Spectrum Subtraction Research Articles

A Novel, Sustainable, and Eco-Friendly Spectrophotometric and Chemometric Approach for Determination of Severely Overlapped Spectrum via Unified Regression Equation: Greenness and Whiteness Assessment.

Nebivolol and valsartan (VAL) in combination with each other successfully control blood pressure and improve hypertension patient outcomes. To develop and validate innovative, simple, and sustainable spectrophotometric methods for the simultaneous analysis of nebivolol and valsartan. The new modified difference amplitude modulation (MD-AM) method uses only unified regression equation and does not require any resolution techniques. Other different approaches were also applied for the determination of the same mixture including univariate and multivariate spectrophotometric methods. The multivariate methods were PLS and PCR, whereas the univariate methods were derivative ratio (DD1), ratio difference (RD), constant center (CC), constant center spectrum subtraction (CC-SS), constant value coupled with amplitude difference (CV-AD), advanced concentration value (ACV), and amplitude difference (AD). The proposed methods use a green solvent; thus, the environmental impact of the presented procedures was evaluated qualitatively and quantitatively using six well-known evaluation tools. All methods were applied successfully for the analysis of the studied drugs in their bulk powder, pharmaceutical dosage form Byvalson®, and in vitro release at intestinal pH (7.4) using a USP dissolution tester. Results obtained were compared statistically with the reported method and with each other using a one-way ANOVA statistical test, and no significant differences were found. All green and white analytical chemistry evaluation tools results confirm the safety, sustainability, and cost-effectiveness of the approaches, indicating that the methods are regarded green and sustainable. Results were agreeable, encouraging their applicability in quality control laboratories for dosage form and making these methods an eco-friendly substitute for the analysis of this combined dosage form and for evaluating the dissolution profile. For the first time, a severely overlapped spectrum was determined using a unified regression equation without the need of extended part or zero contribution regions by the novel method MD-AM. The proposed methods are the first study of in vitro dissolution profiling of nebivolol hydrochloride (NEB) and VAL and the first sustainable and green methods applied without compromising the analytical criteria.

Considerations in Raman Spectroscopy for Real-Time API Concentration Measurement at Tablet Press Feed Frame

Raman spectroscopy is one of the important process analytical technology tools available for implementation in the continuous manufacturing of oral solid dosages. The aim of this study was to investigate several practical considerations in generating real-time measurements using Raman spectrometer at a tablet press feed frame, including the effects of fluorescence interference, photobleaching, feed-frame rpm, and material particle size. Fluorescence, in particular, is a significant drawback of Raman spectroscopy, compared to the use of near-infrared spectroscopy. Potential material sparing strategies were also investigated, including using stationary powders for calibration and isolation of feed-frame materials. Acetaminophen was used as the main active pharmaceutical ingredient (API), and microcrystalline cellulose (MCC) and lactose were used as excipients. The fluorescent behavior of MCC at 785 nm laser wavelength was reported and discussed. Raman spectra of a blend of MCC and acetaminophen and lactose and acetaminophen were collected at the feed frame of the tablet press. A series of preprocessing steps applied to remove the fluorescence interference was found to be effective, including the use of standard normal variate, subtraction of spectra of fluorescent material, baseline correction, and smoothing. Three different PLS models were prepared for different scenarios and their performances were compared. The models were able to predict the concentration of acetaminophen with root mean squared error prediction (RMSEP) of 0.29% w/w when there was no fluorescence interference and 0.57% w/w when there was fluorescence interference in background spectra. The study demonstrated the feasibility of using Raman spectroscopy for API concentration prediction even in the case of fluorescent interference and showed that Raman measurements were robust; that is, they were not much affected by feed-frame rpm and excipient particle size.

