Method For Quantitative Determination Research Articles

Quantitative determination of total flavonoids in Glycyrrhiza Glabra L. herbs

Licorice herb (Glycyrrhiza glabra L.) is a promising herbal raw material, which can be comprehensively used to develop drugs with an anti-inflammatory action.The aim of the article was to development a quantitative determination method of total flavonoids in Glycyrrhiza glabra L. herbs.Materials and methods. The subjects of research were 5 samples of licorice herb harvested in summer in various places of growing and cultivation. Pinostrobin was used as a standard sample. The registration of the electronic spectra was carried out with a spectrophotometer (Analytik Jena AG, Germany) by differential spectrophotometry, 96% ethanol was used as a solvent.Results. The methods for quantitative determination of total flavonoids in Glycyrrhiza glabra L. was carried out at an analytical wavelength of 310 nm equivalent to pinocembrin. The optimum parameters for the extraction of total flavonoids from Glycyrrhiza glabra L. were as follows: the extractant – 90% ethanol; the «raw material-extractant» ratio was 1:50; the extraction time was 60 min; the degree of atomization was 2 mm. The content of total flavonoids for the Glyccyrhiza glabra L. herb has been determined, it varies from 0.39±0.002 to 3.41±0.015% with the humidity of the vegetative raw material from 9.97±0.003 to 10.03±0.003% depending on the place of the vegetation, cultivation and year of the raw material collection. The error of the single determination with a 95% confidence level was ±0.73%.Conclusion. The developed methods for the quantitative determination of total flavonoids in Glycyrrhiza glabra L. herbs can be used to solve the issues of standardization of these medicinal plant raw materials.

Cost-Weighted TF-IDF: A Novel Approach for Measuring Highway Project Similarity Based on Pay Items’ Cost Composition and Term Frequency

State highway agencies (SHAs) often need to cluster or bundle projects in accordance with their scope similarity for various construction management tasks, including historical data-driven time, cost estimating, and project bundling. Conventionally, SHAs categorize similar projects into work types based on subjective judgment about the similarity between major pay items. A few quantitative methods for project similarity determination are found in the literature, but they mostly use one single source of information, either the cost contribution of pay items or the keywords of pay items descriptions, for measuring project similarity. This paper presents the first attempt to integrate multiple information sources for project similarity measurement. This research proposes a novel cost-weighted term frequency-inverse document frequency (CW-TF-IDF) method that incorporates the cost information of pay items into the traditional TF-IDF word embedding method to measure project similarity. The effectiveness of the proposed method in supporting project clustering and bundling was tested using the historical bid data collected from an SHA. The findings showed that the CW-TF-IDF method significantly improves project clustering performance compared to the most recent state-of-the-art method. The CW-TF-IDF method also showed its outperformance in project bundling as it yielded a cosine similarity of over 0.9 for most of the bundled projects in the testing data. This proposed method is expected to help SHAs accurately identify similar projects and eventually improve their project management effectiveness.

In-line quantitative estimation of ammonium polyphosphate flame retardant in polyolefins via industrial hyperspectral imaging system and machine learning

Due to developments in European legislation, several halogenated flame retardants are banned due to their toxicity, and the use of phosphor-based flame retardants in plastics is increasing. A revision of ammonium polyphosphate (APP) flame retardant revealed that it is an eye irritant and toxic, thus posing a health issue. Hence APP identification is needed for enabling safe recycling of plastic waste streams. Herein an industrial in-line method for quantitative estimation of APP in low density polyethylene (LDPE) and polypropylene (PP) is demonstrated, by using an industrial hyperspectral imaging system (955 to 1700 nm) and principal component analysis (PCA). Spectra of plastic samples with varying concentrations of APP were applied to build and calibrate a quantitative determination method. PCA and band area ratios (of selected bands) were made and fitted with continuous functions for concentration determination. The plastic samples were characterised by elemental analysis, attenuated total reflection, differential scanning calorimetry, and thermogravimetric analysis. The PCA model outperforms the band area ratio model and predicts APP concentrations between 24.3 and 1.5 wt% in LDPE (R2 = 0.98) and 20.0 and 1.7 wt% in PP (R2 = 0.97). Unknown samples with APP ranging from 23.7 to 2.7 wt% in LDPE and from 18.6 to 2.3 wt% in PP were predicted and correlated to the actual concentrations. The proposed approach is valuable for the plastic recyclers and waste management industries where inline concentration determination of flame retardants is key.

