Average Percentage Recovery Research Articles

Improved and Novel Methods for Investigating Organophosphate Esters in Particulate Matter

A pressurized liquid extraction (PLE) method for the extraction of 31 organophosphate esters (OPEs) and novel organophosphate esters (NOPEs) has been developed. Unlike previously published methods, this method utilizes the high-throughput nature of PLE (as opposed to Soxhlet or sonication methods) without using potentially harmful organic solvents like methylene chloride. Combinations of hexane and acetone and hexane and ethyl acetate at various temperatures were examined. Extracts were concentrated and analyzed via gas chromatography–mass spectrometry. The final optimized method utilized 1:1 v/v hexane/ethyl acetate at 100 °C for three static cycles (5 min each) at 80% flush volume and a 100 s N2 purge. This provided average surrogate corrected target analyte percent recoveries in spike and recovery experiments (n = 6) for OPEs and NOPEs of 106 ± 13%, with average surrogate recoveries of 88.6 ± 7.3%. The developed method was further validated using standard reference materials and was then applied to atmospheric particulate matter samples collected in the city of Providence, RI. The dataset reflected ambient concentrations of 16 OPEs and NOPEs (reported in pg m−3) for the first time in the greater Providence metropolitan area, including one of the first reports of NOPEs in atmospheric particulate matter in the U.S.

Analysis of Aspirin (Acetylsalicylic Acid): Development and Validation using RP-HPLC Methods - A Component of Anti-hypertensive Drugs

A precise, sensitive, and focused liquid chromatographic method has been developed to assess the quantity of aspirin in its bulk form. The chromatographic conditions involved utilizing a C-18 column (250 x 4.6 mm, 5 µm particle size) with a mobile phase consisting of water containing 0.1% orthophosphoric acid (v/v) at pH 3.0 and acetonitrile in a ratio of 45:55. The flow rate was set at 1 ml per minute, and the total run time was 20 minutes, with a detection wavelength of 237 nm. The retention time was observed to be 4.01 minutes, and the method exhibited an average recovery percentage of 99.9%. The proposed procedure adhered to the guidelines established by the ICH and is applicable for analyzing aspirin as a standalone bulk drug and in combination with other pharmaceuticals.

VERIFIKASI KUALITAS ANALISIS MANGAN MENGGUNAKAN TEKNIK ICP-OES DALAM SAMPEL AIR MINUM

Drinking water quality, including the levels of dissolved metals, is an important public health consideration. Manganese (Mn) is a naturally occurring metal that can be present in drinking water sources, and excessive intake of Mn can have adverse health effects. The objective of this study was to verify the performance of the analytical method for the determination of manganese (Mn) concentration in drinking water samples using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) techniques at the PT XYZ Laboratory. The method verification included tests for analyte identity confirmation, linearity, precision, accuracy, as well as the determination of the Method Detection Limit (MDL) and Limit of Quantification (LOQ). The verification results showed that the ICP-OES method met the established performance requirements. The linearity test yielded a correlation coefficient (r) of 0.9998, fulfilling the criteria of r ≥ 0.995. The percent relative standard deviation (% RSD) value in the precision test was 1.41%, meeting the requirement of % RSD ≤ 2/3 % CV Horwitz. The accuracy test provided an average percent recovery of 98.66%, which is within the acceptable range of 85-120%. The determined MDL was 0.0006 mg/L, while the LOQ was 0.002 mg/L, both meeting the criteria of MDL < spiked concentration < 10 MDL and LOQ < environmental quality standard. In conclusion, the method for the determination of Mn concentration in drinking water using ICP-OES has been verified and can be used for routine analysis at the PT. XYZ Laboratory, supporting the monitoring and control of Mn levels in drinking water to ensure public health protection.