Objective Quantification of Detrusor Overactivity Using Spectral Measures of Cystometry Data

To develop scalable objective methods for differentiating patients with and without detrusor overactivity (DO) using quantitative Fast Fourier Transform (FFT)-based measures and routinely captured cystometry data. Retrospective cystometry data were collected as prevoid vesical and abdominal pressure signals from 18 DO and 10 SUI (non-DO) cystometry recordings. Data were filtered and divided into two equal-duration segments, Early and Late Fill, representing the first and second halves of filling. FFT was applied, followed by subtraction of abdominal spectra from vesical spectra. Spectral Power (SP) and Weighted Average Frequency (WAF) measures were calculated for each segment spectra within 1-6 cycles min-1. Compared to non-DO, the mean SP was significantly higher in DO patients for both Early and Late Fill segments. WAF was significantly lower in DO patients for both segments. Changes in spectral pressures appeared to be linked to the presence of detrusor contractions (DCs) and were especially visible when DCs were present in the Early Fill segments of cystometry. FFT-based spectral measures derived from routinely captured cystometry data are significantly different between DO and non-DO patients. This preliminary method is clinically scalable and can be further developed to facilitate the detection of DO, classify disease phenotype, and capture therapeutic efficacy.

Spider chart and whiteness assessment of synergistic spectrophotometric strategy for quantification of triple combination recommended in seasonal influenza – Detection of spurious drug

Trimed Flu® Tablets are commonly specified to treat the cold, cough, and fever in clinical management protocol for seasonal influenza. These tablets comprise three active ingredients namely, paracetamol (PAR), pseudoephedrine sulphate (PSE), and loratadine (LOR) in a challengeable ratio (100:24:1), respectively. In order to analyze their pharmaceutical formulation with minor component, this study proposes a brand-new, potent, white synergistic spectrophotometric technique. In-silico synergistic strategy (ISS) is applied by means of three innovative methods i.e. extended absorbance difference (EAD) at 300.0 nm and 306.0 nm for PAR and absorbance resolution (AR) for LOR at 232.6 nm and 262.6 nm combined with spectrum subtraction (SS) for PSE. While leveling synergistic strategy (LSS) is accomplished via cumulative response method (CR) for LOR and PAR at 248.0 nm using one regression equation. A commendable correlation was revealed in the concentration ranges (1.5-17.0 μg/mL), (4.0-40.0 μg/mL), (3.5-35.0 μg/mL) for PAR, PSE and LOR, correspondingly. The mixtures and dosage forms were successfully analyzed using these spectrophotometric techniques, and the purity of the extracted parent spectra of each drug was confirmed using a spectral similarity index to identify any erroneous components. The concepts of green analytical chemistry were applied to the proposed methods, and the proposed methods' eco-friendliness was confirmed by different greenness evaluation tools including Greenness Index with Spider Charts, Analytical greenness metric (AGREE) and Analytical Eco-Scale (AES). Additionally, the recently released White Analytical Chemistry (WAC) was wont to examine the whiteness properties.

Smart UV Derivative Spectrophotometric Methods for Simultaneous Determination of Metformin and Remogliflozin: Development, Validation and Application to the Formulation

Abstract: Background: The result of pharmaceutical industry research for the new class and the new combination of drugs for the treatments of diabetes is the newly approved combination of metformin (MET) and remogliflozin (REM). For the quality control of this formulation, three smart, reproducible and non-sophisticated spectroscopic techniques were developed by modification of UV spectra. Materials and Methods: The first two methods were based on the measurements of the peak height of the third derivative and second derivative ratio spectra of MET and REM and the third method was the constant center spectrum subtraction method. Results: The proposed methods exhibited Beer’s law in the range of 2.5 to 30 μg/ml and 1 to 24 μg/ml for MET and REM correspondingly by all three methods. The mean percentage recovery was found to be in the range of 99.08% to 100.15% for MET and 98.73% to 100.27% for REM. Further, both analytes were quantified from the formulation using proposed spectroscopic methods with high accuracy. Comparison of all three methods with the reported HPLC method showed no variation in the assay outcomes in relation to accuracy and precision. Conclusion: The suggested techniques are simple, accurate and reproducible, hence could be used for regular quality control of formulation consisting of MET and REM. Key words: Metformin, Remogliflozin, UV, Derivative spectroscopy, Validation, Formulation.

