Respective Calibration Curves Research Articles

Characteristics and electrochemical membrane sensors for selective study and determination of some antidepressant drugs in their pharmaceutical preparations

The construction and electrochemical characterisation of potentiometric sensors of the PVC-membrane type are described being developed for the determination of selected antidepressants; namely: Olanzapine, Oxazepam, and Lorazepam. The sensing PVC-membranes incorporate the ion-associates of the drug cations with ammonium reineckate as selective materials dispersed in 2-nitrophenyl-octylether (NPOE) or dibutyl sebacate (DBS) as the plasticizers of choice. These ISEs exhibit rapid, stable and nearly Nernstian response over a relatively wide concentration range of 1 ´ 10-7 M – 0.01 mol L-1 for Olanzapine and 1 ´ 10-6 – 0.01 mol L-1 for Oxazepam and Lorazepam, in mild acidic solutions with pH 4.5. No interferences caused by either inorganic or organic species were found. The three electrodes developed have been tested for potentiometric titrations of all three drugs, as well as for their direct determination via the respective calibration curves. The individual experiments then resulted in average recovery rates in an interval of 98.4-99.2 %, with the R.S.D. of ca. ±1.5 % (n = 3) for all three analytes of interest. Finally, the method proposed has been applied to the determination of the three drugs in pharmaceutical formulations and in urine, when the results obtained were comparable to those obtained with the reference HPLC measurements.

Chemical characterization, antimicrobial activity and cardiac effects in rat heart of the ethyl acetate fraction of Syzygium cumini (L.) Skeels

Plants are important sources of secondary metabolites responsible for various biological activities. In this research, was evaluated the effect action ethyl acetate fraction of Syzygium cumini leaves (Sc-AcOEt) in the antimicrobial activity, contractile and electrical effects in isolated rat hearts and the chemical characterization. Antimicrobial activity was assessed using the disk-diffusion method and the determination of the minimum inhibitory concentration. The contractile and electrical effects were tested using the Langendorf method. The chemical characterization was evaluated through quantification and HPLC analyzes. P. aeruginosa was not viable in any concentration of the fraction (MIC 0,125 mg/mL), while S. aureus showed a MIC of 0.5 mg/mL. K. pneumoniae and E. coli had the highest MIC (1 mg/mL). A reduction in LVDP was observed after heart perfusion with 0.1 mg/mL of Sc-AcOEt. No change was observed in the duration of systole and diastole at all concentrations and in the electrocardiographic parameters. Total phenols, total flavonoids and total flavonols contents of Sc-AcOEt, calculated from the respective calibration curves, were 21.556µg/mg AGE, 617.222µg/mg QE and 315,222µg/mg RE, respectively. In addition, the HPLC analysis of Sc-AcOEt showed the presence of gallic acid, quercetin-3-glucoside, naringin and myricetin as main components. Thus, the Sc-AcOEt has important antimicrobial and cardiac activities possibly due to its chemical constituents.

Sonochemical Synthesis and Characterization of Rod-Shaped Bi2O3/ZnO Anchored with f-MWCNT Nanocomposite for the Electrochemical Determination of Ofloxacin

Detection of trace quantities of pharmaceutical drug ofloxacin (OFL) must be very simple and accurate. Innovative honeycomb-like structures have received considerable attention over the years due to their superior electrochemical and mechanical character. Herein, rod-shaped Bi2O3/ZnO and multiwalled carbon nanotubes were assembled to form a honeycomb structure like nanocomposite (hc-Bi2O3/ZnO:f-MWCNT). The new hc-BZM was synthesized via the cost-effective sonochemical method. A simple and convenient electrochemical determination of OFL was developed based on hc-BZM modified GCE. The physicochemical and electrochemical characterization was investigated by CV and DPV. The respective calibration curve has good linearity with current vs the concentration of OFL in the range of 0.5 to 39 μM with a correlation coefficient of R2 = 0.991. From the calibration curve slope, the detection limit and sensitivity were determined to be 0.03 μM and 1.063 μA μM–1 cm–2. The proposed sensor explained the structural advantages of simple design, low cost, wide linear range, good selectivity, and reusability. Also, the suggested hc-BZM composites can provide a new platform for the simultaneous determination of OFL, PXM, and DA. Finally, the sensor was successfully applied for the determination of OFL in human urine and serum sample, the obtained results have good agreement with added and the recovery value.