Rapidly and simply detecting Cr (VI) in aqueous media via a diketopyrrolopyrrole-based chemosensor with both high selectivity and low LOD

BackgroundThe high toxicity of hexavalent chromium [Cr (VI)] could not only cause harmful effects on humans, including carcinogenicity, respiratory issues, genetic damage, and skin irritation, but also contaminate drinking water sources, aquatic ecosystems, and soil, impairing the reproductive capacity, growth, and survival of organisms. Due to these harmful effects, detecting toxic Cr (VI) is of great significance. However, the rapid, simple, and efficient detection at a low Cr (VI) concentration is extremely challenging, especially in an acidic condition (existing as HCrO4−) due to its low adsorption free energy. ResultsA diketopyrrolopyrrole-based small molecule (DPPT-PhSMe) is designed and characterized to act as a chemosensor, which allows a high selectivity to Cr (VI) at an acidic condition with a low limit of detection to 10−8 M that is two orders of magnitude lower than the cut of limit (1 μM) recommended by World Health Organization (WHO). Mechanism study indicates that the rich sulfur atoms enhance the affinity to HCrO4−. Combining with favorable features of diketopyrrolopyrrole, DPPT-PhSMe not only allows dual-mode detection (colorimetric and spectroscopic) to Cr (VI), but also enables disposable paper-based sensor for naked-eye detection to Cr (VI) from fully aqueous media. The investigation of DPPT-PhSMe chemosensor for the quantification of Cr (VI) in real life samples demonstrates a high reliability and accuracy with an average percentage recovery of 102.1 % ± 4 (n = 3). SignificanceDPPT-PhSMe represents the first diketopyrrolopyrrole-derived chemosensor for efficient detection to toxic Cr (VI), not only providing a targeted solution to the bottleneck of Cr (VI) detection in acidic conditions (existing as HCrO4−) caused by its low adsorption free energy, but also opening a new scenario for simple, selective, and efficient Cr (VI) detection with conjugated dye molecules.

Smartphone-based imaging colorimetric assay for monitoring the quality of curcumin in turmeric powder.

This research developed a colorimetric assay for semi-quantitative curcumin detection. The screening test was performed using a ferric chloride to form a brownish color which was further used to evaluate the amount of curcumin in the turmeric powder samples. The quantitative assay was performed based on the color intensity of the curcumin target using a smartphone digital image colorimetry with a developed lightbox constructed with a white light-emitting diodes (LED) light source as the measurement device. Images in red, green, and blue (RGB) color were processed to obtain relevant colors from the image and the color values were used to analyze curcumin concentrations. The intensity of the ΔB was correlated to the concentration of curcumin with high sensitivity. The method showed a linear range between 0.25 and 5mg L-1 with the LOD and LOQ of 0.12 and 0.41mg L-1, respectively. Sample analysis was carried out in turmeric powders. Curcumin in turmeric powder samples was simply extracted using acetonitrile followed by dilution 100 times for sample preparation. The accuracy was tested by spiking 0.25, 1.00, and 4.00mg L-1 of standard curcumin into the turmeric sample solution. The average percentage recoveries were acceptable in all samples (90-104%). The method was validated by comparing the results obtained from the proposed method and high-performance liquid chromatography (HPLC). There was no statistically significant difference between the two methods (P = 0.05).

Estimation of Lexisinatide in Bulk and Tablets by RP‐UPLC Method Developed by Quality by Design Concept

AbstractThe primary goal of the proposed study is to establish and validate a low‐cost, sensitive, reliable, and trouble‐free RP‐UPLC process with improved performance for the direct estimation of Lixisenatide in pure powder and fixed‐dose tablet form. The proposed method is optimized by implementing quality by design studies. The method is optimized using quadratic model of central composite design (CCD) of randomized response surface study. Successful separation of Lixisenatide is obtained by the use of Phenyl‐XBD (1.7 µm, 2.1 mm × 100 mm) column and a mobile phase of acetonitrile: 0.1% w/v OPA (60:40) with 0.5 mL min−1 flow rate. The separated Lixisenatide and its degradants are explorated with PDA detector which has the ability to provide comprehensive spectral information, rapid data acquisition, quantitative analysis, and peak purity analysis of all compounds simultaneously. The RT of Lixisenatide is found to be 1.34 min. The lowest concentration of Lixisenatide's limit of detection and limit of quantification makes guarantees regarding the method's sensitivity. For the provided range of linear concentrations (1.25–7.5 µg mL−1), the regression coefficient is found to be 0.999. The computed average percentage recoveries of Lixisenatide in spiked solutions ranged from 98.9% to 101.2%. The % degradation of Lixisenatide in the presence of a variety of forced conditions confirms the existing method's stability. Lixisenatide is significantly photo sensitive when compared to other stressful conditions such as acid, base hydrolysis, and oxidation. The proposed UPLC approach separates Lixisenatide with high sensitivity, a short retention time, and an affordable solvent system.

