Spider chart, greenness and whiteness assessment of experimentally designed multivariate models for simultaneous determination of three drugs used as a combinatory antibiotic regimen in critical care units: Comparative study.

In this study, five earth-friendly spectrophotometric methods using multivariate techniques were developed to analyze levofloxacin, linezolid, and meropenem, which are utilized in critical care units as combination therapies. These techniques were used to determine the mentioned medications in laboratory-prepared mixtures, pharmaceutical products and spiked human plasma that had not been separated before handling. These methods were named classical least squares (CLS), principal component regression (PCR), partial least squares (PLS), genetic algorithm partial least squares (GA-PLS), and artificial neural network (ANN). The methods used a five-level, three-factor experimental design to make different concentrations of the antibiotics mentioned (based on how much of them are found in the plasma of critical care patients and their linearity ranges). The approaches used for levofloxacin, linezolid, and meropenem were in the ranges of 3-15, 8-20, and 5-25 µg/mL, respectively. Several analytical tools were used to test the proposed methods' performance. These included the root mean square error of prediction, the root mean square error of cross-validation, percentage recoveries, standard deviations, and correlation coefficients. The outcome was highly satisfactory. The study found that the root mean square errors of prediction for levofloxacin were 0.090, 0.079, 0.065, 0.027, and 0.001 for the CLS, PCR, PLS, GA-PLS, and ANN models, respectively. The corresponding values for linezolid were 0.127, 0.122, 0.108, 0.05, and 0.114, respectively. For meropenem, the values were 0.230, 0.222, 0.179, 0.097, and 0.099 for the same models, respectively. These results indicate that the developed models were highly accurate and precise. This study compared the efficiency of artificial neural networks and classical chemometric models in enhancing spectral data selectivity for quickly identifying three antimicrobials. The results from these five models were subjected to statistical analysis and compared with each other and with the previously published ones. Finally, the whiteness of the methods was assessed by the recently published white analytical chemistry (WAC) RGB 12, and the greenness of the proposed methods was assessed using AGREE, GAPI, NEMI, Raynie and Driver, and eco-scale, which showed that the suggested approaches had the least negative environmental impact. Furthermore, to demonstrate solvent sustainability, a greenness index using a spider chart methodology was employed.

Charge transfer complex-based spectrophotometric analysis of famotidine in pure and pharmaceutical dosage forms.

A straightforward and efficient spectrum technique was created using Ortho-chloranil as the electron acceptor (-acceptor) in a charge transfer (CT) complex formation reaction to determine the concentration of famotidine (FMD) in solutions. Compared to the double-distilled blank solution, the reaction result detected a definite violet colour at a maximum absorption wavelength of 546 nm, For concentrations range 2-28 µg/ml, the technique demonstrated excellent compliance with Beer-Law and Lambert's, as evidenced by its molar absorptivity of 2159.648 L mol-1 cm-1. Lower detection limits of 0.3024 µg/ml and 1.471 µg/ml, respectively, were discovered. The complexes of famotidine and Ortho-chloranil were found to have a 2:1 stoichiometry. Additionally, the suggested approach effectively estimated famotidine concentrations in pharmaceutical formulations, particularly in tablet form.

Quantification of ternary mixture of paracetamol, chlorzoxazone and ibuprofen present in tablet dosage form using ratio subtraction spectrophotometric approaches.

