Retention Indices Research Articles

EI-MS fragmentation routes of CWC-related organoarsenic compounds: The electron ionization and DFT studies.

For unambiguous identification of Chemical Weapons Convention-related chemicals in environmental and biological samples, access to mass spectra and expertise in spectral interpretation is required. As of today, there is no mass spectrum available for dialkyl alkylarsonodithioites in the literature. Therefore, it is essential to obtain spectral information about these compounds. The CWC-related organoarsenic compounds were synthesized and analyzed by GC-MS, and their retention index (RI) was calculated by Van Den Dool's method. The relationship between RI and DFT-calculated polarizability (⍺) and molecular weight was also studied. Electron ionization (EI) mode was used to investigate the general fragmentation patterns of the synthesized compounds. A DFT analysis of some major fragment ions was performed in order to confirm the fragmentation pathways. A linear relationship between RI and ⍺ is observed. The mass spectra of compounds 5-7 are affected by alkyl groups on sulfur and arsenic atom. The molecular ion of compounds 5-7 can be observed in their EI-MS with relatively good abundance. EI-MS studies revealed some interesting fragmentation pathways, such as the formation of arsenic analogue of benzilic and tropylium in EI-MS of chemicals 6. By analyzing the mass spectra and RI values, it is possible to detect CWC-related chemicals in aqueous, blood, and urine samples during an on-site or off-site inspection.

Characterizing fabric shape retention by sequential image analysis

Fabric shape retention is one of the most important attributes of fabrics that can influence the quality of the end use product. In this paper, we present a computer vision-based method to analyze the sequential images, which records the dynamic change of a deformed fabric, to model the recovery process, and extract the features of the recovery curve to characterize the shape retention after the deformation. Image processing and the perceptual hash algorithm were used to convert the measurements of a fabric shape variable at different times into Hamming distance points. The recovery function of the fabric shape was formed by fitting the Hamming distance points with exponential function, and three new shape retention indexes, that is, the average slope, the abscissa of the inflation point, and the radius of curvature at the inflation point, were defined based on the recovery function. The experiment showed that the shape retention of 12 fabric samples after deformation could be effectively distinguished by the new indexes. This paper also discussed the relationships between the new indexes and the transitional measurements indicating the fabric shape retention.

Smart anti-vascular nanoagent induces positive feedback loop for self-augmented tumor accumulation

How to achieve efficient drug accumulation in the tumor with low vascular density is a great challenge but the key to push the limit of anti-vascular therapeutic efficacy. Herein, we report a charge-reversible nanoparticles of gambogenic acid (CRNP-GNA) that would induce the positive feedback loop between increased tumor vascular permeability and improved drug accumulation. This positive feedback loop would remarkably improve tumor vascular permeability for efficient drug accumulation through few residue vessels. As compared to its charge-irreversible analogue in the latter injections, the accumulation in tumor and vascular permeability and retention indexes (VPRI) in CRNP-GNA group respectively boosted from nearly equal to 8.32 and 60 times, while its tumorous microvessel density decreased from nearly equal to only 7%. The self-augmented accumulation consequently amplified the antitumor efficacy via multiple pathways of anti-angiogenesis, vascular disruption and pro-apoptosis, where 5 out of 6 tumors in animal models were completely cured by CRNP-GNA. This work confirms that the underlying positive feedback loop for anti-vascular therapy could be induced by charge-reversible drug delivery nanosystem to achieve efficient and self-augmented drug accumulation even in the tumor with few vessels. It provides a novel strategy to conquer the dilemma between anti-vascular efficacy and drug accumulation.

Estimation of Uncertainty of Measurements of Linear Retention Indices with Increasing Temperature of the Capillary Chromatographic Column

Estimation of Uncertainty of Measurements of Linear Retention Indices with Increasing Temperature of the Capillary Chromatographic Column

A new approach to the epoxidation of natural rubber through a sonochemical method

