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Purslane (Portulaca oleracea) and spinach (Spinacea oleracea) are species with elevated levels of oxalic acid, an antinutrient that interferes in the bioaccessibility of minerals such as calcium and iron. Evaluating methods to determine oxalic acid content with reduced matrix interference, such as employing Flame Atomic Absorption Spectrometry (FAAS), can enhance the specificity of determinations. The different matrices of purslane (whole plant, leaves, and juice) and spinach (whole plant) were tested using three extraction methods (M1, M2, and M3). The oxalic acid content was evaluated by UV-vis spectrophotometry and FAAS (Flame Atomic Absorption Spectrometry). The absence of the precipitation step in M1 resulted in high levels of oxalic acid in the investigated matrices. The quantification of oxalic acid by FAAS for M2 (6M HCl for 1 hour at 100°C) and M3 (0.25N HCl for 15 minutes at 100°C) in the samples of purslane leaves and spinach whole plants yielded statistically similar results. However, the analysis by UV-vis spectrophotometry for M2 and M3 showed significant discrepancies in all evaluated samples, suggesting interference from colored compounds in the food matrix.â¢Comparison of methods of extractionâ¢Comparison of UV-vis spectrophotometer and FAAS in the quantification of oxalic acidâ¢Analysis of antinutrients in plant matrices.
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The conditions for the smart colorimetric determination of cetylpyridinium chloride and sodium dodecyl sulfate by reaction with Coomassie brilliant blue G (CBBG) have been proposed. The nature of the absorption and fluorescence spectra of aqueous solutions of CBBG as a function of acidity has been investigated. A variety of reagent forms and associations with ionic surfactants have been demonstrated. The composition of the associates formed in the CBBG-cationic surfactant system has been established. The increase in the analytical signal of the cationic surfactant and the stabilization of the colloid-chemical state of the system during reactions in the organized medium of the nonionic surfactant Triton X-100 has been demonstrated. These effects are realized through association in premicellar solutions and as a result of the solubilization of components in Triton X-100 micellar solutions. The addition of long-chain cationic surfactants to the reagent occurs with the replacement of the heteroatom proton. The absorption of CBBG-cationic surfactant associates solutions increases with the length of the cationic surfactant hydrocarbon chain. Ethanol additives decrease the aggregation of CBBG. The technique of cationic surfactant determination has been tested in the analysis of the pharmaceutical. The results show that the simplicity of analytical signal registration with satisfactory correctness and acceptably high sensitivity of determination is an advantage of the developed technique.
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Foods contaminants pose a challenge for food producers and consumers. Due to its spontaneous formation during heating and storage, hydroxymethylfurfural (HMF) is a prevalent contaminant in foods rich in carbohydrates and proteins. Colorimetric assays, such as the Seliwanoff test, offer a rapid and cost-effective method for HMF quantification but require careful optimization to ensure accuracy. We addressed potential interference in the Seliwanoff assay by systematically evaluating parameters like incubation time, temperature, and resorcinol or hydrochloric acid concentration, as well as the presence of interfering carbohydrates. Samples were analyzed using a UV-Vis spectrophotometer in scan mode, and data obtained were validated using HPLC, which also enabled quantification of unreacted HMF for assessing the protocol's accuracy. Incubation time and hydrochloric acid percentage positively influenced the colorimetric assay, while the opposite effect was observed with the increase in resorcinol concentration. Interference from carbohydrates was eliminated by reducing the acid content in the working reagent. HPLC analyses corroborated the spectrophotometer data and confirmed the efficacy of the proposed method. The average HMF content in balsamic vinegar samples was 1.97 ± 0.94 mg/mL. Spectrophotometric approaches demonstrated to efficiently determine HMF in complex food matrices. The HMF levels detected in balsamic vinegars significantly exceeded the maximum limits established for honey. This finding underscores the urgent need for regulations that restrict contaminant levels in various food products.