A sensitive and selective spectrophotometric approach comprising of successive ratio subtraction was developed for quantification and resolution of spectrum of mixture containing three components without prior separation. Three components, namely paracetamol, chlorzoxazone and ibuprofen were present in tablet dosage form. The linearity studies were carried out by recording zero order spectra and measuring absorbances at 285.0, 282.0 and 220.0 nm for paracetamol, chlorzoxazone and ibuprofen respectively. The drugs exhibited linear response in the concentration range of 6.0-18.0, 3.0-15.0 and 4.0-20.0 µg / mL for paracetamol, chlorzoxazone and ibuprofen respectively. The spectrum of paracetamol was most extended which was subsequently followed by moderately extended spectrum of chlorzoxazone and unextended spectrum of ibuprofen. The ratio spectra were manipulated successfully for quantification of paracetamol, chlorzoxazone, and ibuprofen. The developed method was validated as per ICH guidelines for the parameters of specificity, linearity, precision and accuracy. The percent recoveries for all the three drugs were in the range of 98.0-102.0 % with mean recovery of paracetamol, chlorzoxazone and ibuprofen were 99.72, 99.02 and 100.34 % respectively. Additionally the validity of the method is assured by analyzing marketed formulation.

Dissociation constants of relevant secondary organic aerosol components in the atmosphere.

The presented studies focus on measuring the determination of the acidity constant (pKa) of relevant secondary organic aerosol components. For our research, we selected important oxidation products (mainly carboxylic acids) of the most abundant terpene compounds, such as α-pinene, ß-pinene, ß-caryophyllene, and δ-3-carene. The research covered the synthesis and determination of the acidity constant of selected compounds. We used three methods to measure the acidity constant, i.e., 1H NMR titration, pH-metric titration, Bates-Schwarzenbach spectrophotometric method. Moreover, the pKa values were calculated with Marvin 21.17.0 software to compare the experimentally derived values with those calculated from the chemical structure. pKa values measured with 1H NMR titration ranged from 3.51 ± 0.01 for terebic acid to 5.18 ± 0.06 for ß-norcaryophyllonic acid. Moreover, the data determined by the 1H NMR method revealed a good correlation with the data obtained with the commonly used potentiometric and UV-spectroscopic methods (R2 = 0.92). In contrast, the comparison with in silico results exhibits a relatively low correlation (R2Marvin = 0.66). We found that most of the values calculated with the Marvin Program are lower than experimental values obtained with pH-metric titration with an average difference of 0.44 pKa units. For di- and tricarboxylic acids, we obtained two and three pKa values, respectively. A good correlation with the literature values was observed, for example, Howell and Fisher (1958) used pH-metric titration and measured pKa1 and pKa2 to be 4.48 and 5.48, while our results are 4.24 ± 0.10 and 5.40 ± 0.02, respectively.

Smart Multivariate Spectrophotometric Determination of Two Co-Administered Autoimmune Drugs; Sulfasalazine and Pentoxifylline; in Bulk and Spiked Human Plasma.

BACKGROUND: Sulfasalazine and pentoxifylline are co-prescribed together to treat psoriasis and pemphigus vulgaris. Sulfasalazine is an anti-inflammatory, immunosuppressant, and antibiotic drug, while pentoxifylline is a vasodilator and immunosuppressant. The spectra of the two drugs and plasma suffer from severe overlap. OBJECTIVE: This work aims to simultaneously determine sulfasalazine and pentoxifylline in their binary mixture and spiked human plasma by the assessment of their UV spectral data. METHODS: Two model updated chemometric methods were established using principal component regression and partial least-squares regression models. The two models were validated in accordance with the U.S. Food and Drug Administration guidelines for bioanalysis and were applied for the determination of both drugs in synthetic mixtures or spiked human plasma. RESULTS: Accuracy and precision were within the accepted limits. In addition, three different assessment methods were used to evaluate the environmental greenness of the proposed models. CONCLUSION: The two updated models are simple, rapid, sensitive, and precise, and could be easily applied in QC laboratories for determination of sulfasalazine and pentoxifylline, without any preliminary separation steps or interference from plasma matrix. HIGHLIGHTS: Two updated chemometric models called principlal component regression and partial least-squares regression were established for determination of sulfasalazine and pentoxifylline in spiked human plasma using UV spectrophotometric data.

A Simple UV Spectrophotometric Method Based on Continuous Wavelet Transform and Multivariate Calibration Model for the Concurrent Analysis of Three Water-Soluble Vitamins in Fertility Supplements.

