Simple Method For Determination Research Articles

A simple analytical method for simultaneous determination of currently used pesticide (CUP) residue in river water using LC-MS/MS

A simple analytical method for simultaneous determination of currently used pesticide (CUP) residue in river water using LC-MS/MS

A simple and low-cost method for determination of methanol in alcoholic solutions

Methanol poisoning can occur through consumption of methanol-containing alcohols, especially in areas where production, distribution, sale and consumption of alcohol is lawfully prohibited. Due to its toxic potency, determination of methanol in alcoholic solutions is important. The aim of the present study was to develop a rapid, simple and inexpensive method for quantification of methanol in alcoholic solutions that uses minimal equipment available in most laboratories. The method developed is based microdistillation and chromotropic acid, which can be conducted without sophisticated instruments or personal. The system consists of a micro-tube suspended in a falcon tube to function as a collector. Methanol is separated from wine by microdistillation at 90°C in water bath and converted to formaldehyde in the collector. The collector contains an acidic permanganate solution that converts methanol to formaldehyde. Formaldehyde was then quantified by use of chromotropic acid in concentrated sulfuric acid. Experimental variables were optimized by using central composite design (CCD). Method detection and quantification limits were 183 mg L−1 and 584 mg L−1, respectively. The percent relative standard deviation (RSD%) were between 6.4 and 7.9. Accuracies were between 89.6 % and 92.4 %. Concentrations of methanol in five alcoholic solutions were between 2.9×104 and 3.0×104, mg/L, v/v (ppm). Due to its simplicity and cost effectiveness, this method can be used for routine, real-time determination of methanol in alcoholic solutions.

A New Validated Method for Rapid Determination of OLEU Concentration in Dietary Supplements: Comparison with Total Phenol Content and Antioxidant Activity

The market for olive leaf dietary supplements is expanding rapidly and is valued at $437.15 million today. However, information on the control of these products is sketchy and the origin and variety of olives are rarely stated. The aim of this research was to validate a simple and rapid screening method for oleuropein determination in olive leaf dietary supplements. A matrix blank was prepared by removal of oleuropein from a mixture of dietary supplements and the matrix was then spiked with known concentrations to create a spiked matrix calibration curve in the range 5 - 40% oleuropein. Five replicate extractions and analyses of the matrix standards were carried out over 10 days. Precision was less than 6% RSD and linearity was demonstrated by the Fischer test. Extraction recovery was > 90% and there was a strong linear relationship between authentic and matrix standards. All tested products conformed to the label claim which was strongly correlated with total polyphenols measured by the Folin-Ciocalteau method. Antioxidant activity was measured by the DPPH assay and was found to be strongly correlated with total phenol content and oleuropein concentration.

A simple UFLC method for determination of montelukast in human plasma

A simple UFLC method for determination of montelukast in human plasma

Exploiting a carbon black paste electrode modified with palladium nanoparticles entrapped in aluminum hydroxide matrix for selective detection of 2(3)-t-Butyl-4-hydroxyanisole antioxidant in biodiesel samples

A simple and selective method for determination of 2(3)-t-Butyl-4-hydroxyanisole (BHA) based on carbon black (CB) paste electrode modified with Palladium nanoparticles entrapped in aluminum hydroxide matrix (PdNPAH) is described for the first time. The materials were characterized by Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The composition of the paste was studied using different amounts of each material. The voltammetric studies of the behavior of BHA on PdNPAH/CBP electrode demonstrated a catalytic activity for the oxidation process of BHA. Also, the voltammetric studies showed that it is possible to determine BHA in presence of 3,5-Di-tert-butyl-4-hydroxytoluene (BHT) and 2-(1,1-Dimethylethyl)-1,4-benzenediol (TBHQ). Under optimized conditions, the method showed a linear response for BHA from 1-5000 µmol/L and a detection limit of 0.20 µmol/L. The proposed method presented good selectivity, precision and it was successfully applied for detection of BHA in biofuel with recovery values from 98.80 % to 105.29 %, showing a good accuracy for the proposed method.