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Furaldeído , Espectrofotometria , Furaldeído/análogos & derivados , Furaldeído/análise , Espectrofotometria/métodos , Cromatografia Líquida de Alta Pressão/métodos , Resorcinóis/análise , Resorcinóis/química , Contaminação de Alimentos/análise , Análise de Alimentos/métodos , Ácido Acético/análise , Ácido Acético/químicaRESUMO
Spectral differences in ambient light can affect animal behavior and convey crucial information about an individual's environment. The ability to perceive and respond to differences in ambient light varies widely by taxa and is shaped by a species' ecology. Mexican jumping bean moths, Cydia saltitans, spend their entire larval period encased in fallen host seeds and contend with potentially lethal environmental temperatures when host seeds are in direct sunlight. We investigate if and how C. saltitans larvae in host seeds respond to lighting conditions associated with these thermal risks in their natural environments. In a temperature-controlled experiment, we identified that larvae exhibited distinct behavioral ("jumping") responses corresponding to four lighting treatments (white, red, green, and purple), despite extremely minimal light penetration through host seed walls. Red light induced the highest larval activity (measured by probability of movement and by displacement from origin), suggesting that larvae have mechanisms to perceive low levels of red light and/or to detect subtle increases in heat produced by red/near infrared-biased light spectra, possibly providing them with an early-warning mechanism against thermal stress. Our findings highlight the interplay of environmental lighting, behavior, and potential thermosensory adaptations in a species with a visually constrained environment.
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Normal-phase (NP) liquid chromatography is one of the most effective methods for separating isomers with sensitive structural features, including xanthophyll isomers. In this work, reverse-phase (RP) and NP liquid chromatography (LC), with silica gel and diol phase, respectively, were evaluated for the separation of xanthophyll isomers. The results showed that RP LC with monomeric C18 phase not only poorly separate all xanthophyll isomers in egg yolk but also requires additional sample preparation to eliminate triacylglycerols in egg yolk. The diol phase of NP-LC provided the highest efficiency for separating lutein, zeaxanthin, and their cis-isomers with isocratic separation using mobile phases consisting of n-hexane and polar modifiers (such as acetone, methyl tert-butyl ether, or ethyl acetate). To determine the xanthophyll content, peak areas from LC and total absorbance from spectrophotometry measurements were used. The approach was applied to analyze the xanthophylls of nine commercial egg samples. The results revealed that five out of nine analyzed samples contained a high level of canthaxanthin, which contributes to color enhancement but not to prevent age-related macular degeneration. Together, it shows that NP LC with diol phase combined with spectrophotometry is a powerful tool to monitor xanthophylls in eggs.
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Gema de Ovo , Xantofilas , Gema de Ovo/química , Cromatografia Líquida de Alta Pressão , Xantofilas/análise , Xantofilas/química , Espectrofotometria , Animais , IsomerismoRESUMO
OBJECTIVE: There is still disagreement about whether to routinely use spectrophotometry to detect xanthochromia in cerebrospinal fluid (CSF) or whether visual inspection is adequate. We aimed to evaluate the diagnostic accuracy of these methods in detecting an aneurysmal subarachnoid hemorrhage in patients with sudden onset severe headache. BACKGROUND: When a patient presents to the emergency department with a headache for which there is suspicion of a subarachnoid hemorrhage, the gold standard to rule this out is to perform a CSF analysis for xanthochromia with or without spectrophotometry if the cranial non-contrast computed tomography (CT) upon admission is negative. METHODS: Having applied the gold standard, we retrospectively included patients with acute headache who underwent both CT scan and CSF spectrophotometry at our hospital in the period 2002-2020. Patients were excluded if the cranial CT