Polar Column Research Articles

An analytical method for the determination of glyphosate and aminomethylphosphoric acid using an anionic polar pesticide column and the application in urine and serum from glyphosate poisoning patients.

An analytical method for the determination of glyphosate (GLY) and aminomethylphosphoric acid (AMPA) in biological fluid samples (serum and urine) from poisoning patients using liquid chromatography-tandem mass spectrometry (LC-MS/MS) is established. After the sample pretreatment, including protein precipitation and a modified liquid-liquid extraction method, the chromatographic separation was conducted on a trifunctional modified hydrophilic column. The mobile phases in the gradient program were 2.5% formic acid aqueous solution and acetonitrile. The multiple reaction monitoring (MRM) models and the isotope-labeled internal standards were used in the acquisition process. Good linearities and satisfying recovery rates were obtained in two sample matrices with good RSDs. The detection limits of GLY and AMPA were <2 μg L-1, which were close to those obtained in our previous research. The established method was applied to biological samples from five patients with glyphosate intoxication. The analysis of the trend for the concentration of GLY and AMPA in two biological samples was investigated, and the difference in the downward trend of AMPA in urine was found in patients with a relatively higher concentration of GLY in serum.

Trace Detection Method for Tetramine in Drinking Water by Atmospheric Pressure Gas Chromatography-Mass Spectrometry

This study reports a trace detection method for tetramine in drinking water using atmospheric pressure gas chromatography-tandem mass spectrometry (APGC-MS/MS). After dilution with acetone, the drinking water samples were directly measured using APGC-MS/MS. Separation of tetramine was achieved using a DB-5MS weak polar column (30 m × 0.25 mm, 0.25 μm) and detected with APGC ionization source in positive ion mode. Cone gas and auxiliary flow rates were optimized to 250 L/h and 350 L/h, respectively. Quantitative and qualitative analysis was conducted by monitoring two molecular ions of the target compound (m/z 121.6 and m/z 92.6) under multiple reaction monitoring mode (MRM). The linear relationship between tetramine and its concentration was good in the range of 5-100 ng/L, with a correlation coefficient of 0.9999. The detection limit of the method was 0.3 ng/mL and the quantification limit was 1.0 ng/mL. The recovery of the samples was approximately 80.63% to 86.84%, with an intra-day RSD of 1.2% to 3.5% and an inter-day RSD of 2.9% to 4.9%, which met the requirements for trace detection. This method is simple, fast and highly sensitive and it is suitable for the trace detection of tetramine in drinking water.

Chemical Composition of Thymus leucotrichus var. creticus Essential Oil and Its Protective Effects on Both Damage and Oxidative Stress in Leptodictyum riparium Hedw. Induced by Cadmium.

The chemical profile of the essential oil (EO) of the aerial parts of Thymus leucotrichus var. creticus (Lamiaceae), a taxon not previously studied, was investigated by GC-MS analysis, using a DB-Wax polar column. Oxygenated monoterpenes and monoterpene hydrocarbons dominate the EO, with thymol (46.97%) and p-cymene (28.64%) as the main constituent of these two classes, respectively. The ability of the EO of T. leucotrichus to reduce Cd toxicity was studied in aquatic moss Leptodictyum riparium. To study EO-induced tolerance to Cd toxicity, apex growth, number of dead cells, DNA damage and antioxidant response in gametophytes were examined. The exogenous application of the EO yields a resumption of growth rate and a reduction in the number of dead cells; it also reduces the oxidative stress induced by Cd, as demonstrated by the reduction of the ROS content (with a decrease of 1.52% and 5%) and by the increased activity of antioxidant enzymes such as superoxide dismutase (SOD) (with an increase of 1.44% and 2.29%), CAT catalase (1.46% and 2.91%) and glutathione-S-transferase GST (1.57% and 1.90%). Furthermore, the application of the EO yields a reduction of DNA damage. These results clearly indicate the protective capacity of the EO of T. leucotrichus in modulating the redox state through the antioxidant pathway by reducing the oxidative stress induced by Cd.