Non-enzymatic electrochemical sensing platform based on metal oxide-loaded biopolymer for voltammetric measurement of hepatoprotective metadoxine drug in pharmaceutical formulation and human blood serum

This study focuses on the first-ever high-sensitivity, low-cost, and quick response electrochemical estimation of metadoxine (MTD) in pharmaceuticals and human blood serum using a non-enzymatic nanocomposite modified glassy carbon electrode (CuO/CH/GCE) loaded with chitosan. The electroactive surface of GCE was produced by drop-casting a suspension of CuO/CH nanocomposite in N,N-dimethylformamide (DMF) onto the non-enzymatic electrode surface. Synthesized nanocomposite was characterised by using XRD, XPS, EDX, TEM, Raman and FESEM techniques. EIS technique was utilized to study the enhanced charge-transfer phenomenon occurring at the surface of modified sensor. The electrooxidation of MTD at CuO/CH/GCE surface is depending at pH of supporting electrolyte, scan rate and concentration of analyte. CV and SWV technique were used to carry out electrochemical study, optimised voltammetric response is observed in the BR buffer at pH 2.5, with irreversible diffusion-controlled process. Within the linear concentration range of MTD from 1.99 μg/L to 29.56 μg/L, this sensor exhibited lowest LOD (0.64 μg/L) and LOQ (2.14 μg/L). The MTD in pharmaceutical formulation and human blood serum can be determined with this highly selective peak potential (Ep ∼ 1.2 V), repeatable (%RSD 0.91), and reproducible (%RSD 2.31) method. The average percentage recovery in human blood serum and pharmaceutical formulation is 99.89% and 99.90%. This paper reports a lowest LOD value for MTD detection in the comparison with other reported methods (Table S1). None of the selected excipients were found to interfere more than 5% with redox potential of MTD without affecting the performance of sensor.

Use of a rhodamine-based chelator in a microfluidic paper-based analytical device for the in-situ copper quantification in natural waters

This work describes the development of a microfluidic paper-based analytical device (μPAD) for the determination of copper in fresh and marine waters. A functionalized rhodamine-based chelator was synthesized and used as a chromogenic reagent, forming a highly intense pink complex with the analyte. The aim was to create a paper device that offers optimal performance and provides in-situ, rapid and cost-effective analysis in line with World Health Organization guidelines. The influence on the determination of several physical and chemical parameters was evaluated aiming to achieve the best performance. Under optimised conditions, a linear correlation was established in the range of 0.05–0.50 mg L−1 of copper, with a limit of detection of 10 μg L−1. The accuracy of the proposed method was assessed by comparing the results obtained with the developed μPAD and the results obtained with Inductively Coupled Plasma measurements (RE < 10 %). Recovery studies were also performed using different types of water samples with no need for any prior sample pre-treatment: tap, well, river and seawater. The average recovery percentage of 101 % (RSD = 4.3 %) was obtained, a clear indication of no multiplicative matrix interferences.

A facile on-off fluorescence approach for fluvoxamine determination in pharmaceutical tablets; application to content uniformity testing.

A green-complied spectrofluorimetric approach for quantification of the antidepressant, fluvoxamine, has been established. The method that has been suggested relies on the development of an association complex between fluvoxamine and erythrosine B in an acetate buffer solution. After being excited at 530 nm, the quenching in erythrosine B's native fluorescence caused by complex formation with fluvoxamine was detected at a wavelength of 552 nm. The values of fluorescence quenching at the most optimal reaction conditions were rectilinear at the concentration range of 0.2-2.0 μg mL-1, with a good correlation coefficient (r = 0.9998). The detection limit for the method was 0.03 μg mL-1 while the quantitation limit was 0.09 μg mL-1. The suggested approach has been validated according to the ICH. The established approach was effectively used to determine the drug under study in its dosage form with an average percent recovery of 98.92 ± 0.87 (n = 5), with no effect caused by the existing excipients. The proposed approach was also successfully used for the content uniformity test.