The Use of Wrist EMG Increases the PPG Heart Rate Accuracy in Smartwatches

The impact of tissue movements on the accuracy of heart rate (HR) estimates is a challenge in today’s wearable technology. Tissue movements are caused by muscle activity that modifies the optical path of the reflectance photoplethysmography (PPG), leading to motion artifacts (MAs) that mask the true HR. This kind of MA is not always detected using accelerometers (ACCs). In this study, we propose a method to increase the PPG HR accuracy of a wristwatch using wrist surface electromyogram (EMG) and ACC using spectrum subtraction algorithms. We collected the wrist EMG, wristwatch PPG, ACC data, and the electrocardiogram (ECG) from nine subjects. Data were recorded during four frequent hand movements and three activities (weightlifting and running/walking with and without holding a racket). The added value of the EMG was studied. Visual results indicate that wrist EMG correlates well with the MA seen in the PPG signal and provides additional information over the typically used ACC data. Our analysis showed that the proposed artifact removal method using EMG and ACC decreases the HR estimation error on average by 49% compared to only ACC. Our results showed that wrist EMG contains complementary information on the PPG artifacts and offers a novel signal modality for improving optical HR estimation accuracy in smartwatches.

Degree Square Subtraction Spectra and Energy

This paper defines and computes the degree square subtraction matrix, its characteristic polynomial and spectra in terms of the first Zagreb Index. We explore its bounds for spectral radius and energy.

Degree Square Subtraction Spectra and Energy

This paper defines and computes the degree square subtraction matrix, its characteristic polynomial and spectra in terms of the first Zagreb Index. We explore its bounds for spectral radius and energy.

In Vitro Dissolution Profile of Antihypertensive Mixture: Comparison Between Multivariate Methods and Statistical and Graphical Representation of Different Univariate Spectrophotometric Data.

Triplixam® is a new antihypertensive drug combination consisting of perindopril, amlodipine, and indapamide, which have a synergistic mechanism of action in combination with each other. Comparative study of different spectrophotometric approaches used for the simultaneous determination of perindopril, indapamide, and amlodipine in bulk powder and in dosage form Triplixam. The methods include univariate and multivariate spectrophotometric methods depending on either mathematical calculation or graphical representation of data. For the univariate methods: perindopril was resolved from other components using constant multiplication followed by spectrum subtraction resolution technique, and then two base point, AUC, constant value, and concentration value (CNV) methods were applied. For both amlodipine and indapamide: constant multiplication resolution technique was used, and then constant value and CNV methods were applied. CNV depends on graphical representation of data rather than statistical data. PLS and PCR chemometric assisted spectrophotometric techniques were also applied. The proposed methods are considered a green alternative to the reported methods as the greenness of the proposed methods was evaluated qualitatively and quantitatively by four green analytical evaluation tools. The methods were applied for the analysis of the mixture in the pharmaceutical dosage form Triplixam and in vitro release at intestinal pH (7.4) using a USP dissolution tester. The proposed green analytical methods are considered to be greener than the reported methods and simpler, so they could be used as an alternative for routine analysis of the mixture in quality control laboratories for the reason of their accurate results beside minimum manipulation steps that reduced the error and time required of the analysis with no harmful effect on analyst health as well as the environment. The study was the first in vitro dissolution profiling of perindopril, amlodipine, and indapamide. The developed methods were excellent green methods without compromising the analytical criteria.

Constraining the stochastic gravitational wave background with photometric surveys

The detection of the Stochastic Gravitational Wave Background (SGWB) is essential for understanding black hole populations, especially for supermassive black hole binaries. The recent promising results from various Pulsar Timing Array (PTA) collaborations allude to an imminent detection. In this paper, we investigate the relative astrometric gravitational wave detection method, which can contribute to SGWB studies in the microhertz range. We consider the Roman Space Telescope and Gaia as candidates and quantitatively discuss the survey sensitivity in both the frequency and spatial domains. We emphasize the importance of survey specific constraints on performance estimates by considering mean field of view (FoV) signal subtraction and angular power spectrum binning. We conclude that if the SGWB is at a similar level as in PTA estimates, both Roman and Gaia have the potential to detect this frequency-domain power excess. However, both Roman and Gaia are subject to FoV limitations, and are unlikely to be sensitive to the spatial pattern of the SGWB.