Structural similarities of phytochemicals significantly contribute to species delimitation of Nigella and Garidella (Ranunculaceae)

ABSTRACT The genera Nigella and Garidella are two members of the Nigelleae tribe. Among all the taxa of the tribe, black cumin (Nigella sativa L.) is one of the most important plants concerning economic and medicinal uses. In this study, volatiles were analyzed in detail to elucidate the phytochemical profiles and to understand the taxonomic patterns of secondary metabolites for 19 taxa of Nigella and Garidella collected from Turkey and the neighboring countries. Volatiles were analyzed by gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC/MS) using different polarity columns. Seventeen Nigella and two Garidella taxa were investigated, with 130 volatile oil components characterized. Structural similarities of the compounds were clustered by a machine learning algorithm using the molecular fingerprinting method. Our results depict that the phytochemicals produced by Nigelleae can be classified independently of their chemical families and significantly contribute to genera delimitation by their structural distances.

Novel, Selective Calix[6]Arene - Polyethylene Glycol (C6A-PEG) Stationary Phase for Capillary Gas Chromatography (GC)

A novel calix[6] arene polymer stationary phase (C6A-PEG) is reported that combines the π-electron-rich cavity of calix[6] arene (C6A) with polyethylene glycol (PEG) units for gas chromatography (GC). Thermogravimetric analysis revealed a 5% weight loss of C6A-PEG at 318 °C, and its static-coated capillary column showed high efficiency of 2924 plates/m (k = 3.48) determined by 1-octanol at 120 °C. As a result, the moderate polar C6A-PEG column showed clearly advantageous performance for the Grob reagent and a mixture of 25 analytes with high selectivity for hydrogen-bonded acids. Also, it exhibited high resolving performance for various isomer mixtures, in particular high-resolution performance (R > 2.2) for the challenging toluidine and dimethylaniline systems with distinct advantages compared to the C6A and PEG columns (R < 1.5 for some pairs). This work demonstrates the potential of calixarene-based polymers as novel stationary phases for gas chromatographic analysis.

Association between Glucose Consumption and Oocyte Maturation Competence in Mice with Polycystic Ovarian Syndrome.

This study evaluated association between glucose uptake by individually cultured oocyte and their maturation competence in mice with polycystic ovarian syndrome (PCOS). In this experimental study, PCOS and non-PCOS cumulus-oocyte complexes (COCs), and cumulus-denuded oocytes (DOs) were cultured individually and categorized in four groups: i. PCOS DOs (n=83), ii. PCOS COCs (n=35), iii. Non-PCOS DOs (n=61) and iv. Non-PCOS COCs (n=62). After the culture period, 50 μl aliquots of the spent drops were used for glucose change analysis using high performance liquid chromatography. Polar NH2 column was used for the study of carbohydrates, acetonitrile with deionized water as the solvent phase and UV as detectors. Oocyte quality (growth differentiation factor 9: GDF-9), viability [bcl-2-like protein 4 (BAX) and B-cell lymphoma2 (BCL2)], in addition to fertilization and embryonic development rates were also evaluated in relation to glucose consumption rate of each oocyte. Maturation rate was significantly higher in non-PCOS COCs and DOs compared to PCOS COCs (IV: 70.9% vs. II: 45.71%) and DOs (III: 67.2% vs. 1: 53.01%), respectively. There was a significant negative correlation between high glucose intake (38.17 ppm) and BCL2 gene expression (P=0.03) in PCOS COCs compared to non-PCOS COCs. There was a significant difference in the GDF-9 gene expression from PCOS DOs (0.66 ± 0.02, P=0.003) and COCs (0.37 ± 0.02, P=0.0001) compared to non-PCOS DOs and COCs, respectively. A negative correlation was also observed between quality of PCOS-DOs and -COCs with glucose intake. Non-PCOS COCs significantly showed higher rate of successful IVF and development compared to PCOS COCs (P=0.01). Based on the importance of metabolic analysis, the glucose consumption by DOs and COCs in culture medium can be a suitable criterion for their quality assessment. So that, glucose consumption may reflect oocyte maturation competence.