BACKGROUND: Owing to the presence of overlapping spectra in pharmaceutical components, classical spectrophotometry is hard for concurrent determination. The advance of chemometrics along with UV-Vis spectrophotometry has contributed to solving this problem. OBJECTIVE: In this study, a fast, easy, precise, accurate, low-cost, and eco-friendly spectrophotometric technique was introduced and validated for the simultaneous analysis of vitamin B6, vitamin B12, and vitamin C in fertility supplements for men and women using continuous wavelet transform (CWT) and partial least squares (PLS) techniques without using time-consuming extraction process and organic solvents. METHOD: In the CWT method, the zero-crossing technique was applied to obtain the optimum points for plotting calibration curves for each component. The validation of both methods was evaluated by analyzing several mixtures with different concentrations. The efficiency of the proposed methods was also surveyed on commercial capsules. RESULTS: Wavelet families, including Symlet (sym2) at 230, Biorthogonal (bior1.3) at 378 nm, and Daubechies (db2) at 261, were considered for vitamins B6, B12, and C, respectively. The linear range was found to be 8-20, 8-20, and 10-25 µg/mL with the coefficient of determination (R2) equal to 0.9982, 0.9978, and 0.9701 for B6, B12, and C, respectively. Low limit of detection (LOD) (<0.09 µg/mL) and limit of quantification (LOQ) <0.9 µg/mL were achieved. The mean recovery values in synthetic mixtures were from 98.38 to 98.89% and from 99.83 to 99.99%, where root-mean-square error (RMSE) of not more than 0.4 and 0.05 using the CWT and PLS methods, respectively. CONCLUSIONS: The obtained results from the commercial capsules, applying the suggested techniques, were compared to those yielded by the high-performance liquid chromatography (HPLC) method using the analysis of variance (ANOVA) test. According to the results, there are no significant differences, and they were in good agreement. According to all the mentioned cases, the proposed approaches can replace the time-consuming and costly HPLC method in quality control laboratories. HIGHLIGHTS: Green spectrophotometry coupling chemometrics methods were proposed. Simultaneous determination of three water-soluble vitamins in fertility supplements was done using these approaches. Rapidity, simplicity, low cost, and accuracy are the benefits of the proposed methods. A HPLC technique was used as a reference method to compare with the chemometrics methods.

A Green-and-White Integrative Analytical Strategy Combining Univariate and Chemometric Techniques for Quantifying Recently Approved Multi-Drug Eye Solution and Potentially Cancer-Causing Impurities: Application to the Aqueous Humor.

BACKGROUND: Drug impurities are now seen as a major threat to the production of pharmaceuticals around the world and a major part of the global contamination problem, especially when it comes to carcinogenic impurities. OBJECTIVE: We present the first spectrophotometric strategy based on a combination of univariate and multivariate methods as impurity profiling methods for the estimation of lignocaine (LIG) and fluorescein (FLS) with their carcinogenic impurities: 2,6-xylidine (XYL) and benzene-1,3-diol (BZD). METHOD: The data processing strategy depends on overcoming unresolved bands by employing five affordable, accurate, selective, and sensitive methods. The methods applied were a direct UV univariate spectrophotometric analysis (D0) and four multivariate chemometric methods, including classical least squares (CLS), principal component regression (PCR), partial least squares (PLS), and genetic algorithm (GA-PLS). FLS analysis (1-16 µg/mL) was performed using the D0 method at 478 nm; then, the application of the ratio subtraction method (RSM) allowed the removal of interference caused by the FLS spectrum. From the resulting ratio spectra, LIG, XYL, and BZD can be efficiently determined by chemometrics. The calibration set was carefully selected at five concentration levels using a partial factorial training design, resulting in 25 mixtures with central levels of 160, 40, and 3 µg/mL for LIG, XYL, and BZD, respectively. Another 13 samples were applied to validate the predictive ability. RESULTS: The statistical parameters demonstrated exceptional recoveries and smaller prediction errors, confirming the experimental model's predictive power. CONCLUSIONS: The proposed approach was effectively tested using newly FDA-approved LIG and FLS pharmaceutical preparation and aqueous humor. Additionally, it was effectively assessed for whiteness, greenness, and sustainability using five assessment tools. HIGHLIGHTS: With its remarkable analytical performance, sustainability, affordability, simplicity, and cost-efficiency, the proposed strategy is an indispensable tool for quality control and in situ analysis in little-equipped laboratories, increasing the proposed approach's surveillance ability.