Targeted quantitative metabolomics with a linear mixed-effect model for analysis of urinary nucleosides and deoxynucleosides from bladder cancer patients before and after tumor resection.

In the present study, we developed and validated a fast, simple, and sensitive quantitative method for the simultaneous determination of eleven nucleosides and deoxynucleosides from urine samples. The analyses were performed with the use of liquid chromatography coupled with triple quadrupole mass spectrometry. The sample pretreatment procedure was limited to centrifugation, vortex mixing of urine samples with a methanol/water solution (1:1, v/v), evaporation and dissolution steps. The analysis lasted 20min and was performed in dynamic multiple reaction monitoring mode (dMRM) in positive polarity. Process validation was conducted to determine the linearity, precision, accuracy, limit of quantification, stability, recovery and matrix effect. All validation procedures were carried out in accordance with current FDA and EMA regulations. The validated method was applied for the analysis of 133 urine samples derived from bladder cancer patients before tumor resection and 24h, 2weeks, and 3, 6, 9, and 12months after the surgery. The obtained data sets were analyzed using a linear mixed-effect model. The analysis revealed that concentration level of 2-methylthioadenosine was decreased, while for inosine, it was increased 24h after tumor resection in comparison to the preoperative state. The presented quantitative longitudinal study of urine nucleosides and deoxynucleosides before and up to 12months after bladder tumor resection brings additional prospective insight into the metabolite excretion pattern in bladder cancer disease. Moreover, incurred sample reanalysis was performed proving the robustness and repeatability of the developed targeted method.

Validated UPLC-MS/MS method for the determination of ivosidenib in rat plasma: Application to a pharmacokinetic study

AbstractIvosidenib (AG-120) is an unlisted, but estimated to be valid, oral inhibitor for isocitrate dehydrogenase 1 (IDH1) in the phase Ⅰ study of IDH1-mutated acute myeloid leukemia (AML) patients. This paper presents the investigation and validation of a rapid, effective, qualitative and quantitative determination method of ivosidenib in rat plasma by ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). The samples were treated using acetonitrile precipitation to remove protein influence. Then, the supernatant was extracted to analyze plasma concentration traits. In the UPLC system, acetonitrile and water containing 0.1% formic acid were selected as a cosolvent mobile phase, applying a gradient elution to isolate compounds in a C18 column. Mass detections were performed on a triple quadruple mass spectrometer in positive ion mode. Electroshock characteristic fragment ionization was used for m/z 583.95→214.53 for ivosidenib for quantitative determination, m/z 583.95→186.6 for qualitative determination, and m/z 492.06→354.55 for IS. The selectivity, linearity, stability, accuracy and precision were verified by reaching the guideline criteria from European Medicine Agency (EMA) and the Food and Drug Administration (FDA). The calibration curve was linear over the concentration range of 2–2,000 ng mL−1 for ivosidenib in rat plasma with a lower limit of quantification (LLOQ) of at least 2 ng mL−1. Additionally, there was no distinct matrix effect or carry-over phenomenon. The method was successfully established and applied to separate ivosidenib from plasma, with the entire analytical process being performed within 3 min for each sample, which shows high-efficiency and convenience for further studies of ivosidenib.

PHARMACOPOEIAL METHODS FOR THE ANALYSIS OF CARDIAC GLYCOSIDES IN PLANT RAW MATERIALS AND MEDICINES (REVIEW)

The review of modern methods of analysis of cardiac glycosides (CG) offered by pharmacopoeias of Russia, Europe, England, USA, India, Japan and China is presented. The purpose of the review is a comparative analysis of pharmacopoeial methods of identification and quantitative determination of the content of CG in plant raw materials and medicines. It is shown that in the Russian Pharmacopoeia, instrumental methods for the analysis of car-diac glycosides are not widely represented. In this regard, the search for effective methods of analyzing this group of substances in plant raw materi-als and medicines is relevant.