Application of two different spectrophotometric approaches for the determination of a new antihypertensive combination: Graphical and statistical representation of the data

Specific, and precise spectrophotometric methods are developed and validated for the simultaneous determination of the binary antihypertensive mixture nebivolol hydrochloride and valsartan in the zero-order spectrum. The methods applied for the determination of this antihypertensive mixture are constant center spectrophotometric resolution technique, constant center spectrum subtraction resolution technique, and advanced concentration value. Nebivolol hydrochloride was determined by its zero order spectra at 280 and 213 nm while for valsartan it determined by its zero order spectra at 250 nm. All developed methods were applied for the determination of the cited drugs in the pharmaceutical formulation and the results obtained were statistically compared with each other and with those of the reported method. The comparison showed that there is no significant difference between the proposed methods and the reported method regarding both accuracy and precision.

Design of near field noise reduction system for printing press based on Noise Recognition Technology

The near-field noise reduction system of printing press is designed based on the correlation principle of noise signal generation, the characteristics of noise signal and the algorithm of noise related knowledge. Through the analysis and comparison, two methods of segmented signal-to-noise ratio and waveform are selected as the objective method and subjective method to evaluate the algorithm. Considering the factor of time, aiming at the traditional printing press near-field spectrum subtraction, the traditional noise estimation method is used to estimate the minimum statistics and optimal smoothing noise of printing press near-field noise. According to the characteristics of spectrum subtraction, the noise processing method is realized. Finally, the simulation results show that the near-field noise reduction system based on noise recognition technology has higher effectiveness in the practical application process, and fully meets the research requirements.

Critical assessment of smart calculation-based spectroscopy versus chemometric-assisted methods: Application to combined antibiotic formulations

This work describes a comparative study of two multivariate chemometric and univariate spectrophotometric methods for the determination of a ternary drug mixture containing oxytetracycline HCl, bromhexine HCl, and lidocaine HCl. All methods show high sensitivity and similar linearity range. Meanwhile, the chemometric method has the advantage of higher accuracy, higher specificity and better regression parameters. The two spectrophotometric methods are constant multiplication coupled with spectrum subtraction and successive ratio subtraction coupled with spectrum subtraction while the chemometric method used partial least square and principal component regression models. In addition, a spiking technique was used to increase the concentration of bromhexine HCl in the dosage form, allowing its determination despite its low contribution. Methods were successfully applied in the dosage form Oxyclear® veterinary injection in pure powder as well as in its pharmaceutical formulation. Statistical comparison showed no significant difference between the developed methods and the reference method.

Eco-friendly spectrophotometric evaluation of triple-combination therapies in the treatment strategy of patients suffering from hypertension during coronavirus pandemic – Spectralprint recognition study