Quantitative 1-D LIBS measurements of fuel concentration in natural gas jets at high ambient pressure

Fuel concentration information is critical to the development of high-efficiency combustion system of direct-injection natural gas engines. In this study, a one-dimensional (1-D) measurement approach based on laser induced breakdown spectroscopy (LIBS) is developed to quantitatively measure 1-D fuel concentration distributions in gas jets at high ambient pressures. Except for the spectral dimension, another dimension of the intensified charge coupled device (ICCD) is employed for the spatial resolution of measurements. The effects of laser energy and ambient pressure on plasma dynamics are investigated to explore the feasibility of 1-D LIBS in concentration measurements at high ambient pressure. Since the peak intensity ratio (PIR) of H656/N746 shows significant spatial variations in the plasma volume, a 1-D calibration strategy is developed by establishing respective calibration curves at different spatial positions to quantify the fuel concentration distributions. The measurement uncertainties are evaluated, including both the systematic and random errors. The temporal variations of the 1-D fuel concentration distributions in methane jets are presented, and the shot-to-shot fluctuations are analyzed in detail. The results show that the coefficient of variation of equivalence ratio is lowest at the end of injection (EOI), suggesting that ignition at the EOI could enable a relatively stable flame kernel formation. Along the radial direction of the jet, a high ignitable mixture percentage appears at approximately 3.0 mm from the jet axis at the EOI, suggesting an optimal ignition position. The results reveal that the 1-D LIBS could be a powerful tool for calibration of numerical models and optimal designs of combustion engines taking advantage of high-pressure gas jets.

Quantification of tea-derived catechins without the requirement for respective calibration curves by single reference liquid chromatography based on relative molar sensitivity.

Many studies report the monitoring of catechins in tea samples by chromatographic techniques. Unfortunately, only a small number of screening assays for catechins exist as a result of the complexity of authentic standards for the respective calibration curves. In the present study, a single reference (SR) exhaustive assay for the simultaneous quantification of tea-derived catechins by liquid chromatography (LC) with photodiode array and fluorescence detectors based on relative molar sensitivity (RMS) was developed as a screening assay of common tea samples without respective calibration curves using authentic standards. Three original SR standards were proposed based on flavonoid structures, evaluated by quantitative 1 H-NMR based on an indirect standard (1,4-bis(trimethylsilyl) benzene-d4 ) and successfully separated in a LC chromatogram. In tea samples with these added SR calculated based on RMS, the concentrations of eight tea-derived catechins could be measured with a relative SD of < 8.5% by a single LC run. This LC screening assay based on RMS allows reliable quantification without the requirement for respective calibration curves using authentic standards. © 2020 Society of Chemical Industry.

An automated spectrophotometric method for the direct determination of nitrite and nitrate in seawater: Nitrite removal with sulfamic acid before nitrate reduction using the vanadium reduction method

A reverse flow injection method was established for simultaneous spectrophotometric determination of NO2− and NO3− in seawater. Vanadium chloride, a nontoxic and soluble reductant, was used to replace highly toxic cadmium for the reduction of NO3− to NO2−. Sulfamic acid was used in the automated spectrophotometric method, to remove NO2− interference before NO3− reduction was performed. The concentrations of NO2− and NO3− were directly quantified using their respective calibration curves. The experimental parameters for both NO2− and NO3− determination were optimized with a univariate experimental design process. The salinity effect was investigated, indicating that measurement correction was not necessary. Method detection limits of the proposed method for NO2− and NO3− detection were 0.09 µM and 0.18 µM, with linearity up to 12 µM and 70 µM, respectively. Recovery from seawater samples varied from 95.0% to 105.0% for NO2− and 95.0% to 104.3% for NO3−. The relative standard deviations of spiked samples with different concentrations were all below 1.2% (n = 7). The accuracy of the method was validated by comparison with the copper-coated cadmium column reduction method, showing that the results were satisfactory. The proposed method was then successfully applied to NO2− and NO3− concentration determination in seawater samples. The proposed method exhibited no significant interference from salinity, with easier operation and calculation methods, making it highly suitable for routine analysis and potentially for underway monitoring.