was interpreted as positive, there was a bloody CSF, or if visual assessment data of the CSF was unavailable. We scrutinized the patients' medical records and evaluated the benefit of spectrophotometry compared to visual inspection. The net bilirubin absorbance cut-off for support of subarachnoid hemorrhage was set at >0.007 absorbance units. The spectrophotometry was also considered positive if the net bilirubin absorbance was ≤0.007 and net oxyhemoglobin absorbance was ≥0.1 absorbance units. We calculated and compared the sensitivity and specificity of CSF spectrophotometry and visual inspection of the CSF. RESULTS: In total, 769 patients, with a mean age of 42.3 ± (standard deviation [SD] = 17.3) years, were included. The headache onset was classified as a thunderclap headache in 41.5%, and 4.7% had a sudden loss of consciousness. Fifteen patients (2%) were finally diagnosed with a subarachnoid hemorrhage, six (0.8%) had an aneurysmal subarachnoid hemorrhage, seven (0.9%) had a perimesencephalic hemorrhage, one (0.1%) had a cortical cerebral sinus venous thrombosis, and one (0.1%) had a spinal epidural hematoma. Four patients (0.5%) had a subarachnoid hemorrhage that was not detected by visual inspection, and two were caused by an aneurysmal rupture. One of these two patients died just before intervention, and the other underwent coiling for an anterior communicating aneurysm. The number needed for lumbar puncture to detect a subarachnoid hemorrhage was 51, but 128 to detect an aneurysmal hemorrhage. The corresponding numbers needed for CSF spectrophotometric analysis were 192 and 385, respectively. Spectrophotometry was positive in 31 patients (4.0%), of whom 18 (2.3%) also had visually detected xanthochromia (11 true positive). The mean net bilirubin absorbance in the 13 samples with visually clear CSF was 0.0111 ± (SD = 0.0103) absorbance units, compared to 0.0017 ± (SD = 0.0013) in the CSF with negative spectrophotometry. The corresponding figures for net oxyhemoglobin absorbance were 0.0391 ± (SD = 0.0522) versus 0.0057 ± (SD = 0.0081). The sensitivity of spectrophotometric xanthochromia detection was 100% (95% confidence interval [CI], 78-100), compared to 73% (95% CI, 45-92) for visual xanthochromia detection. The specificity of spectrophotometric xanthochromia detection was 98% (95% CI, 97-99) compared to 99% (95% CI, 98-100) for visual xanthochromia detection. Both methods had high negative predictive values: 100% (95% CI, 99.5-100) versus 99.5% (95% CI, 98.6-99.9), respectively. CONCLUSIONS: Both visual inspection and spectrophotometry have high diagnostic accuracy for detecting CSF xanthochromia, but the lower sensitivity of visual assessment makes it unreliable, and we recommend the use of spectrophotometry in clinical practice.
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Valorization of residual yeast of the bakery industry for use in the remediation of oil-contaminated soils as an emulsifier is a biocompatible and effective process that will reduce environmental pollution. The aim of this study was to use concentrated ß-glucan obtained from residual baker's yeast, Saccharomyces cerevisiae, as an emulsifier to remove total petroleum hydrocarbons (TPH) from the contaminated sands of two beaches affected by the oil spill that occurred in January 2022 north of Lima, Peru. The extraction and concentration of ß-glucan from sand were performed at a pilot scale using autolysis with 3 % sodium chloride, temperature elevation, treatment with organic solvents and water, hydrolysis via proteases, and vacuum filtration. The chemical composition and functional properties of concentrated ß-glucan were evaluated to determine its quality and efficacy. In addition, the values of TPH removal efficiency obtained using concentrated ß-glucan, water, and the commercial emulsifier Tween-80 were compared. The mass recovery of concentrated ß-glucan was 5.59 %, with a ß-glucan content of 38.60 %. The efficiency of ex-situ removal of TPH from hydrocarbon-impacted sands containing 78323 mg/kg of TPH reached 50 % and 70 % when the concentrated ß-glucan concentrations used were 70.3 % and 80.3 %, respectively. These efficiency values are higher than those obtained when water was used for TPH removal but lower than those obtained when Tween-80 was used for TPH removal.