Application of the relative molar sensitivity method using GC-FID to quantify safranal in saffron (Crocus sativus L.).

Safranal is one flavor component of saffron, which is used as a spice, food additive, and crude drug. In ISO3632, safranal is defined as the compound that contributes to the quality of saffron, and many quantitative determination methods for safranal have been reported. However, safranal is volatile and degrades easily during storage, and an analytical standard with an exact known purity is not commercially available, making it difficult to quantify accurately the content of safranal in saffron. Here, we developed a method for quantifying safranal using relative molar sensitivity (RMS), called the RMS method, using a GC-flame ionization detector (GC-FID). We determined the RMS of safranal to 1,4-bis(trimethylsilyl)benzene-d4, a certified reference material commercially available, by a combination of quantitative NMR and chromatography. Using two GC-FID instruments made by different manufacturers to evaluate inter-instrument effect, the resultant RMS was 0.770, and the inter-instrument difference was 0.6%. The test solution, with a known safranal concentration, was measured by the RMS method, with an accuracy of 99.4-101%, repeatability of 0.81%, and reproducibility of 0.81-1.3%. Given the ease of degradation, high volatility, and uncertain purity of safranal reagents, the RMS method is a more accurate quantification approach compared to the calibration curve method and methods based on absorption spectrophotometry. Moreover, our findings revealed that the GC-FID makeup gas affected the RMS and quantitative values.

Development of enantioselective high-performance liquid chromatography-tandem mass spectrometry method for quantitative determination of methylone and some of its metabolites in oral fluid

In the present study an enantioselective high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the first time for quantitative determination of the recreational drug of abuse methylone and its major metabolites in oral fluid. The simultaneous chemo- and enantioseparation of methylone and its major metabolites was performed on a polysaccharide-based chiral column based on amylose tris(5-chloro-3-methylphenylcarbamate) as chiral selector (Lux i-Amylose-3) with methanol containing 0.4 % (v/v) aqueous ammonium hydroxide as mobile phase. The time required for enantioselective analysis of methylone and its 2 major metabolites was 15 min. This method was fully validated following the Organization of Scientific Area Committees (OSAC) for Forensic Science guidelines.This method was applied for the enantioselective determination of methylone and its metabolites in oral fluid and enantioselectivity in metabolism and pharmacokinetic of the parent compound and metabolites was observed.While the first enantiomer of methylone was found at higher concentration, both metabolites shown greater concentration for the second enantiomer. The results revealed that MET undergoes an enantioselective biotransformation to its metabolites HMMC and MDC, with S-(−)-MET more rapidly metabolized and eliminated from the body.

Development of a method for the quantitative determination of glibenclamide in tablets

Aim. To develop and validate a spectrophotometric technique for quantitative determination of glibenclamide in tablets by reaction with 2,3-dichloro-1,4-naphthoquinone. Materials and methods. In the study, the substance glibenclamide of pharmacopoeial purity was used, tablets – “Maninil” 5 mg and “Glibenclamid-Zdorovye” 5 mg, 2,3-dichloro-1,4-naphthoquinone of the “CFA” qualification was chosen as a reagent, as a solvent – dimethylformamide (DMF) “CFA”. The following analytical equipment was used for the research: spectrophotometer “Specord-200” (Analytic Jena AG, Germany), water bath “MEMMERT WNB7”, laboratory electronic scales RADWAG XA 210. 4Y, measuring laboratory vessels of class A. Results. A new, simple spectrophotometric method of quantitative determination of glibenclamide in tablets by reaction with 2,3-dichloro-1,4-naphthoquinone in DMF medium was developed. The absorption maximum was at 489–491 nm. The value of the detection limit is 10.9 μg/ml, which indicates sufficient sensitivity of the reaction. Subordination to the basic law of light absorption is within the limits of concentrations of 13.7–27.4 mg/100 ml. In the process of developing the methodology, the following validation characteristics were determined: specificity, linearity, precision, correctness, and robustness. Conclusions. The methodology for the quantitative determination of glibenclamide was developed and validated according to the requirements of the State Pharmacopoeia of Ukraine. It has been proven that the method is simple, accessible, and validated for such characteristics as linearity, convergence and robustness and can be used for application in laboratories for quality control of medicinal products.