High-sensitivity simultaneous quantification of tacrolimus and 13-O-demethyl tacrolimus in human whole blood using ultra-performance liquid chromatography coupled to tandem mass spectrometry.

Blood concentrations of tacrolimus show large variability among patients and the narrow therapeutic range is related to adverse effects. Therefore, therapeutic drug monitoring is needed for strict management. 13-O-Demethyl tacrolimus (13-O-DMT) was reported as the major metabolite formed by cytochrome P450 (CYP)3A such as CYP3A5. In previous studies, the best lower limit of quantification (LLOQ) was 0.1 ng/mL for both substances. However, this LLOQ may not be low enough now because the dosage of tacrolimus has decreased in recent years. The purpose of this study was to develop and validate a high-sensitivity and high-throughput assay for simultaneous quantification of tacrolimus and 13-O-DMT in human whole blood using ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS). Thirty-five stable kidney transplant recipients receiving tacrolimus were recruited in this study. The calibration curve range was 0.04-40 ng/mL. All calibration samples and quality control samples fulfilled the requirements of the US Food and Drug Administration and the European Medicines Agency guidelines for assay validation. Trough concentrations of tacrolimus and 13-O-DMT in 35 stable kidney transplant recipients receiving tacrolimus were within the range of the respective calibration curve. Our novel UPLC-MS/MS method is more sensitive than previous methods for quantification of tacrolimus and 13-O-DMT.

Development of a Wireless Surface Acoustic Wave Methane Sensor Using a Metal-Organic Framework As a Sensing Layer for Natural Gas Pipelines

Methane emission from the processing and transportation of fossil fuels can create serious environmental and safety issues as well as a financial burden. The need to monitor the energy infrastructure creates an opportunity for developing low-cost and robust sensors with wireless options. Wireless surface acoustic wave (SAW) devices, which are highly sensitive, cost-efficient, and passive, are a potential candidate for these applications. Nanoporous metal-organic frameworks (MOFs), which can selectively adsorb large amounts of gases in engineered pores at ambient conditions, are potential sensing layers. Here, we present on the development of a wireless and passive SAW sensor using the MOF zeolitic imidazolate framework-8 (ZIF-8) as the sensing layer for methane detection at ambient conditions. The SAW delay lines (nominal operating frequency = 436 MHz) were custom fabricated on Y-Z LiNbO3 piezoelectric substrates and coated with a 500 nm thick ZIF-8 layer using a dip coating method. The devices were excited by 428 MHz RF pulses to test for various concentrations of CO2 and CH4 in N2 background at a constant gas flow rate. Wireless measurements were performed via dipole antennas of nominal resonant frequency 433 MHz. When the sensor was exposed to the gases, surface acoustic wave phase shifted in a negative direction relative to the N2 baseline. This shift was attributed to the decrease in SAW velocity due to the increased mass of the MOF film upon gas adsorption. The CO2 and CH4 sensitivities extracted as the slopes of the respective calibration curves were 1.26 deg/vol-% and 0.03 deg/vol-%, respectively. It is important to note that currently tested minimum concentrations of CO2 and CH4 were 1% and 20%, respectively. Also, the wireless measurements were highly affected by the housing and metal reflectors around it. The demonstration on wireless methane sensing is of great importance for remote monitoring of methane emission sites and transmission pipelines. Our current investigations are focused in advancing the detection limit for leak detection and addressing the electromagnetic interferences in wireless measurement caused by the housing.