A simple and accurate method for the determination of Rh, Pd, and Pt in e-waste and spent automotive catalysts using HR-CS FAAS for assessing the value of secondary raw materials

This work presents a simple and accurate method for the fast sequential determination of Rh, Pd, and Pt in spent automotive catalysts and e-wastes using high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). Extensive research was carried out in model systems on the impact of potential interfering substances on analyte's signals measured in two types of flame (air-C2H2 and N2O–C2H2). Mutual analyte interactions were also taken into account. Different background corrections offered by the HR-CS AAS spectrometer were tested to obtain interference-free analyte signals and the best detectability. Using an air-C2H2 flame and 1 % La solution as a spectrochemical buffer provided good sensitivity and accurate determinations of Rh, Pd, and Pt using a simple calibration graph. Microwave-assisted leaching of PGE from waste samples with aqua regia at 240 °C for 60 min efficiently leached all target metals, which significantly simplified and shortened the sample preparation step. The detectability of the method (detection limit of 0.4, 0.6, and 5 mg kg−1 for Rh, Pd, and Pt, respectively) and precision (< 7 %) were satisfactory. The accuracy of the method was confirmed by analysis of certified reference materials (spent automotive catalyst (ERM-EB504), electronic scrap (BAM-M505a)), and calculated zeta score values. The recoveries for Rh, Pd, and Pt in ERM-EB504 were 93, 101, and 96 %, respectively, and for Pd in BAM-M505a, 97 %. The developed method can be used to assess the value of secondary raw materials, such as various types of spent catalysts and e-waste containing Rh, Pd, and Pt.

A smartphone-based simple method for determination of the permeability of free space

A smartphone-based simple method for determination of the permeability of free space

Adsorptive transfer cyclic square-wave voltammetry and HPLC with tandem electrochemical detection – Two novel methods for determination of chili peppers pungency

The pungency of chili peppers, the most popular hot spice used worldwide, is caused by capsaicinoids (CPDs), the content of which can vary greatly due to varietal differences and growing conditions. For the first time, a novel simple method for the fast determination of CPDs in chili peppers and chili products was developed based on adsorptive transfer cyclic square-wave voltammetry (AdTCSWV), using adsorption of lipophilic CPDs on an unmodified glassy carbon electrode surface from methanolic extracts of chili pepper samples. The CSWV is based on short oxidation of adsorbed CPDs to quinoid products, and their subsequent reduction and re-oxidation to provide specific analytical signals with a linear range from 0.05 to 1.00 mg L−1. This principle was also implemented in tandem coulometric and amperometric detection of CPDs after HPLC separation. The two-step electrochemical detection provides increased selectivity for CPDs in case of CPDs co-elution with other electrochemically oxidizable components that cannot be reversibly reduced.

An efficient voltammetric sensing platform for trace determination of Norfloxacin based on nanoplate-like α-zirconium phosphate/carboxylated multiwalled carbon nanotube nanocomposites

Norfloxacin (NOR) residues pose a potential threat to our health and ecosystem, so it is highly urgent to develop a simple but accurate method for NOR determination. Therefore, an efficient voltammetric sensing platform was constructed for trace detection of NOR based on nanoplate-like α-zirconium phosphate/carboxylated multiwalled carbon nanotubes (α-ZrP/CMWCNT). The physiochemical characteristics of α-ZrP/CMWCNT were scrutinized using various microscopic, spectroscopic, and electrochemical means. In order to pursuit higher voltammetric responses, detection conditions of NOR such as accumulation potential, accumulation time and buffer pH, were explored comprehensibly. The α-ZrP/CMWCNT enlarged the electrochemically active surface area and lowered the charge transfer resistance. Owing to the synergistic interactions between nanoplate-like α-ZrP NPs and CMWCNTs, the α-ZrP/CMWCNT boosted the voltammetric response signals and reduced the over-potential of NOR. Consequently, the α-ZrP/CMWCNT demonstrated remarkably catalytic activity for NOR electrooxidation, with two broad linear detection ranges (0.01–0.1 μM; 0.1–10.0 μM) and a low detection limit (2.8 nM). The α-ZrP/CMWCNT modified glassy carbon electrode (GCE) exhibited strong anti-interfering ability even in excess of other antibiotics and common metal ions, and maintained robust response peaks up to two weeks. The α-ZrP/CMWCNT/GCE realized accurate determination of NOR from complicated matrices at trace levels with good recoveries (99.00–104.40 %).

