High-performance Liquid Chromatography System Research Articles

Human exposure and health risk assessment of an increasingly used antibacterial alternative in personal care products: Chloroxylenol

The ban of some antibacterial ingredients, such as triclosan (TCS) and triclocarban (TCC), in personal care products (PCPs) in some countries (but not in China) has resulted in the increasing use of antibacterial alternatives, such as chloroxylenol (PCMX). However, the underlying human health risks and environmental impacts of PCMX exposure are largely unknown. Thus, the distribution characteristics of PCMX in PCPs and susceptible populations and the major routes and health risks of human exposure to PCMX were investigated. The PCMX, TCS, and TCC concentrations in PCPs, urine, drinking water, and surface water were determined using high-performance liquid chromatograph system equipped with diode array detector or triple quadrupole mass spectrometer. Results showed that PCMX is widely used in antibacterial hand sanitizers and household disinfectants in China. The addition of PCMX as an antibacterial ingredient in PCPs showed an increasing trend. The geomean concentrations of urinary PCMX in children and pregnant women were 21.6 and 31.9 μg·L−1, respectively, which were much higher than TCS and TCC. A considerable concentration of PCMX ranging from 1.62 to 9.57 μg·L−1 was observed in the aquatic environment, suggesting a potential massive-use of PCMX by humans. Human PCMX exposure via drinking was negligible because the PCMX concentrations in drinking water were less than 2.00 ng·L−1. During human simulation experiment, we found that dermal contact was the dominant route of human PCMX exposure, accounting for 92.1% of the urinary PCMX concentration. The estimated daily intake of PCMX in 9.68% of children and 5.66% of pregnant women was higher than the reference dose. However, the urinary 8-hydroxy-2′-deoxyguanosine concentrations remained stable despite the elevated PCMX concentrations, thereby suggesting that daily PCMX exposure may not cause oxidative DNA damage in humans. Nevertheless, the potential ecotoxicity and health risks induced by chronic PCMX exposure cannot be ignored because of its increasing use.

Effects of Chronic Secondhand Smoke (SHS) Exposure on Cognitive Performance and Metabolic Pathways in the Hippocampus of Wild-Type and Human Tau Mice.

Background:Exposure to secondhand smoke (SHS) is a risk factor for developing sporadic forms of sporadic dementia. A human tau (htau) mouse model is available that exhibits age-dependent tau dysregulation, neurofibrillary tangles, neuronal loss, neuroinflammation, and oxidative stress starting at an early age (3–4 months) and in which tau dysregulation and neuronal loss correlate with synaptic dysfunction and cognitive decline.Objective:The goal of this study was to assess the effects of chronic SHS exposure (10 months’ exposure to ) on behavioral and cognitive function, metabolism, and neuropathology in mice.Methods:Wild-type (WT) and htau female and male mice were exposed to SHS (90% side stream, 10% main stream) using the SCIREQ® inExpose™ system or air control for 168 min per day, for 312 d, 7 d per week. The exposures continued during the days of behavioral and cognitive testing. In addition to behavioral and cognitive performance and neuropathology, the lungs of mice were examined for pathology and alterations in gene expression.Results:Mice exposed to chronic SHS exposure showed the following genotype-dependent responses: a) lower body weights in WT, but not htau, mice; b) less spontaneous alternation in WT, but not htau, mice in the Y maze; c) faster swim speeds of WT, but not htau, mice in the water maze; d) lower activity levels of WT and htau mice in the open field; e) lower expression of brain PHF1, TTCM1, , and HSP90 protein levels in WT male, but not female, mice; and f) more profound effects on hippocampal metabolic pathways in WT male than female mice and more profound effects in WT than htau mice.Discussion:The brain of WT mice, in particular WT male mice, might be especially susceptible to the effects of chronic SHS exposure. In WT males, independent pathways involving ascorbate, flavin adenine dinucleotide, or palmitoleic acid might contribute to the hippocampal injury following chronic SHS exposure. https://doi.org/10.1289/EHP8428

Recent advances in column switching high-performance liquid chromatography for bioanalysis

