Buffer Ratio Research Articles

BOX-BEHNKEN DESIGN ASSISTED ECO-FRIENDLY RP-HPLC-PDA METHOD FOR THE QUANTIFICATION OF PACLITAXEL: APPLICATION TO EVALUATE THE SOLUBILITY OF PACLITAXEL-CYCLODEXTRIN COMPLEX

Objective: Paclitaxel (PTX) is one of the oldest chemotherapeutic agents for cancer treatment. However, PTX is a class IV drug under the Biopharmaceutical Classification System (BCS), and its oral administration is restricted due to its low bioavailability. Complexing PTX with Beta-Cyclodextrin (β-CD) is an option to overcome the low solubility and bioavailability. This study aims to optimize and develop an RP-HPLC analytical method for quantifying PTX from the fabricated β-CD complex. Methods: The HPLC settings were optimized using Design-of-Experiments (DOE) software. The independent variables for the optimization process were buffer ratio, buffer pH, flow rate, and injection volume. The responses were Retention Time (RT), peak area, Tailing Factor (TF), and number of Theoretical Plates (TP) of PTX. The validated method was then used to measure the % entrapment from the PTX-β-CD complex. Results: The developed and optimized RP-HPLC method was validated as per International Council for Harmonisation (ICH) Q2 (R1) guidelines. The developed method showed linearity R2 = 0.999 with a 0.5-20 µg/ml range. The Limit of Detection (LOD) and Limit of Quantification (LOQ) were 95 and 125 ng/ml, respectively. The accuracy and precision for the developed method came under the acceptance criteria. The developed method was used to evaluate the enhancement of solubility of the prepared PTX-β-CD complex. The method was also used in the evaluation of % drug loading, % drug release and stability of the PTX-β-CD complex. The study clearly showed that the solubility of PTX increased from 0 to 1.14±0.53 µg/ml at pH 1.2 and 0 to 3.18±0.61 µg/ml at pH 6.8, respectively. The PTX-β-CD complex showed 73±3.75% drug release in 120 min at pH 1.2 and 87±3.51% at pH 6.8. The developed RP-HPLC method was found to be eco-friendly as per the Analytical Greenness (AGREE) metric approach and software analysis. Conclusion: An eco-friendly RP-HPLC analytical method was successfully developed and optimized for the quantification of PTX from the PTX-β-CD complex.

A-271 Expansion of sample viability for self-collected urine specimens containing CT/NG & TV/MG utilizing the Roche cobas® 6800 System

Abstract Background The CDC estimates that 1 in 5 Americans have an STI. Home collection for STIs could help mitigate the stigma, cost, and accessibility, which contribute to low diagnosis rates and disparities in diagnosis and treatment. Home self-collected specimens occasionally arrive in the lab with volumes higher or lower than what is required by the assay manufacturer’s specifications for self-collection. This study demonstrates that sample stability is retained after temperature fluctuation via shipping - even when the correct ratio of buffer to sample has been disturbed, a precise and accurate measurement persists. Our goal is to improve accessibility to discreet, patient collected STI tests. Methods Positive samples were prepared by spiking negative urine with organisms near the manufacturer’s limit of detection (LoD). Properly collected samples were aliquoted into tubes with 5mL volumes as per manufacturer specifications. Improperly collected samples were either overfilled (9mL for CT/NG, 7mL for TV/MG) or underfilled (1mL for CT/NG, 2mL for TV/MG). Samples underwent temperature cycling to mimic summer or winter shipping conditions. Ambient temperature studies were conducted on over/underfilled specimens. All samples were baseline tested and compared qualitatively to the manufacturer's claimed LoD using the Roche c6800 and the IVD assays for CT/NG & TV/MG. Results Improperly filled samples were stable at ambient temperature for 63 days for CT/NG, and 59 days for TV/MG. See chart for temperature cycling results. All samples (n=164) showed 100% qualitative agreement with their baseline result after summer and winter shipping challenges. Conclusions Urine samples that fail to satisfy the manufacturer’s self-collection specifications or have endured temperature fluctuations still yield accurate CT/NG & TV/MG results. These results indicate the potential to enhance sample viability and patient accessibility utilizing validated IVD assays.