Multiplex antibiotic susceptibility testing of urinary tract infections using an electrochemical lab-on-a-chip

Urinary tract infections (UTIs) represent the most prevalent type of outpatient infection, with significant adverse health and economic burdens. Current culture-based antibiotic susceptibility testing can take up to 72 h resulting in ineffective prescription of broad-spectrum antibiotics, poor clinical outcomes and development of further antibiotic resistance. We report an electrochemical lab-on-a-chip (LOC) for testing samples against seven clinically-relevant antibiotics. The LOC contained eight chambers, each housing an antibiotic-loaded hydrogel (cephalexin, ceftriaxone, colistin, gentamicin, piperacillin, trimethoprim, vancomycin) or antibiotic-free control, alongside a resazurin bulk-modified screen-printed electrode for electrochemical detection of metabolically active bacteria using differential pulse voltammetry. Antibiotic susceptibility in simulated UTI samples or donated human urine with either Escherichia coli or Klebsiella pneumoniae could be established within 85 min. Incorporating electrochemical detection onto a LOC provides an inexpensive, simple method for the sensitive determination of antibiotic susceptibility that is significantly faster than using a culture-based approach.

Development of an electrochemical sensor based on platinum nanoparticles/iron-based metal–organic framework composite for efficient determination of butylated hydroxyanisole

Butylated hydroxyanisole (BHA), a synthetic antioxidant, is widely used in the food industry to prevent the oxidative deterioration of food products. Developing rapid, simple and sensitive methods for BHA determination is of great importance to ensure the safety and quality of food. In this study, we developed an amperometric sensor based on iron-based metal–organic framework and platinum nanoparticle modified glassy carbon electrode (PtNP/Fe-MOF/GCE) for efficient determination of BHA. The Fe-MOF was synthesized by the solvothermal method and characterized using various techniques such as powder X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. The synthesized Fe-MOF was modified onto GCE, and platinum nanoparticles were electrodeposited onto the Fe-MOF/GCE. Scanning electron microscopy and energy dispersive X-ray spectroscopy were utilized to enlighten the surface morphologies of the electrodes during the modification steps. Electrochemical characterization of the modified electrodes was performed by cyclic voltammetry and electrochemical impedance spectroscopy. Under the optimum conditions, the PtNP/Fe-MOF/GCE showed excellent electrocatalytic activity towards BHA oxidation due to its large surface area, porosity, and metal sites. The PtNP/Fe-MOF/GCE sensor exhibited a wide linear range from 6.0 × 10-8 to 5.4 × 10-5 M and a low detection limit of 9.4 × 10-9 M. The analytical applicability of the PtNP/Fe-MOF/GCE was tested by the analysis of BHA in potato chips samples.

A simple and quick run time RP-HPLC method for simultaneously analysis of pyrazosulfuron ethyl and pretilachlor content on GR formulation

Aim of the study was to develop and validate simple and quick run time reverse phase HPLC method for the simultaneous determination of pyrazosulfuron ethyl and pretilachlor in the pesticide formulation of GR. The method was executed toward using the Agilent Eclipse XDB C-18 column (150 x 4.6 mm; 3.5 μm), alongside the mobile phase comprising of 0.1 % (ortho phosphoric acid) with water: acetonitrile (30:70) at a column rate of flow 1.2 mL per minute and determination has been carried out in 220 nm. The retention time for Pyrazosulfuron Ethyl as well as Pretilachlor have been determined at 1.99 as well as at 4.58 minute, correspondingly with runtime 7 min. The method's effectiveness has been validated using SANCO recommendations for LOD, robustness, accuracy, precision, linearity, selectivity and specificity. There are several analytical methods reported for individual content estimation, but single method is not available to determine simultaneous content. The developed method has been utilized to estimate pyrazosulfuron ethyl and pretilachlor content in industries.