Quality characteristics and volatile compounds of oil extracted from njangsa seed

AbstractUnconventional and underutilized plant oils are increasing popular and helping to meet demand for food, health and other industrial application. In recent years, the search for alternative sources that deliver healthful benefits, low‐environmental impact and ethical responsibility have become a priority to both scientists and industry. Oil from njangsa seed (Ricinodendron heudelotti) was recovered using four selected enzymes—hemicellulase, protease, pectinase, and amylase in an enzyme‐assisted aqueous extraction (EAE) and the recovery, quality indices and fatty acid composition was compared to solvent extraction using hexane (HE). Njangsa seed oil (NSO) recovered from the EAE ranged between 29 and 36% and were significantly (p &lt; 0.05) lower than HE (46%), and the quality indices (free fatty acid, peroxide, para‐anisidine, and thiobarbituric acid values) were consistently lower and better than HE‐NSO. The fatty acid profile of EAE‐NSO was qualitatively and quantitatively comparable to HE‐NSO, with differences among the enzymes used. Alpha‐eleostearic acid was the most abundant fatty acid and was consistently ca 41% among the samples. Among the volatile compounds analyzed on the polar and nonpolar columns, 13 (2 alcohols, 9 aldehydes, and 2 esters) were detected in EAE‐NSO using hemicellulase, and 35 (4 aldehydes, 1 ester, and 30 hydrocarbons) in HE‐NSO. The most abundant flavor compounds identified were pentanal, methylcyclopentane, cyclohexane, 3‐methylpentane, (E,E)‐2,4‐nonadienal, (E)‐2‐heptenal, hexanal, 1‐butanol, and butanal. This study suggests that the amount, quality, and content of oil and volatile compounds in NSO can be influenced by the choice of extractant.

4. 1-Etylo-2-pirolidon. Metoda oznaczania w powietrzu na stanowiskach pracy z zastosowaniem chromatografii gazowej

1-Ethyl-2-pyrrolidone (NEP) is a colorless liquid with ammonia-like odor. It belongs to the organic compounds from the lactam group, i.e., the ethyl derivative of 2-pyrrolidone. 1-Ethyl-2-pyrrolidone, due to similar physicochemical proper-ties, is used in industry as a substitute for 1-methyl-2-pyrrolidone (NMP). It is used as a solvent in polymer, petroche-mical, paint and varnish, and electronic industries. Moreover, it has been used as a cleaning agent for removing paints, varnishes, adhesives, oil or grease. 1-Ethyl-2-pyrrolidone can be absorbed through the skin as well as through inhalation and food. The aim of the this study was to develop and validate a method for determining 1-ethyl-2-pyrrolidone in work-place air. The developed method of NEP determination consists in adsorption of vapors of this substance on coconut shell charcoal, extraction with a dichloromethane and chromatographic analysis of the obtained solution. The study was performed using a gas chromatograph coupled with mass spectrometer (GC-MS), equipped with a polar ZB-WAXplus capillary column (length 60 m, diameter 0.25 mm and the film thickness of the stationary phase 0.5 µm). The developed method is linear in the concentration range of 15.0–320.0 µg/ml, which corresponds to the range of 1.5–32.0 mg/m3 for a 10-L air sample. The analytical method described in this paper makes it possible to determine 1-ethyl-2-pyrrolidone in workplace air in the presence of comorbid substances. The method is precise, accurate and it meets the criteria for procedure for measuring chemical agents listed in Standard No. PN-EN 482. Developed method of determining 1-ethyl- 2-pyrrolidone at workplace air has been recorded as an analytical procedure (see Appendix). This article discusses the problems of occupational safety and health, which are covered by health sciences and environmental engig.

Validated single urinary assay designed for exposomic multi-class biomarkers of common environmental exposures.

