Limit Of Quantification Values Research Articles

Application of a needle trap device packed with a MIP@MOF nano-composite for efficient sampling and determination of airborne diazinon pesticide.

In this research, a novel, selective, and efficient porous adsorbent nano-composite comprising a molecularly imprinted polymer and a metal–organic framework (MIP@MOF) was employed for sampling, extraction and analysis of diazinon from the air by a needle trap device (NTD), for the first time. The synthesized MIP@MOF sorbent was characterized by the FT-IR, XRD, FE-SEM, TEM, and EDS techniques. Then, the effective parameters of the sampling (temperature and humidity) and desorption (time and temperature) process were optimized by response surface methodology (RSM). The optimum values of temperature and humidity of the sampling chamber were estimated to be 20 °C and 25.0%, respectively. Also, the highest response during the analyte desorption was obtained at 262 °C and 4.5 minutes. For more details, the performance of the MIP@MOF:NTD method was evaluated by determination of important parameters such as repeatability, reproducibility, the limit of detection (LOD), and the limit of quantification (LOQ), and then compared with the NIOSH 5600 standard method. The values of LOD and LOQ for the targeted analyte were determined to be 0.02 and 0.1 μg m−3, respectively. Also, the repeatability and reproducibility of the proposed method were obtained in the range of (3.9–5.1)% and (5.1–6.4)%, respectively, which proved the acceptable precision of the method. Furthermore, the results of this study exhibited a high correlation coefficient (R2 = 0.9781) between the proposed method and the recommended NIOSH method. Finally, the proposed procedure was utilized for sampling and determination of the airborne diazinon in real conditions. These results indicated that the proposed MIP@MOF:NTD method can be employed as a fast, simple, environmentally friendly, selective, and effective procedure for sampling and determining diazinon in air.

Validation of a New Sensitive Method for the Detection and Quantification of R and S-Epimers of Ergot Alkaloids in Canadian Spring Wheat Utilizing Deuterated Lysergic Acid Diethylamide as an Internal Standard.

Ergot sclerotia effect cereal crops intended for consumption. Ergot alkaloids within ergot sclerotia are assessed to ensure contamination is below safety standards established for human and animal health. Ergot alkaloids exist in two configurations, the R and S-epimers. It is important to quantify both configurations. The objective of this study was to validate a new ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for quantification of six R and six S-epimers of ergot alkaloids in hard red spring wheat utilizing deuterated lysergic acid diethylamide (LSD-D3) as an internal standard. Validation parameters such as linearity, limit of detection (LOD), limit of quantification (LOQ), matrix effects, recovery and precision were investigated. For the 12 epimers analyzed, low LOD and LOQ values were observed, allowing for the sensitive detection of ergot epimers. Matrix effects ranged between 101–113% in a representative wheat matrix. Recovery was 68.3–119.1% with an inter-day precision of <24% relative standard deviation (RSD). The validation parameters conform with previous studies and exhibit differences between the R and S-epimers which has been rarely documented. This new sensitive method allows for the use of a new internal standard and can be incorporated and applied to research or diagnostic laboratories.

FORCED INDICATING UPLC-DAD METHOD DEVELOPMENT AND VALIDATION FOR ESTIMATION OF APALUTAMIDE IN BULK AND IN PHARMACEUTICAL DOSAGE FORM

A new analytical method was developed for the estimation of apalutamide in bulk and its pharmaceutical formulation. The sensitive, précise and accurate method was developed by using Waters Acquity UPLC system equipped with quaternary gradient pump. The column used was Waters C18 150 X 2.1 mm X 1.7 µm and mobile phase was 0.2 % OPA buffer in water : acetonitrile in the ratio of 25:75 V/V. The buffer pH was maintained at 4.5. The fl ow rate of mobile phase was 0.5 mL min-1 and detection was at 272 nm by using PDA detector. The method was performed at ambient temperature. The retention time of the apalutamide was 1.27 min. The % RSD value in precision was &gt;2 %. The accuracy of the method was found to be between 99.54 % - 100.01 %. The limit of detection and limit of quantifi cation values were found to be 0.14 µg mL-1 and 0.48 µg mL-1, respectively. The linearity concentration range was found to be 11.25 - 67.5 µg mL-1, it show wide linearity concentration range. The method was proved to have good robustness after changing parameters of fl ow rate, temperature and mobile phase composition. The method showed good ability towards different stress conditions of acidity, alkalinity, peroxide and UV-light. The method can be used for the routine analysis of apalutamide in bulk and its pharmaceutical dosage form by using UPLC.

