Isomer Ratios Research Articles

Health risks of environmentally persistent free radicals in atmospheric particulate matter during the spring festival travel season in Tainan, Taiwan.

Environmentally persistent free radicals (EPFRs) and polycyclic aromatic hydrocarbons (PAHs) are persistent pollutants in atmospheric particulate matter that are detrimental to human health. This study collected atmospheric particulate matter during and after the spring festival travel season in Tainan, Taiwan, from various locations and analyzed the carbon composition and PAH isomeric ratios to identify the sources. In this study, EPFR concentrations were measured using electron paramagnetic resonance spectroscopy, with the highest concentration found to be 3.04 × 10(12) spins/m3. EPFRs contained predominantly oxygen-centered radicals in PM2.5, which are mainly existed in PM1. The results show that EPFR concentrations on PM, measured per unit volume (spins/m3) or mass (spins/g), were highest during the spring festival travel season. The daily inhalation exposure to the sum of EPFRs and PAHs in PM2.5 was estimated to be equivalent to inhaling 0.11-0.15 cigarette tar EPFRs per day. This report is the first to document EPFRs in environmental atmospheric particulate matters in Taiwan, which has significantly contributed to local air pollution control and reduced exposure risks to public health in Tainan.

Determination of phenolics and proteins causing sediment formation in pomegranate juice using “Tannase+Lactonase” and “Protease”

In this study, pomegranate juice (PJ) was treated with “tannase+lactonase [human-derived (H-PON-1) or rabbit-derived (R-PON-1)]” or “protease [aspartic protease (AP) or cysteine protease (CP)].” After treatment, effects of tannins, proteins and amino acids on sediment formation were determined during storage at 20℃. Among proteins, prolamin showed the highest effect in PJ treated with “tannase+H-PON-1/R-PON-1” and CP. While amino acids did not affect sediment formation in “tannase+H-PON-1/R-PON-1” or AP treatments, only glycine increased sediment content in CP treatment. Removal of galloyl and/or HHDP groups from HHDP-galloyl-glucose-isomer, pedunculagin-2 and punigluconin by “tannase+H-PON-1/R-PON-1” was very effective in preventing sediment formation. Prolamin:galloyl glucose isomer ratio and HHDP-galloyl-hexoside-2 and HHDP-galloyl-glucuronide contents should be 23.244±1.162 and, 1.254±0.063 and 0.679±0.034 mg/L to prevent sediment, respectively. Since common parameters preventing sediment formation in both methods that target removal of tannins and/or proteins were punigluconin content and prolamin:punicalagin-2 ratio, these two parameters must also be considered in sediment-free PJ production.

Independent isomeric yield ratios of fission products in the epi-cadmium neutron induced fission of 235U

In the epi-cadmium neutron induced fission of 235U, independent isomeric yield ratios (IR) of fission products 130,132Sb, 131,133Te, 134,136I, 135Xe and 138Cs have been measured by using an off-line gamma-ray spectrometric technique. The average neutron energy of the epi-cadmium reactor neutron spectrum is 1.9 MeV. From the IR values, the root mean square fragment angular momenta (JRMS) were deduced by using spin dependent statistical model analysis. The IR and JRMS values of considered fission products in the epi-cadmium neutron induced fission of 235U were compared with the literature data in the thermal neutron induced fission of 235U to examine the influence of excitation energy on nuclear structure effect.

Organochlorine pesticides and polybrominated diphenyl ethers in giant African snail from the Niger Delta, Nigeria: Implications for dietary exposure and health risk assessment

The concentrations of organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs) were evaluated in snails from different locations in the Niger Delta of Nigeria to provide data about their sources and possible risk to humans from the consumption of snails. The OCP and PBDE concentrations in snail samples ranged from 0.31 to 12.2 ng g-1 and 0.21 to 10.9 ng g-1, respectively. The distribution patterns indicated the dominance of chlordanes and penta-BDEs for OCPs and PBDEs, respectively. The hazard index and total cancer risk values for human exposure to OCPs and PBDEs through consumption of these snails were less than 1 and 10-6 (acceptable risk value), respectively, indicating unlikely adverse health effects. The isomer ratios of OCPs in these snails reflected both historical and recent contamination, while the distribution patterns of PBDEs in these snails indicated sources linked to the use of the penta-BDE and octa-BDE formulations rather than the deca-BDE mixture in this region.