Epidemiological studies often call for analytical methods that use a small biospecimen volume to quantify trace level exposures to environmental chemical mixtures. Currently, as many as 150 polar metabolites of environmental chemicals have been found in urine. Therefore, we developed a multi-class method for quantitation of biomarkers in urine. A single sample preparation followed by three LC injections was optimized in a proof-of-approach for a multi-class method. The assay was validated to quantify 50 biomarkers of exposure in urine, belonging to 7 chemical classes and 16 sub-classes. The classes represent metabolites of 12 personal care and consumer product chemicals (PCPs), 5 polycyclic aromatic hydrocarbons (PAHs), 5 organophosphate flame retardants (OPFRs), 18 pesticides, 5 volatile organic compounds (VOCs), 4 tobacco alkaloids, and 1 drug of abuse. Human urine (0.2 mL) was spiked with isotope-labeled internal standards, enzymatically deconjugated, extracted by solid-phase extraction, and analyzed using high-performance liquid chromatography-tandem mass spectrometry. The methanol eluate from the cleanup was split in half and the first half analyzed for PCPs, PAH, and OPFR on a Betasil C18 column; and pesticides and VOC on a Hypersil Gold AQ column. The second half was analyzed for tobacco smoke metabolites and a drug of abuse on a Synergi Polar RP column. Limits of detection ranged from 0.01 to 1.0 ng/mL of urine, with the majority ≤0.5 ng/mL (42/50). Analytical precision, estimated as relative standard deviation of intra- and inter-batch uncertainty, variabilities, was <20%. Extraction recoveries ranged from 83 to 109%. Results from the optimized multi-class method were qualified in formal international proficiency testing programs. Further method customization options were explored and method expansion was demonstrated by inclusion of up to 101 analytes of endo- and exogenous chemicals. This exposome-scale assay is being used for population studies with savings of assay costs and biospecimens, providing both quantitative results and the discovery of unexpected exposures.

TECHNICAL NOTE: Analysis of volatile fatty acids in rumen fluid by gas chromatography mass spectrometry using a dimethyl carbonate extraction.

Analysis of rumen fluid volatile fatty acids (VFA) is typically conducted by injecting acidified aqueous rumen fluid into a gas chromatograph (GC) with a flame ionization detector (FID). Aqueous samples are highly problematic because of the large vapor volume that can lead to poor peak shape and contamination of inlets, potentially causing sample carryover. Methods using aqueous samples are not well suited for use in a mass spectrometer (MS) detector system. The objective of this project was to validate a dimethyl carbonate (DMC) extraction process and GCMS method for rumen VFA analysis. To perform the extraction, 100 µL of sample, KHSO4 (500 g/L), and 2-ethylbutyrate (internal standard; 8.5 mM) were added to a microcentrifuge tube (in order) followed by 1 mL of DMC. The mixture was thoroughly vortexed and centrifuged. The organic layer (top) was removed and placed in a GC vial. The DMC extract was injected (0.5 µL) into an Agilent 5977B GCMS (8:1 split injection) with a polar DB-FFAP column. The column was held at 105 °C for 5 min, increased at 10 °C/min to 150 °C, then 65 °C/min to 240 °C, and held constant for 10 min. The peak area of acetate relative to the internal standard is linear from approximately 2 mM to at least 130 mM and encompasses the expected values of rumen concentrations for the other VFA. Recovery of VFA from spiked rumen fluid was tested at three concentrations in rumen fluid from steers fed a finishing diet or grazing wheat pasture. Recovery was not affected by the diet of the animals (P > 0.10) or the amount of VFA spiked (P > 0.19) for acetate, propionate, isobutyrate, or butyrate. There was an interaction of amount of VFA spiked and the diet of the animal (P = 0.021) for valerate and a tendency for an interaction (P = 0.051) for isovalerate, due to the recovery of the VFA being lower in the medium spike amount in rumen fluid from cattle on wheat pasture. Overall, recovery was greatest for propionate (101.9 ± 1.67%) and lowest for valerate (95.7 ± 1.95%). Including the 10-min hold at 240 °C at the end of each run prevented carryover from sample to sample. This method appears to perform well in a GCMS system and accurately and precisely quantifies rumen fluid VFA.