Sequential separation of uranium and plutonium in urine sample using UTEVA resin

This article describes the process of separating uranium (U) and plutonium (Pu) sequentially in urine samples through the use of UTEVA resin. The manuscript optimizes several parameters, including the concentration of nitric acid in the loading solution, the repeatability of results across the multiple uses of the column, and most significantly, implementation of distinctive eluting agents. These eluting agents encompass a combination of 0.002M sulfamic acid and 0.002M ascorbic acid in 2M HNO3, as well as 1.5M NH2OH, HCl (hydroxylamine hydrochloride) in 2M HCl, all aimed at enhancing recovery percentages. The selection of 0.002M sulfamic acid and 0.002M ascorbic acid in 2M HNO3 have been observed to be exceptionally effective in achieving higher radiochemical recoveries. The standardized methodology presented here is characterized by its swiftness and robustness, particularly when compared to the traditional ion exchange method and numerous other published works related to extraction chromatography materials. Radiochemical recoveries for spiked urine samples of 232U and 242Pu consistently fall within the range of 93%–100% and 71%–96%, demonstrating an average recovery percentage with a standard deviation of 96.2% ±2.4% and 82.4% ±10.1%, respectively.

Green Spectrophotometric Method for Determination of Mesalazine Drug by Oxidative Coupling Reaction with Phenoxazine

A novel green, straightforward, and precise spectrophotometric method for determination of mesalazine drug has been developed. This method relies on an oxidative coupling reaction between mesalazine and the environmentally friendly phenoxazine reagent in an acidic medium within the presence of potassium iodate as an oxidizing agent. The resulting colored product exhibits maximum absorbance at 549 nm. The calibration graph was rectilinear over the range of 0.2- 30 µg mL-1 (1.31×10-6 -1.96×10-4 mol L-1 ) with determination Coefficient (R2 ) of 0.9994 and molar absorptivity of 4.8×103 L mol-1 cm-1 . The limits of detection and quantitation were found to be 0.191 and 0.638 µg mL-1 , respectively. The average recovery percentage was 100.9 with a relative standard deviation less than 3.1. The proposed method was effectively applied to determine mesalazine in tablet dosage forms from three different sources, yielding highly satisfactory results that closely align with the standard method outlined in the British Pharmacopeia.

MoS2 Quantum Dots-based Low-cost and Disposable Electrochemical Sensor for the Detection of Lead (II) Ions

After the discovery of graphene, two-dimensional (2D) nanomaterials have received great attention due to their excellent physico-chemical properties. Application of 2D-nanomaterials as receptors of a sensor can achieve high sensitivity and specificity as every atom of the material directly interacts with the analyte. In the present work, MoS2 quantum dots (MSQD) for the ultrasensitive electrochemical detection of lead (Pb2+) ions. MSQDs were prepared by mechanical shear exfoliation method. Size of the QDs and inter planar distance of the crystalline QDs were studied using transmission electron microscope (TEM). The prepared quantum dots were drop casted on a shiny surface of well-polished pencil graphite electrode (PGE). In order to obtain the highest sensitivity for Pb2+-ion sensing, anodic stripping DPV (ASDPV) was employed and consequently, the effect of pH, deposition potential and time were optimized. The sensor shows a linear range from 5.66 10−9 M to 491.93 10−9 M with a calculated detection limit 1.96 10−9 M for the detection of Pb2+-ion. The sensor’s response for Pb2+-ion was unaffected in the presence of any other metal ions. A remarkable average recovery percentage around 99.50% from the Pb2+-ion spiked agriculture soil and ground water samples proves the practical applicability of the sensor.