SPECTROPHOTOMETRIC DETERMINATION OF TAMSULOZIN IN REFERENCE SAMPLES AND DRUGS, VALIDATION OF METHODS

The article presents the results of quantitative spectrophotometric determination of tamsulosin in a standard sample, in “Tulosin” and “Ornadex” capsules using 96% ethyl alcohol as a solvent. The relative error of determination is ±0.25% for the standard sample of tamsulosin, ±0.93% for “Tulosin” capsules, ±1.43% for “Ornadex” capsules. The proposed method of quantitative determination was validated according to the specified parameters: specificity, linearity, and accuracy. When determining the linearity of the method, the concentration of 0.4-1.6 mg was determined as the working interval of the standard sample of tamsulosin hydrochloride (r=0.994). When determining the accuracy, it was found that the working solutions prepared in 96% ethanol do not change the optical density at the absorption maxima in a short period of time (RSD = 0.622). When determining the specificity, it was found that the excipients do not interfere with the analysis.

Development and validation of a new spectrophotometric method for the determination of gabapentin in capsules

In Ukraine, there are about 100 thousand people with epilepsy. Gabapentin is an effective antiepileptic agent for oral use, presented in capsules of different dosages from different manufacturers. Therefore, the urgent task of pharmaceutical analysis today is the development of highly accurate, reliable, affordable and fast methods of quantitative determination. The aim of the work is to develop a spectrophotometric technique for the quantitative determination of gabapentin in capsules based on the reaction with diazole red 2J in compliance with the SPhU. Material and methods. As reagent and solvent, diazole red 2J of AR grade, acetone of AR grade and purified water was used. Analytical equipment: Specord 200 and Specord 250 Plus spectrophotometers, ABT-120-5DM and Radwag XA 210.4Y electronic scales, Elmasonic E 60H and Sonorex Digitec DT100H ultrasonic baths, measuring glassware of A class. Results. A simple, accurate and eco-friendly colourimetric method was developed for the quantification of gabapentin in capsules. The method was based on the reaction of gabapentin with diazole red 2J to give a coloured product having analytical maxima at 390 nm. Factors affecting colour development and stability were optimized and incorporated into the procedure. Regression analysis of Beer's plot showed a good correlation (not less than 0.999) in a concentration range of 2.10 – 3.64 mg/100 ml. The detection and quantification limits were 2.25 % and 6.19 %, respectively. The intra- and inter-laboratory precision demonstrates and reflects no interference by the capsule additives and confirms the reproducibility of the method in the selected concentration range. The prediction of the total uncertainty of the results of the developed method is calculated and displayed to assess the correctness of the reproduction of the method. Conclusions. It has been proven that the developed method meets the requirements of the State Pharmacopoeia of Ukraine and allows to perform the correct quality control of medicinal products.

THE PROBLEMS TO IMPROVE THE STANDARDISATION OF YARROW HERB

Relevance. It is known the method of quantitative determination of the total flavonoids in the herb of common yarrow (Achillea millefolium L.) includ-ed in the State Pharmacopoeia of the Russian Federation XIV edition, according to which at the stage of extraction of these raw materials should be ac-id hydrolysis with ethyl alcohol 96% containing 1% hydrochloric acid concentrated, followed by determination of the amount of flavonoids in recalcula-tion on luteolin. The flavonoid glycosides, including 7-O-glucosides luteolin (cynaroside) and apigenin (cosmosiin), difficult to acid hydrolysis, which does not allow for complete hydrolysis and exhaustive extraction of the target substances. Determination of the main groups of biologically active substances by thin-layer chromatography (TLC) involves the use of a standard sample of sudan III, not contained in the raw material. The purpose of this study is the improvement of methods of qualitative and quantitative analysis of herb of Achillea millefolium L. Material and methods. Yarrow herb harvested in 2021 was used as study materials. Extraction of individual substances from yarrow herbs was car-ried out using column chromatography on silica gel KSC 50/100 under conditions of gradient elution with chloroform-ethanol solvent mixture in different ratios. Along with the isolated individual flavonoids, we used working standard samples of flavonoids obtained by the authors in previous studies of herbal plants containing flavonoids, characterized using UV and NMR spectroscopy: rutin, quercetin, kaempferol, cynaroside, luteolin. Flavonoid content was determined by thin-layer chromatography and by differential spectrophotometry. Results. TLC analysis revealed the presence of three dominant and diagnostically significant flavonoids: cosmosiin, cynaroside and apigenin. Analysis of UV spectra also confirmed that the spectral characteristics of the water-alcoholic extracts from common yarrow herbs, especially under the condi-tions of differential spectrophotometry, are mainly determined by the dominant flavones (cosmosiin, cynaroside and apigenin). Conclusions. The obtained results of studies on the flavonoid composition and spectral characteristics of the isolated dominant flavonoids suggest the feasibility of conducting of the qualitative and quantitative analysis of common yarrow herbs using cynaroside as a standard sample.