Bioanalysis is a relevant area of analytical chemistry for clinical studies. Biological samples are complex and diverse, so sample preparation represents a challenge when chromatographic methods are developed. According to the principles of green analytical chemistry (GAC), recent trends in sample preparation include miniaturization, automation (online coupling to the analytical instrument), and high-throughput performance. In this context, column switching liquid chromatography stands out as a multidimensional chromatographic method in which an extraction column is directly coupled to high-performance liquid chromatography (HPLC) systems. This online method consists of two steps and involves two columns, the extraction and the chromatographic columns. In the former column, the analytes are isolated from the sample and preconcentrated; in the latter column, the analytes are separated. Online systems improve the sensitivity and accuracy of analytical methods, consume lower amounts of organic solvents, and minimize sample handling. This review summarizes state-of-the-art column switching liquid chromatography and focuses on selective stationary phases for preconcentration of analytes (first dimension), including reversed phases, monolithic phases, restricted access materials (RAMs), and molecularly imprinted polymers (MIP). Principles, instrumental aspects, applications in bioanalysis, and future trends in column switching liquid chromatography are also discussed.

Morpho-Physiological Responses and Secondary Metabolites Modulation by Preharvest Factors of Three Hydroponically Grown Genovese Basil Cultivars.

Sweet basil (Ocimum basilicum L.) is an economically important leafy vegetable especially in Mediterranean countries. In Italian gastronomy, the large elliptical leaves of the Genovese type are mostly used for the well-known pesto sauce, and almost all (>90%) professional production is for the food industry. The growing demand for fresh leaves with standardized technological and sensory characteristics has prompted basil producers to adopt advanced cultivation methods such as the floating raft system (FRS). The aim of this study was to evaluate the productive, qualitative, and physiological performance of three Genovese basil cultivars (“Aroma 2,” “Eleonora,” and “Italiano Classico”) in two successive harvests and at two densities (159 and 317 plants m–2). Caffeic, chicoric, rosmarinic, and ferulic acid were determined through the high-performance liquid chromatography (HPLC) system, whereas the extraction and quantification of the volatile organic compounds (VOCs) were performed by solid-phase microextraction (SPME) and gas chromatography coupled to a mass spectrometer (GC/MS). “Aroma 2” showed the highest fresh yield and photosynthetic rate together with the lowest nitrate content. For all the tested cultivars, the higher density, while reducing the number of leaves per plant, resulted in higher fresh and dry production per unit area, without altering the aroma profile. Successive harvests resulted in a significant increase in both the yield (37.5%) and the total phenolic acids (75.1%) and favored Eucalyptol and 1-octen-3-ol accumulation (+25.9 and +15.1%, respectively). The here presented comprehensive and multifactorial assessment of the productive and qualitative response of basil provides evidence of the positive effects (from biomass to specialized metabolites) that can be obtained from the management of the pre-harvest factors in soilless cultivation. In addition, it also highlights the role and constraints of the genetic factor in the observed response. We also discuss the implications of our work considering the impact for the food processing industry. Future research may explore the phenolic acids accumulation as a possible fortification means to extend the pesto sauce shelf life, reducing the need of added antioxidants and thermal processing.

Phenolic compounds in the leaves and inflorescences of <i>Spiraea baldshuanica</i> B. Fedtsch.

For the first time, the composition and content of phenolic compounds in the leaves and inflorescences of Spiraea baldshuanica B. Fedtsch. was investigated. Research material was collected in June 2019 from a natural population in the Republic of Tajikistan. Phenolic compounds were studied in 40% water- ethanol extracts by the method of high-performance liquid chromatography (HPLC). The analytical HPLC system used consisted of an Agilent 1200 (USA) liquid chromatograph equipped with a diode array detector, an autosampler and a ChemStation system for collecting and processing chromatographic data. 15 and 11 compounds of phenolic nature were found in native extracts from inflorescences and leaves, respectively. Among them, the following substances were identified: chlorogenic and cinnamic acids, quercetin, kaempferol, hyperoside, isoquercitrin, avicularin and astragalin. The chromatographic profiles of leaves and inflorescences were found to be different. Such substances as isoquercitrin, avicularin, kaempferol were discovered in the inflorescences of S. baldshuanica , rather than in its leaves. Compared to the leaves, the concentration of all detected phenolic compounds was higher in the inflorescences under study. The major component in the inflorescences was astragalin (3.16 mg/g), whereas its concentration in the leaves was 5 times lower (0.60 mg/g). Flavonoid aglycones were obtained from the water-ethanol extracts of the leaves and inflorescences under study by acid hydrolysis using hydrochloric acid (1:1). The hydrolysates of extracts from the leaves and inflorescences of S . baldshuanica were found to contain 3 flavonoid aglycones: quercetin, kaempferol and isorhamnetin. By recalculating the concentration of aglycone for the corresponding glycoside, it was determined that quercetin glycosides prevails: 6.67 mg/g – in the inflorescences and 1.19 mg/g – in the leaves. S. baldshuanica differs significantly from other representatives of the Spiraea genus, section Calospira , in terms of the chromatographic profile of phenolic compounds contained in the leaves. This information serves as an additional argument for differentiating S. baldshuanica as a separate series of the Decumbentes group by morphological signs.