RP-HPLC Method Development and Validation for Simultaneous Determination of Sofosbuvir and Ledipasvir: A Pharmaceutical Application Study

The objective of the present work was to develop a simple, precise, accurate, reproducible, and specific reversed-phase high performance liquid chromatographic method for the simultaneous determination of sofosbuvir and ledipasvir in pharmaceutical dosage form. The HPLC system (Shimadzu, LC-2030) consisted of Hypersil ODS - C18 (250 mm, 4.6 mm, 5 μm- Thermo Scientific) was used for the isocratic elution using mobile phase composed of sodium phosphate buffer (pH 3.5) and acetonitrile in the ratio of 40:60% (v/v). Both sofosbuvir and ledipasvir were detected at 260 nm with a flow rate of 1 mL/min. The mean retention time of sofosbuvir was 3.094, whereas ledipasvir was 6.22 minutes. A linear relationship was found in the concentration ranged from 0.54 to 162 μg/mL for sofosbuvir (r2 = 0.9993) and 0.14 to 42 μg/mL for ledipasvir (r2 = 0.9994). The RSD values for recovery test were found 0.99% for sofosbuvir and 0.22% for ledipasvir. The lower limit of detection (LOD) were 0.054 mcg/mL and 0.012 mcg/mL, and the limit of quantification (LOQ) were 0.135 mcg/mL and 0.030 mcg/mL for sofosbuvir and ledipasvir, respectively. The method was successfully applied to the assay and in-vitro dissolution studies of sofosbuvir and ledipasvir in tablet dosage form and all the results were found within the acceptance limits.

Introduction of a spectrophotometric method for salivary iodine determination on microplate based on Sandell-Kolthoff reaction.

Iodine is an essential element for the synthesis of thyroid hormones. Therefore, a reliable marker of iodine supply is important. Iodine is predominantly excreted via kidneys, but also via salivary glands. Our aim was to introduce a new and simple method for determination of salivary iodine concentration (SLIC). Self-prepared chemicals and standards for Sandell-Kolthoff reaction on microplate with ammonium peroxydisulfate (AP) in the range 0-400 µg/L were used. Suitability of water-based standards (WBS) and artificial saliva-based standards (ASS) for standard curve were tested. We followed standards for method validation, defined concentration of used AP and compared our results with Inductively Coupled Plasma Mass Spectrometry (ICP-MS). WBS gave more reliable results than ASS as an underestimation of iodine concentration was found for ASS. LoB was 6.5 µg/L, LoD 12.0 µg/L, therefore analytical range was 12-400 µg/L. Intra- and inter-assay imprecisions at iodine concentrations, namely 20, 100, 165, and 350 µg/L were 18.4, 5.1, 5.7, and 2.8%, respectively, and 20.7, 6.7, 5.1, and 4.3%, respectively. Suitable molarity of AP was 1.0 mol/L and showed no difference to 1.5 mol/L (P values for samples with concentration 40, 100, and 150 µg/L, were 0.761, 0.085, and 0.275, respectively), whereas there was a significant change using 0.5 mol/L (P<0.001). Saliva samples could be diluted up to 1:8. There was no interference of thiocyanate and caffeine up to 193.5 mg/L. Our original method was comparable to ICP-MS. Spaerman coefficient was 0.989 (95% CI: 0.984-0.993). The new method for SLIC determination is in excellent agreement with ICP-MS and easy-to-use.

APPLICATION OF VALIDATED RP-HPLC METHOD FOR SIMULTANEOUS DETERMINATION OF METAXALONE AND DICLOFENAC POTASSIUM IN PLASMA

Objective: The present investigation demonstrates a simple, sensitive and accurate high-pressure liquid chromatographic (HPLC) method for simultaneous determination of metaxalone (MTX) and Diclofenac potassium (DIC) in plasma by using Valsartan (VSN) as internal standard. Methods: The chromatographic separation was achieved within 10 min by using methanol: potassium dihydrogen phosphate buffer pH 4.5 adjusted with orthophosphoric acid (60:40) as mobile phase on Altima Grace Smart C-18 column (5μ; 250×4.6 mm) at flow rate of 1.0 ml/min with injection volume 25µl. The drug was extracted from plasma by liquid-liquid extraction using methanol as a solvent. The retention times of drugs (MTX and DIC) and internal standard were found to be 5.83, 9.65 and 11.79 min, respectively. This method was validated as per United States Food and Drug Administration (US-FDA) guidelines. Results: The results of the validation parameters were found to be within the acceptance limits. The method was linear in the concentration range from 25-1000 ng/ml (r2= 0.9998) and the extraction recovery was found to be 77.06% for MTX and 78.37% for DIC. The lower limit of quantification was found to be 25ng/ml and the stability of recovered samples at different conditions were found to be more than 95% for both the drugs. Conclusion: The developed method possesses good selectivity specificity, there was no interference found in the plasma blanks at retention times of MTX and DIC. We found good correlation between the peak area and concentration of the drug under prescribed conditions. Furthermore, the method can also be used to estimate the pharmacokinetic parameters of MTX and DIC simultaneously.