In this study, epoxidized natural rubber (ENR) was synthesized using a sonochemical method. Acoustic cavitation was employed for the epoxidation reaction instead of heat and agitation. The effects of reaction time and temperature on the epoxidation degree (EPD) were studied. The chemical structure and EPD of ENR were assessed by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) techniques. At low reaction times (≤45 min), the EPD was independent of the reaction temperature but tended to increase with increasing reaction time. However, at sufficiently long reaction times (>45 min), the EPD depended on both reaction time and temperature, i.e., it increased slightly with an increase in reaction time up to 60 min before leveling off at the reaction temperatures of 20 °C and 30 °C. However, at a higher reaction temperature (40 °C), it tended to decline slowly with increasing reaction time, possibly due to the ring-opening reaction. The highest EPD, at approximately 30%, was achieved when synthesized by a sonochemical method at 30 °C for 60 min, which is equivalent to that of the ENR synthesized by a conventional method at 60 °C for 6 h. The properties of the raw ENR samples (with ∼30% epoxidation) prepared by different methods were also investigated. It was found that the ENR sample prepared by the sonochemical method possessed a slightly higher viscosity, initial plasticity number, and plasticity retention index than the ENR sample prepared by the conventional method. The results reveal the potential of the sonochemical method to supplant the conventional method for ENR synthesis, as it requires a considerably lower reaction temperature and time.

Determination of The Essential Oil Components of Some Sage (Salvia Sp.) Species Naturally Distributed in The Isparta Province

Aim of the study: This study was performed to determine the essential oil components of Salvia tomentosa Mill., Salvia argentea L. and Salvia bracteata Bank et Sol. Area of study: The study was carried out in two districts (Eğirdir and Şarkikaraağaç) located at Isparta province in Turkey. Material and methods: The isolation of essential oil components was performed from shoots with leaves and flowers. Qualitative analysis of essential oils was carried out by using a Shimadzu 2010 Plus GC-MS device. The identification of the constituents was carried out by comparing the retention index (RI) and mass spectral data (MS) to those reported in the literature. Main results: As a result of the GC-MS analysis, the major components of the essential oil were (-)-caryophyllene oxide (49.56%), β-vatirenene (7.87%), and α-Muurolol (6.78%) in S. tomentosa, sclareol (40.01%), germacrene-D (13.93%) and β-pinene (11.93%) in S. argentea and eucalyptol (1,8-cineole) (16.6%), β-pinene (14.7%) and cembrene (10.88%) in S. bracteata. Sclareol, which was determined at a high concentration in S. argentea in this study, is an economically valuable component that is widely used as flavoring in food and tobacco industry and as a perfume ingredient in the cosmetic industry. Highlights: According to this study, the cultivation of S. argentea can provide high economic returns

Assisting the automated analysis of chemical–analytical measurements in spirits using validated algorithms and an intuitive user interface

Abstract. Exhaustive analysis of chemical measurements requires considerable expenditure of time and personnel. However, many aspects of this can be automated by translating manual work into objective algorithmic routines. To this end, we developed adaptable software for gas chromatography data and validated analysis steps using whisky samples. We employed an unspecific, larger, in-house volatile organic compound (VOC) database and another specifically curated database of 217 known whisky chemicals, to automate database-matching based on mass spectra and retention indices. We managed to reduce the amount of necessary interaction, facilitated complex analysis for the less experienced user, and showed that characteristic whisky components constituted the majority of detected molecules in all 16 analyzed samples. With this approach, we present a decisive contribution towards the automated assessment of aroma profiles in food.

Is oropharyngoesophageal scintigraphy the method of choice for assessing dysphagia in systemic sclerosis? A single center experience

ObjectivesTo evaluate the performance of oropharyngoesophageal scintigraphy (OPES) in the assessment of dysphagia in patients with systemic sclerosis (SSc), and to compare OPES results with those of barium esophagogram.MethodsAdult SSc patients who underwent OPES for the assessment of dysphagia were enrolled. OPES was performed with both liquid and semisolid boluses and provided information regarding oropharyngeal transit time, esophageal transit time (ETT), oropharyngeal retention index (OPRI), esophageal retention index (ERI), and site of bolus retention. Barium esophagogram results were also collected.ResultsFifty-seven SSc patients (87.7% female, mean age 57.7 years) with dysphagia were enrolled. OPES identified at least one alteration in each patient and findings were generally worse for the semisolid bolus. Esophageal motility was widely impaired with 89.5% of patients with an increased semisolid ERI, and middle-lower esophagus was the most frequent site of bolus retention. However, oropharyngeal impairment was highlighted by widespread increased OPRI, especially in anti-topoisomerase I positivity. Older patients and with longer disease duration presented slower semisolid ETT (p = 0.029 and p = 0.002, respectively). Eleven patients with dysphagia had a negative barium esophagogram: all of them presented some alterations in OPES parameters.ConclusionOPES revealed a marked SSc esophageal impairment, in terms of both slowed transit time and increased bolus retention, but also shed light on oropharyngeal swallowing alterations. OPES showed high sensitivity, being able to detect swallowing alterations in dysphagic patients with negative barium esophagogram. Therefore, the use of OPES for the assessment of SSc-related dysphagia in clinical practice should be promoted.