Electrochemical detection of food preservative SO2 in red wine using SiO2 coated CdS nanomaterials

Cadmium sulfide is an important chalcogenide semiconductor nanoparticle prepared by reverse micelle method using cetyltrimethylammonium bromide (CTAB), surfactant. Toxic CdS is coated with silica using tetraethyl orthosilicate (TEOS) precursor and are well characterized. SiO2 provides a sufficient contrast to show the core homogeneously surrounded by the silica shell. The coating can be made thicker by the addition of TEOS resulting in monodispersed silica spheres with CdS core. SO2 is the most important chemical (as preservative and antioxidant) used to prevent wine oxidation. CdS@SiO2 is serving as adsorbent for the detection of SO2 in wine. The detection mechanism and the sensitivity of the method were validated using limit of detection and the limit of quantification values which are determined from differential pulse voltammetric technique. This electrochemical sensing is found to be simple and reliable to detect the free SO2 present in the wine sample.

Development of a rapid and reliable high-performance liquid chromatography method for determination of water-soluble vitamins in veterinary feed premix.

Background and Aim:Determination of trace amounts of vitamins in multi-component feed premix is a troublesome analytical procedure. In this study, a simple and rapid high-performance liquid chromatography (HPLC) method was developed and validated for the concurrent detection and quantitation of four water-soluble vitamins such as thiamine, riboflavin, pyridoxine, and cyanocobalamin in veterinary feed premixes.Materials and Methods:The chromatographic separation of the vitamins was carried out at 35°C temperature on a reversed-phase C18 column using a gradient pump mode. Mobile phase constituents were solvent (a): 25 mM Potassium dihydrogen phosphate and 5 mM sodium hexanesulfonate in deionized water having pH-4.0 and solvent and (b) 5 mM sodium hexanesulfonate in methanol. Detection was performed with HPLC ultraviolet/visible detection set at 278 and 361 nm wavelength in two different channels. The flow rate was 1.2 mL/min and the total run time was 25 min.Results:The method was validated according to the International Conference on Harmonization and Food and Drug Administration guidelines and acceptance criteria for system suitability, precision, linearity, and recovery were met in all cases. The relative standard deviation for system suitability and precision was <2% for all vitamins. The linearity of the calibration curves was excellent (R2>0.999) at concentration of 5, 10, 15, 20, 25, and 30 μg/mL for all vitamins. The limits of detection values were 0.0125, 0.0017, 0.0064, and 0.0065 μg/mL for thiamine, riboflavin, pyridoxine, and cyanocobalamin, respectively, and the limits of quantification values were 0.0378, 0.0051, 0.0213, and 0.0198 μg/mL for thiamine, riboflavin, pyridoxine, and cyanocobalamin, respectively. The recovery percentages ranged from 88% to 115%.Conclusion:The overall parameters of the proposed method met the validation criteria and this method could be a highly desirable technique for routine analysis of water-soluble vitamins in veterinary feed premix.

Liquid Biopsy Hotspot Variant Assays: Analytical Validation for Application in Residual Disease Detection and Treatment Monitoring.

Analysis of circulating tumor DNA (ctDNA) in plasma is a powerful approach to guide decisions in personalized cancer treatment. Given the low concentration of ctDNA in plasma, highly sensitive methods are required to reliably identify clinically relevant variants. We evaluated the suitability of 5 droplet digital PCR (ddPCR) assays targeting KRAS, BRAF, and EGFR variants for ctDNA analysis in clinical use. We investigated assay performance characteristics for very low amounts of variants, showing that the assays had very low limits of blank (0% to 0.11% variant allele frequency, VAF) and limits of quantification (0.41% to 0.7% VAF). Nevertheless, striking differences in detection and quantification of low mutant VAFs between the 5 tested assays were observed, highlighting the need for assay-specific analytical validation. Besides in-depth evaluation, a guide for clinical interpretation of obtained VAFs in plasma was developed, depending on the limits of blank and limits of quantification values. It is possible to provide comprehensive clinical reports on actionable variants, allowing minimal residual disease detection and treatment monitoring in liquid biopsy.