Qualitative and quantitative protease activity tests based on protein degradation in three-dimensional structures

The pattern of the activity of proteases is related to distinct physiological states of living organisms. Often activity changes of a certain protease can be assigned to a specific disease. Hence, they are useful biomarkers and a simple and fast determination method of their activity could be a valuable tool for the efficient monitoring of numerous diseases. Here, two different methods for the qualitative and quantitative determination of protease activity are demonstrated using the model system of proteinase K. The first test system is based on a protein-modified and colored 3D silica structure that changes color when exposed to the enzyme. This method has also been used for the detection of matrix metallo-protease 2 (MMP2) with gelatine as protease substrate on the plates. The second detection system uses the decrease in the voltammetric signal of a cytochrome c/DNA multilayer electrode after incubation with a protease to quantitatively determine its proteolytic activity. While activities down to 0.15 U/ml can be detected with the first method, the second one provides detection limits of about 0.03U/ml (for proteinase K.) The functionality of both systems can be demonstrated and ways for further enhancement of sensitivity have been elucidated.

Determination of Chlorogenic Acid in Solid-lipid Nanoparticles: Validation by UV-spectroscopy

Objective: The objective of the research was the development and validation of a simple, sensitive, accurate, robust, and precise UV-spectroscopic method for the quantitative determination of chlorogenic acid loaded in solid-lipid nanoparticles as per the guidelines of the International Conference on Harmonization. Methods: The solid-lipid nanoparticles of chlorogenic acid were prepared using the hot melt emulsification method and the high-speed homogenizer method. Glyceryl monostearate was used as a solid lipid, and Tween 80 was used as a surfactant for the preparation of chlorogenic acid-loaded solid lipid nanoparticles. The method was validated in terms of linearity, accuracy, precision, robustness, ruggedness, limit of detection, and limit of quantification. Results: The chlorogenic acid exhibited absorption maxima at the wavelength of 330 nm. The regression equation from the calibration curve was y=0.006x + 0.0193 with a correlation coefficient of 0.9989. The percentage recovery was found to be 99.92, 99.80, and 99.86, respectively (within the acceptable limit of 98-102%), which validated the accuracy of the method. Furthermore, the method exhibited precision, robustness, and ruggedness, as illustrated by a relative standard deviation (RSD) of less than 2%. The limit of detection and limit of quantification were found to be 6.97 and 21.13 μg/ml, respectively. Conclusion: It was concluded that the proposed spectrophotometer analytical method for the determination of Chlorogenic acid was found reliable, accurate, consistent, precise, accurate, and robust. Therefore, the proposed analytical technique could be an integral part of further evaluation and characterization of Chlorogenic acid-solid lipid nanoparticles.

Concepts for a New Rapid and Simple HPLC Method for Simultaneous Determination of Rosuvastatin and Perindopril in Dosage Forms

ABSTRACTSimultaneous determination of a tandem of drugs like perindopril and rosuvastatin with differences in water and organic solvent solubilities, hydrophobicity, polarities, and UV‐absorbing possibilities between them necessitates careful selection of chromatographic conditions. The four specified and different bonded reversed‐phase columns were tested with running mobile phases containing various composition contents concepts; the concept of using diluted trifluoroacetic acid in mobile phase composition with acetonitrile enabled simultaneous acidification and weak ion‐pairing with protonized molecules of analytes, yielding appropriate, short, reasonable run times and resolutions of analytes, satisfying UV‐transparency, and good peak symmetries. These facts especially stand for the peak of perindopril, as a member of the group of proline‐containing moiety in its structure, often and easily prone to peak‐tailing, skewing, or splitting on the high‐performance liquid chromatography chromatograms, which is usually solved by using alkyl‐sulfonate base and ion pairs on higher concentrations of buffering salts with low pH values and with column temperatures increasing by 50°C–60°C. Linearity range was 0.002/004–0.5 mg/mL. The score for method AGREE was 0.73–0.77. The method development approaches, with all columns employing our concepts in mobile phases and experimental conditions, can cover the complete needs and demands of quality control departments and laboratories as simple high‐throughput analysis methods.