Exciting Advances in Sustainable Spectrophotometric Micro-Quantitation of an Innovative Painkiller "Tramadol and Celecoxib" Mixture in the Presence of a Toxic Impurity, Promoting Greenness and Whiteness Studies.

BACKGROUND: Tramadol (TRM) and celecoxib (CLX) form a novel mixture that helps relieve acute pain when other painkillers have no action. It is also reported that these drugs, TRM and CLX, are used to control COVID-19 symptoms. OBJECTIVE: The current work highlights three important pillars of modern pharmaceutical analysis, which are as follows; impurity profiling, greenness/whiteness studies and simplicity accompanied by sensitivity. Since 4-methyl acetophenone inhibits the human carbonyl reductase enzyme (type I) and since this compound may pose a health risk, it is crucial to regulate its concentration in all dosage forms of CLX. METHODS: Two simple and green spectrophotometric methods were developed, namely third derivative (D3) and Fourier self- deconvulation (FSD), for resolving severely overlapped spectra of TRM and CLX in the presence of 4-methyl acetophenone (4-MAP) as a process-related impurity in their novel tablet combination. RESULTS: The two approaches showed acceptable linearity with an excellent correlation coefficient. In both methods, TRM was measured when CLX and 4-methyl acetophenone were zero-crossing. The same procedure was applied for measuring CLX and its process-related impurity 4-MAP. CONCLUSION: The methodologies developed were thoroughly validated in compliance with ICH (International Council on Harmonisation) guidelines. Student t- and F-tests revealed no statistically significant variation among the current methods and the reported method. HIGHLIGHTS: No spectrophotometric methods have been published previously for the simultaneous analysis of TRM and CLX along with 4-MAP. As a result, the newly developed spectrophotometric approaches have great relevance and originality in the field of pharmaceutical analysis.

Comparison of the effect of Sodium Chloride concentration on protein determination: Bradford and Biuret methods.

Protein quantification methods using spectrophotometry are widely used in laboratory routines for different purposes. Samples generally contain non-protein components that can interfere with the quality of the analysis. A simple and quick test with different concentrations of sodium chloride demonstrated that the Bradford method is significantly affected by the presence of salt, while Biuret remains stable. Therefore, the choice of method is an important factor in reducing errors and ensuring more reliable results.

A Novel Spectrophotometric Method for Determination of Percarbonate by Using N, N-Diethyl-P-Phenylenediamine as an Indicator and Its Application in Activated Percarbonate Degradation of Ibuprofen.

Sodium percarbonate (SPC) concentration can be determined spectrophotometrically by using N, N-diethyl-p-phenylenediamine (DPD) as an indicator for the first time. The ultraviolet-visible spectrophotometry absorbance of DPD•+ measured at 551 nm was used to indicate SPC concentration. The method had good linearity (R2 = 0.9995) under the optimized experimental conditions (pH value = 3.50, DPD = 4 mM, Fe2+ = 0.5 mM, and t = 4 min) when the concentration of SPC was in the range of 0-50 µM. The blank spiked recovery of SPC was 95-105%. The detection limit and quantitative limit were 0.7-1.0 µM and 2.5-3.3 µM, respectively. The absorbance values of DPD•+ remained stable within 4-20 min. The method was tolerant to natural water matrix and low concentration of hydroxylamine (<0.8 mM). The reaction stoichiometric efficiency of SPC-based advanced oxidation processes in the degradation of ibuprofen was assessed by the utilization rate of SPC. The DPD and the wastewater from the reaction were non-toxic to Escherichia coli. Therefore, the novel Fe2+/SPC-DPD spectrophotometry proposed in this work can be used for accurate and safe measurement of SPC in water.