Validation of the spectrophotometric method for the dosing of some combined capsule

Background: UV-Vis spectrophotometry remains the most accessible spectral method with a high degree of sensitivity and information. The advantage of the method consists in its universality, the ability to combine with other methods, the minimum error, as well as its economic efficiency. The objective of this study was the determination of some validation parameters for the spectrophotometric method of dosing piracetam and nicergoline in combined capsules. Material and methods: Agilent 8453 UV-Vis spectrophotometer, reference standards of piracetam and nicergoline, 0.1 M HCl methanolic solution. Validation of the spectrophotometric method according to the requirements of the ICH guide “Q2R1: For analytical procedures and validation”. Results: Linearity was investigated on concentration ranges 5-40 µg / mL. The regression (R2 ) values were 0.9998 for nicergoline and 0.998 for piracetam, respectively. The limit of detection was 1.737 µg / mL for nicergoline and 0.369 µg / mL for piracetam. Quantification limit values were also calculated as 5.265 and 1.118 µg / mL for nicergoline and piracetam, accordingly. The results obtained showed that the developed spectrophotometric method is accurate, precise and robust, because the value of the relative standard deviation was less than 1.0%. Conclusions: The developed spectrophotometric method showed specificity, linearity, accuracy, precision and robustness, and can be applied on the concentration range between 80-120% of the nominal value of the content of nicergoline and piracetam in the preparation.

UV Spectrophotometric Method Development and Validation of Esomeprazole in Bulk and Pharmaceutical Dosage Forms

The work discusses method development and validation. An uncomplicated, accurate, and straightforward method was developed for the drug Esomeprazole in bulk as well as Pharmaceutical dosage form. NaOH was used as the solvent. The maximum wavelength (ʎ max) for Esomeprazole was found to be 305nm. The validation was performed as per International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines for Accuracy linearity, precision, Limit of Detection (LOD) and Limit of Quantification (LOQ). Esomeprazole's recovery percentage (%) was 100.20%, respectively. Linearity for Esomeprazole was observed between 5-25µg/ml, respectively. Regression equation y=0.0407x-0.0122, regression coefficient (r²) is 0.9963 for Esomeprazole. Inter day and intraday precision were checked, % relative standard deviation values were less than 2. The regression equations were used to derive the Limit of Detection (LOD) and Limit of Quantification (LOQ) values. LOD value was found to be 0.734 µg/mL and LOQ value was 2.224 µg/mL for Esomeprazole. The assay of the marketed formulation was performed, which was between 98-102%. So the method developed was simple and economical that can be adopted for routine tests.

Development and Validation of UV Spectrophotometric Method of Mesalamine Using Hydrotropic Solubilizing Agents

The work was proposed to discuss method development and validation of the drug Mesalamine by using hydrotropic solubilizing agents. An uncomplicated, accurate, and precise method was developed for the drug Mesalamine in bulk as well as Pharmaceutical dosage form. 5M Urea was used as the hydrotropic solubilizing agent to enhance the solubility of the drug. The maximum wavelength (ʎ max) for Mesalamine was found to be 241nm. The validation was performed as per International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines for Accuracy, linearity, precision, Limit of detection (LOD) and Limit of quantification (LOQ). Percentage recovery (%) of Mesalamine was ascertained to be between 95 to 98%. Linearity for Mesalamine was observed between 2-10 µg/ml. Regression equation y=0.0571x-0.0186, regression coefficient (r²) is 0.9996 for Mesalamine. Inter day and intraday precision were checked, % relative standard deviation values were less than 2 for both the methods. Limit of detection (LOD) and Limit of quantification (LOQ) values were derived using regression equations. LOD value was found to be 0.55 µg/ml. LOQ value was found to be 1.67 µg/ml. The assay of the marketed formulation was performed and the results of the assay were obtained by the proposed method. The results are in between 98-102%. So, the method developed was simple and economical that can be adopted for routine tests.