A Sustainable Chromatographic Method for Simultaneous Analysis of Fluoxetine and Olanzapine Antidepressants: Assessment of Greenness with Green Metric Tools .

The combination of Fluoxetine HCL and Olanzapine treats depression in bipolar disorder and patients unresponsive to other antidepressants. The research aims to optimize a sensitive, simple, rapid, reliable, eco-friendly liquid chromatographic method by minimizing feedstock’s, reagents, energy, and waste to protect the environment and conserve resources, additionally assessed the environmental impact of a method using various green metric tools, and applied the method to pharmaceuticals. The separation was conducted using isocratic RP-HPLC with a DAD at 227nm. The mobile phase used was a 40:40:20 (v/v/v) ratios of buffer, acetonitrile, and ethanol. An L1 column (150 x 4.6mm, 5µm) was utilized with a flow rate of 1.5mL/min and injection volume of 5µL. The column oven and auto-sampler were both maintained at 45°C and 25°C respectively. The optimized method was validated as per ICH guidelines and found to be specific, precise, and robust to slight changes in mobile phase flow, column temperature, and buffer pH. Linearity was demonstrated from 0.1-150µg/mL for olanzapine and 0.4-610µg/mL for fluoxetine HCL. The accuracy was tested with recovery ranges of 0.1–157 µg/mL for olanzapine and 0.4–606 µg/mL for fluoxetine HCl in tablet placebo, and 0.1–150 µg/mL for olanzapine and 0.4–605 µg/mL for fluoxetine HCl in capsule placebo, indicating that the method is suitable for both tablet and capsule dosage forms. The method’s greenness was evaluated using AES, NEMI, GAPI, and AGREE tools. The optimized method was successfully applied to pharmaceutical analysis. The newly optimized method found simple, sensitive, rapid, eco-friendly, incorporating green analytical concepts, has been successfully achieved for the identification and quantification of Fluoxetine HCL and Olanzapine present in pharmaceuticals.

Development and Validation of an ICH-Compliant Optimized RP-HPLC Method for Quantitative Analysis of Favipiravir

Favipiravir (FAV) has emerged as a promising antiviral agent. It is particularly effective against influenza and other RNA virus infections. The aim and objective of the present study was developing and optimizing chromatographic conditions for faster analysis of FAV and demonstrating its applicability for tablet assay. The chromatographic separation was obtained using mobile phase with 90:10 % v/v ratio of ammonium acetate buffer (pH 4.5) and methanol on a Waters C18 column (250 x 4.6 mm, 5 µ). A flow rate of 1.4 mL/min was optimized. Chromatographic detection was perform at a wavelength of 323 nm. The FAV retention time was 6.46 min, indicating the efficiency and speed of the method. The developed method was rigorously validated according to ICH guidelines. A strong linear correlation (r2 = 0.9995) was established in the 5–60 μg/mL range, indicating adequacy for quantitative analysis. The method demonstrated high accuracy, with FAV recovery ranging from 98.77 % to 100.89 %. The % RSD results of less than 2% for intermediate precision and repeatability showed that the method exhibited high precision. The developed HPLC method reduces the Rt. Notably, this method complies with regulatory standards, establishing it as a valuable tool for quality assurance, pharmacological evaluation, and clinical monitoring of FAV. Thus, this validated RP-HPLC method provides a robust and sensitive method for routine FAV quantification, with high accuracy, precision, and compliance results, supporting its potential use in the clinical pharmaceutical industry.

Curiosity model policy optimization for robotic manipulator tracking control with input saturation in uncertain environment.