Spectrophotometric Study of Charge-Transfer Complexes of Ruxolitinib with Chloranilic Acid and 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone: An Application to the Development of a Green and High-Throughput Microwell Method for Quantification of Ruxolitinib in Its Pharmaceutical Formulations.

Ruxolitinib (RUX) is a potent drug that has been approved by the Food and Drug Administration for the treatment of myelofibrosis, polycythemia vera, and graft-versus-host disease. This study describes the formation of colored charge-transfer complexes (CTCs) of RUX, an electron donor, with chloranilic acid (CLA) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), the π-electron acceptors. The CTCs were characterized using UV-visible spectrophotometry. The formation of CTCs in methanol was confirmed via formation of new absorption bands with maximum absorption at 530 and 470 nm for CTCs with CLA and DDQ, respectively. The molar absorptivity and other physicochemical and electronic properties of CTCs were determined. The molar ratio was found to be 1:1 for both CTCs with CLA and CTCs with DDQ. The site of interaction on RUX molecules was assigned and the mechanisms of the reactions were postulated. The reactions were employed as basis for the development of a novel green and one-step microwell spectrophotometric method (MW-SPM) for high-throughput quantitation of RUX. Reactions of RUX with CLA and DDQ were carried out in 96-well transparent plates, and the absorbances of the colored CTCs were measured by an absorbance microplate reader. The MW-SPM was validated according to the ICH guidelines. The limits of quantitation were 7.5 and 12.6 µg/mL for the methods involving reactions with CLA and DDQ, respectively. The method was applied with great reliability to the quantitation of RUX content in Jakavi® tablets and Opzelura® cream. The greenness of the MW-SPM was assessed by three different metric tools, and the results proved that the method fulfills the requirements of green analytical approaches. In addition, the one-step reactions and simultaneous handling of a large number of samples with micro-volumes using the proposed method enables the high-throughput analysis. In conclusion, this study describes the first MW-SPM, a valuable analytical tool for the quality control of pharmaceutical formulations of RUX.

Development of Visible Spectrophotometric Methods for the Determination of Tricyclic Antidepressants Based on Formation of Molecular Complexes with p-Benzoquinones.

Tricyclic antidepressants are commonly employed in the management of major depressive disorders. The present work describes two visible (VIS) spectrophotometric techniques that utilize the formation of charge transfer complexes between four antidepressant compounds, namely, amitriptyline hydrochloride (AMI), imipramine hydrochloride (IMI), clomipramine hydrochloride (CLO), and trimipramine maleate (TRI) acting as electron donors and two p-benzoquinones, namely, p-chloranilic acid (pCA) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), serving as electron acceptors. The stoichiometry of the compounds produced exhibited a consistent 1:1 ratio in all instances, as established by Job's method. Molar absorptivities, equilibrium association constants, and several other spectroscopic properties were determined for all complexes. The developed spectrophotometric techniques were validated intra-laboratory and successfully applied for quantitative assessment of the four antidepressant active ingredients in several commercial pharmaceutical formulations. The methods are relatively simple, fast, and use readily available laboratory instrumentation, making them easily applicable by most quality control laboratories worldwide.

Different spectrophotometric methods for simultaneous quantitation of Vericiguat and its alkaline degradation product: a comparative study with greenness profile assessment.