Evaluating the reliability of solid phase extraction techniques for hydrocarbon analysis by GC–MS

Saturate and aromatic compounds are essential in the petroleum industry for assessing the thermal maturity of source rocks and oils, which is critical for basin modeling and sweet-spot mapping. These compounds also play a role in environmental applications, such as oil spill fingerprinting and biogeochemistry. However, the analysis of these compounds by gas chromatography-mass spectrometry (GC–MS) requires meticulous and time-consuming separation processes. Traditional methods like normal-phase liquid column chromatography (LCC) involve large volumes of harmful solvents. This study evaluates the effectiveness of five different sorbents using solid-phase extraction (SPE) techniques—neutral Si, SiOH, Ag-ion, neutral Al, and Ag-ion mixed with activated silica—compared to LCC. The goal was to discern differences in peak resolution, concentration, and isomer ratios of saturate and aromatic compounds for thermal maturity and source rock assessments. The results show that SiOH, neutral Si, and neutral Al do not fully separate aromatic compounds from the saturate fraction, sometimes leaving 40–100% of aromatics within the saturate fraction. Ag-ion mixed with activated silica provided the best separation, resulting in up to 23 times higher aromatic concentration than SiOH. This method is more reliable for quantifying both saturate and aromatic compounds, increases the efficiency of hydrocarbon evaluations, and reduces solvent consumption by 63%, offering a more sustainable approach to hydrocarbon analysis.

Synthesis of Ce(IV) Heteroleptic Double-Decker Complex with a New Helical Naphthalocyanine as a Potential Gearing Subunit.

This paper describes the synthesis of a cerium(IV)-based molecular gear composed of a thioether functionalized phthalocyanine anchoring ligand, and a helical naphthalocyanine rotating cogwheel functionalized with four carbazoles. The naphthalocyanine ligand 9 was obtained after eleven steps (overall yield of 0.2 %) as a mixture of three geometrical isomers, two of which are chiral and exhibit high levels of steric hindrance, as shown by DFT calculations. Their attributions have been made using 1H-NMR based on their different symmetry groups. The ratio of isomers was also determined and the prochiral C4h naphthalocyanine shown to be the major compound (55 %). Its heteroleptic complexation with cerium (IV) and the anchoring phthalocyanine ligand 10 gave the targeted molecular gear in a 16 % yield.

Characteristics and sources of polycyclic aromatic hydrocarbons in dew in urban ecosystems in Northeast China

The concentrations of polycyclic aromatic hydrocarbons (PAHs) in the atmospheres above major cities in Northeast China are relatively high. Dew is an effective way to settle and remove particulate and gaseous matter in the formation process. Notably, 16-PAH concentration dew analysis was conducted in four major cities (Harbin, Changchun, Shenyang and Dalian) from April to November 2023. In the study area, 2–3-ring PAHs dominated in dew in both the dissolved and particle phases, followed by 4-ring and 5–6-ring PAHs. Phe was the most common individual PAH in dew. Because PAHs in wet deposition are closely related to those in the atmosphere, the concentration of PAHs in dew was much lower than that in snow. The proportions of the gaseous-phase scavenging ratio (Wg) to the total scavenging ratio (Wt) in Harbin, Changchun, Shenyang and Dalian increased with increasing temperature, reaching 22.98%, 29.02%, 30.71% and 33.22%, respectively, which indicated that the ability of dew to remove PAHs in the particle phase was greater than that to remove PAHs in the gas phase. The concentration of dissolved-phase PAHs in dew was lower than that of particle-phase PAHs. The total PAH fluxes were 43.25, 33.35, 32.16, and 25.63 ng/m2·d in Harbin, Changchun, Shenyang and Dalian, respectively, decreasing from north to south. The dew amount was much smaller than the rainfall and snow amount (by two orders of magnitude), and the PAH flux in dew was much lower than that in rain and snow. Isomeric ratio assessment coupled with principal component analysis (PCA) indicated that the source of PAHs in dew was a combination of vehicle emissions and biomass and coal combustion. PAHs in dew mainly originated from local sources rather than from long-range atmospheric transport. This study revealed the effects of PAHs in dew on the air quality and the removal of PAHs by dew.

Concentration of polycyclic aromatic hydrocarbons (PAHs) in bread and health risk assessment across the globe: A systematic review and meta-analysis.