Patulin Imprinted Nanoparticles Decorated Surface Plasmon Resonance Chips for Patulin Detection

In this study, the patulin imprinted and the non-imprinted nanoparticles are synthesized by the two-phase mini emulsion polymerization method and characterized by zeta-size analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy. Afterwards, the patulin imprinted and the non-imprinted nanoparticles are attached on the surface of surface plasmon resonance (SPR) chips. The patulin imprinted and the non-imprinted SPR nanosensors are characterized by using atomic force microscope, ellipsometer, and contact angle measurements. Kinetic studies for patulin detection are carried out in the concentration range of 0.5 nmolar–750 nmolar. The limit of detection and the limit of quantification values are obtained as 0.011 nmolar and 0.036 nmolar, respectively. In all kinetic analysis, the response time is 13 min for equilibration, adsorption, and desorption cycles. The selectivity studies of the patulin imprinted and the non-imprinted SPR nanosensors are determined in the presence of ochratoxin A and aflatoxin B1. In order to demonstrate the applicability, validation studies of the patulin imprinted SPR nanosensor are performed by liquid chromatography-tandem mass spectrometry (LC-MS).

METHOD DEVELOPMENT AND VALIDATION OF OLMESARTAN AND HYDROCHLOROTHIAZIDE BY UV SPECTROSCOPY

In the present work a simple, inexpensive, rapid, easy, sensible and reproducible UV Spectrophotometric method has been developed and validated for determination of Olmesartan (OLM) and Hydrochlorothiazide (HCT) in bulk drug and pharmaceutical dosage form. A simple double beam UV spectrophotometric method has been developed using area under curve method and validated with different parameters such as linearity, precision, Accuracy, limit of detection (LOD), Limit of Quantification (LOQ), accuracy as per ICH guidelines. UV-visible spectrophotometric method, measurement of absorption at maximum wavelength in 10 ml methanol and volume make with water solvent system as reference OLM and HCT were found to be at 256 nm and 276 nm respectively. The drug obeyed the Beer’s law and showed good correlation. Beer’s law was obeyed in concentration range 2-32 µg/ml for Olmesartan and Hydrochlorothiazide respectively with correlation coefficient was 0.999. LOD values for OLM and HCT were found to be 0.056 µg/mL and 0.1050 µg/mL respectively and LOQ values for OLM and HCT were found 0.1698 µg/mL and 0.3183 µg/mL respectively. The proposed method is precise, accurate and reproducible and can be used for routine analysis of OLM and HCT in bulk and pharmaceutical dosage form.

Determination of Arsenic(III) and Total Arsenic at Trace Levels in Baby Food Samples via a New Functionalized Magnetic Graphane Oxide Nanocomposite.

Baby food safety is an essential issue in health policy. For this reason, a simple, cheap, and fast analytical procedure to developed arsenic(III) and total arsenic determination in baby food samples using functionalized magnetic graphane oxide nanocomposite. A new nanocomposite anchored of tiopronin (TSH) magnetic graphane oxide (GO-PG4@Fe3O4-TSH) was first synthesized/characterized and used as an adsorbent to determine arsenic(III) and total arsenic for baby food samples. Arsenic(III) was directly determined on GO-PG4@Fe3O4-TSH nanocomposite at pH 4.5. The determination of total arsenic used KI and L( +) ascorbic acid solution as reducing reagents. The parameters influential on arsenic(III) determination in the baby food samples including the sample's pH, adsorption time, amount of GO-PG4@Fe3O4-TSH, eluent type, sample volume, reducing reagent type and amount, and also foreign ion effect were investigated. The GO-PG4@Fe3O4-TSH carrying As(III) could easily be separated from baby food samples via applying an external magnetic field. The detection limit for arsenic(III) was found as 0.11μg L-1, while the limit of quantification values was computed as 0.37μg L-1. The precision of results, expressed as relative standard deviation, was always lower than 1.6% at 1mg L-1 As(III) levels. The accuracy of this method was confirmed by analysis of certified reference material. The method was successively applied to determine arsenic(III) and total arsenic in baby food samples.