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Oxidative stress-related pathologies have guided the scientific community into delving into natural product-based research on plant-based metabolites. Plant secondary metabolites serve as a valid alternative in managing oxidative stress-related pathologies. In this study, we present the secondary metabolite constituents of the polar extract (PE) and nonpolar extract (NPE) from the leaves of Bryophyllum pinnatum. These constituents were determined through qualitative and quantitative phytochemical screening. The functional groups and structures of these metabolites were determined based on FTIR and GC-MS experiments, respectively. Antioxidant and free radical scavenging (FRS) activities were determined using standard methods, including phosphomolybdenum, FRAP, DPPH, HRSA, and reducing power assays, with comparisons made to the ascorbic acid (AA) standard. Through Pearson correlation analysis, we estimated the relationship between antioxidant and FRS activities. The DPPH results revealed IC50s of 380.104 ± 0.001, 16.763 ± 0.001, and 7.684 ± 0.003 µg/ml for NPE, AA, and PE, respectively, indicating a trend of PE > AA > NPE. However, all other experiments showed a trend of AA > PE > NPE in antioxidant and FRS activities. These results showed the potential antioxidant and FRS properties of both PE and NPE. Additionally, the correlation analysis indicated a strong positive correlation between the antioxidant and FRS activities of PE and NPE. The research results suggest high antioxidant and FRS activities of PE and validate the use of B. pinnatum in managing free radical-related pathologies.
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BACKGROUND: Previous studies have suggested that light rays may interact with contact lenses, potentially affecting their transmittance. AIM: This study aimed to investigate the effects of visible and ultraviolet (UV)-A light sources on the transmittance of some commercially available daily, weekly, and monthly contact lenses. METHODS: Nine commercially available soft contact lenses were irradiated with a solar simulator, light-emitting diode (LED) source, laser source, and UV-A source. The average transmittance of the tested lenses before and after irradiation in the UV, visible, and infrared light wavelength ranges was determined using an Agilent UV-visible spectrophotometer, model 8453. RESULTS: The results showed a partial or complete block of UV transmission at the UV-B region (300 nm) and the UV-A region (355 nm) by the Bio true daily contact lens, as well as the Acuvue Oasys, Avaira, and Biomedics 55 weekly lenses. At the visible region (555 nm), irradiation of the contact lenses by different light sources resulted in reduced light transmittance. At the infrared region (900 nm), the weekly and monthly contact lenses partially blocked infrared transmission, while the daily lenses showed either increased or decreased infrared transmission. CONCLUSIONS: Solar and artificial lighting, as well as high-powered lasers, constitute a major concern on the contact lenses' light transmission and optical properties. It is essential to develop soft contact lenses that have photoprotective properties while maintaining visible light transmittance.
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OBJECTIVES: The aim of this study was to evaluate the peri-implant perfusion, such as oxygen saturation, the relative amount of hemoglobin, and blood flow, in implants placed in pristine bone and avascular and microvascular grafts using a non-invasive measurement method. MATERIALS AND METHODS: A total of 58 patients with 241 implants were included. Among them, 106 implants were based in native bone (group I), 75 implants were inserted into avascular bone grafts (group II), and 60 implants were placed in microvascular bone grafts (group III). Gingival perfusion was measured using laser Doppler flowmetry and tissue spectrophotometry (LDF-TS). Implants with signs of gingival inflammation were excluded to analyze healthy implant perfusion in different bony envelopes. RESULTS: The mean values for oxygen saturation, relative hemoglobin levels, and blood flow did not differ significantly between the groups (p = 0.404, p = 0.081, and p = 0.291, respectively). There was no significant difference in perfusion between implants that were surrounded by mucosa and implants based within cutaneous transplants (p = 0.456; p = 0.628, and p = 0.091, respectively). CONCLUSION: No differences in perfusion were found between implants inserted into native bone and implants involving bone or soft tissue augmentation. However, implants based in avascular and microvascular transplants showed higher rates of peri-implant inflammation. CLINICAL RELEVANCE: Peri-implant perfusion seems to be comparable for all implants after they heal, irrespective of their bony surroundings. Although perfusion does not differ significantly, other factors may make implants in avascular and microvascular transplants vulnerable to peri-implant inflammation.