Simple Method for Calcium Determination in Crude Oil Emulsion Using Digital Image Colorimetry

A portable device for digital image colorimetry (DIC) is reported for the determination of Ca in crude oil emulsions. ASTM D4807 was used for sample preparation for the isolation of saline species containing Ca. DIC was evaluated based on the complexation reactions with Ca using calcein, murexide, and calcon. Partial least squares (PLS) provided the best determination coefficients (higher than 0.990) for all complexing reagents. Significant interference of Mg was observed for the determination of Ca using calcein. PLS models with the lowest root mean square error of cross validation (RMSECV) values were obtained for murexide and calcon for a concentration of 0.250 mmol L−1 at pH of 13. The best conditions for camera focal length were 11 and 2 mm for murexide and calcon. For light intensity, the optimized conditions for murexide and calcon was 180 lux. Stabilities of color complexes over the time were 30 and 15 min for murexide and calcon, respectively. DIC/murexide provided the lowest root mean square error of prediction (RMSEP) and a linear response was observed from 0.5 to 10 mg L−1 Ca and the relative standard deviation (RSD) was lower than 10%. Significant differences were not observed between the results obtained by DIC/murexide and those obtained by microwave-assisted wet digestion (MAWD) with determination by inductively coupled plasma-optical emission spectrometry (ICP-OES). A limit of quantification of 0.50 mg kg−1 Ca were obtained using DIC/murexide. This approach is an alternative and useful method for the determination of Ca in crude oil samples, with advantages of miniaturization, low cost, and ease of operation.

Ceftobiprole quantification in human serum by HPLC-UV to implement routine TDM in clinical practice

Background and aimsCeftobiprole is a recent 5th generation parenteral cephalosporin with antibacterial activity against a large range Gram+ and Gram− bacteria. Therapeutic drug monitoring (TDM) is an essential tool for maintaining plasma concentrations of antibiotics above the MIC by the end of the dosing interval, thus preventing the resistant strain diffusion. TDM is already recommended for other cephalosporins, and it is a reasonable tool contributing to the safety and efficacy of these drugs. During the treatment of patients in real-life, a number of pharmacokinetic (PK) changes not normally seen in healthy volunteers can occur which can impair the pharmacokinetic/pharmacodynamic target attainment.We aimed to develop simple and rapid HPLC-UV method for determination of ceftobiprole in human serum to implement TDM in clinical practice and support PKs and pharmacokinetic/pharmacodynamic (PK/PD) studies. Materials and methodsSamples preparation of calibration standards, QC, and anonymous patients serum samples was performed by protein precipitation by adding 0.01 ml of sulphosalicylic acid at 30 % to 0.1 ml of each sample. Then samples were vortexed and the centrifuged at 12,000 rpm for 10 min at 4 °C. Fifty microlitres of clear supernatant were diluted 1:1 with mobile phase and transferred into HPLC autosampler held at 8 °C. Chromatographic separation was carried out in a gradient mode at 35 °C on an ultra-Biphenyl column using a Thermo Scientific chromatographic system with a Diode array. Data management was performed with Chromeleon 7.4 software. ResultsThe HPLC-UV method proved to be linear over wide concentration ranges (0.5–50.0 mg/L) and was accurate and reproducible in the absence of matrix effects, allowing for robust, specific, and rapid quantification of ceftobiprole from a low amount of serum (0.1 mL). The mean steady state Ctrough and Cend values measured in the anonymous patients’ samples were 6.26 ± 3.81 mg/L and 22.56 ± 15.69 mg/L, respectively. ConclusionsWe report a broadened simple and fast HPLC with UV detection method for quantification of ceftobiprole in human serum to implement ceftobiprole TDM as clinical routine, and support future (PK/PD) studies in special patients’ population.