Although bread is the principal food in most countries, polycyclic aromatic hydrocarbons (PAHs) may be present and pose a potential risk to consumers. The aim of this review is to provide a comprehensive report on the concentration and health risks associated with PAHs in bread around the world. Various databases, such as Scopus, PubMed, Science Direct, and Google Scholar, were searched from their beginnings until December 2023 for this systematic review, which included 34 potentially relevant articles with data relating to 1057 bread samples. Utilizing a multilevel regression modeling approach, the study evaluated various factors such as fuel type, bread type, and geographical location. Following the initial evaluation, in 26.47% and 20.28% of all studies, the levels of Bap and PAH4 were higher than the permissible limit values, respectively. Based on the isomer ratios, 55.88% of the studies associated the presence of PAHs in bread samples with pyrogenic/coal combustion sources. According to the carcinogenic risk results, bread consumers in all studies have been exposed to moderate or high levels of carcinogenicity. The most significant risk levels are associated with the consumption of bread in Egypt, Kuwait, Iran, and India. Moreover, meta-regression analysis demonstrated significantly higher toxicity equivalent quotient and cancer risk mean values in bread baked using fossil fuels compared to other sources (p<.05). The high concentrations of PAHs, especially Benzo[a]pyrene, in bread pose a serious public health risk. Stringent regulations and monitoring are crucial to reduce contamination. Further research is necessary to develop safe processing methods to remove PAHs in bread.

The application of diamondoids indices for oils from Block 4 of the Muglad Basin in the middle of Africa

The abundances and distribution diamondoids were studied with a series of crude oil samples from Block 4 of the Mugald Basin in Sudan, to investigate the validity of various diamondoid parameters on the oil source, thermal maturity and biodegradation information. All crude oils of Block 4 were generated by lacustrine source in lower part of the Abu Gabra Formation as a whole, and can be further divided into two crude oil groups: oil group of the Neem-Azraq Uplift and oil group of K-3 well and B-1 well. They are all mature oils within oil window and four crude oils from the Neem-Azraq Uplift were slightly biodegraded. The concentrations of diamondoids in oils of K-3 well and B-1 well, especially the concentration of diamantanes, are higher than those of oils from the Neem-Azraq Uplift. The concentrations of diamondoids are mainly controlled by source of oil, while the influence of thermal maturity and biodegradation may be limited. The isomerization ratios as indicators of thermal maturity are inapplicable at the mature stage, but DMDI-2, 4,8/3,4-DMD and 1-EA/3-EA can clearly distinguish the two groups of crude oils. The concentration ratios of oils from K-3 and B-1 wells are significantly lower than these of oils from Neem-Azraq Uplift, and these concentration ratios including newly proposed parameters such as MAs/DMAs, DMAs/TMAs, D/MDs, MDs/DMDs and so on, are effective indicators on organofacies and oil group division within oil window.

Measurements of the 128Te(n, 2n)127m,gTe reaction cross sections and isomeric cross section ratio of 127m,gTe at the neutron energy of 14 MeV* *Supported by the National Natural Science Foundation of China (12165006, 12375295)

In this study, measurements of the 128Te(n, 2n)127m,gTe reaction cross sections and the computation of the isomeric cross section ratio were performed around the neutron energy of 13−15 MeV. We used a γ-ray spectrometric technique to conduct the measurements. The neutron energy was produced by the 3H(d,n)4He reaction. For the 128Te(n, 2n)127m,gTe reaction, the excited state, ground state, total cross section, and isomeric cross section ratio were determined using the TALYS-1.96 code, a theoretical nuclear model that allows for variations in density options. The initial experimental data, assessed nuclear data, and theoretical calculations based on the TALYS-1.96 algorithm were compared with the measurement results. The new data produced by this study are essential for validating nuclear models and establishing parameters for nuclear reactions.

A study on source identification of contaminated soil with total petroleum hydrocarbons (aromatic and aliphatic) in the Ahvaz oil field.

