Optimizing the Vanillin-Acid Sulfuric Method to Total Saponin Content in Leaves of Yerba Mate Clones.

Yerba mate (Ilex paraguariensis) is a forest species consumed in the form of non-alcoholic beverages in South America, with applications in foods, cosmetics, and pharmaceutical industries. The species leaves are globally recognized for their important bioactive compounds, including, saponins. We adjusted the vanillin-acid sulfuric method for determining spectrophotometrically the total saponin in yerba mate leaves. Seeking to maximize the extraction of saponins from leaves, a Doehlert design combined with Response Surface Methodology (RSM) was used, considering ethanol:water ratios and ultrasound times. In addition, the same methodology was used for the analysis of times and temperatures in the vanillin-sulfuric acid reaction heating. The contents of total saponin in mature leaves were compared in four yerba mate clones. The extraction was maximized using 40 % ethanol:60 % water and 60 minutes of ultrasound assisted extraction (UAE) without heating. For the reaction conditions, 70 °C for 10 minutes heating is recommended, and UV/Vis reading from 460 to 680 nm. Using the optimized methodology, total saponin contents ranged from 28.43 to 53.09 mg g-1 in the four yerba mate clones. The significant difference in saponin contents between clones indicate great genetic diversity and potential for clones' selection and extraction of these compounds from yerba mate leaves.

Low consumption and portable technology for dithionite detection based on potassium ferricyanide differential spectrophotometry method in related advanced oxidation processes.

Carbon neutrality has been received more attention and emerged in wastewater treatment processes. Due to the development of treating technologies with the rising of new-emerging pollutants, the coupled chemical processes also should remain current for the goal of carbon-neutral operation. Among of those updated strategies, several advanced oxidation processes (AOPs) based on dithionite (DTN, S2O42-), a common water treatment agent, have been established for refractory organic contaminations removal. However, in terms of DTN detection, the traditional formol-titration method has several application limits including the low detection sensitivity and high consumption of formaldehyde. In this study, compared with traditional method, a low energy consumption technology has been developed based on the potassium ferricyanide with the carbon consumption decreasing by about 5 times. Moreover, detection limit of DTN (mmol/L level) also was lower than the titration method. The method was established based on the fact that every 1 mol of DTN can react with 2 mol [Fe(CN)6]3- under alkaline condition. According to that potassium ferricyanide (K3 [Fe(CN)6]) has the maximum absorption at 419 nm wavelength, a fitting equation based on the linear relationship between the absorbance variation of K3 [Fe(CN)6] and DTN amount in the ranges of 0-30 µmol with the detection limit of 0.6 µmol was established with the determination coefficient of 0.99935. It was found that there was no obvious influence of the ubiquitous foreign species with the amount lower than 6 mM, 4 mM, 6 mM, 4 mM and 1 mg/L for Cl-, HCO3-, NO3-, SO42- and NOM, respectively. Moreover, methanol and tert-butanol were employed to verify the influence of the presence of organic matters on the determination of DTN and no impact was observed in this study. The proposed method provides a new way for DTN detection with stable and countable performance in the related AOPs with the low electric energy and carbon source consumption and high detection efficiency.

An expedient ion chromatography based method for high-throughput analysis of phytic acid in groundnut kernels.

A study was made to expedite ion chromatography method using IonPac analytical column and self-regenerating anion suppressor for phytic acid determination in groundnut seeds and compared with a widely adopted spectrophotometric method based on enzymatic hydrolysis. The Ion Chromatography method equipped with AG11 guard and AS11 analytical columns in isocratic mode using 65 mM NaOH mobile phase at 1 mL min-1 flow rate showed a sharp peak for phytic acid with a retention time of 2.42 ± 0.2 min. The peak area was plotted v/s concentration showed linearity with an R2 value of 0.997, detection limit of 0.028 mg L-1 and recovery of 98% as against R2 value of 0.988 and detection limit of 0.065 mg L-1 in the spectrophotometric method. The study demonstrates that Ion Chromatography method was more accurate with a better detection limit than spectrophotometry. Also, this method provides robust handling with lesser reagent requirements due to combined eluent generation and self-regenerating suppression. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-022-05527-9.

Charge-transfer complex-based spectrophotometric method for the determination of mesotrione in environmental samples.