A comprehensive study on retention of selected model substances in β-cyclodextrin-modified high performance liquid chromatography

The quantitative structure-retention relationship (QSRR) models are not only employed in retention behaviour prediction, but also in an in-depth understanding of complex chromatographic systems. The goal of the present research is to enable the comprehensive understanding of retention underlying the separation in β-cyclodextrin (CD) modified reversed-phase high performance liquid chromatography (RP-HPLC) systems, through the development of mixed QSRR models. Moreover, the amount of β-CD adsorbed on the stationary phase surface (β-CDA) is added as the model's input in order to evaluate its contribution to both model performances and retention. Nuclear magnetic resonance (NMR) experiments were conducted to confirm the predicted inclusion complex structures and support the application of in silico tools. The most significant descriptors revealed that retention is governed by the steric factors 7.5 Å distant from the geometrical centre of a molecule, 3D arrangement of atoms determining the molecular size and shape, lipophilicity indicated by topological distances, as well as the unbound system's energy, related to the inclusion complex formation. In addition, a notable effect of the pH of the aqueous phase on the retention of ionizable analytes was shown. In the case of pH of the aqueous phase and β-CDA the change in retention behaviour of the studied analytes was observed only at the highest β-CDA value (5.17 μM/m2), but it was not related to the ionization state of analytes. When the analytes did not change the ionization form across the investigated studied pH range, and the acetonitrile content in the mobile phase was 25% (v/v), the retention factor had low values regardless of the β-CDA; under these circumstances the retention is probably acetonitrile driven.

Forensic profiling of non-volatile organic compounds in soil using ultra-performance liquid chromatography: a pilot study

Soil is of particular interest to the forensic community because it can be used as valuable associative evidence to link a suspect to a victim or a crime scene. Liquid chromatography is a powerful analytical tool for organic compound analysis. Recently, high-performance liquid chromatography (HPLC) has proven to be an efficient method for forensic soil analysis, especially in discriminating soils from proximity locations. However, ultra-performance liquid chromatography (UPLC), which is much more sensitive than HPLC, has never been explored in this context. This study proposed a UPLC method for profiling non-volatile organic compounds in three Malaysian soils (red, brown and yellowish-brown soils). The three soils were analysed separately to assess the effects of individual chromatographic parameters: (a) elution programme (isocratic vs. two gradient programmes); (b) flow rate (0.1 vs. 0.2 mL/min); (c) extraction solvent (acetonitrile vs. methanol) and (d) detection wavelength (230 vs. 254 nm). The injection volume and total run time were set to 5 µL and 35 min, respectively. Consequently, each soil sample gave 24 different chromatograms. Results showed that the most desirable chromatographic parameters were (a) isocratic elution; (b) flow rate at 0.2 mL/min and (c) acetonitrile extraction solvent. The proposed UPLC system is expected to be a feasible method for profiling non-volatile organic compounds in soil, and is more chemical-efficient than a comparable HPLC system.