In uncertain environments with robot input saturation, both model-based reinforcement learning (MBRL) and traditional controllers struggle to perform control tasks optimally. In this study, an algorithmic framework of Curiosity Model Policy Optimization (CMPO) is proposed by combining curiosity and model-based approach, where tracking errors are reduced via training agents on control gains for traditional model-free controllers. To begin with, a metric for judging positive and negative curiosity is proposed. Constrained optimization is employed to update the curiosity ratio, which improves the efficiency of agent training. Next, the novelty distance buffer ratio is defined to reduce bias between the environment and the model. Finally, CMPO is simulated with traditional controllers and baseline MBRL algorithms in the robotic environment designed with non-linear rewards. The experimental results illustrate that the algorithm achieves superior tracking performance and generalization capabilities.

Pengaruh Leverage, Komite Audit dan Kualitas Audit Eksternal Terhadap Penghindaran Pajak

The income that a country has in developing the economy in each region is generated by the APBN budget, one of which is revenue from taxes, where taxes are a sector that dominates the main source of state income and can be used for people's welfare. However, there is often an inappropriate target in tax management, where there are still taxpayers who carry out tax avoidance actions which can have an impact on the stability of the country. Tax avoidance is often caused by taxpayers having higher debt than capital, as well as other things such as the performance of external auditors which is not optimal and lack of supervision by the audit committee every time a financial report is submitted. This research aims to identify leverage, audit committee and external audit quality variables on tax avoidance in manufacturing companies listed on the IDX within a period of 4 years, namely 2019 - 2022. This research uses objects on 22 companies listed on the Stock Exchange Indonesian Effect 2019-2022, analysis technique using panel data regression using the fixed effect model (FEM). The results show that overall the quality of external audits and audit committees has a positive influence at a significance level of 0.05, while leverage (DER) with a probability value of 0.88 > 0.05 means that companies that are the object of research tend to have higher liabilities and tax burdens. . Apart from that, this research, from the results of the unit root test and cointegration test, can be interpreted as saying that the variables used are appropriate and have a long-term nature and are supported by the absence of elements of classical assumptions. Apart from that, the value of r-square is 0.7394 (73.94%) where the remaining 26.06% is influenced by types of variables outside this research such as the tax gap, capital buffer and other financial ratios.

Improving performance metrics in WBANs with a dynamic next beacon interval and superframe duration scheme

The advancement of networking, information, and communication technologies has fueled the popularity of Wireless Body Area Networks (WBANs) in both medical (remote patient monitoring) and non-medical sectors. Due to low, medium, and high data traffic requirements, WBAN performance suffers during the synchronization process that generates periodic beacon frames between sensor nodes and the coordinator. It also suffers when sensor nodes implicitly send data to the coordinator during the fixed time slot using the Contention Access Period (CAP). In this study, we propose a solution called Dynamic Next Beacon Interval and Superframe Duration Scheme (DNBISD) to tackle these issues of the IEEE 802.15.4 standard. This standard relies on a Beacon Interval (BI) and CAP for synchronization and data transmission between sensor nodes and the coordinator. However, the standard must adapt to BI and CAP's changing traffic load requirements, resulting in drawbacks such as prolonged packet delays, increased energy consumption, and potential data loss, particularly in real-time patient monitoring applications. In order to overcome these challenges, our DNBISD scheme employs a fuzzy approach to adapt the BI and CAP based on requested synchronization and data considering input parameters like packet received ratio and buffer ratio. The inference system utilizes the Takagi, Sugeno, and Kang (TSK) fuzzy model for rational quantitative analysis. Simulations demonstrate that our proposed scheme significantly enhances data transmission, boosts the average packet delivery ratio and throughput, and reduces the coordinator's average packet loss ratio and energy consumption. Consequently, this improvement allows for more efficient data transfer among numerous nodes within the specified superframe structure.