Method of Quantitative Determination of the Total Flavonoid Content in Leaves of Giant Cephalaria

Method of Quantitative Determination of the Total Flavonoid Content in Leaves of Giant Cephalaria

Absolute Configuration, Enantioselective Bioactivity, and Mechanism Study of the Novel Chiral Fungicide Benzovindiflupyr.

Benzovindiflupyr has gained increasing attention as a new chiral succinate dehydrogenase inhibitor fungicide; however, its determination, bioactivity, and mechanism at the enantiomeric level are very limited. In the present study, optical rotation determination and X-ray single-crystal diffraction results identified that the absolute configurations were (+)-(1R,4S)-benzovindiflupyr and (-)-(1S,4R)-benzovindiflupyr. A quantitative determination method for enantiomers was established using high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) for pesticide detection. The stereoselective bioactivity assay indicated that (-)-(1S,4R)-benzovindiflupyr exhibited greater potency than (+)-(1R,4S)-benzovindiflupyr against seven phytopathogenic fungi. Molecular docking analysis showed that (-)-(1S,4R)-benzovindiflupyr possessed a stronger binding affinity to succinate dehydrogenase than (+)-(1R,4S)-benzovindiflupyr. The binding modes between enantiomers and the mutant with H272(B) predicted that the phytopathogenic fungi with H272(B) of succinate dehydrogenase mutation would not be resistant to benzovindiflupyr enantiomers. This study provides a basis for residue evaluation, risk assessment, and the safe application of benzovindiflupyr at the enantiomer level.

Quantitative determination of potassium ions by flame photometry in the drug “Panangin”

Annotation. Determination of the quantitative content of potassium ions by flame photometry in the drug “Panangin”® produced by “Gedeon Richter” Plc (Hungary) and study the accuracy of this method by calculating the measurement error. The drug “Panangin”® was used in the form of film-coated tablets. The filtrate was quantified with potassium ions on a BWB-XP flame photometer using a propane-butane mixture. Calibration of the device was performed using solutions of potassium chloride of the following concentrations: 1,00, 10,00, 25,00 and 50,00 mg / l, the reference solution was deionized water. The quantitative content of potassium ions was measured using flame photometry. The proposed method of quantitative determination of K+ ions in the drug “Panangin”® belongs to the analytical and pharmaceutical chemistry and is intended for quality control of drugs containing potassium. According to the results of the study, we can see that the method of flame photometry gives reproducible results.

Simultaneous Determination of Nirmatrelvir and Ritonavir in Human Plasma by HPLC-MS/MS