Impacts of Environmental Variations on Quality and Chemical Contents of Oriental Tobacco

Summary Basma tobaccos, in addition to Izmir and Samsun type tobaccos, are the most important high-quality oriental tobacco types grown in Turkey. This research was carried out to determine the effects of a variety of environmental conditions, in four locations on different altitudes on the yield as well as on nicotine, sugar and phenolic substances content. The plant material of the study included 21 Basma lines, which were selected according to their morphological differences and from genotypes separated by DNA fingerprint analysis, and four standard cultivars/lines (checks). The quality grade index of the genotypes was determined by the American grading method and chemical analyses were carried out using a high-performance liquid chromatography (HPLC) system. All the parameters investigated indicated that genotypes were significantly affected by the variation in environmental conditions. Organoleptic observations showed that the quality grade index of genotypes ranged from 24.17 to 100%, and the ERB-7, ERB-13, ERB-15, ERB-19 and ERB-38 lines had the best quality. Nicotine contents of tobacco lines were between 0.31 and 3.15% dry matter (DM). Glucose, fructose and their sum (reducing sugar) contents of genotypes ranged from 1.16 to 8.88% DM, from 2.60 to 8.66% DM and from 4.44 to 15.03% DM, respectively. The ERB-21 and ERB-30 lines are noteworthy tobacco types in terms of reducing sugar contents. The values of chlorogenic acid, one of the phenolic compounds, ranged from 40.67 to 1119.76 ppm, the values of rutin from 121.05 to 1021.53 ppm, and the sum of these two phenolic compounds was from 174.94 ppm to 2019.41 ppm. The effect of variations in the environment on the quality of Oriental tobacco can be clearly explained by the variations in the parameters.

QuEChERS with Ultrasound-Assisted Extraction Combined with High-Performance Liquid Chromatography for the Determination of 16 Polycyclic Aromatic Hydrocarbons in Sediment.

Polycyclic aromatic hydrocarbons (PAHs) have attracted worldwide attention due to their carcinogenic, teratogenic, and mutagenic effects, environmental persistence, and bioaccumulation characteristics. Therefore, the sensitive, reliable, and rapid detection of PAHs in sediment is of great importance. To develop a high-performance liquid chromatography (HPLC) with fluorescence and ultraviolet detection after Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) treatment for simultaneous determination of 16 U.S. Environmental Protection Agency priority PAHs in sediment samples. The samples were ultrasonically extracted with acetone and then the supernatant was purified with a modified QuEChERS method. After centrifugation, the supernatant was injected into the HPLC system for analysis. The separation was accomplished on a ZORBAX Eclipse PAH column (150 × 4.6 mm, 3.5 μm) and the column temperature was set at 30 °C. The flow rate of the mobile phase consisting of water and acetonitrile in gradient elution mode was fixed at 0.9 mL/min. Detection was conducted on an ultraviolet detector and a fluorescence detector simultaneously. The qualitative analysis was based on retention time and the quantification was based on standard curves. Under the optimal conditions, this method showed good linearities in the range of 10-200 μg/L with correlation coefficients greater than 0.9993. The method had LODs ranging from 0.00108 to 0.314 ng/g. The mean recoveries ranged from 78.4 to 117% with intra-day and inter-day RSDs of 0.592-10.7% and 1.01-13.0%, respectively. The proposed method was successfully applied to the detection of 16 PAHs in sediment samples collected from the Funan River in Chengdu, China with total contents of 431-2143 ng/g·dw. The established method is simple, rapid, environmentally friendly, and cost-effective. It can be applied to the analysis of 16 PAHs in sediment samples. A method of QuEChERS with ultrasound-assisted extraction combined with HPLC has been established for the analysis of 16 PAHs in sediment samples and the proposed method has been successfully applied to the analysis PAHs in real sediment samples.

Association of the kynurenine pathway metabolites with clinical, cognitive features and IL-1β levels in patients with schizophrenia spectrum disorder and their siblings