The oil industry in Khuzestan province (Southwest Iran) is one of the main reasons contributing to the pollution of the environment in this area. TPH, including both aromatic and aliphatic compounds, are important parameters in creating pollution. The present study aimed to investigate the source of soil contamination by TPH in the Ahvaz oil field in 2022. The soil samples were collected from four oil centers (an oil exploitation unit, an oil desalination unit, an oil rig, and a pump oil center). An area outside the oil field was determined as a control area. Ten samples with three replicates were taken from each area according to the standard methods. Aromatic and aliphatic compounds were measured by HPLC and GC methods. The positive matrix factorization (PMF) model and isomeric ratios were used to determine the source apportionment of aromatic compounds in soil samples. The effects range low and effects range median indices were also used to assess the level of ecological risk of petroleum compounds in the soil samples. The results showed that Benzo.b.fluoranthene had the highest concentration with an average of 5667.7 ug/kg in soil samples in the Ahvaz oil field. The highest average was found in samples from the pump oil center area at 7329.48 ug/kg, while the lowest was found in control samples at 1919.4 ug/kg-1. The highest level of aliphatic components was also found in the pump oil center, with a total of 3649 (mg. Kg-1). The results of source apportionment of petroleum compounds in soil samples showed that oil activities accounted for 51.5% of the measured PAHs in soil. 38.3% of other measured compounds had anthropogenic origins, and only 10.1% of these compounds were of biotic origin. The results of the isomeric ratios also indicated the local petroleum and pyrogenic origin of PAH compounds, which is consistent with the PMF results. The analysis of ecological risk indices resulting from the release of PAHs in the environment showed that, except for fluoranthene, other PAHs in the oil exploitation unit area were above the effects range median level (ERM) and at high risk. The results of the study showed that soil pollution by total petroleum hydrocarbons (TPH), both aromatic and aliphatic, is at a high level, and is mainly caused by human activities, particularly oil activities.

Computational analysis of the thermodynamic stability and isomeric composition of cholestane

Cholestane is produced by diagenesis of cholesterol in the geosphere being known to have four main stereoisomers. The abundance ratios of these stereoisomers are important indicators of the geospheric thermal history. However, it has been unclear whether the isomeric ratios are caused by kinetic or thermodynamic dominance. In this study, we analyzed the isomeric ratios of cholestane under thermodynamic dominance using the density functional theory. The calculated isomeric ratios are in good agreement with the limit values in the geosphere, indicating that the isomeric ratios in the geosphere can be obtained under thermodynamic control. We also discussed the factors contributing to their stabilities.

Independent isomeric yield ratios of fission products in the epi-cadmium neutron-induced fission of 245Cm

Abstract Independent isomeric yield ratios (IR) of 128,130,132Sb, 131,133Te, 132,134I, 135Xe and 138Cs in the epi-cadmium neutron-induced fission of 245Cm have been measured for the first time by using an off-line gamma-ray spectrometric technique. The average energy of the epi-cadmium neutron spectrum (&lt;E n &gt;) is 1.9 MeV. From the IR values, root mean square fragment angular momenta (J RMS) were deduced by using the spin dependent statistical model analysis. The IR and JRMS values of the fission products from the present work were compared with the literature data in the thermal neutron-induced fission of 245Cm to examine the role of excitation energy. Effect of nuclear structure on J RMS value was also examined.

Dietary exposure to polycyclic aromatic hydrocarbons-contaminated Talinum Triangulare grown along polluted river.

The research aims to evaluate the source, dispersion, and human health risk assessment of PAH-contaminated Talinum Triangulare grown along the polluted Ikpoba River. The freeze-dried vegetables were sonicated with dichloromethane for an hour and then concentrated using a rotary evaporator. The extract was purified using a glass column with anhydrous Na2SO4 and silica gel and analyzed using gas chromatography-mass spectrometry (GC-MS). The distribution of the contaminants showed that Pyrene < Benzo(a)anthracene ≤ Fluorene < Phenathrene ≤ Naphthalene ≤ Acenaphthene < Anthracene ≤ Acenaphthylene, while Pyrene < Benzo(a)anthracene < Fluorene < Phenathrene < Acenaphthalene ≤ Naphthalene < Anthracene < Acenaphthylene in wet and dry periods, respectively. The average ∑8 PAHs was 0.85mg/kg and 0.75mg/kg in wet and dry periods, respectively, and showed a decrease of 17.64% from wet to dry periods. The daily average dose revealed that the infant male and the adult female consumed the least and highest doses of T. Triangulare (TT), respectively. Furthermore, the hazard quotient and hazard index were < 1 for all the target groups, with adult females having higher values in both seasons. However, the incremental life cancer risk of the target group was between potential and high-potential cancer risk, with adolescent males and adult females more prone to low and high cancer risk, respectively. The isomer ratio and multivariate statistics revealed the sources of the PAH-contaminated TT to be more from pyrolysis.