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Implantes Dentários , Fluxometria por Laser-Doppler , Espectrofotometria , Humanos , Fluxometria por Laser-Doppler/métodos , Masculino , Estudos Prospectivos , Feminino , Pessoa de Meia-Idade , Adulto , Idoso , Implantação Dentária Endóssea/métodos , Gengiva/irrigação sanguínea , Transplante Ósseo/métodosRESUMO
The present study compared the performance of Ultra-high performance liquid chromatography (UHPLC) and UV-Vis spectrophotometry for the quantification of metformin hydrochloride in five commercially available metformin hydrochloride products with different strengths. The metformin hydrochloride was measured in the UHPLC with a mobile phase consisting of a mixture of 0.05 M phosphate buffer solution and methanol (35:65, v/v) with a pH of 3.6. Metformin hydrochloride was determined spectrophotometrically at 234 nm using a mixture of methanol and water as a blank. The methods' linearity for metformin hydrochloride was within the concentration range of (2.5-40 µg/ml) in both techniques. The validation process encompassed assessments of specificity, selectivity, linearity, accuracy, precision, the lower limit of quantification (LLOQ), the lower limit of detection (LLOD), robustness, and system suitability. For the UHPLC validation method, the repeatability and reproducibility (expressed as relative standard deviation) were less than 1.578 and 2.718 %, respectively. The LLOQ for metformin hydrochloride was 0.625 µg/ml, and the LLOD was 0.156 µg/ml. For the UV-Vis spectrophotometric validation method, the repeatability and reproducibility (stated as relative standard deviation) were less than 3.773 and 1.988 %, respectively. The percentage recovery results for the five brands of metformin hydrochloride tablets were (98-101 %) and (92-104 %) for the UHPLC and UV-Vis spectrophotometric methods, respectively. In conclusion, the described methodologies were successfully employed for the quantitative analysis of metformin hydrochloride in different pharmaceutical tablet products.
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Sepsis is a life-threatening condition characterized by organ dysfunction resulting from a dysregulated host response to infection. Dysregulated tryptophan (TRP) metabolites serve as significant indicators for endogenous immune turnovers and abnormal metabolism in the intestinal microbiota during sepsis. Therefore, a high coverage determination of TRP and its metabolites in sepsis is beneficial for the diagnosis and prognosis of sepsis, as well as for understanding the underlying mechanism of sepsis development. However, similar structures in TRP metabolites make it challenging for separation and metabolite identification. Here, high-performance liquid chromatography coupled with a diode array detector (HPLC-DAD) was developed to determine TRP metabolites in rat serum. The first-order derivative spectrophotometry of targeted metabolites in the serum was investigated and proved to be promising for chromatographic peak annotation across different columns and systems. The established method separating the targeted metabolites was optimized and validated to be sensitive and accurate. Application of the method revealed dysregulated TRP metabolites, associated with immune disorders and NAD + metabolism in both the host and gut flora in septic rats. Our findings indicate that the derivative spectrophotometry-assisted method enhances metabolite identifications for the chromatographic systems based on DAD detectors and holds promise for precision medicine in sepsis.