Rapid and sensitive electrochemical detection of oxidized form of glutathione in whole blood samples using Bi-metallic nanocomposites

We report a facile one-pot synthesis of bimetallic nickel-gold (Ni–Au) nanocomposite for ultra-sensitive and selective electrochemical detection of oxidized glutathione (GSSG) by electrochemical deposition on fluorine doped tin oxide (FTO) substrate. The electrodeposition of Ni–Au nanocomposite on FTO was confirmed by various characterization techniques such as field emission scanning electron microscopy (FE-SEM), X-ray diffractometer (XRD) and Fourier transform infra-red (FTIR) spectroscopy. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) was utilized for the electrochemical characterization of glutathione reductase (GR)/Ni–Au/FTO working electrode at each stage of modification. The GR enzyme immobilized on the Ni–Au/FTO working electrode via glutaraldehyde cross-linking exhibited excellent selectivity against GSSG in the presence of nicotinamide adenine dinucleotide phosphate (NADPH). The immobilized GR enzyme breaks down the GSSG to reduced glutathione (GSH) and converting NADPH to NADP+ whereby generating an electron for the electrochemical sensing of GSSG. The synergistic behavior of bimetals and good electro-catalytic property of the fabricated sensor provided a broad linear detection range from 1 fM to 1 μM with a limit of detection (LOD) of 6.8 fM, limit of quantification (LOQ) of 20.41 fM and sensitivity of 0.024 mA/μM/cm2. The interference with other molecules such as dopamine, glycine, ascorbic acid, uric acid and glucose was found to be negligible due to the better selectivity of GR enzyme towards GSSG. The shelf-life and response time of the fabricated electrode was found to be 30 days and 32 s, respectively. The real sample analysis of GSSG in whole blood samples showed average recovery percentage from 95 to 101% which matched well with the standard calibration plot of the fabricated sensor with relative standard deviation (RSD) below 10%.

A simple, fast, and cost-effective high-performance liquid chromatography-ultraviolet validated method to quantify lacosamide in therapeutic drug monitoring

Lacosamide is a third-generation anticonvulsant used in the treatment of epilepsy. While therapeutic levels for various patient subpopulations are still under investigation to achieve optimal responses, therapeutic drug monitoring has been proven to be useful in improving patient management. To ensure the reliability of results, it is essential to establish a reliable quantitative method. Thus, the aim of this study was to develop and validate a simple and feasible method for quantifying lacosamide in human plasma, with the specific aim of facilitating drug monitoring purposes. A high-performance liquid chromatography method with ultraviolet detection was developed for the quantification of lacosamide in human plasma. Analyte recovery was achieved through ethyl acetate extraction, with propranolol serving as the internal standard. A C18 column and a mobile phase consisting of 10 mM phosphate buffer and acetonitrile (70:30 v/v, pH = 3.5) were employed. Validation parameters included specificity, linearity, repeatability, precision, accuracy, sensitivity, and stability. The method exhibited linearity within the range of 2.5 &amp;ndash; 30 &amp;mu;g/ml (R2 = 0.997), with a limit of quantitation of 2.29 &amp;mu;g/ml. The average recovery percentage was 100.2%, and it proved to be accurate, precise, and specific. In plasma samples, the drug content remained stable for 72 h at 4&amp;deg;C, 1 month at &amp;minus;20&amp;deg;C, and 2 years at &amp;minus;80&amp;deg;C. The post-processed sample remained stable for 1 week under all tested conditions. Due to its simplicity, short analysis time, sensitivity, and cost-effectiveness, the proposed analytical method proves to be useful for therapeutic monitoring and pharmacokinetic studies of lacosamide.

Chemometric Assisted UV-Spectrophotometric Quantification of Tigecycline in Parenteral Dosage Form

Relating to the current study, the quality by design (QbD) concept is used for creating and validating an unique, resilient, accurate, and reliable spectrophotometric approach to quantify Tigecycline (TIG) in injections. Fractional factorial design (FFD) was a design implemented to screen the initial parameters. Moreover, the variables went through the central composite design (CCD) to assess the dependency and optimize the design. Several measures were analyzed statistically to determine the appropriateness of the data obtained from the experiments. At 250 nm, by the use of ethanol, TIG displays an absorption maximum. Variables like screening, slit-width, and sampling interval were recognized as critical method and again, evaluation was done by a CCD. A good linearity was produced for TIG within a range of 2 to 12 μg/mL, with R2 less than 0.999. The process was determined to be perfect, having a good average percent recovery (greater than 100%). According to ICH guidelines, validation of the developed method was performed. By the implementation of QbD principles, spectrophotometric techniques were created and planned to, integrate the qualities into the methods. These processes were manifested for being flexible and pertinent for identifying TIG in pharmaceutical dose regimens.