Exploring the essential features influencing the synthesis of methylenedianiline to support industrial processes

The most important intermediate of methylene diphenyl diisocyanate (MDI), the most widely and quantitatively produced isocyanate in the world, is methylenedianiline (MDA). MDA is industrially produced from the reaction of aniline and formaldehyde catalysed by inorganic acids, most commonly HCl. The reaction parameters used during the synthesis of MDA have a fundamental impact on the quality parameters of the resulting MDA product mixture, and thus on the properties of the final MDI product mixture as well. Although MDA is an important industrial intermediate, currently its synthesis at the industrial level is based on empirical rules, knowledge and rule of thumbs, the effects of production parameters and their magnitude on product properties are not known and not published in the literature. In this study, the correlations between the independent operating parameters and dependent product quality parameters characterizing the MDA mixture were explored by developing different regression models with the use of experimental laboratory synthesis data in order to support the industrial synthesis process with easily deployable models with satisfactorily high accuracy. After investigating the laboratory experiment data from a total of 46 individual laboratory experiments, it was found that with machine learning models almost all of the independent parameters can be described with satisfactory accuracy. The models presented in this work demonstrate that it is possible to develop models that can be used to adjust the ring distribution, isomer ratios and selectivity of the reaction with minimising by-product quantities according to market demands or to different objective functions by fine-tuning the production parameters., thus achieving an optimal product portfolio and operating cost for the industrial process as well.

Physical and Chemical Properties of Galactic Molecular Gas toward QSO J1851+0035

Atacama Large Millimeter/submillimeter Array (ALMA) data toward QSO J1851+0035 (l = 33.°498, b = +0.°194) were used to study absorption lines by Galactic molecular gas. We detected 17 species (CO, 13CO, C18O, HCO+, H13CO+, HCO, H2CO, C2H, c-C3H, c-C3H2, CN, HCN, HNC, CS, SO, SiO, and C) and set upper limits to 18 species as reference values for chemical models. About 20 independent velocity components at 4.7–10.9 kpc from the Galactic center were identified. Their column density and excitation temperature estimated from the absorption study, as well as the CO intensity distributions obtained from the FUGIN survey, indicate that the components with τ ≲1 correspond to diffuse clouds or cloud outer edges. Simultaneous multiple-Gaussian fitting of CO J = 1–0 and J = 2–1 absorption lines shows that these are composed of narrow- and broad-line components. The kinetic temperature empirically expected from the high HCN/HNC isomer ratio (≳4) reaches ≳40 K and the corresponding thermal width accounts for the line widths of the narrow-line components. CN-bearing molecules and hydrocarbons have tight and linear correlations within the groups. The CO/HCO+ abundance ratio showed a dispersion as large as 3 orders of magnitude with a smaller ratio in a smaller N(HCO+) (or lower A V) range. Some of the velocity components are detected in single-dish CO emission and ALMA HCO+ absorption but without corresponding ALMA CO absorption. This may be explained by the mixture of clumpy CO emitters not resolved with the ∼1 pc single-dish beam surrounded by extended components with a very low CO/HCO+ abundance ratio (i.e., CO-poor gas).

Cyclic Ion Mobility of Isomeric New Psychoactive Substances Employing Characteristic Arrival Time Distribution Profiles and Adduct Separation.

Analysis of new psychoactive substances (NPS), which is essential for toxicological and forensic reasons, can be made complicated by the presence of isomers. Ion mobility has been used as a standalone technique or coupled to mass spectrometry to detect and identify NPS. However, isomer separation has so far chiefly relied on chromatography. Here we report on the determination of isomeric ratios using cyclic ion mobility-mass spectrometry without any chromatographic separation. Isomers were distinguished by mobility separation of lithium adducts. Alternatively, we used arrival time distribution (ATD) profiles that were characteristic of individual isomers and were acquired for protonated molecules or fragment ions. Both approaches provided comparable results. Calculations were used to determine the structures and collision cross sections of both protonated and lithiated isomers that accurately characterized their ion mobility properties. The applicability of ATD profiles to isomer differentiation was demonstrated using direct infusion and flow injection analysis with electrospray of solutions, as well as desorption electrospray of solid samples. Data processing was performed by applying multiple linear regression to the ATD profiles. Using the proposed ATD profile-based approach, the relationships between the determined and given content of isomers showed good linearity with coefficients of determination typically greater than 0.99. Flow injection analysis using an autosampler allowed us to rapidly determine isomeric ratios in a sample containing two isomeric pairs with a minor isomer of 10% (determined 9.3% of 3-MMC and 11.0% of 3-FMC in a mixture with buphedrone and 4-FMC). The proposed approach is not only useful for NPS, but also may be applicable to small isomeric molecules analyzed by ion mobility when complete separation of isomers is not achieved.