A novel technique for detection of vanaspati ( hydrogenated fat ) in cow ghee ( clarified butter fat ) using flash gas chromatography electronic nose combined with chemometrics

This study aimed to detect various proportions of vanaspati mixed with cow ghee using an electronic nose (e-nose) based on fast gas chromatography. The e-nose apparatus was equipped with a non-polar and medium polar column used to generate two chromatograms simultaneously along with the volatile compound information. Further investigation on the adulteration detection in ghee was carried out using chemometric analysis such as principal component analysis (PCA), discriminant function analysis (DFA), and soft-independent modeling of class analogy (SIMCA). An outstanding differentiation among all the samples was obtained using PCA and DFA with 99.85% and 99.83% classification accuracy in the e-nose dataset. SIMCA presented a validation score of 76, indicating SIMCA could also be a potential method to detect higher levels of adulteration in ghee. The validation study shows good agreement between FGCEN and GC–MS methods. Practical applications Cow ghee is frequently adulterated with vanaspati, due to its high market demand. The existing methods for adulteration detection are time-consuming, and require tedious sample preparation and expertise in these fields. The e-nose based on fast GC combined with chemometric analysis turned out to be a reliable and promising technique for various proportions of adulteration detection in pure cow ghee. The technique was efficient enough to get the volatile compound information from the samples in a fast-performing way. The chemometrics used has shown to be effective to confirm adulterations in ghee.

Rapid, sensitive and selective detection of glyphosate in wheat and rice flour using a polar stationary phase by LC–MS/MS

Rapid, sensitive and selective method was studied for the determination of glyphosate in rice and wheat flour using a Raptor Polar column. Samples were extracted with acidified methanol solution. Isotope labeled internal standard was added with the extraction solvent to ensure accurate tracking and quantitation. The glyphosate was analyzed by liquid chromatography tandem mass spectrometry using a Raptor Polar column. Method performance was evaluated through a series of parameters that include accuracy, precision, linearity, limit of detection (LOD), limit of quantitation (LOQ) and matrix effect. Mean recoveries for all matrices were within 96–116% at three fortification levels. Precision for replicates was ≤19% relative standard deviation (RSD%) for wheat and ≤9% RSD% for rice across all fortification levels. Linearity was good for both matrices with a correlation coefficient >0.999 and residual <20% in the concentration range 0.025–1 mg kg−1. LOD was 0.005 mg kg−1for both rice and wheat flour and the LOQ was 0.05 mg kg−1for both matrices. The matrix effect was also studied. A successful method for the analysis of glyphosate in wheat and rice flour assure that the criteria of acceptability of the maximum residue levels (MRLs) are insured.

Identification of novel compounds in rose absolute with gas chromatography/high‐resolution mass spectrometry

AbstractGas Chromatography/High‐Resolution Mass Spectrometry (HRMS) was used to identify new compounds in Rosa damascena and Rosa centifolia absolutes. These compounds were esters derived from the main alcohols of rose absolute (phenylethyl alcohol, geraniol, citronellol, nerol, and (E,E)‐farnesol). Based on low‐resolution mass spectrometry (LRMS) and HRMS data of rose absolutes, hypotheses were first formulated. In a second stage, the standards of these candidate structures were synthetized and analyzed by LRMS using apolar and polar columns. LRMS spectra of these standards, and apolar and polar retention indices (RI) were compared with those of candidate structures. Only four out of nineteen molecules were validated by these three criteria mostly due to an important difference of polar RIs between the standards and the compounds detected in rose absolutes. In a third stage, absolutes were spiked with synthesized standards and were analyzed by HRMS on both apolar and polar columns to confirm the presence of these candidate structures. Finally, 19 new compounds were identified in Rosa damascena and Rosa centifolia absolutes.

Analysis of biodiesel-diesel blends: Does ultrafast gas chromatography provide for similar separation in a fraction of the time?

Ultrafast gas chromatography (UFGC) using a moderately polar column was compared to traditional gas chromatography (GC) for evaluation of biodiesel-diesel blended fuels. Several biodiesel feedstocks (soybean, tallow, canola, palm, camelina) and concentrations (1–20%) were evaluated, with specific attention to the separation of fatty acid methyl esters (FAMEs) from the biodiesel component. UFGC is compared to traditional GC using a similar column chemistry. Principal component analysis (PCA) is performed to identify clustering based on feedstock and concentration. UFGC proves an effective and fast technique, comparable to traditional GC, for the analysis of biodiesel-diesel blended fuels.

