electrochemical Sensor Coupled with a Graphene-Oxide-Based Aptasensor for Glycated Albumin Detection

Biosensors ◽

10.3390/bios11030085 ◽

2021 ◽

Vol 11 (3) ◽

pp. 85

Author(s):

Wassa Waiwinya ◽

Thitirat Putnin ◽

Dechnarong Pimalai ◽

Wireeya Chawjiraphan ◽

Nuankanya Sathirapongsasuti ◽

...

Keyword(s):

Graphene Oxide ◽

Electrochemical Sensor ◽

Detection Method ◽

Limit Of Detection ◽

Glycated Albumin ◽

Cost Effective ◽

Logarithmic Scale ◽

Electrochemical Aptasensor ◽

Alternative Approach

An immobilization-free electrochemical sensor coupled with a graphene oxide (GO)-based aptasensor was developed for glycated human serum albumin (GHSA) detection. The concentration of GHSA was monitored by measuring the electrochemical response of free GO and aptamer-bound GO in the presence of glycated albumin; their currents served as the analytical signals. The electrochemical aptasensor exhibited good performance with a base-10 logarithmic scale. The calibration curve was achieved in the range of 0.01–50 µg/mL. The limit of detection (LOD) was 8.70 ng/mL. The developed method was considered a one-drop measurement process because a fabrication step and the probe-immobilization process were not required. This simple sensor offers a cost-effective, rapid, and sensitive detection method, and could be an alternative approach for determination of GHSA levels.

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Spectrofluorimetric Determination of Hydrochlorothiazide by a Carbon Dots-Based Probe via Inner Filtering Effect and Resonance Rayleigh Scattering

Journal of the Brazilian Chemical Society ◽

10.21577/0103-5053.20210155 ◽

2022 ◽

Author(s):

Ali Ghafarloo ◽

Reza Sabzi ◽

Naser Samadi ◽

Hamed Hamishehkar

Keyword(s):

Carbon Dots ◽

Rayleigh Scattering ◽

Limit Of Detection ◽

Fluorescent Sensor ◽

Emission Spectra ◽

Cost Effective ◽

Inner Filter Effect ◽

Resonance Rayleigh Scattering ◽

Excitation Spectra ◽

One Pot

Synthesis of carbon dots (CDs) from natural resources not only enables green synthesis and production of environmentally friendly materials, but also provides a cost-effective probe as a fluorescence nanosensor. The proposed sensor introduces a unique one-pot hydrothermal CDs synthesis from alfalfa leaves, which is promising for sensing hydrochlorothiazide (HCTZ) via inner filter effect (IFE) and resonance Rayleigh scattering (RRS). The as-prepared CDs had wide emission spectra, excitation-dependent emission, high solubility, high stability, and visible fluorescence light with a quantum yield of up to 11%. The absorption of HCTZ overlapped with the excitation spectra of CDs. Therefore, CDs represented excellent quenching due to IFE when HCTZ was gradually added. Furthermore, this fluorescent sensor was successfully used to quantify HCTZ in the linear ranges (0.17-2.50 μg mL-1) with the limit of detection of 0.11 μg mL-1. The sensing system was simple as no surface functionalization was required for CDs, leading to less laborious steps and more cost-effective synthesis. The reaction time was short, i.e., less than 2 min, indicating a simple approach for rapid analysis of HCTZ. By optimizing conditions, successful measurements were carried out on pharmaceutical tablets.

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Determination of carcinogenic herbicides in milk samples using green non-ionic silicone surfactant of cloud point extraction and spectrophotometry

Royal Society Open Science ◽

10.1098/rsos.171500 ◽

2018 ◽

Vol 5 (4) ◽

pp. 171500 ◽

Cited By ~ 1

Author(s):

N. I. Mohd ◽

N. N. M. Zain ◽

M. Raoov ◽

S. Mohamad

Keyword(s):