The Leaf Essential Oil of Gynoxys buxifolia (Kunth) Cass. (Asteraceae): A Good Source of Furanoeremophilane and Bakkenolide A

The present study describes the chemical and enantiomeric composition of a new essential oil, distilled from the dry leaves of Gynoxys buxifolia (Kunth) Cass. The chemical analysis was conducted by GC-MS and GC-FID, on two orthogonal capillary columns. A total of 72 compounds were detected and quantified with at least one column, corresponding to about 85% by weight of the whole oil mass. Of the 72 components, 70 were identified by comparing the respective linear retention indices and mass spectra with data from the literature, whereas the two main constituents were identified by preparative purification and NMR experiments. The quantitative analysis was carried out calculating the relative response factor of each compound according to their combustion enthalpy. The major constituents of the EO (≥3%) were: furanoeremophilane (31.3-28.3%), bakkenolide A (17.6-16.3%), caryophyllene oxide (6.0-5.8%), and (E)-β-caryophyllene (4.4%). Additionally, the hydrolate was also analyzed with respect to the dissolved organic phase. About 40.7-43.4 mg/100 mL of organic compounds was detected in solution, of which p-vinylguaiacol was the main component (25.4-29.9 mg/100 mL). Finally, the enantioselective analysis of some chiral terpenes was carried out, with a capillary column based on β-cyclodextrin chiral stationary phase. In this analysis, (1S,5S)-(-)-α-pinene, (1S,5S)-(-)-β-pinene, (S)-(+)-α-phellandrene, (S)-(+)-β-phellandrene, and (S)-(-)-terpinen-4-ol were detected as enantiomerically pure, whereas (S)-(-)-sabinene showed an enantiomeric excess of 69.2%. The essential oil described in the present study is a good source of two uncommon volatile compounds: furanoeremophilane and bakkenolide A. The former lacks bioactivity information and deserves further investigation, whereas the latter is a promising selective anticancer product.

Monitoring tafamidis treatment with quantitative SPECT/CT in transthyretin amyloid cardiomyopathy.

Tafamidis treatment positively affects left ventricular (LV) structure and function and improves outcomes in patients with transthyretin amyloid cardiomyopathy (ATTR-CM). We aimed to investigate the relationship between treatment response and cardiac amyloid burden identified by serial quantitative 99mTc-DPD SPECT/CT. We furthermore aimed to identify nuclear imaging biomarkers that could be used to quantify and monitor response to tafamidis therapy. Forty wild-type ATTR-CM patients who underwent 99mTc-DPD scintigraphy and SPECT/CT imaging at baseline and after treatment with tafamidis 61 mg once daily [median, 9.0 months (interquartile range 7.0-10.0)] were divided into two cohorts based on the median (-32.3%) of the longitudinal percent change in standardized uptake value (SUV) retention index. ATTR-CM patients with a reduction greater than or equal to the median (n = 20) had a significant decrease in SUV retention index (P < 0.001) at follow-up, which translated into significant benefits in serum N-terminal prohormone of brain natriuretic peptide levels (P = 0.006), left atrial volume index (P = 0.038), as well as LV [LV global longitudinal strain: P = 0.028, LV ejection fraction (EF): P = 0.027, LV cardiac index (CI): P = 0.034] and right ventricular (RV) [RVEF: P = 0.025, RVCI: P = 0.048] functions compared with patients with a decrease less than the median (n = 20). Treatment with tafamidis in ATTR-CM patients results in a significant reduction in SUV retention index, associated with significant benefits for LV and RV function and cardiac biomarkers. Serial quantitative 99mTc-DPD SPECT/CT imaging with SUV may be a valid tool to quantify and monitor response to tafamidis treatment in affected patients. 99mTc-DPD SPECT/CT imaging with determination of SUV retention index as part of a routine annual examination can provide evidence of treatment response in ATTR-CM patients receiving disease-modifying therapy. Further long-term studies with 99mTc-DPD SPECT/CT imaging may help to evaluate the relationship between tafamidis-induced reduction in SUV retention index and outcome in patients with ATTR-CM and will demonstrate whether highly disease-specific 99mTc-DPD SPECT/CT imaging is more sensitive than routine diagnostic monitoring.