ObjectiveThere is evidence suggesting that tryptophan (TRP)-kynurenine (KYN) pathway dysregulation is involved in the pathophysiology of schizophrenia and is regulated by inflammatory cytokines. The study investigate for the first time whether this dysregulation occurs in advanced stages of the disease as a byproduct or emerges as one of the early and inherited manifestations of schizophrenia. MethodSera of 148 patients with schizophrenia spectrum disorders (SCZ), 139 unaffected siblings (SIB) and 210 controls were investigated. Serum interleukin (IL)-1β levels were measured by ELISA, and TRP, KYN and kynurenic acid (KYNA) levels were measured by a high-performance liquid chromatography system. Also, we collected clinical data by applying Comprehensive Assessment of Symptoms and History in SCZ, and SIS-R in SIB and control groups. ResultsCompared to controls, SCZ and SIB groups had lower TRP and higher KYNA levels. TRP levels showed significant differences only between SCZ and controls (p < 0.01). KYNA levels of both SCZ (p ≤ 0.001) and SIB (p < 0.05) were higher than controls. No statistical significance was found for KYN levels across groups. SCZ and SIB groups had higher serum IL-1β levels than controls (p ≤ 0.001). ConclusionsPatients with SCZ and their siblings exhibited similar clinical features and TRP metabolite levels suggesting that TRP-KYN dysregulation may be an inherited component of the disease putatively conferring increased risk to schizophrenia. Elevation of IL-1β is one of the factors promoting overconsumption of the TRP-KYN pathway leading to increased production of neuroregulatory KYNA and presumably to neurodegeneration.

Novel materials as capillary coatings for in-tube solid-phase microextraction for bioanalysis.

In-tube solid-phase microextraction with a capillary column as extraction device can be directly coupled with high-performance liquid chromatography systems (HPLC). The in-tube solid-phase microextraction technique has been continuously developed since it was introduced in 1997. New couplings have also been evaluated on the basis of state-of-the-art HPLC instruments. Different types of capillaries (wall-coated open tubular, porous layer open tubular, sorbent-packed, porous monolithic rods, or fiber-packed) with selective stationary phases (monoliths, magnetic nanoparticles, conducting polymers, restricted access materials, ionic liquids, carbon, deep eutectic solvents, and hybrid materials) have been developed to boost in-tube solid-phase microextraction performance (sorption capacity and selectivity). This technique has been successfully applied to analyze biological samples (serum, plasma, whole blood, hair, urine, milk, skin, and saliva) for therapeutic drug monitoring, to study biomarkers, to detect illicit drugs, to conduct metabolomics studies, and to assess exposure to drugs. This review describes current advances in in-tube solid-phase microextraction extraction devices and their application in bioanalysis.

Screening of Dry Blood Spots from Newborns by Two High Performance Liquid Chromatography (HPLC) Systems: A Comparison of Their Ability to Diagnose Both Sickle and Non-sickle Hemoglobinopathies.

Screening of newborns for the presence of sickle hemoglobin (HbS) is aimed at reducing the morbidity and mortality associated with sickle cell disease in early childhood. The high cost and limited availability of dedicated high performance liquid chromatography (HPLC) systems specially designed for screening of dry blood spots (DBS), however, restrict a wider application of this preventive approach. Therefore, we examined the ability of a commonly used HPLC system for detection of hemoglobinopathies in DBS samples in order to find an alternative for the dedicated newborn screening (NBS) HPLC system. DBS samples from 7522 newborns were first examined by Variant NBS HPLC system (Bio Rad, USA) for the presence of hemoglobinopathies. Positive samples were then analysed by Variant II system (Bio Rad, USA), another platform commonly used for hemoglobinopathy screening of anticoagulated blood samples. Eighty six newborns (1.1%) showed the presence of hemoglobinopathies (HbS 28, HbE 21, HbD 27, HbQ India 9 and Hb Barts 1) by Variant NBS system-all in heterozygous state. There was 100% correlation between the two sets of results obtained by the two HPLC systems. Newborns with HbQ India showed an additional Hb peak in HPLC resulting from combination of the abnormal alpha globin chain of HbQ India with the normal gamma chain of HbF-'HbF Q India'. Variant II HPLC system, used for routine hemoglobinopathy screening in anticoagulated blood, can also be used for screening DBS samples. This obviates the need for a dedicated NBS system for hemoglobinopathy screening in newborns. We also demonstrated that both the systems are equally competent in detecting non-sickle Hb variants in DBS samples.

Sun-induced production of vitamin D3 throughout 1 year in tropical and subtropical regions: relationship with latitude, cloudiness, UV-B exposure and solar zenith angle.