A simple, accurate, sensitive, and selective spectrophotometric method has been developed for the determination of mesotrione. This method is based on the reaction of mesotrione with Fe(III) to form a charge transfer metal complex having λmax at 348 nm. Beer's law was obeyed in the concentration range of 0.2-10.0 µg mL-1 with limit of detection (LOD) and limit of quantification (LOQ) equal to 0.053 and 0.162 µg mL-1, respectively. The percent recovery of mesotrione from different environmental and agricultural samples was found to be 95.00-106.50% at various levels. Notably, the developed method was successfully employed for the determination of mesotrione in environmental (pond water, canal water, tap water, and soil) and agricultural (maize grains) samples.

Constraining the carbonate system in soils via testing the internal consistency of pH, pCO2 and alkalinity measurements.

Inorganic carbon exists in various dissolved, gaseous and solid phase forms in natural waters and soils. It is important to accurately measure and model these forms to understand system responses to global climate change. The carbonate system can, in theory, be fully constrained and modelled by measuring at least two of out of the following four parameters: partial pressure (pCO2), total alkalinity (TA), pH and dissolved inorganic carbon (DIC) but this has not been demonstrated in soils. In this study, this "internal consistency" of the soil carbonate system was examined by predicting pH of soil extracts from laboratory measurement of TA through alkalinity titration for solutions in which pCO2 was fixed through equilibrating the soil solution with air with a known pCO2. This predicted pH (pHCO2) was compared with pH measured on the same soil extracts using spectrophotometric and glass electrode methods (pHspec and pHelec). Discrepancy between measured and calculated pH was within 0.00-0.1 pH unit for most samples. However, more deviation was observed for those sample with low alkalinity (≤ 0.5 meq L-1). This is likely attributable to an effect of dissolved organic matter, which can contribute alkalinity not considered in the thermodynamic carbonate model calculations; further research is required to resolve this problem. The effects of increasing soil pCO2 was modelled to illustrate how internally consistent models can be used to predict risks of pH declines and carbonate mineral dissolution in some soils.

Optimization of the Biocatalysis for D-DIBOA Synthesis Using a Quick and Sensitive New Spectrophotometric Quantification Method.

D-DIBOA (4-hydroxy-(2H)-1,4-benzoxazin-3-(4H)-one) is an allelopathic-derived compound with interesting herbicidal, fungicidal, and insecticide properties whose production has been successfully achieved by biocatalysis using a genetically engineered Escherichia coli strain. However, improvement and scaling-up of this process are hampered by the current methodology for D-DIBOA quantification, which is based on high-performance liquid chromatographic (HPLC), a time-consuming technique that requires expensive equipment and the use of environmentally unsafe solvents. In this work, we established and validated a rapid, simple, and sensitive spectrophotometric method for the quantification of the D-DIBOA produced by whole-cell biocatalysis, with limits of detection and quantification of 0.0165 and 0.0501 µmol·mL-1 respectively. This analysis takes place in only a few seconds and can be carried out using 100 µL of the sample in a microtiter plate reader. We performed several whole-cell biocatalysis strategies to optimize the process by monitoring D-DIBOA production every hour to keep control of both precursor and D-DIBOA concentrations in the bioreactor. These experiments allowed increasing the D-DIBOA production from the previously reported 5.01 mM up to 7.17 mM (43% increase). This methodology will facilitate processes such as the optimization of the biocatalyst, the scaling up, and the downstream purification.

Electrochemical and Spectrophotometric Methods for Polyphenol and Ascorbic Acid Determination in Fruit and Vegetable Extracts.