HPLC BASED PROCEDURE DEVELOPMENT FOR MONITORING ACETIC ACID IN DACLATASVIR DRUG

A process for determination of acetic acid (AAD) in Daclatasvir (DAC) active medicinal ingredients applying HPLC technique was developed. The process involved separation AAD using Phenomenex made Synergi polar RP-80A column with gradient manner of elution, employing mobile solvent phase with 0.1% phosphoric acid (solvent A) and acetonitrile (solvent B), at flow velocity of 0.6 ml/min and UV sensor examination at 210 nm. AAD linearity range was 5.01289μg/ml to 30.07733μg/ml with sensitivity of 1.65425μg/ml (LOD) and 5.01289μg/ml (LOQ). Accuracy towards AAD recoveries were 111.3 to 113.0%, 86.7 to 94.4% and 90.9 to 95.7%, and precision towards AAD’s RSD was 1.197% and 3.367%. The projected HPLC process could be applied to analysis of AAD in DAC active medicinal ingredients with sharp selectivity, better sensitivity, and high point accuracy.

Development and validation of an LC-MS/MS method for the quantification of artificial sweeteners in human matrices.

Artificial sweeteners are widely used as substitutes for sugar. The sweeteners are generally considered safe, however their whereabouts during pregnancy and lactation and the effect on child development are poorly explored. There is a need for new tools to measure these substances during pregnancy and lactation. Here, we describe the development and validation of a sensitive liquid chromatography–tandem mass spectrometry method for the simultaneous quantification of acesulfame, cyclamate, saccharin and sucralose in human plasma, umbilical cord blood, amniotic fluid and breast milk. The samples were prepared by protein precipitation and separated on a Luna Omega Polar C18 column (2.1 × 50 mm, 1.6 μm). Electrospray ionization in negative mode and multiple reaction monitoring were used to monitor the ion transitions. The validated concentration ranges were from 1 to 500 ng/ml (10–500 ng/ml for sucralose). Interassay precisions were all ≤15% and the accuracies were within ±15%. Stability, linearity, dilution integrity, carryover and recovery were also examined and satisfied the validation criteria. Finally, this analytical method was successfully applied on spiked samples of plasma, umbilical cord blood, amniotic fluid and breast milk, proving its suitability for use in clinical studies on artificial sweeteners, including during pregnancy and lactation.

Quantitative analysis of short-chain fatty acids in human plasma and serum by GC-MS.

Short-chain fatty acids (SCFAs) are volatile fatty acids produced by gut microbial fermentation of dietary nondigestible carbohydrates. Acetate, propionate, and butyrate SCFA measures are important to clinical and nutritional studies for their established roles in promoting healthy immune and gut function. Additionally, circulating SCFAs may influence the metabolism and allied function of additional tissues and organs. The accurate quantification of SCFAs in plasma/serum is critical to understanding the biological role of SCFAs. The low concentrations of circulating SCFAs and their volatile nature present challenges for quantitative analysis. Herein, we report a sensitive method for SCFA quantification via extraction with methyl tert-butyl ether after plasma/serum acidification. The organic extract of SCFAs is injected directly with separation and detection using a polar GC column coupled to mass spectrometry. The solvent-to-sample ratio, plasma volume, and amount of HCl needed for SCFA protonation were optimized. Method validation shows good within-day and inter-day repeatability. The limit of detection was 0.3-0.6µg/mL for acetate and 0.03-0.12µg/mL for propionate and butyrate. Successful application of this method on clinical plasma and serum samples was demonstrated in six datasets. By simplifying the sample preparation procedure, the present method reduces the risk of contamination, lowers the cost of analysis, increases throughput, and offers the potential for automated sample preparation.

Enantiomeric Composition, Antioxidant Capacity and Anticholinesterase Activity of Essential Oil from Leaves of Chirimoya (Annona cherimola Mill.).