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Microbioma Gastrointestinal , Sepse , Triptofano , Triptofano/metabolismo , Animais , Sepse/microbiologia , Sepse/metabolismo , Ratos , Cromatografia Líquida de Alta Pressão/métodos , Masculino , Ratos Sprague-Dawley , EspectrofotometriaRESUMO
During the key event 1 of skin sensitization defined as covalent binding or haptenization of sensitizer to either thiol or amino group of skin proteins, a sensitizer not only covalently binds with skin proteins but also interacts with nucleophilic small molecules such as glutathione (GSH). Although GSH would not be directly associated with skin sensitization, this interaction may be applied for developing an alternative test method simulating key event 1, haptenization. Thus, the aim of the present study was to examine whether N-acetyl-L-cysteine methyl ester (NACME), a thiol-containing compound, was selected as an electron donor to determine whether NACME reacted with sensitizers. Following a reaction of NACME with a sensitizer in a 96-well plate, the remaining NACME was measured spectrophotometrically using 5,5'-dithio-bis-(2-nitrobenzoic acid) (DTNB). Following the optimization of test conditions with two different vehicles, such as acetonitrile (ACN) and dimethyl sulfoxide (DMSO), 64 test chemicals were tested to determine the predictive capacity of current NACME test method. The results obtained showed, the predictive capacity of 94.6% sensitivity, 88.9% specificity, and 92.2% accuracy utilizing DMSO as a vehicle with a cutoff NACME depletion of 5.85%. The three parameters were also over 85% in case of ACN. These values were comparable to or better than other OECD-approved test methods. Data demonstrated that a simple thiol-containing compound NACME might constitute as a reliable candidate for identifying reactive skin sensitizers, and that this method be considered as practical method as a screening tool for assessing a chemical's tendency to initiate skin sensitization.
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Acetilcisteína , Acetilcisteína/análogos & derivados , Espectrofotometria , Humanos , Pele/efeitos dos fármacos , Ácido Ditionitrobenzoico/química , Haptenos/toxicidade , Haptenos/química , Alternativas aos Testes com Animais/métodos , AnimaisRESUMO
A novel cloud-point extraction (CPE) procedure for the determination of ultra-trace amounts of arsenic species in real samples, purchased from the local market by spectrophotometer was developed. Inorganic arsenic species analysis in water, beverages, and foods has become increasingly important in recent years, as arsenic species are considered carcinogenic and are assessed at significant levels in samples. The technique is established on a selective ternary complex of As(V) with astrazon orange G (AOG+) in the presence of tartaric acid and polyethylene glycol tertoctylphenyl ether (Triton X-114) at pH 4.0. The calibration curve developed within range 3.0-160 ng/mL with a correlation coefficient of 0.9988 for As(V) provided a preconcentration factor of 200 and a limit of detection (3S blank/m) of 0.88 ng/mL under optimum investigation conditions. The results of molar absorptivity and Sandell sensitivity are calculated and found to be 4.38 × 105 L/mol cm and 0.018 ng cm-2, respectively. The statistical treatment of data obtained from the proposed and GF-AAS procedures are compared in terms of Student's t-tests and variance ratio F-tests has revealed no significant differences. The methodology has been effectively confirmed by assessing real samples and comparing it to the GF-AAS method statistically.
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Arsênio , Compostos Azo , Limite de Detecção , Espectrofotometria , Arsênio/análise , Espectrofotometria/métodos , Compostos Azo/química , Compostos Azo/análise , Fenóis/análise , Fenóis/química , Concentração de Íons de Hidrogênio , Reprodutibilidade dos TestesRESUMO
In this work, the xanthene dye, erythrosine B, was employed as a probe for the determination of olanzapine using two fast and highly simple analytical approaches. The assay was based on the formation of a binary complex between the drug and erythrosine B in a slightly acidic aqueous buffered solution. In the first method, the absorbance of the formed product was monitored at 558 nm. The reaction stoichiometry was investigated, and the stability constant of the formed complex was estimated. The linear range of the method that obeyed Beer's law was in the concentration range of 0.6-8.0 µg/ml. The calculated detection and quantitation limits were 0.2 and 0.6 µg/mL. Upon adding the drug solution to erythrosine B, the native fluorescence of the dye was quenched and monitored at 550 nm after excitation at 528 nm. Thus, the fluorescence quenching was utilized as the quantitative signal in the spectrofluorimetric approach. The extent of quenching in the fluorescence intensity was rectilinear with the drug concentration in a range of 0.1-2.5 µg/ml with a detection limit of 0.032 µg/ml. Both approaches were analytically validated based on the guiding rules of the ICH with acceptable results, and were utilized efficiently in the analysis of olanzapine in commercial tablets containing the cited drug. In addition, owing to its high sensitivity and selectivity, the spectrofluorimetric method was applied for drug analysis in spiked human plasma with satisfactory % recoveries. Finally, the greenness of the methods was confirmed using eco-score scale and Analytical Green Evaluation metrics.