RESEARCH BACKGROUND: Fresh-cut fruits and vegetables are considered sources of antioxidant compounds. However, their shelf life is limited due to nutritional, quality and safety deterioration. Therefore, in recent decades, various methods have been reported for food processing and preservation, as well as for the determination of antioxidant compounds, due to their many benefits when consumed. The aim of the present work is to compare the performance of electrochemical and spectrophotometric methods in the analysis of the content of polyphenolic compounds and ascorbic acid in extracts from fruits (eggplant), edible roots (carrot) and leaves (rocket, lettuce and chard), and evaluate their capability to detect small changes in the antioxidant content in the eggplant extracts previously irradiated with different UV-C light intensities. EXPERIMENTAL APPROACH: Polyphenolic compounds and ascorbic acid were determined by electrochemical and spectrophotometric methods. An enzymatic biosensor and a nanocomposite sensor were used for polyphenolic compounds and ascorbic acid, respectively, in electrochemical measurements, while Folin-Ciocalteu and Kampfenkel methods were used for spectrophotometric measurements. RESULTS AND CONCLUSION: Results obtained through the different methodologies were comparable and consistent with each other. Both methods allowed determining the content of ascorbic acid and polyphenolic compounds in the fruit and vegetable extracts. Moreover, both techniques enable the detection of the analyte concentration changes in samples exposed to different UV-C intensities and storage days. Finally, it was observed that the antioxidant capacity depends on the type of food, treatment and storage period. NOVELTY AND SCIENTIFIC CONTRIBUTION: Both methodologies were suitable for the quantification of analytes; however, the electrochemical sensors provided higher specificity and selectivity, applicable to different fruit and vegetable matrices, obtaining results with higher precision, in shorter time and with a smaller sample volume, minimizing the economic costs because of the lower consumption of reagents.

Improvisation of a spectrophotometric method to quantify hydroxycitric acid.

Existing spectrophotometric method to quantify hydroxycitric acid (HCA), although is specific and sensitive; finds limited use owing to poor stability of HCA-metavanadate complex. Present study describes improvisation of this method with respect to source of HCA standard and assay parameters. Assay system consisting of HCA and metavanadate reagent was modified to include 1 M NaOH to neutralize excess acidity. Resulting complex showed λmax at 485 nm, obeying Beer-Lambert's law within concentration range of 33-677 µg/ml, with linear calibration curve showing a good coefficient of determination (R2 = 0.998). Moreover, HCA-metavanadate complex showed enhanced stability retaining up to 70% absorbance even after 60 min of its formation. Similar consistency in scaled-down assay system renders the method suitable for high-throughput screening of HCA-producing microbes. Of the tested metabolites and media components, only tartrate interfered with the spectrophotometric estimation of HCA; a correction factor to eliminate which was also established. Accordingly measured HCA level in the culture supernatant of a bacterial isolate IT6 was comparable to that determined using the standardized HPLC method. The proposed procedure therefore is a convenient, sensitive, accurate and high-throughput method suitable for primary screening of HCA producing microbes; the only ecofriendly alternative source of optically pure HCA.

[Laboratory diagnostics of ovarian cancer among the elderly in the parameters of immunoglobulins and phagocytic activity of blood.]

Due to the increase in the proportion of elderly women, the prevalence of ovarian cancer is increasing, which requires the search for new methods of its diagnosis. The aim of the work is to analyze the content and informativeness of immunoglobulins and phagocytic activity of peripheral blood to improve the diagnosis of ovarian cancer among elderly women. In 78 patients with ovarian cancer aged 65-70 years immunological and spectrophotometric methods studied phagocytic activity and the level of peripheral blood immunoglobulins. 42 women of the same age with no ovarian cancer served as control. The primary importance of circulating immune complexes, phagocyte migration inhibition index and neutrophil activity index for laboratory diagnosis of ovarian cancer among the elderly was established. The use of highly informative parameters of systemic immunity improves the diagnosis of ovarian cancer in the elderly.

Spectrophotometric method for the quantitative assay of N-hydroxysulfosuccinimide esters including extinction coefficients and reaction kinetics.

A quantitative spectrophotometric method has been developed for the analysis of N-hydroxysulfosuccinimide (sulfo-NHS), a chromophore with a maximum absorbance at 268 nm. The extinction coefficients were determined between pH 6.0 and 8.0 and found to vary in a nonlinear manner. This spectrophotometric profile is not present in its esters which however release an equimolar amount of sulfo-NHS when they react with nucleophilic groups or hydrolyze in aqueous solution. This fact facilitates the determination in solution of the concentration and purity of bis(sulfosuccinimidyl) suberate (BS3) used as a model, as well as the examination of hydrolysis and aminolysis half-lives in different reaction conditions, these parameters being valuable in optimization of the use of the active esters.

Spectrophotometric analyses of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in water.