Cloud point method applied to the extraction and preconcentration of thiabendazole pesticide from whole grape juice samples and amperometric detection by HPLC.

A cloud point method was developed and applied for the first time to extract and preconcentrate thiabendazole (TBZ) from commercial whole grape juice samples, with determination by high performance liquid chromatography coupled to electrochemical detection (HPLC/EC), using a cathodically pretreated boron-doped diamond electrode (BDD). The best conditions for extraction and preconcentration of TBZ by cloud point extraction (CPE) were performed at pH 6.0, by adding 1 mL of the surfactant Tergitol TMN-6 at 10% (mass-to-mass ratio), without heating (at 27 °C) and ultrasonic stirring time of (20 kHz) for 60 min. The HPLC/EC determination was duly validated in a C8 column, in mobile phase with a 69 : 31 ratio (V/V) of phosphate buffer (pH 7.0):ACN, at a flow rate of 1.2 mL min-1 and electrochemical detection with BDD electrode by applying 1.40 V × Ag/AgCl (3.0 mol L-1). Under these conditions, the procedure showed a preconcentration factor (FC) of 21.7, and limits of detection (LOD) and quantification (LOQ) of 6.64 × 10-9 mol L-1 (or 1.33 μg L-1) and 1.66 × 10-8 mol L-1 (or 3.34 μg L-1), respectively. The method provided a percent recovery of 81% to 98%, with a coefficient of variation between 3% and 15%.

Stability indicating reversed-phase-high-performance liquid chromatography method development and validation for pyridostigmine bromide and sodium benzoate in oral solution.

The present study focuses on the development of a simple, rapid, specific, and stability-indicating HPLC method for the simultaneous analysis of pyridostigmine bromide (PGB) and sodium benzoate (SBN) in oral liquid dosage forms. Analytical techniques should enhance sensitivity and specificity for the estimation of pharmaceutical drug products. Stress studies were conducted under various International Conference on Harmonization (ICH) conditions for evaluation. The further optimized HPLC method was validated in accordance with the current ICH guidelines. Chromatographic separation was accomplished using a mobile phase consisting of a 950:50 v/v ratio of perchloric acid buffer and acetonitrile as mobile phase-A, and 100% acetonitrile as mobile phase-B. The flow rate is 1.0 mL/min, and the injection volume is 20 μL. Detection of components was carried out at 220 nm for PGB and 228 nm for SBN. The validated HPLC method demonstrated high specificity, with linearity ranging between 24 and 72 μg/mL for PGB and 5.2-15.6 μg/mL for SBN. The correlation coefficient for both drugs exceeded 0.999. The method demonstrated high accuracy, exceeding 97%. In stress studies, PGB was found to be sensitive to alkaline stress conditions. The results reveal the successful applicability of the current method for the estimation of PGB and SBN in its marketed formulation, which can be reasonably inferred to assess other formulation systems.

PSVI-27 Evaluation of Coated and Non-Coated Seed Species Pertinent to the Great Basin in Response to in Vitro Ruminal Incubation