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Limite de Detecção , Olanzapina , Espectrometria de Fluorescência , Olanzapina/sangue , Olanzapina/análise , Humanos , Espectrometria de Fluorescência/métodos , Eritrosina/química , Reprodutibilidade dos Testes , Antipsicóticos/sangue , Antipsicóticos/química , Benzodiazepinas/sangue , Benzodiazepinas/análise , Benzodiazepinas/químicaRESUMO
OBJECTIVES: To evaluate the color-match with extracted natural teeth of three single-shade universal composites, a group-shade universal composite, and a highly translucent-shade conventional composite. METHODS: Twenty extracted human teeth were divided into light- and dark-shade groups (n = 10, LSG and DSG). A preparation was restored with the 3 single-shade universal composites, OMNICHROMA (OMC), Admira Fusion x-tra U (AFU), and Essentia U (ESU); a highly translucent-shade conventional composite, Tetric EvoCeram T (TEC-T); and two shades of a group-shade universal composite-Filtek Universal Restorative (FUR A1 and A4). Composites were photopolymerized, polished, and stored in water for 24 h. The ΔE00 value between the unprepared and restored surfaces was obtained using a spectrophotometer. Composite placement and measurements were repeated three times per tooth. Color differences were statistically analyzed with the within-between-subjects t-test and repeated-measures analysis of variance (ANOVA), followed by post hoc pairwise comparisons with a Bonferroni adjustment (α = 0.05). RESULTS: There were no statistically significant differences between OMC and FUR (A1 and A4). AFU and ESU showed significantly higher ΔE00 values than OMC and TEC-T (p < 0.05). Single-shade composites exhibited significantly higher ΔE00 values in the DSG than in the LSG except ESU (p < 0.05). None of the composites satisfied the criteria for an acceptable match (ΔE00 >1.8). CONCLUSION: OMC showed the same color matching ability as a group-shade universal composite. A highly translucent-shade conventional composite and OMC exhibited better color matching ability than other single-shade composites. Overall, single-shade universal composites performed better in lighter-shaded teeth. CLINICAL SIGNIFICANCE: Single-shade universal composites have the potential to reduce chair time by eliminating shade selection in cavities with lighter-shade teeth. Highly translucent incisal conventional composites also may be used if the appropriate shade of composite is not available.
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The ninhydrin reaction is commonly used for the detection of amino acids. However, in the literature, different conditions with respect to the buffer system, its pH and concentration, type of organic solvent, incubation time, and temperature, as well as the concentrations of the reagents, are described. To identify the most suitable conditions, colour development with reagents of varying compositions and different reaction temperatures and times were investigated using asparagine as a model amino acid. Asparagine was selected since it is one of the most abundant free amino acids in many types of samples. The optimal reaction mixture consisted of 0.8 mol L-1 potassium acetate, 1.6 mol L-1 acetic acid, 20 mg mL-1 ninhydrin and 0.8 mg mL-1 hydrindantin in DMSO/acetate buffer 40/60 (v/v) (final concentrations). The best reaction condition was heating the samples in 1.5 mL reaction tubes to 90 °C for 45 min. Afterwards, the samples were diluted with 2-propanol/water 50/50 (v/v) and the absorbance was measured at 570 nm. The proteinogenic amino acids showed a similar response except for cysteine and proline. The method was highly sensitive and showed excellent linearity as well as intra-day and inter-day reproducibility.