Determination of Diosmin in Pharmaceutical Products with Chemically Modified Voltammetric Sensors.

In this paper, the electrochemical behavior of two types of sensors based on modified screen-printed electrodes (one screen-printed electrode based on carbon (SPCE) and another screen-printed electrode modified with Prussian Blue (PB/SPCE)) was studied with the aim of sensitive detection of diosmin, an active pharmaceutical compound from the class of flavonoids. The scan electron microscopy technique was used for the morphological characterization of PB/SPCE. The preliminary analysis assessed the electrochemical behavior of SPCE and PB/SPCE in KCl solution and in a double solution of potassium ferrocyanide–potassium chloride. It was shown that the active area of PB/SPCE is superior to the one of SPCE, the greater sensitivity being related with the presence of the electroactive modifier. Similarly, in the case of diosmin detection, the PB/SPCE sensor detect more sensitivity the diosmin due to the electrocatalytic effect of PB. From the study of the influence of reaction rate on the sensor’s electrochemical response, it was shown that the detection process is controlled by the adsorption process, the degree of surface coverage with electroactive molecules being higher in the case of PB/SPCE. From the PB/SPCE calibration curve, it wasdetermined that it has high sensitivity and low detection and quantification limit values (limit of detection 5.22 × 10−8 M). The applicability of the PB/SPCE sensor was confirmed by sensitive analysis of diosmin in pharmaceutical products. The voltammetric method is suitable for the detection and quantification of diosmin in pharmaceutical products. The method is simple, accurate, and quick and can be used in routine analysis in the examination of the quality of pharmaceutical products and other types of samples.

Optimization and Validation Methods for Assay of Acyclovir Cream Determination by High Performance Liquid Chromatography

The aim this study is to obtain an effective and efficient of method for assay of acyclovir cream determination. Chromatographic separation on a reverse phase a YMC - Triart C18 column (4.6 x 150 mm, 5 μm), the mobile phase consisted of water and acetonitrile (95: 5 v/v) at a flow rate 1.2 mL/min with UV-Vis detection at 252 nm, volume injected was 20 μL, with UV detection at 252.0 nm. The retention time of acyclovir was ± 3.5 min. Validation studies were achieved by using the limit of detection (LOD) and limit of quantification (LOQ), precision, accuracy, selectivity parameter. The LOD and LOQ values were 0.27 µg/mL and 0.83 µg/mL. The average standard deviation (RSD) value of precision is 0.35% and accuracy is 0.34%. Robustness shows that the method is resistant to variation in the mobile phase, the Acyclovir cream analysis method meets the ICH 1994 requirements, so it can be applied to the assay of Acyclovir determination in Cream dosage forms.

Conjugate of graphene quantum dots and glutaminase for the sensing of L-glutamine: Electrochemical vs. fluorescent sensing approaches

This research describes the synthesis of a covalent bioconjugate of graphene quantum dots (GQDs) and glutaminase (10 units·mg−1) for electrochemical and photoluminescent (PL) detection of L-glutamine (Gln). As synthesized GQDs exhibited uniform size distribution, (average diameter ~5–10 nm, and discrete blue emission characteristics (λex = 391 ± 2 nm and λem = 480 ± 2 nm)). Accordingly, the immobilization of glutaminase over the surface of the GQDs was confirmed by the characteristic Fourier-transform infrared (FTIR) spectroscopy peaks of the amide bond at 1,703 and 1,390 cm−1. The conjugate was used to detect Gln using electrochemical and PL approaches on a parallel basis over a concentration range of 100–1,000 µM. Electrochemical analysis of Gln using cyclic voltammetry revealed a limit of detection (LOD) and limit of quantification (LOQ) values of 360.4 µM and 1,100 µM, respectively. In comparison, quantification of Gln based on the PL approach yielded a Stern-Volmer quenching constant, LOD, and LOQ values of 2.2 × 103 M−1, 9.42 µM, and 28.57 µM, respectively. As such, the PL spectroscopy-based analysis was seen to have better sensitivity for Gln quantification than the electrochemical analysis. The PL-based approach is a more recommendable option for Gln quantification with high sensitivity and rapidity.