289 Dosimetric characterization of a 2D digital mammography (2DDM) unit equipped with narrow-angle and wide-angle digital breast tomosynthesis (DBT)

Purpose To perform a dosimetric characterization of a mammographic unit for 2DDM equipped with narrow-angle and wide-angle DBT in a clinical setting. Methods A retrospective dosimetric characterization was performed on Fujifilm Innovality system for three available modalities: 2DDM, Standard-DBT (DBT-ST, acquisition angle 15°) and High-Resolution DBT (DBT-HR, acquisition angle 40°). All images were obtained with the AEC enabled in normal mode and in a clinical setting between January and May 2017. Both cranio-caudal and mediolateral-oblique views were included in the study. Screening trial patients and patients that already underwent surgery were excluded. For each exam, an automated process obtained the values of compressed breast thickness (CBT) and AGD. AGD was evaluated against CBT. Exponential fitting was performed and compared with calibration curves at various thickness of polymethyl-methacrylate (PMMA). Results 1561 images of patients receiving 2DDM, 383 DBT-ST and 350 DBT-HR were included in the study. Dosimetric fitting curves showed different trends (Fig. 1). 2DDM and DBT-ST exponential fitting curves (Table 1) were established to be widely lower than achievable dose-limits for 2DDM, especially at high CBT. On the other hand, DBT-HR exponential fitting curve was significantly higher and then very close to acceptable dose-limit for 2DDM, especially at low CBT. For all modalities, although well-known inter-individual variability mainly due to the individual amount of glandular tissue inside the breast, PMMA calibration curves were reliable representation of clinical curves: about 75% of patients’ AGD values took place in a neighbourhood ( ± 20%) of the respective calibration curves. Conclusions Dosimetric characterization of the 2DDM and DBT system was performed, as well as a high level of agreement with the PMMA calibration curves was confirmed. The well-known better performance of wide-angle DBT in terms of vertical axis resolution is paid by a higher AGD with respect to narrow-angle DBT. This suggests the adoption of different DBT modalities to different clinical settings. Download high-res image (489KB) Download full-size image

Self-absorption correction: an effective approach for precise quantitative analysis with laser induced breakdown spectroscopy

The light emitted from plasma created by the interaction of a laser beam with the sample surface is always subject to self-absorption (SA) from its cold outer region. This phenomenon affects the precision and the uncertainty of the quantitative analysis by laser-induced breakdown spectroscopy. To overcome this inherent flaw of spectroscopy, different methods of SA corrections (SACs) have been proposed. In this work laser induced breakdown spectroscopy was performed on a set of metal alloys of reference standard samples and the respective quantitative calibration curves were plotted. The SAC was performed by adopting a method based on the ratio of electron density calculated from Stark broadening of the absorbed line and non-absorbed one emitted by the low concentration element present in the air atmosphere. The quality of the linear relationship between the normalized spectral line intensity and analytic concentration was estimated by the coefficient of determination and the quality coefficient of the regression lines. The validation of this procedure by the measurement of two new standards confirms the improvement of the quantitative analysis using the SAC especially for the single ionized emitted line in laser induced breakdown spectroscopy.

The evidence of proteases in sprouted seeds and their application for animal protein digestion

It has been experimentally proven that germinated plant seeds, such as leek, red clover, broccoli, and others contain proteases, which are able to digest animal protein such as gelatin, bovine albumin, casein, and egg albumin. Preliminary tests were carried out with the use of a semi-qualitative gelatin test, which is often applied to prove the presence of fruit enzymes. Quantitative examinations were carried out with the use of a ninhydrin reaction for amino acid determination as well as the Bradford and Smith methods for protein determination. Respective calibration curves were obtained for glycine (amino acid analysis) as well as for egg albumin, bovine albumin, and gelatin (protein analysis), with a full statistical evaluation including Mandel and Lack-of-Fit tests to check for linearity. It has been proven that the selected germinated seeds containing proteases can be applied as an effective aid for animal protein digestion.

42. Computation of the RT dose of the day from mapping CBCT information to the planning CT using an optimized elastic registration method