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Aminoácidos , Ninidrina , Ninidrina/química , Aminoácidos/química , Aminoácidos/análise , Concentração de Íons de Hidrogênio , Solventes/química , Temperatura , Reprodutibilidade dos Testes , Asparagina/química , Asparagina/análiseRESUMO
BACKGROUND: There is an increasing interest of scientific community in developing innovative methodologies for their analysis needs within green analytical chemistry framework. UV spectrophotometry is one of the most promising eco-friendly methods, which is integrated with advanced chemometric tools to enhance the selectivity of the analysis of complex mixtures with severe overlapped signals. OBJECTIVES: Simultaneous determination of a triple-combination of pseudoephedrine hydrochloride (PSE), carbinoxamine maleate (CRX), and paracetamol (PAR) using an artificial intelligence system and multivariate calibration methods. This combination is recently recommended for COVID-19 home-treated patients as part of a symptomatic treatment. METHODS: Namely, the suggested models are: Artificial Neural Networks, Partial Least Squares, and Principal Component Regression. The proposed algorithms were optimized and developed with the aid of a five-level, three-factor experimental design. RESULTS: The investigated methods were applied over the concentration range of 100-180 µg/mL, 18-16 µg/mL, and 4-12 µg/mL for PSE, CRX, and PAR, respectively. The models validation results demonstrated excellent recoveries (around 98 to 102%), signaling the approaches outstanding resolution capacity for the cited compounds in the presence of common excipients. The outcomes of the studied methods were statistically compared to the official approaches, and no significant difference was found. CONCLUSION: The suggested models were efficiently employed to determine the selected drugs in their combined tablets without any initial separation steps. The impact of these methods on the environment was evaluated via greenness tools, namely; National Environmental Method Index, Raynie and Driver's green assessment method, analytical Eco-Scale, Green Analytical Procedure Index, and Analytical Greenness Metric. HIGHLIGHTS: Green chemometric quality assessment of PSE, CRX, and PAR in their pure and pharmaceutical dosage forms. The established approaches are innovative, sustainable, smart, fast, selective, and cost-effective. These models are potential green nominees for routine analysis of the investigated mixture in quality control laboratories.
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This work describes determining urea in milk samples using a multicommuted approach with a urease enzyme immobilized in bacterial cellulose and solid MOF as a colorimetric reagent. The Cu(2+)-MOF was characterized by FTIR spectroscopy, XRD, and SEM. The urea quantification was based on the urea hydrolysis reaction catalyzed by urease and reacted with Cu(2+)-MOF forming [Cu(NH3)4]2+, monitored at 450 nm. Linear responses were obtained from 1.0 to 50.0 mg dL-1 urea (R = 0.9959, n = 11), detection and quantitation limits of 0.082 mg dL-1 and 0.272 mg dL-1 respectively, analytical frequency of 8 determinations per hour, 0.8 mL sample solution consumption. Potential interfering studies have shown the selectivity of the proposed method. Addition and recovery tests were performed obtaining variation from 90 to 103%. Applying the F-test and t-test, the results showed no significant difference at the 95% confidence level Comparing the proposed and the reference method.
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In the search of innovative methods within radiation dosimetry to provide solutions to the high demanding modern ionizing radiation applications, this work proposes an original approach to combine microorganisms and gel dosimetry characteristics by adapting biotechnology and molecular biology procedures. The design of bacterial culture media and the evaluation of viability as systems for radiation dosimetry are reported. In preliminary assessments, a highly promising dose-response has been observed for samples stored at 4 °C, displaying a linear trend within the investigated dose range. This underscores a promising performance, indicating the potential utility of the system as a radiation dosimeter.