Development and Validation of a Effective and Reliable HPLC Method for the Quantification of Levodopa and Carbidopa in Pharmaceutical Formulations

A convenient and simple high performance liquid chromatography method for simultaneous separation, determination and identification of levodopa and carbidopa in pharmaceutical formulation has been developed. The analysis was carried out using Ace C18 (4.6 x 250 mm, 5 µm) column, and the separation was performed using a mobile phase consisting of 50 mM KH2PO4 (pH 2.3) pumped at a flow rate of 1.2 mL min-1 with UV detection at 280 nm. The method has been successfully validated on the basis of the International Conference on Harmonization (ICH) acceptance criteria. The method is selective, since no interferences corresponding to these analytes were found at retention times. Retention times for both drugs were 2.939 min and 5.018 for levodopa and carbidopa, respectively. The method was validated and shown to be linear in the concentration range of 25-125 µg mL-1 and 6.25-31.25 µg mL-1 for levodopa and carbidopa, respectively. The method exhibited good linearity (R2 &amp;gt; 0.999) over the assayed concentration range and showed good intra-day and inter-day precision. The limit of detection (LOD) and limit of quantification (LOQ) were determined based on standard deviation of the intercept and the slope of the calibration curve. LOD and LOQ values were 0.70 µg mL-1 and 2.13 µg mL-1 for levodopa and 1.31 µg mL-1 and 3.96 µg mL-1 for carbidopa, respectively. The method's accuracy was tested by adding known volume of standard solution (75 percent, 100 percent, and 125 percent concentration of the sample) to the 100 percent concentration pre-analyzed sample solution. The percentage mean recovery by standard addition experiments of levodopa and carbidopa is 99.75% and 99.55%, respectively. This method has also been successfully used for the determination of levodopa and carbidopa in pharmaceutical formulations.

Design and strategy for spectrofluorimetric determination of tranexamic acid in its authentic form and pharmaceutical preparations: application to spiked human plasma.

A creative, very sensitive and noncomplicated spectrofluorimetric technique was established and further validated to determine tranexamic acid in both its authentic form and its pharmaceutical preparation dosage forms. In the introduced technique, a reaction was found between the aliphatic primary amino group of tranexamic acid and ninhydrin/phenylacetaldehyde reagents in the presence of Torell and Steinhagen buffer pH 7.0, which led to the production of a highly fluorescent product; fluorescence intensity was measured at 475 nm after excitation at 391 nm. A calibration curve was drawn with a linear range of 0.3-2 μg/ml. Limit of detection and limit of quantification values were 0.051 and 0.155 μg/ml respectively. The introduced technique was validated based on the International Council for Harmonisation guidelines and agreed for determination of tranexamic acid in its pharmaceutical formulation. Finally, this simple method was also applied for determination of tranexamic acid in spiked human plasma.

Quantitative PCR for detection and quantification of Phytophthora cactorum in the cultivation of strawberry

In this study, we report on the development of two quantitative PCR assays for the detection and quantification of the soilborne plant pathogen Phytophthora cactorum causing root and crown rot of strawberry. The assays rely on the use of SYBR Green I chemistry and use the internal transcribed spacer region 2 (ITS2) and the Ras-related protein gene Ypt1 as detection markers. An extensive list of Phytophthora isolates was included in the study to evaluate assay specificity. High specificity was obtained when Ypt1 was used as detection marker, with cross-reactions only occurring with the closest relatives of P. cactorum, including P. hedraiandra, P. idaei and P. pseudotsugae. In contrast, the ITS-based assay was less specific, resulting in a larger number of cross-reactions (eight species when tested at 10 pg DNA). In sensitivity tests, P. cactorum DNA was detected down to 10 fg using the ITS-based assay, while the limit of detection (LOD) for the Ypt1-based assay was 1 pg DNA, irrespective of the presence of background DNA from strawberry or soil. When strawberry, growth substrate and soil samples were spiked with a 10-fold dilution series of P. cactorum zoospores, the LOD for the ITS-based assay was 10 zoospores g−1 plant material, growth substrate or soil. The limit of quantification (LOQ) of the assay was 109 zoospores g−1 plant material, 15.8 zoospores g−1 growth substrate, and 106 zoospores g−1 soil. For the Ypt1-based assay, the LOD and LOQ values were 1000 and 5910 zoospores g−1 plant material, 1000 and 1818 zoospores g−1 growth substrate, and 1000 and 3823 zoospores g−1 soil, respectively. In terms of detection, analysis of field samples suggested that the Ypt1-based assay almost performed equally well compared to the ITS-based assay, especially for plant and growth substrate samples. Further, our results showed that both qPCR assays outperformed classical plating, illustrating their power to be used for diagnostic purposes. Interestingly, P. cactorum was also detected in soil and growth substrate samples from areas with no symptoms, suggesting that the assays can also aid in early pathogen detection before the disease manifests.