This study evaluated the differences in vitamin D3 synthesis in two different latitudes throughout 1 year using an in vitro model, which simulates cutaneous vitamin D photoproduction. Borosilicate ampoules containing 7-dehydrocholesterol (7-DHC) were exposed to sunlight hourly throughout the daylight hours, 1 day per month for a year, in Fortaleza (latitude 03° 43' 01" S-LAT3° S) and Sao Paulo (latitude 23° 32' 53" S-LAT23° S). Later, vitamin D3 and photoisomers of 7-DHC (tachysterol and lumisterol) were measured by a high-performance liquid chromatography system (HPLC). Vitamin D synthesis weighted UV radiation (UVBVitD) and solar zenith angle (SZA) were calculated during the same periods for both latitudes. Vitamin D3 synthesis occurred throughout the year in both locations, as expected in latitudes lower than 35°. Median of photoconversion to vitamin D3 through the year was higher in LAT3°S [median (IQR): LAT 3°S 4.1% (6.0); LAT 23°S 2.9% (4.5); p value = 0.020]. Vitamin D3 production strongly correlated with UV-B (LAT3° S, r = 0.917; p < 0.0001 and at LAT23° S, r = 0.879; p < 0.0001) and SZA (LAT3° S, r = - 0.924; p < 0.0001 and in LAT23°S, r = - 0.808; p < 0.0001). Vitamin D3 production starts later in LAT23° S, especially in winter. Lowest percentages were observed in June in both cities, although, compared to LAT3° S, in LAT 23° S the conversion was over 50% lower in the winter period. Cloudiness impaired photoproduction of Vitamin D3 even in summer months in both latitudes. Our results provide data to help guide medical recommendations for sensible sun exposure to promote the cutaneous production of vitamin D3 at different latitudes, seasonality, time of day and cloudiness status in Brazil.

In Vitro Drug Loading, Releasing Profiles, and In Vivo Embolic Efficacy and Safety Evaluation of a Novel Drug-Eluting Microsphere (CalliSpheres).

Background: To investigate morphology, physical property, loadability, stability, and release profiles of a novel drug-eluting microsphere, CalliSpheres, in vitro and to explore its embolic efficacy and safety in vivo. Materials and Methods: CalliSpheres (50-150 μm, 100-300 μm, and 300-500 μm) and doxorubicin in different amounts (20, 40, 80, and 100 mg) and concentrations (5 and 10 mg/mL) were prepared for experiments. Dynamic light scattering and an Agilent 1260 high-performance liquid chromatography system were used to quantify bead diameters and the efficiency of drug loading and release, respectively. Twelve New Zealand rabbits were treated with catheter-aided hepatic embolization using CalliSpheres. Results: CalliSpheres displayed a red color after loading with doxorubicin, and the mean diameters decreased by 20.7-25.8%. Almost 100% of the drug was incorporated with CalliSpheres in different sizes immersed with doxorubicin 20 mg, while loading efficiency ranged from 75.8% to 100.0% with doxorubicin at 40, 80, and 100 mg dependent on CalliSpheres sizes (smaller sizes, higher loading efficiency). Elevated loading efficiency was observed at higher concentration of doxorubicin solutions. Regarding release profiles, doxorubicin was released from CalliSpheres quickly at the very beginning, and doxorubicin release percentage was increased in the 50-150 μm group (39.2% ± 1.2%) compared with the 100-300 μm group (31.3% ± 1.3%) and 300-500 μm group (31.7% ± 2.5%). Digital subtraction angiography, computed tomography, and histopathologic emanation results proved in vivo safety and embolic efficacy of CalliSpheres. Conclusions: CalliSpheres present with good physical characteristics and satisfactory loading and releasing profiles in vitro and are well tolerated and efficient in embolization in vivo.