Introduction Due to organ motion/deformation, dose distribution from fraction to fraction might be usually different from the intended dose distribution optimized at the planning stage. To evaluate the actual delivered dose in the “patient of the day”, we developed a technique of dose computation in the deformed planning CT (pCTD) using an elastic registration from the kilovoltage-CBCT, with an optimized electron density assignment based on a mapping of CBCT information (pCTD,C). Methods Dose calculation was performed on successive kilovoltage CBCT (kV-CBCT) for patients treated with conformational or IMRT technique. The linac was a Varian Truebeam (Varian Medical System) equipped with a kV-CBCT system. Patient underwent to the planning CT (pCT) on a Toshiba Aquilon/LB model (Toshiba Medical System) and using Eclipse (Varian MS) for planning the treatment. The geometry of the “patient of the day” was acquired once a week with the same kV-CBCT protocol (half fan, 80 kV, 1049mAs). Rigid and elastic registrations of the CBCT to the pCT was made using ISOgray TPS (DOSIsoft S.A., France). The method was first validated using an anthropomorphic thorax phantom (CIRS, Inc., Norfolk, Virginia, USA) with or without added bolus to simulate morphological deformation. A routine was developed using MATLAB2017b to map CBCT information to the pCTD. Dose calculation was performed on the CBCT and pCTD using their respective calibration curve from HUCBCT and HUpCT to electron density. Results Dose calculation using an elastic registration method on an anthropomorphic phantom was quantified with a comparison of typical dose calculation computed with the pCTD,C and the CBCT. Dose distributions were in good agreement. Results on patients are pending and would be evaluated in term of dose prescription, PTV coverage and OARs sparing. Conclusions We evaluated a dose calculation method based on mapping of CBCT information. The method enables us to efficiently calculate dose distribution with a good accuracy to evaluate the true delivered dose fraction to fraction and to bring out differences from the planning treatment.

Evaluation of the impact of matrix effect on quantification of pesticides in foods by gas chromatography–mass spectrometry using isotope-labeled internal standards

The impact of the matrix effect in GC–MS quantification of pesticides in food using the corresponding isotope-labeled internal standards was evaluated. A spike-and-recovery study of nine target pesticides was first conducted using paste samples of corn, green soybean, carrot, and pumpkin. The observed analytical values using isotope-labeled internal standards were more accurate for most target pesticides than that obtained using the external calibration method, but were still biased from the spiked concentrations when a matrix-free calibration solution was used for calibration. The respective calibration curves for each target pesticide were also prepared using matrix-free calibration solutions and matrix-matched calibration solutions with blank soybean extract. The intensity ratio of the peaks of most target pesticides to that of the corresponding isotope-labeled internal standards was influenced by the presence of the matrix in the calibration solution; therefore, the observed slope varied. The ratio was also influenced by the type of injection method (splitless or on-column). These results indicated that matrix-matching of the calibration solution is required for very accurate quantification, even if isotope-labeled internal standards were used for calibration.

Cytokinesis-block micronucleus assay by manual and automated scoring: calibration curves and dose prediction.

The cytokinesis-block micronucleus assay in peripheral blood lymphocytes is one of the best standardized and validated techniques for individual radiation dose assessment. This method has been proposed as an alternative to the dicentric chromosome assay, which is considered the "gold standard" in biological dosimetry because it requires less time and cytogenetic expertise. Nevertheless, for application as a biodosimetry tool in large-scale nuclear or radiological accidents, the manually performed cytokinesis-block micronucleus assay needs further strategies (e.g., the automation of micronucleus scoring) to speed up the analysis. An essential prerequisite for radiation dose assessment is to establish a dose-effect curve. In this study, blood samples of one healthy subject were irradiated with seven increasing doses of x-ray (240 kVp, 1 Gy min⁻¹) ranging from 0.25-4.0 Gy to generate calibration curves based on manual as well as on automated scoring mode. The quality of the calibration curves was evaluated by determination of the dose prediction accuracy after the analysis of 10 blood samples from the same donor exposed to unknown radiation doses. The micronucleus frequencies in binucleated cells were scored manually as well as automatically and were used to assess the absorbed radiation doses with reference to the respective calibration curve. The accuracy of the dose assessment based on manual and automatic scoring mode was compared.