Electrochemical sensing of dopamine via bio-assisted synthesized silver nanoparticles

A simple, environment-friendly, cost-effective procedure is proposed for the synthesis of silver nanoparticles (AgNPs) using aqueous leaf extract of Ziziphus mauritiana (ZmL) as reducing as well as stabilizing agent and its application on glassy carbon electrode (GCE) for the detection of dopamine by cyclic voltammetry (CV). Results showed a substantial enhancement of peak current using Ag@GCE as compared to bare-GCE for the detection of neurotransmitter dopamine. The synthesized ZmL-AgNPs were characterized using ultraviolet–visible (UV–Vis) spectroscopy, Fourier transform infra-red (FT-IR) spectroscopy, X-ray diffraction (XRD) and atomic force microscopy (AFM). We investigated the electrochemical responses of both bare-GCE and Ag-assembled GCE using cyclic voltammetry to delineate the performance enhancement due to ZmL-AgNPs. The present ZmL-AgNP-assembled GCE displayed very high sensitivity and selectivity with excellent linear calibration range 10–100 µM for detection of dopamine with a limit of detection and limit of quantification values 0.1 and 0.3 µM, respectively. The sensor was successfully applied for dopamine detection in real urine samples.

Optimization and Validation of a New HPLC Method for the Determination of Asparagine Active Ingredient in Asparagus lycicus and Phytochemical Characterization of Endemic Asparagus lycicus Specie

A new HPLC method was optimized and validated for the determination of asparagine in Asparagus lycicus plant, an endemic specie found in Turkey, and the phytochemical analysis of this plant was carried out. For asparagine analysis, optimum separation was obtained with water:methanol mixture (95:5, v/v) in the presence of formic acid (FA):ammonium formate (AF) buffer as mobile phase by using a C18 reversed phase column. In this new method, retention time (0.61 min) of asparagine was very short. The linearity, accuracy, precision, limit of detection (LOD), limit of quantification (LOQ), and selectivity parameters were studied for the validation of optimized method. By this method, satisfactory recovery (100.10 ± 2.86%) was obtained for asparagine analysis and LOD and LOQ values were determined to be 0.28 mg L−1 and 0.92 mg L−1, respectively. Freeze-thaw stability of the method is quite high. The results of matrix effect experiments showed that the matrix of Asparagus lycicus plant does not significantly affect the quantification analysis of asparagine. In the phytochemical characterization of endemic Asparagus lycicus plant, asparagine content (6.14 mg g-1 plant), total phenolic (13.22 mg GAE g-1 plant) and flavonoid (3.24 mg CE g-1 plant) contents, phenolic and flavonoid components (28.8 mg rosmarinic acid, 109.2 mg ferulic acid, 531.2 mg chlorogenic acid, 2.8 mg o-coumaric acid, 17.6 mg p-coumaric acid and 6.0 mg sinapic acid per kg plant), total antioxidant activity (13.2 mg mg-1 DPPH), vitamin C content (234.6 mg kg-1 plant), organic acid content as malic acid (2.9 mg kg-1 plant), sugar components (25.15 g fructose and 18.25 g glucose per kg plant), total anthocyanin content (5.15 mg kg-1 plant), total oil content (9.65%) and fatty acid components (oleic acid (55.36%), and linoleic acid (32.01%) and palmitic acid (7.61%)) were determined. The results of this study exhibited that endemic Asparagus lycicus plant might be considered as a promising natural source with antioxidant and bioactive constituents in the potential applications of pharmaceutical and food industries.