Towards using high-performance liquid chromatography at home

In order to make high-performance liquid chromatography (HPLC) more widely available at home and in small-scale settings, we have simplified two of its most costly modules, namely the pump and the detector. This should make the setup affordable for home or small laboratory use. A manual HPLC pump was constructed so as to fit into a caulk gun from a local hardware store enabling the generation of 100-150 bar of pressure. In order to limit the pressure drop during the running of a chromatogram, a pulse dampener was developed. We further modified the electrochemical detection (ECD) system so as to use a cheap boron-doped diamond electrode with an overlay of thin filter paper, causing an eluent flow over the electrode by wicking and gravity. Both the pump and the detector are at least ten times cheaper than conventional HPLC modules.Using a home-packed JupiterⓇ Proteo reversed phase capillary column we show how this low-cost HPLC system generates well resolving chromatograms after direct injection of fresh urine. The ECD did not lose its sensitivity during regular use over more than half a year. For homovanillic acid (HVA), which is of medical interest, we measured a linear dynamic range of two orders of magnitude, a detection limit of HVA in the injected sample of 3 μM and a coefficient of variation <10%. The contribution to peak broadening by the detector was much smaller than the contributions by the injector and by the column. After consumption of table olives containing hydroxytyrosol (HT), its metabolite HVA in the corresponding urine could be measured quantitatively. An approach to quantify HT in table olives is presented, as well. This method provides a new tool for investigating physiology of oneself or of dear ones at home.

QSRR modelling aimed on the HPLC retention prediction of dimethylamino- and pyrrolidino-substitued esters of alkoxyphenylcarbamic acid

Two homologous series of alkoxyphenylcarbamic acids esters with biological activities were subjected to the QSRR (Quantitative Structure–Retention Relationships) study. Retention factors of studied derivatives were measured in four different HPLC (High Performance Liquid Chromatography) systems. Experimental data in combination with in silico calculated molecular descriptors were used for development complex QSRR model for prediction of retention factor and partially for elucidation of separation mechanisms. The best results in QSRR modelling were given by artificial neural networks in the terms of developing one single robust model with high accuracy of logk prediction ( $${Q}_{\mathrm{F}3}^{2}$$ = 0.998) for all studied chromatographic systems. Chemometrical techniques were also used to elucidate the separation mechanisms occurring in the HPLC systems. We found similarities between particular systems and we identified systems which were the most suitable for separation of positional isomers of studied compounds. We observed that solvent significantly influenced the chromatographic separation of positional isomers depending on the used column, whereas combination of acetonitrile and C18-phenyl column caused suppression of π − π interactions, so retention was wholly determined by the hydrophobic interactions.

Schiff base network-1 incorporated monolithic column for in-tube solid phase microextraction of antiepileptic drugs in human plasma

A novel monolithic column incorporated with Schiff base network-1 (SNW-1) was prepared for in-tube solid phase microextraction (SPME) of antiepileptic drugs. The SNW-1 nanoparticles was synthesized by a solvent thermal method and embedded in the poly(glycidyl methacrylate-ethylene glycol dimethacrylate) (GMA-EGDMA) monolithic column by in situ polymerization. The amount of SNW-1 in polymerization solution for preparation of monolithic column was optimized. Fourier transform infrared spectrometry and scanning electron microscope were used to characterize the obtained monolithic column. The SNW-1-monolithic column was connected to the high-performance liquid chromatography (HPLC) system and applied for online extraction and analysis of antiepileptic drugs. The extraction conditions including sample solution flow rate, desorption time, acetonitrile content, pH of sample solution and sample volume were investigated. Under optimal conditions, the proposed SPME-HPLC method showed high extraction efficiency, good linearity, low limits of detection (0.2 ng/mL) and good repeatability (relative standard deviations < 2.41%). This method was also applied to the analysis of antiepileptic drugs in human plasma samples and the recoveries were in the range of 88.6–106.1% with RSDs less than 3.51%.

Influence of Processing Parameters on Phenolic Compounds and Color of Cabernet Sauvignon Red Wine Concentrates Obtained by Reverse Osmosis and Nanofiltration

In this study, Cabernet Sauvignon red wine was subjected to reverse osmosis and nanofiltration processes at four different pressures (25, 35, 45, and 55 bar) and two temperature regimes (with and without cooling). The aim was to obtain concentrates with a higher content of phenolic compounds and antioxidant activity and to determine the influence of two membrane types (Alfa Laval RO98pHt M20 for reverse osmosis and NF M20 for nanofiltration) and different operating conditions on phenolics retention. Total polyphenol, flavonoid, monomeric anthocyanin contents, and antioxidant activity were determined spectrophotometrically. Flavan-3-ols and phenolic acids were analyzed on a high-performance liquid chromatography system and sample colour was measured by chromometer. The results showed that the increase in applied pressure and decrease in retentate temperature were favorable for higher phenolics retention. Retention of individual compounds depended on their chemical structure, membrane properties, membrane fouling, and operating conditions. Both types of membranes proved to be suitable for Cabernet Sauvignon red wine concentration. In all retentates, phenolic compounds content was higher than in the initial wine, but no visible color change (ΔE* &lt; 1) was observed. The highest concentrations of phenolic compounds were detected in retentates obtained at 45 and 55 bar, especially with cooling.