Cloud Point ◽

Cloud Point Extraction ◽

Limit Of Detection ◽

Cost Effective ◽

Silicone Surfactant ◽

Extraction Solvent ◽

Milk Samples ◽

Relative Standard ◽

Limit Of Quantitation

A new cloud point methodology was successfully used for the extraction of carcinogenic pesticides in milk samples as a prior step to their determination by spectrophotometry. In this work, non-ionic silicone surfactant, also known as 3-(3-hydroxypropyl-heptatrimethylxyloxane), was chosen as a green extraction solvent because of its structure and properties. The effect of different parameters, such as the type of surfactant, concentration and volume of surfactant, pH, salt, temperature, incubation time and water content on the cloud point extraction of carcinogenic pesticides such as atrazine and propazine, was studied in detail and a set of optimum conditions was established. A good correlation coefficient ( R 2 ) in the range of 0.991–0.997 for all calibration curves was obtained. The limit of detection was 1.06 µg l −1 (atrazine) and 1.22 µg l −1 (propazine), and the limit of quantitation was 3.54 µg l −1 (atrazine) and 4.07 µg l −1 (propazine). Satisfactory recoveries in the range of 81–108% were determined in milk samples at 5 and 1000 µg l −1 , respectively, with low relative standard deviation, n = 3 of 0.301–7.45% in milk matrices. The proposed method is very convenient, rapid, cost-effective and environmentally friendly for food analysis.

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Determination of Dialkyl Phosphates as Breakdown Products of Organophosphorus Insecticides in Fruit Juices by HPTLC with Fluorescence Detection

Journal of AOAC International ◽

10.1093/jaoac/92.3.691 ◽

2009 ◽

Vol 92 (3) ◽

pp. 691-698 ◽

Cited By ~ 4

Author(s):

Wolfgang Schwack ◽

Tatjana Zeisler ◽

Constanze Stiefel

Keyword(s):

Apple Juice ◽

Degradation Products ◽

Organophosphorus Pesticides ◽

Internal Standard ◽

Barium Chloride ◽

Fruit Juices ◽

Limit Of Quantification ◽

Dimethyl Phosphate ◽

Relative Standard

Abstract Dialkyl phosphates (DAP) are common degradation products of organophosphorus pesticides that are used as urinary biomarkers for human exposure. An HPTLC method was developed for the quantitative determination of DAP in fruit juices, i.e., dimethyl phosphate (DMP), dimethyl thiophosphate (DMTP), diethyl phosphate (DEP), and diethyl thiophosphate (DETP). Dibutyl phosphate (DBP) was used as an internal standard. The method was based on precipitation of fruit acids in the presence of barium chloride and acetonitrile and liquidliquid extraction with acetonitrilediethyl ether. Extracted DAP were derivatized with 1-(bromoacetyl)pyrene (BAP), and the BAP derivatives separated on HPTLC amino plates with dichloromethane as the mobile phase. Densitometry was performed by measurement of fluorescence at 366/>400 nm. The limit of quantification (LOQ) values were between 0.8 and 1.4 ng/zone. Fluorescence enhancement was achieved by dipping the plate into a paraffin oil solution, increasing the sensitivity and resulting in an LOQ of 0.50.6 ng/zone. Repeatabilities with relative standard deviations of 3.5 (n = 5, at 1520 ng/zone) and coefficients of correlation of 0.9999 were highly satisfactory for rapid trace analysis of DAP in the fruit juices by HPTLC. The mean recoveries from apple juice spiked at 0.5 mg/L were 74, 83, 70, and 57 for DMP, DEP, DMTP, and DETP, respectively. If an application volume of 5 L of apple juice extract was applied, the LOQ in apple juice was 300 g/L. However, this can be lowered by application of higher volumes (up to 50 L) or a more concentrated derivatization batch.

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Vortex-Assisted Dispersive Liquid–Liquid Microextraction Coupled with Deproteinization for Determination of Nateglinide in Human Plasma Using HPLC/UV

Journal of Chromatographic Science ◽

10.1093/chromsci/bmaa096 ◽

2020 ◽

Author(s):

Mohamed A Hammad ◽

Amira H Kamal ◽

Reham E Kannouma ◽

Fotouh R Mansour

Keyword(s):