Pitfalls bei Gerinnungsuntersuchungen

Coagulation assays are prone to pre-analytical problems and results may be influenced by varying clinical and pharmaceutical aspects. Particularly anticoagulants interact with coagulation testing in many ways. Thromboplastin time will be prolonged dose-dependently in patients taking vitamin K antagonists; moreover the new oral anticoagulants have been shown to have variable impact on the results of the thromboplastin time as well as on other coagulation tests, depending on the mechanism of action of these new drugs as well as on the mechanism of the coagulation test. When measuring anti-Xa activity it should be realised that all drugs with anti-Xa activity will influence the result, which means not only heparins but also the new anti-Xa inhibitors. Respective calibration curves are an indispensable condition to provide the clinician with valuable results. On the other hand this implies that the laboratory knows which anticoagulant is given to the patient. This is an example among others that clinical aspects are important to know for proper interpretation of the results of coagulation testing. Other examples are e. g. bleeding disorders, actual bleeding status or thromboembolic events. Several cases are discussed which exemplify possible pitfalls in the interpretation of coagulation testing.

Simultaneous Analysis of Guaiacol and Vanillin in a Vanilla Extract by Using High-Performance Liquid Chromatography with Electrochemical Detection

We developed and validated a new high-performance liquid chromatographic analysis for electrochemically detecting guaiacol and vanillin as important components in vanilla extract. Separation was achieved with Capcell Pak C-18 MG, the potential of the working electrode being set at +1000 mV. The respective calibration curves for guaiacol and vanillin were linear in the range of 1.60-460 µg/L and 5.90-1180 µg/L. The respective limits for the quantities of guaiacol and vanillin were 1.60 µg/L and 2.36 µg/L. The related standard deviations of the intra- and inter-day precision of the retention time and peak area were all less than 4%. The recovery of guaiacol and vanillin was both more than 97%, all of the validation data being within an acceptable range. This analysis method is well suited for the simultaneous and convenient analysis of guaiacol and vanillin in a vanilla extract to evaluate the quality of the vanilla extract.

Spatial Emission Profiles for Flagging Matrix Interferences in Axial-Viewing Inductively Coupled Plasma-Atomic Emission Spectrometry: 2. Statistical Protocol

A statistical protocol was developed and verified for automated signaling of matrix interferences in inductively coupled plasma-atomic emission spectrometry (ICP-AES). Spatial emission profiles in ICP-AES are versatile indicators for flagging matrix interference. A family of calibration curves is first generated by measurements of standard solutions at different spatial locations in the plasma. The determined-concentration profile of the analyte along a spatial measurement axis of the plasma is then obtained by analyzing the sample at each spatial location by reference to the respective calibration curve. The absence or presence of a matrix interference is gauged from the shape of the determined-concentration profile of the analyte. A flat determined-concentration profile indicates absence of matrix interference, whereas a dissimilar (i.e., curved) concentration profile offers a clear warning signal that the analytical results are compromised by interferences. The developed protocol automatically classifies a spatial profile as flat or curved; it involves the computation of three statistical parameters: relative range(0.05-0.95), σ(sample), and σ(successive). The term relative range(0.05-0.95) refers to the ratio of the range to the mean of the relative-intensity (or determined concentration) values between the 5th and 95th percentiles in a spatial profile, whereas σ(sample) and σ(successive) refer to the sample standard deviation and the standard deviation of successive values, respectively, of all values in a spatial profile. It was found that whenever the relative range(0.05-0.95) of a spatial profile is below 1.5%, the profile can be considered to be flat and no further statistical testing is needed. If relative range(0.05-0.95) > 1.5%, the σ(successive)/σ(sample) ratio provides useful information on the flatness of the profile. If the profile is flat, σ(successive) will be statistically equivalent to σ(sample) (i.e., σ(successive)/σ(sample) = 1). In contrast, if curvature is present in the profile, σ(successive) will be statistically smaller than σ(sample) (i.e., σ(successive)/σ(sample)< 1). A statistical test, based on the transformation of the experimental σ(successive)/σ(sample) ratio to the z value of a standard normal distribution, was used to judge if the difference between σ(successive) and σ(sample) is statistically significant. This statistical protocol for characterization of flatness in a spatial profile was verified in experiments carried out under the influence of various matrix interferences and different plasma operating conditions.