Annona cherimola Mill. is a native species of Ecuador cultivated worldwide for the flavor and properties of its fruit. In this study, hydrodistillation was used to isolate essential oil (EO) of fresh Annona cherimola leaves collected in Ecuadorian Sierra. The EO chemical composition was determined using a non-polar and a polar chromatographic column and enantiomeric distribution with an enantioselective column. The qualitative analysis was carried out by gas chromatography coupled to a mass spectrometer and quantitative analysis using gas chromatography equipped with a flame ionization detector. The antibacterial potency was assessed against seven Gram-negative bacteria and one Gram-positive bacterium. ABTS and DPPH assays were used to evaluate the radical scavenging properties of the EO. Spectrophotometric method was used to measure acetylcholinesterase inhibitory activity. GC-MS analysis allowed us to identify more than 99% of the EO chemical composition. Out of the fifty-three compounds identified, the main were germacrene D (28.77 ± 3.80%), sabinene (3, 9.05 ± 1.69%), β-pinene (4, 7.93 ± 0.685), (E)-caryophyllene (10.52 ± 1.64%) and bicyclogermacrene (11.12 ± 1.39%). Enantioselective analysis showed the existence of four pairs of enantiomers, the (−)-β-Pinene (1S, 5S) was found pure (100%). Chirimoya essential oil exhibited a strong antioxidant activity and a very strong anticholinesterase potential with an IC50 value of 41.51 ± 1.02 µg/mL. Additionally, EO presented a moderate activity against Campylobacter jejuni and Klebsiella pneumoniae with a MIC value of 500 μg/mL.

Investigation of supercritical fluid chromatography retention behaviors using quantitative structure-retention relationships

Supercritical Fluid Chromatography (SFC), a high-throughput separation technique, has been widely applied as a promising routine method in pharmaceutical, pesticides, and metabolome analysis in the same way as conventional liquid chromatography and gas chromatography. However, the retention behaviors of many compounds in SFC are not fully investigated. In this study, more than 500 pesticides were analyzed on several polar and nonpolar columns using SFC/MS/MS. Then, partial least squares regression (PLS) was used to explore the retention behaviors of pesticides and construct the quantitative structure-retention relationships under practical gradient elution. The optimized relationships between pesticide structures and pesticide retention were established and validated for predicting power using both internal- and external-validations; hence, several important factors affecting retention of the compounds were identified. In the best case, approximately almost all pesticides in the training set and nearly 80% of pesticides in the external validation set could be predicted with the prediction error of less than 0.5 min. Moreover, the proposed workflow successfully established the local interaction profiles, describing the possible interactions in the 8 studied chromatographic systems, and can be further applied for any groups of compounds under any system conditions.

Selective Separation of Polar Unsaturated Organics Using a Water Stationary Phase in Gas Chromatography

A water stationary phase is explored as a novel means of selectively separating unsaturated analytes in gas chromatography. Several unsaturated/saturated analyte pairs consisting mainly of carboxylic acids and alcohols were examined using both a 30-m conventional non-polar HP-5 column and an 11-m water phase column. For most investigated on the HP-5 column, analytes often eluted very close to each other (~ 6–12 s apart) with poor resolution. By comparison, the shorter water phase column well separated each of the analogue pairs by about 3–8 min or more. As well on the water phase, analytes with a triple bond were much more retained than those with two double bonds, which in turn were much more retained than those with one double bond. Conversely, on the HP-5 column these were poorly separated if at all. Additionally, cis/trans isomers were baseline resolved on the water phase but co-eluted on a 30-m conventional polar Carbowax column. Similarly, positional isomers varying the location of the double bond were found to separate with a selectivity value near 1.1 on the Carbowax column, whereas on the water phase column they yielded a value of 1.3 and eluted in the reverse order. Addition of various metal ion salts to the water phase was explored. While Ca2+ ion produced modest increases in selectivity, the addition of Ag+ ion was most influential and further increased the original water phase selectivity by a factor of 2.3. The mechanistic implications of OH–-pi bonding in the water phase was discussed as a potential origin for the selectivity observed. The method was applied to gasoline, essential oil, and food stuff analysis. Results indicate that this method could be a very useful means of selectively separating such unsaturated analytes.Graphical abstract