A simple and accurate spectrophotometric method for on-site analysis of royal demolition explosive (RDX) in water samples was developed based on the Berthelot reaction. The sensitivity and accuracy of an existing spectrophotometric method was improved by: replacing toxic chemicals with more stable and safer reagents; optimizing the reagent dose and reaction time; improving color stability; and eliminating the interference from inorganic nitrogen compounds in water samples. Cation and anion exchange resin cartridges were developed and used for sample pretreatment to eliminate the effect of ammonia and nitrate on RDX analyses. The detection limit of the method was determined to be 100 µg/L. The method was used successfully for analysis of RDX in untreated industrial wastewater samples. It can be used for on-site monitoring of RDX in wastewater for early detection of chemical spills and failure of wastewater treatment systems.

Indopolycarbocyanine dyes as perspective analytical reagents for spectrophotometric determination of nitrite by radical nitration.

A spectrophotometric method for the quantitative determination of nitrite was developed, based on the radical nitration of indopolycarbocyanine dyes in the presence of 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO). The rate of the reaction of the studied dyes with nitrite increases with the lengthening of the polymethine chain and the presence of hydrophilic sulfo groups in the side chain of the dye. TEMPO acts as a co-reagent, significantly accelerating the reaction rate and increasing the sensitivity of nitrite determination. The proposed reaction mechanism is supported by spectrophotometric and HPLC/MS studies. For Ind2 (tetramethine indocarbocyanine cationic dye), the limit of detection for nitrite is 0.50 µM within a linearity range of 1-13 µM. The developed method is sensitive, with a LOD 130 times lower than the maximum contaminant level (MCL) of nitrite in drinking water (65 µM), as specified by the WHO. The method is of low-toxicity and good selectivity, as the determination of nitrite is not significantly affected by the main components of water. The method was successfully applied for the analysis of nitrite in natural and bottled water.

A novel spectrophotometric method based on plasmonic nanoparticles for nicotine detection.

In this paper, a spectrophotometric method for nicotine detection based on plasmonic nanoparticles (AuNPs and AgNPs) is proposed. Due to their specific properties, plasmonic nanoparticles have become interesting to use in the development of sensitive analytical methods. The localized surface plasmon resonance (LSPR) absorption bands for AgNPs and AuNPs with a wavelength at 395.5 nm (A395.5) and 543.5 (A543.5) nm, respectively, are used for the detection. Experimental variables such as solvent type and pH were optimized so as to determine the optimum working conditions. The analytical calibration curve for both AgNPs and AuNPs based on spectrophotometric methods was prepared with nicotine concentrations range from 0.10 to 5.00 µM (R2 = 0.9903) and 0.001-0.300 µM (R2 = 0.9960), respectively. The detection limits were found to be 0.001 µM for AuNPs based method and 0.09 µM for AgNPs based method. The proposed nanoparticle-based spectrophotometric methods showed a good stability, selectivity and low detection limit.

Analytical Quality by Design Driven Development and Validation of UV-Visible Spectrophotometric Method for Quantification of Xanthohumol in Bulk and Solid Lipid Nanoparticles.

Objectives: Xanthohumol (XH) is a prenylated chalcone available naturally and has diverse pharmacological activities. It has some limitations in the physiological environment such as biotransformation and less gastrointestinal tract absorption. To overcome the limitations, we prepared nanoformulations [solid lipid nanoparticles (SLNs)] of XH. Therefore, an analytical method is required for the estimation of XH in the bulk nanoformulations, so we developed and validated a quality by design (QbD)-based ultraviolet (UV)-spectrophotometric method as per the International Conference of Harmonization (ICH) Q2 (R1) guidelines. Materials and Methods: The new analytical Qbd based UV-visible spectrophotometric technique is developed and validated for estimation of XH in bulk and SLNs as per ICH guidelines Q2 (R1). Critical method variables are selected on the basis of risk assessment studies. Optimization of method variables was performed using the a central composite design (CCD) model. Results: Multiregression ANOVA analysis showed an R2 value of 0.8698, which is nearer to 1, indicating that the model was best fitted. The optimized method by CCD was validated for its linearity, precision, accuracy, repeatability, limit of detection (LOD), limit of quantification (LOQ), and specificity. All validated parameters were found to be within the acceptable limits [% relative standard deviation (RSD) <2]. The method was linear between 2-12 g/mL concentration with R2 value 0.9981. Method was accurate with percent recovery 99.3-100.1%. LOD and LOQ were found to be 0.77 and 2.36 µg/mL, respectively. The precision investigation confirmed that the method was precise with %RSD <2. Conclusion: The developed and validated method was applied to estimate XH in bulk and SLNs. The developed method was specific to XH, which was confined by the specificity study.