Chemometric Assisted UV-Spectrophotometric Quantification of Cefaclor in Suspension Dosage Form

In this current study, the quality by design (QbD) concept is used for creating and validating a unique, resilient, accurate, and reliable spectrophotometric approach to quantify cefaclor (CEF) in injections. Fractional factorial design (FFD) was a design implemented to screen the initial parameters. Moreover, the variables went through the central composite design (CCD) to assess the dependency and optimize the design. Several measures were analyzed statistically to determine the appropriateness of the data obtained from the experiments. At 265 nm, by the use of ethanol, cefaclor displays an absorption maximum. Variables like screening, slit-width, and sampling interval were recognized as critical methods and again, evaluation was done by a CCD. A good linearity was produced for cefaclor in the range of 2 to 12 μg/mL, with R2&gt;0.9993. The process was determined for being perfect, having a good average percent recovery (greater than 100%). According to ICH guidelines, validation of the developed method was performed. By implementing QbD principles, the spectrophotometric was created and designed to integrate the quality into the method. The process was manifested for being flexible and appropriate for identifying CEF in pharmaceuticals.

Microbial Detection and Quantification of Low-Biomass Water Samples Using an International Space Station Smart Sample Concentrator.

The pressing need to safeguard the health of astronauts aboard the International Space Station (ISS) necessitates constant and rigorous microbial monitoring. Recognizing the shortcomings of traditional culture-based methods, NASA is deliberating the incorporation of molecular-based techniques. The challenge, however, lies in developing and validating effective methods for concentrating samples to facilitate this transition. This study is dedicated to investigating the potential of an ISS Smart Sample Concentrator (iSSC) as an innovative concentration method. First, the iSSC system and its components were tested and optimized for microgravity, including various testing environments: a drop tower, parabolic flight, and the ISS itself. Upon confirming the system's compatibility with microgravity, we further evaluated its proficiency and reliability in concentrating large volumes (i.e., 1 L) of water samples inoculated with different microbes. The samples carried 102 to 105 colony-forming units (CFUs) of Sphingomonas paucimobilis, Ralstonia pickettii, or Cupriavidus basilensis per liter, aligning with NASA's acceptable limit of 5 × 104 CFU/L. The average retrieved volume post-concentration was ≈450 µL, yielding samples that were ≈2200 times more concentrated for subsequent quantitative PCR (qPCR) and CFU analysis. The average microbial percent recovery, as assessed with CFU counts, demonstrated consistency for C. basilensis and R. pickettii at around 50% and 45%, respectively. For S. paucimobilis, the efficiency oscillated between 40% and 80%. Interestingly, when we examined microbial recovery using qPCR, the results showed more variability across all tested species. The significance of these findings lies not merely in the successful validation of the iSSC but also in the system's proven consistency, as evidenced by its alignment with previous validation-phase results. In conclusion, conducted research underscored the potential of the iSSC in monitoring microbial contamination in potable water aboard the ISS, heralding a paradigm shift from culture-based to molecular-based monitoring methods.