Human Plasma ◽

High Performance ◽

Limit Of Detection ◽

Signal To Noise Ratio ◽

Cost Effective ◽

Salt Addition ◽

Relative Standard ◽

Dispersive Liquid Liquid Microextraction ◽

Liquid Microextraction

Abstract A validated method for preconcentration and determination of nateglinide in plasma was developed using vortex-assisted dispersive liquid–liquid microextraction. Different variables that affect extraction efficiency were studied and optimized, including type and volume of extractant, type and volume of disperser, pH of diluent, salt addition effect, centrifugation and vortex time. Nateglinide was extracted using 30 μL of 1-octanol as an extractant and 200 μL of methanol as a disperser. The enrichment factor reached 330 under the optimum conditions. High-performance liquid chromatography/ultraviolet was used for detection using phosphate buffer (pH 2.5, 10 mM): acetonitrile (45:55, v/v) as a mobile phase at a flow rate of 1 mL/min. The method was linear over the range of 50–20,000 ng/mL with a limit of detection of 15 ng/mL (signal-to-noise ratio = 3). Intra- and inter-day precision had %relative standard deviation <6% (n = 3) and the %recoveries were found to be between 102.5 and 105.9%. The proposed method is simple, sensitive, eco-friendly, cost-effective and powerful for microextraction of nateglinide from human plasma samples.

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A Fluorescence Inner-Filter Effect Based Sensing Platform for Turn-On Detection of Glutathione in Human Serum

Sensors ◽

10.3390/s19020228 ◽

2019 ◽

Vol 19 (2) ◽

pp. 228 ◽

Cited By ~ 3

Author(s):

Shurong Tang ◽

Xiuhua You ◽

Quanhui Fang ◽

Xin Li ◽

Guangwen Li ◽

...

Keyword(s):

Human Serum ◽

Limit Of Detection ◽

Cost Effective ◽

Inner Filter Effect ◽

Disease Diagnosis ◽

Fluorescent Properties ◽

Serum Samples ◽

Turn On ◽

Filter Effect ◽

Sensing Platform

A novel turn-on fluorescence assay was developed for the rapid detection of glutathione (GSH) based on the inner-filter effect (IFE) and redox reaction. Molybdenum disulfide quantum dots (MoS2 QDs), which have stable fluorescent properties, were synthesized with hydrothermal method. Manganese dioxide nanosheets (MnO2 NSs) were prepared by exfoliating the bulk δ-MnO2 material in bovine serum albumin (BSA) aqueous solution. The morphology structures of the prepared nanoparticles were characterized by transmission electron microscope (TEM). Studies have shown that the fluorescence of MoS2 QDs could be quenched in the presence of MnO2 NSs as a result of the IFE, and is recovered after the addition of GSH to dissolve the MnO2 NSs. The fluorescence intensity showed a good linear relationship with the GSH concentration in the range 20–2500 μM, the limit of detection was 1.0 μM. The detection method was applied to the analysis of GSH in human serum samples. This simple, rapid, and cost-effective method has great potential in analyzing GSH and in disease diagnosis.

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Simultaneous Determination of Crypto-Chlorogenic Acid, Isoquercetin, and Astragalin Contents inMoringa oleiferaLeaf Extracts by TLC-Densitometric Method

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2013/917609 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 8

Author(s):

Boonyadist Vongsak ◽

Pongtip Sithisarn ◽

Wandee Gritsanapan

Keyword(s):

Chlorogenic Acid ◽

Limit Of Detection ◽

Cost Effective ◽

Dry Weight ◽

Active Components ◽

Leaf Extracts ◽

Relative Standard ◽

Limit Of Quantitation ◽

Layer Chromatography

Moringa oleiferaLamarck (Moringaceae) is used as a multipurpose medicinal plant for the treatment of various diseases. Isoquercetin, astragalin, and crypto-chlorogenic acid have been previously found to be major active components in the leaves of this plant. In this study, a thin-layer-chromatography (TLC-)densitometric method was developed and validated for simultaneous quantification of these major components in the 70% ethanolic extracts ofM. oleiferaleaves collected from 12 locations. The average amounts of crypto-chlorogenic acid, isoquercetin, and astragalin were found to be 0.0473, 0.0427, and 0.0534% dry weight, respectively. The method was validated for linearity, precision, accuracy, limit of detection, limit of quantitation, and robustness. The linearity was obtained in the range of 100–500 ng/spot with a correlation coefficient (r) over 0.9961. Intraday and interday precisions demonstrated relative standard deviations of less than 5%. The accuracy of the method was confirmed by determining the recovery. The average recoveries of each component from the extracts were in the range of 98.28 to 99.65%. Additionally, the leaves from Chiang Mai province contained the highest amounts of all active components. The proposed TLC-densitometric method was simple, accurate, precise, and cost-effective for routine quality controlling ofM. oleiferaleaf extracts.