Abstract Target grazing has exhibited itself as an effective method of invasive weed mitigation across degraded rangelands in the Great Basin. Additionally, if the seeds of target species are supplemented into the diets of ruminants, they can serve as vectors for the dispersal of native seed species through fecal pats, which may prove to be a useful tactic for rangeland rehabilitation. However, a challenge associated with seed supplementation, is that the seeds of many target species are sufficiently degraded in the rumen. Therefore, the aim of this study was to evaluate the effects of seed coating technologies on germination rates post ruminal in vitro incubation. In vitro incubations were performed on seven species of seeds pertinent to the Great Basin: Achnatherum hymenoides (ACHY), Achillea millefolium (ACMI), Agropyron cristatum (AGCR), Atriplex canascens (ATCA), Elymus elymoides (ELEL), Pseudoregneria spicata (PSSP), and Sphaeralcea grossulariifolia (SPRT) uncoated (control) or coated with either Polyvinylpyrrolidone (PVP) or PVP+ ethocel, as well as uncoated Bromus tectorum (BRTE) seeds. A Daisy II incubator (Ankom Technology, Macedon, NY) was used for the in vitro analysis with rumen inoculum from two rumen-cannulated crossbred Angus steers (body weight = 910.5 ± 34.5 kg) and a buffer ratio of 1:4. Two F57 filter bags containing 1 g of seeds per treatment (control, PVP or PVP+ethocel) were then placed inside of the Daisy II incubator and kept at 39°C for 12 and 24 h for the control treatments, and for 12, 24, and 48 h for the PVP and PVP+ethocel coating treatments. For uncoated seeds, ACHY germination by 24 h was greater when compared with 0 h (P < 0.05), whereas ATCA germination rate decreased linearly by 12 h (P < 0.05). No differences were observed over time on germination rates of BRTE, as well as all of the other uncoated seeds (P > 0.05). When seeds were coated with PVP, ATCA germination rates started to linearly decrease by 12 h (P < 0.05), whereas PVP coated ACMI germination rates only started to decrease by 24 h (P < 0.05). The germination rates of PVP coated ELEL and PSSP seeds only started to significantly decrease by 48 h (P < 0.05). When coated with PVP+ethocel, the observed germination rates were similar to those observed for PVP coated seeds. However, when compared with uncoated seeds, coating with PVP+ethocel seem to decrease germination rates of ACMI and ATCA by 0 h (P < 0.05). No changes on germination rates were observed over time for coated and uncoated AGCR and SPRT (P > 0.05). In conclusion, seed germination rates after in vitro incubation were not increased by coating the seeds with PVP or PVP+ethocel.

Impact of the Purge Flow Density Ratio on the Rim Sealing Effectiveness in Hot Gas Ingestion Measurements

Abstract The rim seals of gas turbines are used to control the ingestion of hot mainstream gas into the wheel space between the rotor disk and the stationary casing. Sealing air, which is generally used to pressurize the cavity space, flows through the seal clearance and then mixes with the flow path in the annulus. Predicting the correct quantity of purge flow necessary to prevent excessive ingestion of hot gases while, at the same time, minimizing the penalties in terms of engine efficiency and stage aerodynamics represents a great challenge for the designers and a crucial point for the design of reliable engines. Such estimate is governed by unsteady phenomena, and computational fluid dynamics (CFD) approaches are still expensive and time consuming, especially if 3D domains and unsteady conditions have to be simulated. Fundamental test cases, replicating actual engines geometries, are still a valid approach to calibrate correlations or simplified models such as the so-called orifice model. However, most of the experimental studies deal with test rigs at room temperature and do not take into account the effect of the density ratio (DR) between purge and main flows. To fill this gap, the present article reports the impact of the density ratio on the rim sealing effectiveness by performing a nonintrusive diagnostic based on the pressure-sensitive paint (PSP) technique on both the stator side and the rotor side. The analysis was performed on a cold rotating cavity rig, developed for the study of hot gas ingestion, where two different values of density ratios were tested by using N2 (DR = 1) and CO2 (DR = 1.52) as purge flow. The data extracted from the PSP seal effectiveness maps allowed to calibrate the orifice model for the stator side and to fit the coefficients of the buffer ratio model for the rotor surface at different flow conditions where the externally induced ingress is the dominant mechanism for gas ingestion. The results highlighted the impact of the DR on the seal effectiveness and on the low-order models considered for the data analysis. In the end, it is shown that the obtained results can be used to scale experimental data, generally collected at DR close to one, toward more representative engine values where the difference between the density of purge and main flows cannot be neglected.