Investigations concerning novel drugs and their induced degradation products are necessary for clinical research and quality control in the pharmaceutical industry. Four spectrophotometric techniques have been performed for simultaneous quantitation of Vericiguat (VER) and its alkali-induced degradation product (ADP) without prior separation. Method A is a dual wavelength method (DW) that estimates the absorbance difference at 314-328 nm, and 246-262 nm for VER and ADP; respectively. Method B uses a ratio difference method (RD) to estimate the ratio spectrum's amplitude difference (DP318-342) and (DP284-292) for VER and ADP; respectively. Method C uses a first derivative ratio method (1DD) to estimate the peak ratio spectrum amplitude of the first derivative at 318 and 275 nm for VER and ADP; respectively. Method D uses the mean centering of the ratio spectra (MCR) to estimate amplitude values for VER and ADP at 337 and 292 nm; respectively. In a concentration range of 5.00-50.00 µg/mL for VER and 5.00-100.00 µg/mL for ADP, the methods were validated following ICH criteria and utilized to estimate VER in bulk and its dosage form. The methods' greenness was assessed via three tools: the green analytical procedure index (GAPI), analytical eco-scale, and analytical greenness assessment (AGREE).

Application of multivariate chemometrics tools for spectrophotometric determination of naphazoline HCl, pheniramine maleate and three official impurities in their eye drops.

This work is concerned with exploiting the power of chemometrics in the assay and purity determination of naphazoline HCl (NZ) and pheniramine maleate (PN) in their combined eye drops. Partial least squares (PLS) and artificial neural network (ANN) were the chosen models for that purpose where three selected official impurities, namely; NZ impurity B and PN impurities A and B, were successfully determined. The quantitative determinations of studied components were assessed by percentage recoveries, standard errors of prediction as well as root mean square errors of prediction. The developed models were constructed in the ranges of 5.0-13.0 µg mL-1 for NZ, 10.0-60.0 µg mL-1 for PN, 1.0-5.0 µg mL-1 for NZ impurity B and 2.0-14.0 µg mL-1 for two PN impurities. The proposed models could determine NZ and PN with respective detection limits of 0.447 and 1.750 µg mL-1 for PLS, and 0.494 and 2.093 µg mL-1 for ANN. The two established models were compared favorably with official methods where no significant difference observed.

Validation of a simple spectrophotometric method for the rapid determination of salicylates in plasma.

INTRODUCTION: The determination of salicylate concentrations constitutes a critical aspect of medical diagnostics, particularly in emergency settings. High-performance liquid chromatography (HPLC) and spectrophotometry are efficient methods commonly utilized for this purpose. In emergency laboratories with limited resources, the validation of a cost-effective and reliable spectrophotometric method for salicylates in plasma becomes imperative. The present study aims to validate such a method, ensuring its applicability in toxicological emergencies within resource-constrained laboratories. MATERIALS AND METHODS: The proposed spectrophotometric analysis relies on detecting salicylic ions amidst the presence of ferric salts, resulting in the formation of a distinct purple chelate complex. To ascertain the method's credibility, the validation guidelines established by the European Medicines Agency (EMA) were employed as a benchmark. A comprehensive validation process was conducted over a three-day period, with three levels of validation standards being considered. RESULTS: Following the EMA protocol, the spectrophotometric method demonstrated commendable fidelity, accuracy, and linearity over a concentration range of 50 to 500 mg/L. The limit of detection and quantification was found to be 10 and 50 mg/L, respectively, and the correlation coefficient was determined to be R2 = 0.998. However, it is essential to acknowledge that interference with phenothiazines occurred at concentrations ranging from 50 to 100 mg/L. Despite this, the method's average sensitivity remains viable for practical use in cases of poisoning. The accuracy per concentration level proved satisfactory, with relative biases remaining below 15%, and the confidence intervals of mean recovery closely approximating the desired target value of 100%. CONCLUSION: In conclusion, the presented spectrophotometric method stands out as an economical, straightforward, and user-friendly approach, ideally suited for toxicological emergencies when resources are limited. The method delivers satisfying results, establishing its practical utility in critical medical scenarios. This validated method holds immense promise for emergency laboratories facing resource constraints.

Development and validation of analytical methods for selective determination of albuterol and budesonide in Airsupra inhalation aerosol using spectrophotometry.