Development of a Plasmodium vivax biobank for functional ex vivo assays

BackgroundPlasmodium vivax is the second most prevalent cause of malaria yet remains challenging to study due to the lack of a continuous in vitro culture system, highlighting the need to establish a biobank of clinical isolates with multiple freezes per sample for use in functional assays. Different methods for cryopreserving parasite isolates were compared and subsequently the most promising one was validated. Enrichment of early- and late-stage parasites and parasite maturation were quantified to facilitate assay planning.MethodsIn order to compare cryopreservation protocols, nine clinical P. vivax isolates were frozen with four glycerolyte-based mixtures. Parasite recovery post thaw, post KCl-Percoll enrichment and in short-term in vitro culture was measured via slide microscopy. Enrichment of late-stage parasites by magnetic activated cell sorting (MACS) was measured. Short and long-term storage of parasites at either − 80 °C or liquid nitrogen were also compared.ResultsOf the four cryopreservation mixtures, one mixture (glycerolyte:serum:RBC at a 2.5:1.5:1 ratio) resulted in improved parasite recovery and statistically significant (P < 0.05) enhancement in parasite survival in short-term in vitro culture. A parasite biobank was subsequently generated using this protocol resulting in a collection of 106 clinical isolates, each with 8 vials. The quality of the biobank was validated by measuring several factors from 47 thaws: the average reduction in parasitaemia post-thaw (25.3%); the average fold enrichment post KCl-Percoll (6.65-fold); and the average percent recovery of parasites (22.0%, measured from 30 isolates). During short-term in vitro culture, robust maturation of ring stage parasites to later stages (> 20% trophozoites, schizonts and gametocytes) was observed in 60.0% of isolates by 48 h. Enrichment of mature parasite stages via MACS showed good reproducibility, with an average of 30.0% post-MACS parasitaemia and an average of 5.30 × 105 parasites/vial. Finally, the effect of storage temperature was tested, and no large impacts from short-term (7 days) or long-term (7–10 years) storage at − 80 °C on parasite recovery, enrichment or viability was observed.ConclusionsHere, an optimized freezing method for P. vivax clinical isolates is demonstrated as a template for the generation and validation of a parasite biobank for use in functional assays.

Assessment of residues of fluchlordiniliprole in rice and its natural environmental matrices by QuEChERS method using HPLC-MS technique and dissipation behavior

Fluchlordiniliprole is a novel insecticide used to kill the rice stem borer (Chilo suppressalis). The concentrations of fluchlordiniliprole residue in the five objects of a pesticide-residue field trial (brown rice, rice husk, rice straw, paddy water, and paddy soil) were investigated by a combination of HPLC-MS and QuEChERS residue analysis. For the five field-trial objects, the LODs of fluchlordiniliprole ranged from 1.53 × 10-1 µg/kg to 7.00 × 10-1 µg/kg, the LOQs ranged from 5.11 × 10-1 µg/kg to 2.33 × 100 µg/kg, the fluchlordiniliprole standard curves showed good linearity (R2-values > 0.9997). The intra-day and the inter-day average percentage recoveries of fluchlordiniliprole and their RSD values were 90.3–117%, 91.2–116% and 1.77–4.35%, 1.73–4.20% respectively. These results indicated the high sensitivity, specificity, accuracy, and precision of the established analytical method. The dissipation of fluchlordiniliprole from paddy water, paddy soil, and rice straw followed first-order kinetics. The half-lives of fluchlordiniliprole in the three field-trial objects were less than 10 days, and the insecticide did not persist in any of the three objects after 75 days. This study concludes that fluchlordiniliprole is safe for the environment and supports the application of the insecticide in rice production around the world.

Development of Efficient Analytical method for the multicomponent analysis of Pravastatin Sodium and Nebivolol Hydrochloride in Bulk Drug by RP-HPLC

Cardiovascular diseases are managed through multi drug regimens. For better patient compliance and cost effectiveness, desired therapeutic efficacy is achieved through combination of more than two drugs in single dosage form. Nebivolol Hydrochloride is β1 receptor blocker and Pravastatin sodium exhibits its pharmacological action through inhibition of cholesterol synthesis. Both drugs are therapeutically compatible and can be administered in single dose formulation. A review of the literature found that there was no effective strategy for the selected drug combination. As a result, an attempt was made to establish a simple, efficient, sensitive, specific, and rapid method for simultaneously estimating Pravastatin sodium and Nebivolol hydrochloride in bulk drugs using RP-HPLC.Column C-18 (Shim-pack) 250 x 4.6 mm, particle size 5 m, mobile phase acetonitrile and water in the ratio 20:80 at 257 nm were found to be the optimal chromatographic conditions. Pravastatin sodium and Nebivolol hydrochloride had retention times of 2.092 and 3.623 minutes, respectively, with average percentage recovery of 99.38% and 99.54%, respectively.The proposed technique was found to be in accordance with the guidelines of the International Conference on Harmonization (ICH).