Method development and validation for simultaneous determination of Eletriptan hydrobromide and Itopride hydrochloride from fast dissolving buccal films by using RP-HPLC

AbstractOne of the most effective, rapid, and simple methods reversed-phase high-performance liquid chromatography (RP-HPLC) was used for simultaneous development and validation of Eletriptan hydrobromide (ELE HBR) and Itopride hydrochloride (ITP HCL) in combination. The method was validated based on the regulations of United States Pharmacopeia (USP) and International Conference on Harmonization (ICH) guidelines. Separation of both drugs was achieved within approximately 5 min by using a mobile phase made up of a 70:30 ratio of phosphate buffer and acetonitrile having a flow rate of 1 mL min−1. Furthermore, a comprehensive study was conducted on precision, accuracy, linearity, inter-day, intra-day studies, an assay of formulated films, and stability studies of combined prepared film. Co-efficient of correlation ranged between 0.9993, and 0.9965 for ELE HBR and ITP HCL respectively. The accuracy of the developed method was accurate as drug recoveries in both cases of ITP HCL, and ELE HBR falls between (99.87, 99.96, and 99.84%) to (99.81, 99.12, and 98.44%) respectively having a concentration range of solutions between 10, 30 and 50 μg mL−1 dilution. Films developed by using both drugs in combination were then validated for assay studies, and it was found that substantial results of 99.05%, and 99.87% were found in the case of ITP HCL and ELE HBR respectively. The stability of the solution and mobile phase showed the method's accuracy as the results were 97% for ITP HCL and 99% for ELE HBR. The proposed method developed for simultaneous determination of ITP HCL and ELE HBR was developed and validation and no interaction of any excipient were found.

A new sample preparation approach for the analysis of 98 current-use pesticides in soil and herbaceous vegetation using HPLC-MS/MS in combination with an acetonitrile-based extraction

A simple acetonitrile-based extraction method for the determination of 98 current-use pesticides (CUPs) in soil and herbaceous vegetation using HPLC-ESI-MS/MS is reported. The method was optimized in terms of extraction time, buffer (ammonium formate) ratio, and graphitized carbon black (GCB) ratio for the clean-up of vegetation. The validated method yielded accuracy in terms of percentage recovery of 71–125% (soil) and 70–117% (vegetation) for the majority of 98 CUPs. The precision in terms of relative standard deviation was at 1–14% (soil), and 1–13% (vegetation). Matrix-matched calibration curves exhibited good linearities (R2 > 0.99). The limits of quantitation ranged between 0.008 and 21.5 μg kg−1 in soil and vegetation. The reported method was applied to soils and vegetation from 13 agricultural sites across Germany. Overall, 44 of the 98 common CUPs were detected in our samples and the qualitative load is well above the average for arable soils in the EU.

Method development for simultaneous estimation of Amlodipine Besylate and Perindopril Tertbutyl amine in fixed-dose

The fixed-dose combination of Amlodipine Besylate (ADB) with Perindopril Tertbutylamine (PTBA) drug is used to treat patients with mild-to-moderate hypertension. In recent times researchers are interested to find the efficient analytical method development and validation for the simultaneous determination of ADB and PTBA in a fixed-dose, film-coated tablet. Therefore, the current study was performed with a reverse-phase liquid chromatography method developed to simultaneously analyze ADB and PTBA in film-coated tablets as fixed-dose combinations. The linearity of the proposed method was calculated by preparing six different mixtures of both ADB and PTBA in the mobile phase. The concentration of both the analytes was analyzed at 56mg/100 mL to 84mg/100 mL and 32mg/100 mL to 48mg/100 mL, respectively. The ratio of acetonitrile and phosphate buffer was 35:65. The flow rate was adjusted to 1.5 ml per minute to reduce the retention time. The validation study was performed for the parameters specificity, linearity, precision, range, limit of detection, limit of quantification, accuracy/biasness, and robustness. The relative percentage standard deviation for Perindopril Tertbutyl amine was 0.148%, and for Amlodipine is 0.312%. These results show that the advanced analysis method for simultaneous analysis of fixed-dose is precise. The theoretical IR spectra were also calculated by Gaussian 9.2 by employing the B3LYP functional at density functional theory (DFT) level study. All these parameters studied in this work authenticate the effectiveness of the developed validation method and ensure its repeatability/reproducibility accordingly. To the best of our knowledge, this is the first time to develop a new fast, and easy method for simultaneous identification and quantification of ADB and PTBA by high-performance liquid chromatography (HPLC) with a time-efficient and cost-effective approach.