Recent studies have reported that using certain antihypertensive therapies such as angiotensin II receptor blockers (ARBs) and calcium channel blocker (CCBs) is associated with reduction of fatal outcomes and improving clinical characteristics of patients suffering from hypertension during coronavirus pandemic. Thus, in the current work an effective, innovative and eco-friendly spectrophotometric manner namely, parent spectrum extraction (PSE)was established for evaluation of recommended triple antihypertensive combination therapies incorporate valsartan (VAL) as ARBs, amlodipine besylate as CCBs (AML) and hydrochlorothiazide (HCT)as diuretic into single-pill in challengeable ratio. PSE manner composed of two complementary steps, auxiliary resolution coupled with data analysis resolution(DAR)and it is characterized by resolving the spectral bands of the drugs and extraction of their discrete parent spectra (D0); accordingly, enabling determination of each analyte at its λmax. Auxiliary resolution of AML in triple mixture was applied to decrease complexity of overlapped spectra via constant multiplication (CM) followed by spectrum subtraction (SS) to obtain resolved mixture of VAL and HCT while data analysis resolution (DAR) of this binary mixture was applied via one of three novel methods namely, absorbance extraction (AE), peak-amplitude extraction (PE) and ratio extraction (RE) along with SS method. The proposed methods had analyzed VAL, AML and HCT in the range of 4.0–44.0 µg/mL, 4.0–40.0 µg/mL and 2.0–24.0 µg/mL, respectively with an excellent correlation coefficient (r ≥ 0.9999). Further, the proposed methods in PSR manner were validated as stated by ICH guidelines and it was found that accuracy and precision results are within the acceptable limit. The suggested procedures were effectively utilized for the concurrent quantification of VAL, AML and HCT in synthetic mixtures and tablets. The greenness of the proposed spectrophotometric methods was evaluated by National Environmental Methods Index (NEMI), the Analytical Eco-Scale, the Green Analytical Procedure Index (GAPI) and Analytical greenness metric (AGREE) where the four tools affirmed the eco-friendly nature of the proposed methods. A comparison between the outcomes of the studied methods with the official and reported ones was performed and no statistical difference was arisen between the methods regarding to accuracy and precision.The achieved results along with the simplicity, affordability and low-cost of the proposed methods recommended their appropriateness for the regular quality control examination and analysis of pure materials and pharmaceutical formulations as well as their applicability for the spectralprint recognition of the studied drugs.

Smart Eco-Friendly Spectrophotometric Methods Resolving Highly Overlapping Spectra: Application to Veterinary Antibiotic Injections.

Over the last few years, mathematical manipulation has proved to be a very powerful means of successfully resolving severely overlapped spectra for various multicomponent mixtures. Smart and environmentally friendly spectrophotometric determination approaches were used for two binary mixtures of fixed dose veterinary injections containing flunixin meglumine (FLU) combined with either florfenicol (FLR), or oxytetracycline HCl (OXY). Regarding the first mixture, both FLU and FLR were determined by three successive resolution techniques, which were; constant multiplication coupled with spectrum subtraction (CM-SS), derivative ratio (DD1), and ratio difference (RD), and two progressive resolution techniques which were absorbance subtraction (AS) and amplitude modulation (AM). Also, graphical representation of concentration of the two drugs through concentration value (CNV) method was also applied. Concerning the second mixture, both FLU and OXY showed severely overlapped spectra and a comparative study was conducted for the determination of each drug by constant center (CC), ratio subtraction via amplitude difference coupled with spectrum subtraction (RS/AD-SS), constant value via amplitude difference (CV-AD), and advanced concentration value (ACV) methods. Calibration graphs of the first mixture were linear over the range 5-40 µg/mL for FLU, and 3-40 µg/mL for FLR. The proposed methods overcame the problem of the overlapped spectra and the presence of a minor component in the mixture. Regarding the second mixture, calibration graphs were linear over the range 2.5-24 µg/mL for FLU and 4-28 µg/mL for OXY. The proposed methods were successfully validated as per International Council for Harmonization (ICH) guidelines. The obtained results were statistically compared with the official or reported methods, showing no significant difference concerning accuracy and precision. The methods were evaluated for greenness by three different assessment tools: NEMI, analytical ecoscale, and GAPI. The methods were successfully applied for the simultaneous determination of the two combinations in synthetic mixtures and their marketed antibiotic veterinary injections: Megluflor® and Floxon®.

Sticking - pulling strategy for assessment of combined medicine for management of tough symptoms in COVID-19 Pandemic using different windows of spectrophotometric Platform-Counterfeit products' detection