FIA- spectrophotometric method for the determination of amoxicillin in pharmaceuticals; application of AES, GAPI, and AGREE greenness assessment tools.

A new, simple, and sensitive FIA-spectrophotometric method has been developed for evaluating pure amoxicillin and pharmaceutical formulations. The FIA method involves the reaction of dapsone with sodium nitrite and hydrochloric acid. Subsequently, the diazotized dapsone is coupled with amoxicillin in an alkaline medium, resulting in a stable orange dye with a maximum wavelength of 440 nm. The developed method was validated according to the ICH guidelines and found to have a concentration range of 1-150 µg/mL, a correlation coefficient of 0.9994, a molar extinction coefficient of 0.273 × 104 L/mol.cm, and a detection limit of 0.074 µg/mL. The FIA method was then evaluated using AES, GAPI, and AGREES analytical greenness assessment tools. The FIA method uses dapsone as an eco-friendly reagent, in addition to the FIA method's advantages of reduced sample and reagent usage, reduced waste generation, and cheaper equipment. So, it has been proposed as an excellent eco-friendly method for the determination of AMX in pharmaceutical formulations.

Green-assisted spectrophotometric techniques utilizing mathematical and ratio spectra manipulations to resolve severely overlapped spectra of a cardiovascular pharmaceutical mixture.

Cardiovascular diseases, in particular hypertension and hypercholesterolemia, are two of the main causes of death worldwide. These conditions are silent killer syndromes that need a variety of pharmacological treatments to be effectively controlled. This study introduces novel, environmentally friendly spectrophotometric techniques for the simultaneous determination of telmisartan (TMS) and rosuvastatin calcium (RVS) in their pharmaceutical dosage forms. For the simultaneous determination of the binary mixture, the suggested methods included the dual wavelength method (DWM) which utilizes mainly the absorbance difference at 233 nm and 253 for TMS determination and, the absorbance difference at 274 nm and 310 for RVS determination as the selected wavelengths for each drug is directly proportional to the drug of interest independent on the other interfering component. The Fourier-self deconvolutions method (FSDM) depends on compressing their bandwidth to resolve the overlap. Ratio difference spectrophotometric method (RDSM) that utilizes TMS 35 µg.mL-1 and RVS 20 µg.mL-1, respectively as divisors to produce the ratio spectra for each drug. Further manipulation of the produced ratio spectra was applied for the determination of the two drugs. Mean centering method (MCM) where a suitable wavelength range was chosen to exclusively use the informative portions and prevent experimental spectrum noises. The investigated methods showed good levels of detection and quantification together with excellent linearity. The suggested methods' greenness was evaluated using two different greenness evaluation tools, which showed that the methods were green in terms of several factors, including the safety of the chemicals, instruments, and waste. The validity of the methodologieswas investigated by resolving prepared laboratory mixtureswith varying TMS and RVS ratios. The standard addition method also assured the newly added methods. Finally, statistical analysis using the reported method did not reveal any appreciable differences in terms of accuracy and precision. The developed methods can be employed in quality control laboratories to ascertain the binary mixture due to their high precision and affordability.

A Simple Spectrophotometric Method for Coccidian Oocysts Counting in Broiler Feces.

PURPOSE: This study aimed to develop a rapid spectrophotometric method for counting coccidian oocysts in broilers feces, based on a standard count method "Malassez cell". METHODS: Therefore, a raw suspension containing purified oocysts of Eimeria known to parasitize broiler chicken was used. Five concentrations of oocyst suspensions were prepared, and three series of counts using the proposed method were compared with the conventional protocol using Malassez cell to quantify oocysts. Calibration curves were drawn to correlate the specific absorbance measurement at 550 nm and the number of coccidian oocysts quantified using Malassez cell counting (oocysts mL-1). RESULTS: The obtained results allowed to establish a formula for an easy estimation of the cell count based on their respective absorbance. The developed method can be used not only for the in vitro evaluation of the anticoccidian activity of natural or synthetic substances, but also for assessing oocysts production and the level of coccidian infection in broilers. CONCLUSION: The estimation formula has been found to be satisfactory and useful for a wide range of Eimeria oocyst suspension, offering a methodology with high potential for automation in anticoccidian tests in vivo and in vitro.