Stability indicating HPLC method for the simultaneous analysis of Gatifloxacin and Loteprednol in eyedrop formulation using design of experiment approach

Design of experiment (DOE) assisted simple, rapid, precise and accurate stability indicating HPLC method has been developed for simultaneous estimation of Gatifloxacin (GTF) and Loteprednol (LOT) along with their forced degradation products. The developed method has been optimized and developed by using central composite design (CCD) in response surface methodology (RSM). Trails have been undertaken and ratio of phosphate buffer in mobile phase, pH of buffer and flow rate are selected as factors. Resolution, tailing factor (GTF) and tailing factor (LOTE) are selected for determining the system response in the process of method optimization. The responses have been optimized using the Derringer’s desirability function. The effective separation is achieved on Phenomenex EVO-C18 column (250 mm x 4.6 mm i.d, 5 μm particle size) with mobile composed of 10 mM phosphate buffer, pH 3.5 and organic phase composed of mixture of acetonitrile and methanol 60:40 % v/v, the flow rate was 1.0 mL/min, the signals were detected at 267 nm. The developed method was validated for linearity, accuracy, precision, and robustness. The method was applied successfully for stability samples.

PM 7/153 (1) Mechanical inoculation of test plants

PM 7/153 (1) Mechanical inoculation of test plants

Effect of process parameters on separation efficiency in a deterministic lateral displacement device

Deterministic lateral displacement (DLD) is a hydrodynamic method known for its high-resolution sorting of particles. It achieves this through a periodic array of obstacles and laminar flow that passively directs particles along in two different directions depending on the particles’ diameter. Many prior publications have been dedicated to the structural and geometrical development of DLD arrays to improve separation performance; however, a successful separation requires much more than a well-designed array. This paper shows how separation performance is affected by process parameters. For this purpose, the design and fabrication of a DLD device are described. Then three experiments show how process parameters affect the performance of the device. The first experiment uses dye solutions to visualize the formation of a hydrodynamically focused sample stream. The second experiment shows that the particle separation performance (of 7- & 15-µm particles) is affected by the way output fluids are collected. Finally, the third experiment looks at the particle separation efficiency as the input flow rates and the ratio of buffer to sample are changed. The results show that the proper range for buffer and sample flow rate in this device is 1–10 and 0.1–1 (µl/min), respectively. The buffer to sample flow rate ratio of 10 gives the highest separation efficiency, but at a lower sample throughput. The optimized values are specific for our device but demonstrate processes that we believe are universal for DLD separations.

Development and Validation of Rapid RP-HPLC Method for determination of Deferasirox in Bulk and Tablet Dosage Forms

The reverse phase high performance liquid chromatographic method has been developed for the estimation of Deferasirox in bulk and in tablet dosage form. Further optimized HPLC method was validated as per the current ICH guidelines. The experiment was conducted on a Inertsil ODS-3V C18, 150mm length, 4.6mm ID, and 5µm particle size column using the chromatographic separation was done with 60:40 v/v ratio of Acetonitrile and Buffer (0.05% Orthophosphoric Acid) as the mobile phase at a flow rate of 1.5mL min-1, and detection of component was made at 250nm. The HPLC method was accurate, with linearity ranging from 10.8 to 162µg/mL of Deferasirox, the correlation coeffient >0.999. The method was exposed to a high accuracy of more than 97%. The results disclose the successful applicability of the current process for the estimation of Deferasirox from its drug substance and marketed formulation, which can be consciously inferred to assess the other formulation systems. The developed method was validated in terms of linearity, accuracy, precision, LOD, LOQ, robustness & ruggedness. The proposed method can be helpful in Quality control laboratories for the determination of Deferasirox in the pharmaceutical dosage form.