Introduction. SARS-CoV-2 (severe acute respiratory syndrome-related coronavirus 2) is expected to remain a persistent global threat. Therefore, development of coronavirus disease 2019 (COVID-19) drugs is the most urgent global issue. Nirmatrelvir and ritonavir combination is an oral antiviral drug combination with activity against SARS-CoV-2. Nirmatrelvir and ritonavir combination is highly efficacious in reducing the risk of COVID-19. The study describes development and validation of high-performance liquid chromatography – tandem mass spectrometry (HPLC-MS/MS) method for the simultaneous determination of nirmatrelvir and ritonavir in human blood plasma. The method could be applied in pharmacokinetic study of nirmatrelvir and ritonavir.Aim. The aim of this study is to develop and validate a HPLC-MS/MS bioanalytical method for the determination of nirmatrelvir and ritonavir in human plasma.Materials and methods. The determination of nirmatrelvir and ritonavir in human plasma by HPLC-MS/MS. The samples were processed by acetonitrile protein precipitation. Internal standard: promethazine. Mobile phase: 0.1% formic acid solution in water (Eluent A), 0.1% formic acid in acetonitrile (Eluent B). Column: Phenomenex Luna C18 50 × 2.0 mm, 5 μm. Analytical range: 50.00–10000.00 ng/mL for nirmatrelvir, 5.00–1000.00 ng/mL for ritonavir in human plasma. Ionization source and ionization: electrospray ionization, positive. Detection conditions: 499.90 → 110.10 m/z, 499.90 → 319.20 m/z (nirmatrelvir), 720.90 → 426.00 m/z, 720.90 → 296.20 m/z, 720.90 → 268.10 m/z, 720.90 → 197.10 m/z, 720.90 → 139.90 m/z (ritonavir), 285.15 → 198.05 m/z (promethazine).Results and discussion. This method was validated for selectivity, matrix effect, calibration curve, accuracy, precision, spike recovery, the lower limit of quantification, carry-over effect and stability.Conclusion. The HPLC-MS/MS method for quantitative determination of nirmatrelvir and ritonavir in human plasma was developed and validated. The analytical range was 50.00–10000.00 ng/mL for nirmatrelvir, 5.00–1000.00 ng/mL for ritonavir in human plasma. This method was applied to investigate the pharmacokinetics of nirmatrelvir and ritonavir.

МЕТОДИКА КОЛИЧЕСТВЕННОЙ ОЦЕНКИ ФЛУОРЕСЦЕНЦИИ ЗУБОПРОТЕЗНЫХ МАТЕРИАЛОВ

Subject. Ceramics based on zirconia can fluoresce through the additional application of fluorescent glazes, fluorescent dyes, as well. To date, there are no methods for assessing the fluorescence of dental materials used in prosthetics.
 The aim –– Development of a method for quantitative determination of the fluorescence intensity of dental prosthetic materials.
 Methodology. The study was conducted in the laboratory of the Faculty of Physics of Moscow State University. Fluorescence was excited by an ultraviolet lamp. The fluorescence spectra of the samples were measured using the Ocean Optics fiber optic spectrofluorometer. Ceramic billets made of zirconia "Ziceram T" A2 of domestic production without and with the staining of fluorescent glaze "Ivocolor fluo", as well as natural teeth were used as samples for patients.
 Results. Samples of domestic zirconia acquire fluorescent properties after applying and sintering the fluorescent glaze. The varied number of layers of the applied glaze explains why the fluorescence intensity increases. The authors compare the fluorescence spectra of two natural teeth with the spectra of zirconia samples with two and three layers of glaze. The spectra coincide well with each other in pairs. A fluorescence spectrum that is similar to one of the natural tooth samples can thus be achieved by varying the number of glaze layers.
 Conclusions. The analysis of the fluorescence spectra of samples of zirconia from domestic production after application and sintering of fluorescent glaze shows a similar fluorescence spectrum to samples of natural teeth.

A simple and reliable isocratic high-performance chromatographic assay for the simultaneous determination of hydrophilic benzophenone-4 and lipophilic octocrylene in sunscreens.