The Chitosan-Based System with Scutellariae baicalensis radix Extract for the Local Treatment of Vaginal Infections.

Scutellarie baicalensis radix, as a flavone-rich source, exhibits antibacterial, antifungal, antioxidant, and anti-inflammatory activity. It may be used as a therapeutic agent to treat various diseases, including vaginal infections. In this study, six binary mixtures of chitosan with stable S. baicalensis radix lyophilized extract were obtained and identified by spectral (ATR-FTIR, XRPD) and thermal (TG and DSC) methods. The changes in dissolution rates of active compounds and the significant increase in the biological properties towards metal chelating activity were observed, as well as the inhibition of hyaluronic acid degradation after mixing plant extract with chitosan. Moreover, the combination of S. baicalensis radix lyophilized extract with a carrier allowed us to obtain the binary systems with a higher antifungal activity than the pure extract, which may be effective in developing new strategies in the vaginal infections treatment, particularly vulvovaginal candidiasis.

Improved spectrophotometric method for nitrite determination in processed foods and dietary exposure assessment for Korean children and adolescents.

A spectrophotometric method based on diazo-coupling reaction for nitrite analysis was established and validated, including inter-laboratory validation, linearity, accuracy, precision, the limit of detection (LOD) and limit of quantification (LOQ). The time-saving and high-recovery method was established by examining the filtration step, colorimetric process and concentration range of the calibration curve. This method showed good linearity (r2 > 0.999) in the range of 0.025-1.0 µg/mL. The three-level recoveries were between 86.7% and 108.6%, with the coefficient of variation (CV) below 5.8%. Mean nitrite concentration ranges in processed foods were ND-33.47 mg/kg. The mean nitrite intake was 0.8% of the Acceptable Daily Intake (ADI, 0.07 mg/kg bw/day) for all children and adolescents and 2.8% for the consumer group. The major contributors for all subjects and consumers were ham, sausage and bacon. These results indicated that the improved method was suitable for analyzing nitrite in processed foods and the nitrite exposure levels were safe.

A rapid spectrophotometric method to identify inhibitors of human erythropoiesis.

Erythropoiesis is a complex physiological process by which erythroid progenitors proliferate and differentiate into nonnucleated red blood cells. Several methods can be used to monitor in vitro the differentiation of erythroid precursors, and hence the toxic effects of drugs, chemicals, or pollutants. One of the most commonly available assay of erythropoiesis is the microscopic observation of differentiated cells after benzidine staining, which forms a blue complex with hemoglobin. However, this method is laborious and does not provide accurate results since it heavily relies on the reader's interpretation. Moreover, benzidine is a carcinogen and a highly reactive molecule which forces the reader to microscopically count differentiated and non-differentiated cells within a short time frame (5 min). Here we have developed a simple, inexpensive, in-vitro spectrophotometric assay to measure erythroid differentiation using K562 cell line as a model. Materials needed included 96-well round-bottomed microplates and a microplate reader. Remarkably, carcinogenic benzidine was replaced by its isomeric tetramethyl derivative, the 3,3', 5,5'- tetramethylbenzidine (TMB), which presents several advantages: it is cheap, not mutagenic and a ready-to-use chromogenic substrate. A small volume (50 µl) of TMB added to the samples forms a blue complex in 15 min, and the reaction can be easily stopped and stabilized by the addition of H2SO4. The yellow precipitate is then solubilized, and the absorbance is measured at 450 nm. In addition, the suitability of the assay to determine the effects of compounds on erythroid differentiation was further tested with known inhibitors (artemisinin derivatives) of K562 differentiation. Overall, the reported methodology permits to measure in an accurate and reproducible manner the K562 differentiation and can be used for medium throughput screenings (MTS) of compounds or environmental toxics with potential erythro-toxicity and ability to inhibit erythroid differentiation.