Optimization for the determination of phenol oxidase activity in subtropical forest soils developed on sandstone

Phenol oxidase plays an important role in the degradation of soil organic matter. There was no standard method to determine soil phenol oxidase activity. To fill such knowledge gap, we investigated the effects of substrate type, pH, soil storage conditions, storage time, substrate concentration, water-soil ratio, incubation time and incubation temperature on soil phenol oxidase activity in three different subtropical forest soils developed on sandstone. The pH of extraction buffers significantly affected the phenol oxidase activity. Using 2,2'-azinobis-(-3-ethylbenzo-thiazoline-6-sulfononic acid)-diammonium salt (ABTS) as substrate acquired higher oxidase activity and was applicable to wider pH range than using 3-(3,4-Dihydroxyphenyl)-L-alanine (L-DOPA) as substrate, indicating that ABTS was more suitable as a substrate for measuring phenol oxidase activity in acidic soils of subtropical forests. The storage condition significantly affected phenol oxidase activity. The phenol oxidase activity declined with time in all the three types of soil. The decreasing rate was air-dried > 4 ℃ refrigerated > -20 ℃ frozen > -80 ℃ frozen, suggesting that the frozen storage method was better than others in maintaining soil phenol oxidase activity if the determination of phenol oxidase activity in fresh soil samples cannot be immediately done. Substrate concentration, water-soil ratio, and incubation time and temperature all affected the activity of soil phenol oxidase. The condition of soil: buffer ratio of 1:100, 2 mmol·L-1 concentration of ABTS with an incubation time of 4 h at 25-30 ℃ was optimal for measuring phenol oxidase activity in acidic soils of subtropical forests, with high repeatability and sensitivity.

Thy-AuNP-AgNP Hybrid Systems for Colorimetric Determination of Copper (II) Ions Using UV-Vis Spectroscopy and Smartphone-Based Detection.

A colorimetric probe based on a hybrid sensing system of gold nanoparticles (AuNPs), silver nanoparticles (AgNPs), and thymine (Thy) was developed for easy and rapid detection of copper (II) ions (Cu2+) in solution. The underlying principle of this probe was the Cu2+-triggered aggregation of the nanoparticle components. Color change of the sensing solution (from red to purple) was clearly observed with naked eyes. The experimental parameters, including pH and concentration of tris buffer, thymine concentration and AgNP dilution ratios, were investigated and optimized. Once optimized, the limits of detection were found to be 1, 0.09 and 0.03 ppm for naked eyes, smartphone application and UV-vis spectrophotometer, respectively. Furthermore, determination of Cu2+ was accomplished within 15 min under ambient conditions. For quantitative analysis, the linearity of detection was observed through ranges of 0.09–0.5 and 0.03–0.5 ppm using smartphone application and UV-vis spectrophotometer, respectively, conforming to the World Health Organization guideline for detection of copper at concentrations < 2 ppm in water. This developed hybrid colorimetric probe exhibited preferential selectivity toward Cu2+, even when assessed in the presence of other metal ions (Al3+, Ca2+, Pb2+, Mn2+, Mg2+, Zn2+, Fe3+, Ni2+, Co2+, Hg2+ and Cd2+). The developed procedure was also successfully applied to quantification of Cu2+ in real water samples. The recovery and relative standard deviation (RSD) values from real water sample analysis were in the ranges of 70.14–103.59 and 3.21–17.63%, respectively. Our findings demonstrated a successful development and implementation of the Thy-AuNP-AgNP hybrid sensing system for rapid, simple and portable Cu2+ detection in water samples using a spectrophotometer or a smartphone-based device.