This work aimed to develop a simple HPLC method for the simultaneous quantitative determination of the ultraviolet (UV) filters, hydrophilic benzophenone-4 and lipophilic octocrylene, in the presence of three other commonly used UV filters, avobenzone, octisalate and homosalate. Reverse-phased HPLC was performed on a C18 column. A scouting gradient was initially used to determine the approximate mobile phase composition required for efficient analyte elution and separation before further optimization. The assay was validated with regard to specificity, linearity, intra- and inter-day accuracy and precision, limits of detection and limits of quantification. An ultrasound dispersion extraction method for the UV filters from a commercial sunscreen was developed, and the extraction efficiencies from spiked samples were calculated. An acetonitrile-methanol-water mixture (20:67:13, v/v/v), where the water component contained 0.2% trifluoroacetic acid (v/v), was found to be the optimal mobile phase at a flow rate of 1.0 mL/min. The assay was linear between 1.0-100 μg/mL for both benzophenone-4 and octocrylene (both correlation coefficients were above 0.999). There was no interference from the excipients of the sunscreen nor from the three other UV filters. The intra- and inter-day accuracy was between 90.0-104.6% for both analytes. Extraction recoveries from a spiked commercial sunscreen were between 95.4 ± 2.1% to 98.5 ± 2.1% for benzophenone-4, and between 87.3 ± 2.3% and 98.9 ± 3.1% for octocrylene. All validation parameters were within the acceptance criteria set out in the International Council for Harmonization (ICH) guidelines. The HPLC assay showed the extracted quantities of benzophenone-4 and octocrylene from the commercial sunscreen closely matched claimed quantities. The developed isocratic HPLC method was suitable for simultaneously determining the hydrophilic benzophenone-4 and lipophilic octocrylene in the presence of other commonly used UV filters. Additionally, the extraction method was simple and effective for accurately quantifying the UV filters in a commercial sunscreen.

Sensitive Instrumental Method for Quantitative Determination of High-Brominated Flame Retardants in Human Serum Samples.

High-brominated flame retardants (BFRs) can be released into the environment from consumer products, such as electric and electronic equipment, and enter the human body by different pathways. Because of their toxicity and the regulations, it is very relevant to know their levels and trends in human samples. However, chromatographic serum analysis of some of these compounds represents nowadays a challenge in the general population. To optimize and validate an instrumental method based on gas chromatography coupled to mass spectrometry, which, together with a simple sample preparation procedure, allows the analysis of decabromodiphenyl ether (BDE-209), decabromodiphenyl ethane (DBDPE), and tetrabromobisphenol A-bis(2,3-dibromopropyl ether) (TBBPA-DBPE) in human serum samples from the general population. To minimize the high degradation during instrumental analysis, GC parameters such as injection volumes, carrier flow rates, and column lengths were assessed and optimized. This instrumental approach in combination with solid-phase extraction (SPE) followed by multilayer silica gel column purification allowed satisfactory analysis using only 1 mL of serum. The performance of the complete method was evaluated at three spiking levels, 0.01, 0.05, and 0.2 ng/mL. Recoveries in the range 87-108% were obtained whereas the relative standard deviation in interday measurements, were, in general, lower than 19%. Limits of detection were in the range of 0.0045-0.0070 ng/mL. The optimized procedure was successfully applied to the determination of the investigated pollutants in real human samples of general population. The proposed method could contribute to the inclusion of these environmental pollutants in human biomonitoring (HBM) studies, increasing the knowledge of levels and trends in the general population. GC-MS parameters optimization to minimize instrumental analytes degradation. Successful application to human serum samples from the general population. Tetrabromobisphenol A bis(2,3-dibromopropyl ether) human serum levels are reported for the first time.

A cloth-based single-working-electrode electrochemiluminescence sensor for simultaneous detection of diabetes complication markers.

As one of the most common noninfectious diseases, diabetes and diabetic complications (DDC) have attracted great attention in the field of life and health. However, simultaneous detection of DDC markers usually requires labor- and time-consuming steps. Here, a novel cloth-based single-working-electrode electrochemiluminescence (SWE-ECL) sensor was designed for the simultaneous detection of multiple DDC markers. For this sensor, three independent ECL cells are distributed on the SWE, which is a simplification of the configuration of traditional sensors for simultaneous detection. In this way, the modification processes and ECL reactions occur at the back of the SWE, eliminating the adverse effects caused by human intervention on the electrode. Under optimized conditions, glucose, uric acid and lactate were determined, with corresponding linear dynamic ranges of 80-4000μM, 45-1200μM and 60-2000μM, and detection limits of 54.79μM, 23.95μM and 25.82μM, respectively. In addition, the cloth-based SWE-ECL sensor exhibited good specificity and satisfactory reproducibility, and its actual application potential was verified by measuring complex human serum samples. Overall, this work developed a simple, sensitive, low-cost and rapid method for the simultaneous quantitative determination of multiple markers related to DDC and demonstrated a new route for multiple-marker detection.