Airsupra inhalation aerosol is a recently approved FDA medication that combines albuterol and budesonide for treating or preventing bronchoconstriction and lowering the risk of relapses in asthma patients who are 18 years of age and older. To selectively determine albuterol and budesonide in both pure and pharmaceutical dosage forms, two analytical methods were developed: the zero-order absorption method and the dual-wavelength method. Even though the two drugs absorption spectra overlapped, the distinctive peak of budesonide at the zero absorbance point of albuterol, 245 nm, allowed for direct detection of budesonide in the combination using the zero-order absorption method. The mathematical dual-wavelength method, on the other hand, allowed for the measurement of both albuterol and budesonide by choosing two wavelengths for each drug in such a way that the absorbance difference for the second drug was zero. Budesonide exhibited comparable absorbance values at wavelengths 227 and 261.40 nm; hence, these two wavelengths were utilized to identify albuterol; similarly, 221.40 and 231.20 nm were chosen to determine budesonide in their binary mixes. The methods were validated according to the ICH guideline for validation of analytical procedures Q2(R1) and demonstrated excellent linearity, sensitivity, accuracy, precision, and selectivity for determining both drugs in synthetic mixed solutions and pharmaceutical formulations. The availability of these analytical methods would be valuable for the pharmaceutical industry and regulatory authorities for quality control and assessment of pharmaceutical formulations containing albuterol and budesonide.

Evaluation of perfusion parameters of gingival inflammation using laser Doppler flowmetry and tissue spectrophotometry- a prospective comparative clinical study.

BACKGROUND: The aim of this study was to determine the values of different perfusion parameters- such as oxygen saturation, the relative amount of hemoglobin, and blood flow- in healthy subjects compared to patients with gingivitis as a non-invasive measurement method. METHODS: A total of 114 subjects were enrolled in this study and separated into subjects with gingivitis (50) and without gingivitis (64) based on clinical examination. Gingival perfusion was measured at 22 points in the maxilla and mandible using laser Doppler flowmetry and tissue spectrophotometry (LDF-TS) with the "oxygen to see" device. All patients underwent measurement of gingival perfusion, followed by the clinical evaluation (measurement of probing depths, evaluation of bleeding on probing, plaque level, and biotype). Perfusion parameters were compared between the groups, associations between the non-invasive and clinical measurements were analyzed, and theoretical optimal cut-off values for predicting gingivitis were calculated with receiver operating characteristics. RESULTS: The mean oxygen saturation, mean relative amount of hemoglobin, and mean blood flow all significantly differed between the groups with and without gingivitis (p = 0.005, p < 0.001, and p < 0.001, respectively). The cut-off value for predicting gingivitis was > 40 AU (p < 0.001; sensitivity 0.90, specificity 0.67). CONCLUSIONS: As a non-invasive method, LDF-TS can help determine gingival hyperemia. Flow values above 40 AU indicate a higher risk of hyperemia, which can be associated with inflammation. The LDF-TS method can be used for the objective evaluation of perfusion parameters during routine examinations and can signal the progression of hyperperfusion before any change in clinical parameters is observed. TRIAL REGISTRATION: All procedures performed in this study involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The study was approved by the institutional Clinical Research Ethics Committee (Ethik-Kommission der Medizinischen Fakultät der RWTH Aachen, Decision Number 286/20) and retrospectively registered by the German Clinical Trials Register (File Number DRKS00024048, registered on the 15th of October 2021).

High-sensitivity hemoglobin detection based on polarization-differential spectrophotometry.