This study presents a comprehensive comparative study of different green spectrophotometric approaches without any physical separation on processing a ternary mixture of Aceclofenac (ACE), Paracetamol (PAR) and Rabeprazole (RAB) in combined medicine for managing tough symptoms in the COVID-19 Pandemic. The different univariate complementary resolutions according to the response used for the assay of the cited drugs after applying the processing steps were implemented using successive in-silico sample enrichment for resolving the ternary mixture via different windows of spectrophotometric platform using sticking - pulling strategy (SPS). Window I; based on manipulation of the data of zero order absorption spectrum of the mixture using novel Extended absorbance difference (EAD) and Absorbance difference (AD) methods coupled with corresponding spectrum subtraction method (SS). Window III; based on manipulation of the data of ratio spectra via Constant value coupled with constant subtraction (CV-CS) and novel Induced dual amplitude difference (IDAD) method coupled with corresponding spectrum subtraction method (SS). Finally, window IV; based on manipulation of the data of derivative of the ratio spectrum of the mixture via novel Factorized derivative ratio null contribution (FDD-NC) and Factorized unlimited derivative ratio (FUDD) methods coupled with corresponding spectrum subtraction method (SS). Synthetic mixtures and commercial medicine were constructively analyzed using the proposed methods while maintaining calibration graphs to be linear over ranges; 4.0–40.0 µg/mL for ACE, 2.0–14.0 µg/mL for PAR and 4.0–30.0 µg/mL for RAB. Moreover, methods' validation was confirmed via performing exhaustive statistical treatment of the experimental findings. The proposed methodologies can be used for the routine analysis of the cited drugs in quality control laboratories. Additionally, Spectral Similarity Index (SSI) was calculated to detect counterfeit products and methods’ greenness profile was finally guaranteed through analytical greenness (AGREE) metric assessment tool.

Using the Autofluorescence Finder on the Sony ID7000TM Spectral Cell Analyzer to Identify and Unmix Multiple Highly Autofluorescent Murine Lung Populations.

Autofluorescence (AF) is a feature of all cell types, though some have more than others. In tissues with complex heterogeneous cellularity, AF is frequently a source of high background, masking faint fluorescent signals and reducing the available dynamic range of detectors for detecting fluorescence signals from markers of interest in a flow cytometry panel. Pulmonary flow cytometry presents unique challenges because lung cells are heterogeneous and contain varying amounts of high AF. The goal of this study was to demonstrate how a novel AF Finder tool on the Sony ID7000™ Spectral Cell Analyzer can be used to identify and screen multiple AF subsets in complex highly AF tissues like murine lungs. In lung single cell suspensions, the AF Finder tool identified four distinct AF spectra from six highly AF subsets. The subtraction of these distinct AF spectra resulted in a resolution increase by several log decades in several fluorescent channels. The major immune and lung tissue resident cells in a murine model of asthma were easily identified in a multi-color panel using AF subtraction. The findings demonstrate the practicality of the AF Finder tool, particularly when analyzing samples with multiple AF populations of varying intensities, in order to reduce fluorescence background and increase signal resolution in spectral flow cytometry.

Novel Spectrophotometric Approaches for the Simultaneous Quantification of Ternary Common Cold Mixture Containing Paracetamol with a Challenging Formulation Ratio: Greenness Profile Evaluation.

BackgroundCommon cold and cough preparations represent a huge segment of the global pharmaceutical market. Recently, cold/cough formulations containing paracetamol (PAR) have attracted significant attention as PAR has been implemented into the supportive treatment of mild cases of COVID-19 as the first-line antipyretic. From a literature review, no method has been reported yet for simultaneous estimation of PAR, pseudoephedrine hydrochloride (PSE) and carbinoxamine maleate (CRX) in any matrix. Thus, there is an urgent need for smart and green methods that would enable quantification of the cited components in their challenging ratio.ObjectivesThe aim of this work is to develop and validate the first UV spectrophotometric methods for simultaneous determination of the selected drugs taking into consideration the list of challenges including the highly overlapping features and spectral interferences in the cited mixture.MethodsNamely, the proposed methods are: direct spectrophotometry, dual wavelength, first derivative, derivative ratio, ratio difference, constant center coupled with spectrum subtraction, and the constant multiplication method paired with spectrum subtraction.ResultsThese methods were linear over the concentration range of 2.5–35 μg/mL, 1.5–20 μg/mL, and 4.5–35 μg/mL for PAR, PSE and CRX, respectively. These methods fulfill the validity parameters according to International Conference on Harmonization (ICH) guidelines. The results obtained were statistically benchmarked to the official ones where no significant difference was noticed.ConclusionThe developed methods are successfully applied for concurrent quantification of the studied components in the marketed dosage form without interference from matrix excipients. The impact on the environment was assessed by five green metrics, namely a recent Analytical greenness (AGREE) metric algorithm based on the green analytical chemistry framework, Green Analytical Procedure Index (GAPI), Eco-Scale, Assessment of Green Profile (AGP), and National Environmental Methods Index (NEMI).HighlightsEco-friendly and successive spectrophotometric methods were firstly developed in this work, for the simultaneous quantification of PAR, PSE and CRX. These approaches incorporate a simple enrichment-aided technique to augment their spectrophotometric signals, facilitating the accurate quantitation of the minor component in the cited mixture.