Estimating angular momenta of fission fragments from isomeric yield ratios using TALYS

Angular momenta of fission fragments considerably higher than that of the fissioning nucleus have been observed in many experiments, raising the question of how these high angular momenta are generated. Wilson have proposed a model for the angular momentum as a function of the mass of fission products based on the assumption that the angular momentum is generated from the collective motion of nucleons in the ruptured neck of the fissioning system. This assumption has caused a lot of debate in the community. To estimate the angular momenta of fission fragments based on the observed isomeric yield ratios in 25-MeV proton-induced fission of U238. A surrogate model of the fission code general description of fission observables (GEF) has been developed to generate properties of primary fission fragments. Based on the excitation energy and angular momentum of fission fragments from GEF, an energy-versus-angular-momentum matrix is reconstructed using a set of parameters. With such matrices as input, the reaction code TALYS is used to calculate the deexcitation of the fission fragments, including the population of the isomers, from which the isomeric yield ratios are obtained. By varying one of the parameters, the root-mean-square angular momentum (Jrms), which determines the angular momentum distribution of the matrix, Jrms-dependent isomeric yield ratios are obtained. Considering all primary fission fragments contributing to the isomeric yield ratio for a given fission product, the average angular momentum of those fragments is estimated. Data of 31 isomeric yield ratios in 25-MeV proton-induced fission of U238 were analyzed. From the analysis, the average Jrms, equivalent to average angular momentum Jav, with uncertainties are obtained for 24 fission products, while in seven cases no conclusive result for the angular momentum could be obtained. Furthermore, considering the neutron emissions of the primary fission fragments, the average angular momentum as a function of the average mass number of the primary fission fragment was estimated. A mass dependency of the average angular momentum is observed in the proton-induced fission of U238. Moreover, the average angular momenta for mass numbers larger than 131 could be fairly well described by the parametrization proposed by Wilson However, the average angular momenta of Sn130 and Te131 cannot be described by Wilson's model, which suggests a different lower limit for the validation of the parametrization in the model. In general, higher average angular momenta for A≥132 are observed in the present work compared to those from Wilson This is likely due to the higher excitation energy of the fissioning nuclei in this work. Furthermore, the first systematic observation of the average angular momenta of fission products in the symmetric mass region is presented. In this region, a decreasing trend with mass number is observed, which cannot be explained by the proposal in Wilson's paper. Thus, a different mechanism is needed to explain this observation.Published by the American Physical Society2024

Метод дослідження ізомерів з великим значенням енергії і моменту

The technique for investigating isomeric states of nuclei with a large values of energy and total momentum created in the neutron capture reaction has been developed. The technique is based on the spectrometry of multiplicity, energy, and time of registration of instantaneous and delayed gamma cascades of isomer occupancy and decay, respectively. The technique was tested in measurements of the isomeric ratio of the 183W level with energy Eiz = 1.285 MeV with total moment Jπiz = 4-, 5- and lifetime Tiz = 8.2 μs in the neutron absorption reaction, which is equal to αiz = (4.7 ± 0.9)⋅10-3. At large values of the efficiency of registration of acts of settlement and decay of the isomer (0.6 - 0.8), the level of the corresponding background of the spectrometer is only 3.5⋅10-4 s-1. At the countable load at the spectrometer input ∼1.5⋅103 s-1, the expected sensitivity of determining the isomeric ratio in measurements with the mono isotope of the sample is αiz ∼(0.3 ± 1.0)⋅10-4.

Determination of Flavonolignan Compositional Ratios in Silybum marianum (Milk Thistle) Extracts Using High-Performance Liquid Chromatography.

Milk thistle is one of the most popular ingredients in the liver protection products market. Silymarin is the main component of milk thistle and contains multiple isomers. There have been few studies focusing on the compositional ratios of silymarin isomers. In this study, we developed an HPLC method for the separation and quantification of silymarin isomers, thereby elucidating their compositional ratios. Through the analysis of more than 40 milk thistle extract products on the market, we found that the ratios, specifically Ratio 1 (the silybin B content to the silybin A content, SBNB/SBNA) and Ratio 2 (the sum of the contents of silybin B and isosilybin B to the sum of the contents of silybin A and isosilybin A, (SBNB + IBNB)/(SBNA + IBNA)), are highly consistent across milk thistle extracts, averaging approximately 1.58 and 1.28, respectively. Furthermore, such ratios were verified in milk thistle seed samples. This study introduces significant findings concerning the stable ratios among silymarin isomers in milk thistle extracts and seeds, thereby offering an innovative approach for quality assurance of milk thistle extracts.