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A Simple and Cost-Effective TLC-Densitometric Method for the Quantitative Determination of Acetylsalicylic Acid and Ascorbic Acid in Combined Effervescent Tablets

Molecules ◽

10.3390/molecules23123115 ◽

2018 ◽

Vol 23 (12) ◽

pp. 3115 ◽

Cited By ~ 2

Author(s):

Alina Pyka-Pająk ◽

Małgorzata Dołowy ◽

Wioletta Parys ◽

Katarzyna Bober ◽

Grażyna Janikowska

Keyword(s):

Ascorbic Acid ◽

Quantitative Determination ◽

Acetylsalicylic Acid ◽

High Performance ◽

Limit Of Detection ◽

Volume Ratio ◽

Cost Effective ◽

Pharmaceutical Formulations ◽

Limit Of Quantification

A new, simple, and cost-effective TLC-densitometric method has been established for the simultaneous quantitative determination of acetylsalicylic acid and ascorbic acid in combined effervescent tablets. Separation was performed on aluminum silica gel 60F254 plates using chloroform-ethanol-glacial acid at a volume ratio of 5:4:0.03 as the mobile phase. UV densitometry was performed in absorbance mode at 200 nm and 268 nm for acetylsalicylic acid and ascorbic acid, respectively. The presented method was validated as per ICH guidelines by specificity, linearity, accuracy, precision, limit of detection, limit of quantification, and robustness. Method validations indicate a good sensitivity with a low value of LOD and LOQ of both examined active substances. The linearity range was found to be 1.50–9.00 μg/spot and 1.50–13.50 μg/spot for acetylsalicylic and ascorbic acid, respectively. A coefficient of variation that was less than 3% confirms the satisfactory accuracy and precision of the proposed method. The results of the assay of combined tablet formulation equal 97.1% and 101.6% in relation to the label claim that acetylsalicylic acid and ascorbic acid fulfill pharmacopoeial requirements. The developed TLC-densitometric method can be suitable for the routine simultaneous analysis of acetylsalicylic acid and ascorbic acid in combined pharmaceutical formulations. The proposed TLC-densitometry may be an alternative method to the modern high-performance liquid chromatography in the quality control of above-mentioned substances, and it can be applied when HPLC or GC is not affordable in the laboratory.

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Simple Spectrophotometric Determination of Torsemide in Bulk Drug and in Formulations

E-Journal of Chemistry ◽

10.1155/2008/853596 ◽

2008 ◽

Vol 5 (3) ◽

pp. 473-478 ◽

Cited By ~ 3

Author(s):

Marothu Vamsi Krishna ◽

Dannana Gowri Sankar

Keyword(s):

Limit Of Detection ◽

Regression Line ◽

Cost Effective ◽

Pharmaceutical Formulations ◽

High Accuracy ◽

Molar Absorptivity ◽

Good Precision ◽

Experimental Parameters ◽

Bulk Drug

A simple and cost effective spectrophotometric method is described for the determination of torsemide in pure form and in pharmaceutical formulations. The method is based on the formation of blue colored chromogen when the drug reacts with Folin-Ciocalteu (F-C) reagent in alkaline medium. The colored species has an absorption maximum at 760 nm and obeys beer's law in the concentration range 30 – 150 ug mL−1. The absorbance was found to increase linearly with increasing concentration of TSM, which is corroborated by the calculated correlation coefficient value of 0.9999 (n=8). The apparent molar absorptivity and sandell sensitivity were 1.896×103L mol−1cm−1and 0.183 μg cm−2, respectively. The slope and intercept of the equation of the regression line are 5.4x10−3and 1.00×10−4respectively. The limit of detection was 0.94.The optimum experimental parameters for the reaction have been studied. The validity of the described procedure was assessed. Statistical analysis of the results has been carried out revealing high accuracy and good precision. The proposed method was successfully applied to the determination of TSM in pharmaceutical formulations.

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