Hemoglobin content is recognized as a momentous and fundamental physiological indicator, especially the precise detection of trace hemoglobin is of great significance for early diagnosis and prevention of tumors, cancer, organic injury, etc. Therefore, high-sensitivity hemoglobin detection is imperative. However, effective detection methods and reliable detection systems are still lacking and remain enormous challenges. Herein, we present a synthetical strategy to break through the existing bottleneck based on polarization-differential spectrophotometry and high-performance single-frequency green fiber laser. Importantly, this framework not only has precisely extracted the two-dimensional information of intensity and polarization during the interaction between laser and hemoglobin, but also has taken advantage of the high monochromaticity and fine directivity in the optimized laser source to reduce the undesirable scattered disturbance. Thus, the hemoglobin detection sensitivity of 7.2 × 10-5 g/L has advanced a hundredfold compared with conventional spectrophotometry, and the responsive dynamic range is close to six orders of magnitude. Results indicate that our technology can realize high-sensitivity detection of trace hemoglobin content, holding promising applications for precision medicine and early diagnosis as an optical direct and fast detection method.

A Novel Spectrophotometric Method Development for Quantification of Desidustat in Bulk and Pharmaceutical Dosage Form.

BACKGROUND: Desidustat (DES) belongs to a new category of drugs, i.e., Hypoxia-Inducible Factor (HIF) propyl hydroxylase inhibitor, and is used for the treatment of anemia in chronic kidney disease. However, no method has yet been reported in the literature for the estimation of drugs. OBJECTIVE: The objective of the study is to develop a simple, precise, and accurate method for determining DES in bulk and pharmaceutical dose form. METHODS: The physicochemical characterization of the drug was performed using methanol as a solvent to establish the identity. According to ICH Q2 criteria, validation characteristics, such as specificity, linearity, accuracy, precision, limits of detection and quantification, and robustness, were assessed. RESULTS: Maximum absorbance wavelength was observed at 229 nm. The sample solution remained stable for up to 12 hours. The linear response from 2 to 12 µg/ml of DES was y = 0.1087x + 0.0962 and r2 = 0.9963. The accuracy was between 100 to 101%. Precision was recorded under three criteria: repeatability, intraday and interday, for which results fell within the acceptable ranges (<2%). The limit of detection (LOD) and limit of quantification (LOQ) of the technique were 0.434 µg/ml and 1.316 µg/ml, respectively. CONCLUSION: The proposed method was found to be beneficial for drug monitoring and the ongoing analysis of DES in research and quality control laboratories. This approach is simple, precise, rapid, economical, and sensitive.

UV-Vis absorption spectrophotometry and LC-DAD-MS-ESI(+)-ESI(-) coupled to chemometrics analysis of the monitoring of sulfamethoxazole degradation by chlorination, photodegradation, and chlorination/photodegradation.

Sulfamethoxazole (SMX) is one of the most widely used antibiotics worldwide and has been detected at high concentrations in wastewater treatment plant effluents and river waters. In this study, the SMX degradation process combining the simultaneous chlorine oxidation and UV photodegradation is assessed and compared with both photodegradation and chlorine oxidation processes individually. Photodegradation and Chlorine/UV tests were performed using Suntest CPS equipment. Different experimental techniques, including UV-Visible spectrophotometry and liquid chromatography coupled to a diode array detector and positive and negative ionization mass spectrometry (LC-DAD-MS-ESI(+)-ESI(-)), were used to evaluate the degradation reaction of SMX. All the analytical data generated have been processed with the Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) method to monitor, resolve, and identify the several transformation products generated during the studied degradation processes. A new data fusion analysis strategy is proposed to examine the three processes simultaneously (with only photodegradation, only chlorination, and simultaneous chlorination+photodegradation). Combined with the analysis of different analytical techniques individually (spectrophotometry, LC-DAD, and LC-MS), the fusion of all generated data improved the description of the degradation processes. Detection using DAD allowed a better correspondence among the species monitored spectrophotometrically (UV-Vis) with those analyzed chromatographically. On the other side, detection using MS in both positive and negative acquisition modes allowed resolving a larger number of chemical compounds (specially SMX degradation subproducts) that could not be detected by UV-Vis spectrometry. The results obtained permitted the comparison of the effects produced by the three different degradation processes.