Accurate identification and quantification of ultra-multi-target flavours in essential oils through a combination of retention index distribution-based parallel dual-column GC-MS/MS and analyte protectants

Accurate identification and quantification of ultra-multi-target flavours in essential oils through a combination of retention index distribution-based parallel dual-column GC-MS/MS and analyte protectants

Application of Liquid Smoke from Rubber Wood Clone PB-340 as Latex Coagulant and Preservation of Natural Rubber Coagulum

The utilization of rubber wood waste in the form of liquid smoke has the potential to overcome environmental problems caused by the industry. Therefore, this study aimed to determine the potential of liquid smoke from rubberwood clone PB 340 to be used as a coagulant and preservative. Rubber wood waste was processed into liquid smoke using the pyrolysis method with a temperature of 400°C. Determination of the composition of liquid smoke was carried out using gas chromatography-mass spectrometry (GC-MS) analysis. The results showed that the rubber wood clone PB 340 contained 57.78% cellulose, 12.16% hemicellulose, and 19.01% lignin. Furthermore, volatile analysis with GC-MS showed that liquid smoke from rubber wood clone PB 340 contained 58 organic compounds. Some compounds in liquid smoke were phenols, furans, furfurals, acetic acid, and cyclopentene. The product was then tested for its performance as a latex coagulant at several concentrations of 5%, 10%, 15%, 20%, and 25% v/v, as well as storage time of 1, 7, and 14 days. The treated latex samples that had turned into coagulums were examined for their sheet quality parameters, including initial plasticity (P0), plasticity retention index (PRI), total volatile compounds, impurity, and ash content. The outcomes from all comparisons of pure liquid smoke concentrations and storage time of up to 14 days of the coagulum samples showed that in the initial plasticity value (P0), the plasticity retention index (PRI), volatile matter, ash content, and dirt content had met the applied Standard Indonesian Rubber (SIR).

Predicting RP-LC retention indices of structurally unknown chemicals from mass spectrometry data

Non-target analysis combined with liquid chromatography high resolution mass spectrometry is considered one of the most comprehensive strategies for the detection and identification of known and unknown chemicals in complex samples. However, many compounds remain unidentified due to data complexity and limited number structures in chemical databases. In this work, we have developed and validated a novel machine learning algorithm to predict the retention index (r_i) values for structurally (un)known chemicals based on their measured fragmentation pattern. The developed model, for the first time, enabled the predication of r_i values without the need for the exact structure of the chemicals, with an R^2 of 0.91 and 0.77 and root mean squared error (RMSE) of 47 and 67 r_i units for the NORMAN (n=3131) and amide (n=604) test sets, respectively. This fragment based model showed comparable accuracy in r_i prediction compared to conventional descriptor-based models that rely on known chemical structure, which obtained an R^2 of 0.85 with an RMSE of 67.

Cocktail effect and synergistic mechanism of two components of Perilla frutescens essential oil, perillaldehyde and carvone, against Tribolium castaneum

Tribolium castaneum (Herbst) is one of the most harmful insects in stored products. The objective of the current study was to search for active constituents of Perilla frutescens (L.) Britt. essential oils from three localities against T. castaneum, as well as to investigate the optimal formula of active constituents and their synergistic mechanism. A total of 38 constituents were identified from the three essential oils by gas chromatography-mass spectrometry (GC-MS) according to the mass spectra and retention index values, and the relative contents of the individual components were determined by the peak normalization method. The following major compounds were identified: perillaldehyde, (R)-(-)-carvone, 2-furyl methyl ketone, d-limonene, and β-caryophyllene. Contact toxicity was assessed by topical application under room temperature, and the insects were reared in a dark incubator for 24 h at approximately 30 °C and 75 % humidity. Of these compounds, perillaldehyde (LD50 =7.71 μg/adult) and R-(-)-carvone (LD50 =10.93 μg/adult) displayed the most significant contact activities against T. castaneum. Synergistic interactions between perillaldehyde and R-(-)-carvone were evaluated using Wadley's model. All nine tested formulas displayed synergistic effects against T. castaneum, and a 1:4 (v:v) mixture exhibited an intense cocktail effect by dramatically reducing the LD50 to 2.73 μg/adult. The results of the RNA-Seq and qRT-PCR analyses suggested that the synergistic effect could be attributed to a reduced capacity for detoxification and elimination of xenobiotics. Three cytochrome P450 genes (CYP6BQ11, CYP6BQ7, and CYP6BK5) in phase I and two multidrug resistance protein genes (MRP4a and MRPX4) in phase III of the detoxification process may play essential roles. These findings provide a basis for the development of novel natural insecticides for the control of storage pests.