Validated TLC-densitometry method for the simultaneous analysis of pyrethroid insecticides in agricultural and domestic products

BackgroundPyrethroids are widely used for the control of pests and insects, as pyrethroids are believed to pose little risk to human health and environment. However, exposure to the pyrethroids exceeding the label directions might adversely affect human health and environment. Hence a careful selection of environment friendly household product is required that must contain exactly the label claimed pyrethroids amount.ResultsA sensitive and robust TLC-densitometric method for simultaneous quantification of commonly used synthetic pyrethroids including esbiothrin, alpha-cypermethrin and cis/trans permethrin in agricultural and domestic products has been developed and validated. TLC aluminum sheets, precoated with 0.2 mm thick layer of silica gel 60 F-254, were used for chromatographic process. Densitometric analysis of chromatoplates was carried out in absorbance mode at corresponding λmax of each pyrethroid. Equally valid common mobile phase for all pyrethroids consisted of hexane-dichloromethane-ethylacetate-formic acid (8:1.5:0.4:0.1 v/v/v/v) which provided sharp and symmetrical peaks of esbiothrin, alpha-cypermethrin, trans-permethrin and cis-permethrin, at Rf 0.31, 0.53, 0.6 and 0.65, respectively. Linear regression data for respective calibration curves showed a good linearity for all pyrethroids with r = 0.991-0.996. Limits of detection (LOD) and limits of quantification (LOQ) for all pyrethroids were found in the range of 1.6-2.8 and 4.9-8.5 ng/spot, respectively.ConclusionsThe developed method is applicable for separating the mixture of pyrethroids and at the same time, it is also valid for separating their isomers. The method is reproducible, precise and accurate for the quantitative determination of pyrethroids in agricultural and domestic products.

Development and Validation of Stability-Indicating HPLC and UPLC Methods for the Determination of Bicalutamide

Six new process related impurities (Imp-08, Imp-09, Imp-10, Imp-12, Imp-13 and Imp-14) of bicalutamide (BCT) have been reported in this paper. BCT was subjected to oxidative, acid, alkaline, hydrolytic, thermal and photolytic degradation conditions and found to degrade in alkaline condition, yielding Imp-11. Stability-indicating high-performance liquid chromatography and ultra-performance liquid chromatography methods were developed for the determination of BCT in the presence of its 14 process-related impurities and 1 degradant by using Zorbax SB phenyl column (150 × 4.6 mm × 3.5 µm) and HSS T3 column (100 × 2.1 mm × 1.8 µm), respectively. Both the methods were validated as per International Conference on Harmonization guidelines. Quantitation limits (QL) were found be in the ranges of 0.02-0.03% for both the methods. Precision was evaluated by replicate analysis in which % relative standard deviation (RSD) values for areas were found below 2.0. Linearity for the impurities was established in the range of QL to 200% of the specification level and the correlation coefficients derived from of the respective calibration curves were approximately 0.999. The recoveries obtained for purity (90-100%) and assay (98-102%) ensured the accuracy of the developed methods.

Salvia Officinalis L.: Composition and Antioxidant-related Activities of a Crude Extract and Selected Sub-fractions

The composition and antioxidant properties of a methanol: acetic acid (99:1, v/v) soluble crude extract isolated from S. officinalis L. leaves through maceration and selected fractions isolated thereof are presented in this study. The total phenol content was estimated as gallic acid equivalents, whilst qualitative-quantitative phenolic content was determined using high performance liquid chromatography with photodiode array detection. Antioxidant evaluation consisted of ferric reductive capacity and 1,1-diphenyl-2-picrylhydrazyl and hydroxyl free radical scavenging determinations. The crude extract contained hydroxybenzoic acids, hydroxycinnamic acids, flavonoids and diterpenoids, whilst caffeic acid, carnosic acid, luteolin, luteolin-7-O-glucoside and rosmarinic acid were identified from their chromatographic and spectral characteristics and quantified from their respective calibration curves. The crude extract and sub-fractions demonstrated varying degrees of efficacy in the antioxidant-related assays used, except the n-hexane fraction, which was unable to reduce iron(III) at reasonable concentrations. Although the positive controls, ascorbic acid, BHA and BHT, were more potent than the S. officinalis samples, two fractions were significantly (p < 0.05) more potent iron(III) reducing agents than pycnogenol, a proanthocyanidin-rich commercial preparation.