Fingerprinting and iso-absorptive resolution techniques for the spectrally overlapping Dutasteride and Silodosin mixture: Content uniformity testing along with greenness profile assessment

The realm of spectrophotometric analysis has witnessed a remarkable progress in inventing faster and simpler resolution techniques for spectrally overlapping drug mixtures. Eco-friendly and progressive spectrophotometric methods were firstly developed in this work, for the simultaneous determination of Dutasteride (DUT) and Silodosin (SLD) in their newly-marketed dosage form. The proposed methods focused on the unique spectral features of this mixture including spectral extension of SLD over DUT spectrum as well as existence of iso-absorptive points. By such way, the methods were classified into two categories; the first one was “fingerprint resolution techniques” including constant extraction coupled with spectrum subtraction and ratio subtraction coupled with constant multiplication methods. The former represented a new modification to the classical constant extraction method where one divisor and lower steps were manipulated instead. The second category was “iso-absorptive resolution techniques”, such as absorptivity centering, absorbance subtraction and amplitude modulation methods. Different solvents were investigated where ethanol was found to be the optimum one regarding drugs solubility, signal sensitivity and environmental, health & safety (EHS) score. Validity of the suggested methods was assessed as per ICH-guidelines and found to be linear over concentration ranges of 5.0–90.0 µg/mL for DUT and 5.0–120.0 µg/mL for SLD. The methods were successfully applied for quantifying the cited drugs in their combined dosage form and evaluating their content uniformity. Moreover, the insignificant statistical difference between the proposed methods and official HPLC ones encourages the utilization of such spectrophotometric methods as greener and faster candidates, especially in modest quality control laboratories. Methods’ greenness profile was finally guaranteed through several assessment tools, namely; national environmental methods index (NEMI), analytical eco-scale, green analytical procedure index (GAPI) and analytical greenness (AGREE) metric.

Identification and quantification of a 60Co radiation source under an intense 137Cs radiation field using an application-specific CeBr3 spectrometer suited for use in intense radiation fields

ABSTRACT Passive γ-ray spectroscopy is a useful technique for surveying the radioactive wastes and spent nuclear fuels under nuclear decommissioning. However, this method depends on material properties such as the activity, density, element, scale, and (especially) for low-energy γ rays from 235U and 239Pu. The γ-decay lines of 134Cs, 137Cs, 60Co, and 154Eu occur at greater energies (than those of 235U and 239Pu), and these nuclides provide significant information on spent nuclear fuel and radioactive wastes. A CeBr3 spectrometer with a small-volume crystal has been previously developed for use in intense radiation measurements. We exposed the spectrometer to radiation dose rates of 0.025, 0.151, 0.342, 0.700, and 0.954 Sv/h under a standard 137Cs radiation field. A 6.38 MBq 60Co calibration source was placed in front of the detector surface. Identification of the full energy peak at 1173 keV was impossible at dose rates higher than 0.700 Sv/h. However, subtraction of the 137Cs radiation spectra from the γ-ray spectra enabled the identification of the full energy peaks at 1173 and 1333 keV at dose rates of up to 0.954 Sv/h; the relative energy resolution at 1173 and 1333 keV was only slightly degraded at this dose rate.