The use of gas chromatography – high resolution mass spectrometry for suspect screening and non-targeted analysis of per- and polyfluoroalkyl substances

This study is a workflow development for the analysis, identification, and categorization of per- and polyfluoroalkyl substances (PFAS) using gas chromatography-high resolution mass spectrometry (GC-HRMS) with non-targeted analysis (NTA) and suspect screening techniques. The behavior of various PFAS in a GC-HRMS was studied with regards to retention indices, ionization susceptibility, fragmentation patterns, etc. A custom PFAS database was constructed from 141 diverse PFAS. The database contains mass spectra from electron ionization (EI) mode, as well as MS and MS/MS spectra from positive and negative chemical ionization (PCI and NCI, respectively) modes. Common fragments of PFAS were identified across a diverse set of 141 PFAS analyzed. A workflow for suspect screening of PFAS and partially fluorinated products of incomplete combustion/destruction (PICs/PIDs) was developed which utilized both the custom PFAS database and external databases. PFAS and other fluorinated compounds were identified in both a challenge sample (designed to test the identification workflow) and incineration samples suspected to contain PFAS and fluorinated PICs/PIDs. The challenge sample resulted in a 100% true positive rate (TPR) for PFAS which were present in the custom PFAS database. Several fluorinated species were tentatively identified in the incineration samples using the developed workflow.

Chemical composition and biological activities of Jamaican Cannabis sativa essential oils as the plant matures

AbstractCannabis sativa is a flowering plant belonging to the Cannabinaceae family. There have been numerous ongoing studies globally on C. sativa which include investigating the yield and quality of essential oils. However, this study is the first to assess the chemical composition and biological activities of Jamaican C. sativa essential oils (EOs) extracted via hydrodistillation as the plants mature from week 8 through to week 12. EOs from fresh landrace female plants were analysed by gas chromatography–mass spectrometry (GC–MS) and GC coupled to a flame ionization detector (GC‐FID). Cannabis sativa essential oils were screened for their in vitro antimicrobial activity using the disc diffusion method and further with tube dilution method. The antioxidant properties were investigated using the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging assay. In total, 36 constituents were identified in the C. sativa EOs by comparison of the Kováts retention indices (RI), the mass spectra data with those in the Natural Institute of Standards and Technology (NIST) library and by co‐elution with authentic samples where available. The major constituents were β‐caryophyllene (25.34%) and α‐humulene (α‐caryophyllene) (10.94%) both at the highest levels in week nine and were the most abundant constituents present at all stages of maturity. All extracted C. sativa essential oils did not exhibit antioxidant properties. However, the C. sativa essential oils exhibit significant to moderate antimicrobial property against the test gram‐positive microorganisms, Enterococcus faecalis, Streptococcus Group A and Streptococcus Group B with MIC values ranging from 16 to 125 μg/mL.

Phytochemical Characterization of Cannabis sativa L. Roots from Northeastern Brazil.

This article describes the phytochemical study of Cannabis sativa roots from northeastern Brazil. The dried plant material was pulverized and subjected to exhaustive maceration with ethanol at room temperature, obtaining the crude ethanolic extract (Cs-EEBR). The volatile compounds were analyzed by gas chromatography coupled with mass spectrometry (GC/MS), which allowed to identify 22 compounds by comparing the linear retention index (LRI), the similarity index (SI) and the fragmentation pattern of the constituents with the literature. By this technique the major compounds identified were: friedelan-3-one and β-sitosterol. In addition, two fractions were obtained from Cs-EEBR by classical column chromatography and preparative thin layer chromatography. These fractions were analyzed by NMR and IR and together with the mass spectrometry data allowed to identify the compounds: epifriedelanol, friedelan-3-one, β-sitosterol and stigmasterol. The study contributed to the phytochemical knowledge of Cannabis sativa, specifically the roots, as there are few reports on the chemical constituents of this part of the plant.

Lime replacement by finely ground clay from the north fluminense region of RJ in mortar for coating walls and ceilings

This work aims to identify the effects of replacing lime to finely ground kaolinitic clay (GC) in mortars for coating walls and ceilings, evaluating the water retention, calorimetry, XRD, mechanical resistance, water absorption and void index, and comparing these properties with a mortar with lime, called reference mortar (RM), and one with the addition of a commercial clay (CC) sold at the local trade. The justificative of this work is due to the fact that clay is empirically incorporated into mortars, as a substitute for lime, in order to improve its workability. However, these replacements modify the properties of the mortars and, therefore, experimental evidence to evaluate the most important properties must be carried out. Through the tests performed, an increase in water consumption in mortars of 36% with CC and 45% with GC was observed, however these results did not influence the properties of water retention. Through the patterns obtained in the XRD test, it was observed that the addition of GC in the mortar consumed the portlandite, meaning that there is a probable pozzolanic reaction in the formation of new C–S–H compounds. These results prove that kaolinitic clay can be added in 1:1:6 mortars, maintaining its most important properties for use as coatings.

A New Essential Oil from the Leaves of Gynoxys rugulosa Muschl. (Asteraceae) Growing in Southern Ecuador: Chemical and Enantioselective Analyses.

An essential oil, distilled from the leaves of the Andean species Gynoxys rugulosa Muschl., is described in the present study for the first time. The chemical composition was qualitatively and quantitatively determined by GC-MS and GC-FID, respectively. On the one hand, the qualitative composition was obtained by comparing the mass spectrum and the linear retention index of each component with data from literature. On the other hand, the quantitative composition was determined by calculating the relative response factor of each constituent, according to its combustion enthalpy. Both analyses were carried out with two orthogonal columns of nonpolar and polar stationary phases. A total of 112 compounds were detected and quantified with at least one column, corresponding to 87.3-93.0% of the whole oil mass. Among the 112 detected components, 103 were identified. The main constituents were α-pinene (5.3-6.0%), (E)-β-caryophyllene (2.4-2.8%), α-humulene (3.0-3.2%), germacrene D (4.9-6.5%), δ-cadinene (2.2-2.3%), caryophyllene oxide (1.6-2.2%), α-cadinol (3.8-4.4%), 1-nonadecanol (1.7-1.9%), 1-eicosanol (0.9-1.2%), n-tricosane (3.3-3.4%), 1-heneicosanol (4.5-5.8%), n-pentacosane (5.8-7.1%), 1-tricosanol (4.0-4.5%), and n-heptacosane (3.0-3.5%). Furthermore, an enantioselective analysis was carried out on the essential oil, by means of two cyclodextrin-based capillary columns. The enantiomers of α-pinene, β-pinene, sabinene, α-phellandrene, β-phellandrene, linalool, α-copaene, terpinen-4-ol, α-terpineol, and germacrene D were detected, and the respective enantiomeric excess was calculated.

Hydrolytic Stability of Unsubstituted Hydrazones of Aromatic Carbonyl Compounds in Reversed-Phase HPLC

Unsubstituted hydrazones RR′C=NNH2 are unstable during gas chromatographic separation. Testing of their resistance to hydrolysis under reversed-phase HPLC showed that aromatic ketone hydrazones are stable. In contrast, aldehyde hydrazones are only stable in neutral methanol–water systems (in the absence of acidic modifiers). In acetonitrile–water systems containing 0.1% of formic acid, only aromatic ketone hydrazones are stable, while aldehyde derivatives are completely hydrolyzed. This difference in stability must be taken into account in determining other compounds of these classes. To detect the hydrolysis of analytes, we compared the retention indices of the initial carbonyl compounds and hydrazones at different volume ratios of organic modifiers and aqueous phases and different pH values of the eluent, the relative absorbance values of the characterized components A(254/220) = A(254)/A(220), and the chromatography–mass spectrometric data.