Development and Validation by Reverse Phase High Performance Liquid Chromatography Method for the Estimation of Piperine and Coenzyme Q10 in Bulk and Pharmaceutical Dosage Form

Today people are focused on their health, as good health is a key to the happiness of our life. Medicine takes a big responsibility to take care of our health. Various supplements are available to meet the nutritional requirement. One such supplement is a combination of piperine and coenzyme Q10. The medicines have to be analyzed properly before introducing them to the market. As no analytical method is available for simultaneous estimation of the combination, hence an attempt was made to develop a validated method for the estimation of piperine and coenzyme Q10 simultaneously in bulk and its dosage form. A simple, precise, accurate and validated reversed phase high performance liquid chromatography technique was developed for the estimation of piperine and coenzyme Q10 in bulk and its tablet formulation. In this developed method, Waters X Bridge C18 column (250 mm×4.6 mm, 5 μm) was used as a stationary phase and acetonitrile, tetrahydrofuran and water was used in 65:32:3 (v/v) ratio as mobile phase with 1 ml/min flow rate. This isocratic separation was accomplished using Waters 2707 Autosampler high performance liquid chromatography system, Waters 515 solvent delivery system, with photodiode array detector detection at 275 nm. Chromatographic data was processed by Empower 2 software. The retention times of coenzyme Q10 and piperine were 4.56 and 8.19 min respectively. The linearity ranges have lied between 4-6 μg/ml, 240-360 μg/ml for piperine and coenzyme Q10 respectively with 0.997 as correlation coefficient for both.

Development and comparison of UPLC-ESI-MS and RP-HPLC-VWD methods for determining microcystin-LR.

Microcystin-LR (MC-LR) generated by cyanobacteria is a kind of potent hepatotoxin, which poses a considerable threat to human health. In the research field of MC-LR removal, the quantitative analysis in a wide concentration range of samples is inevitable. In this paper, we presented the pseudo united use of an Ultra Performance Liquid Chromatography Mass Spectrometry (UPLC-MS) and High Performance Liquid Chromatography system with a Variable Wavelength Ultraviolet Detector (HPLC-VWD) approach to detect MC-LR. The UPLC-MS system was applied to determine MC-LR in trace concentration because of its high sensitivity. However, it is generally believed that the determination of high concentration samples by UPLC-MS will cause problems such as inaccurate quantification and contamination of ion sources. In consequence, the HPLC-VWD was employed to determine the high concentration of MC-LR. The sensitivity, precision and accuracy of the two methods were compared in detail. The linear ranges of UPLC-MS and HPLC-VWD methods were from 0.08 to 10 μg L−1 and 1 to 5000 μg L−1, respectively. The detection and quantification limits of UPLC-MS were 0.03–0.05 μg L−1 and 0.08 μg L−1, and the corresponding two values of HPLC-VWD were 0.6 and 1.0 μg L−1. The recoveries of UPLC-MS and HPLC-VWD were 88.5–106.7% and 98.7–101.6%, with the relative standard deviations of 3.72–5.45% and 0.38–1.69%, respectively. The potential adsorption properties of MC-LR on filter membranes with diverse materials and pore sizes were evaluated and the negative results were obtained. The detection of MC-LR by UPLC-MS was free from matrix effects. The presented UPLC-MS and HPLC-VWD methods were used to analyze the water samples from Erhai Lake, which is located in Dali, Yunnan, China. The results of UPLC-MS analysis indicated that the MC-LR was only identified in water samples of Shuanglang Bay and Xier River, with concentrations of 0.120 and 0.303 μg L−1, whereas MC-LR was not detected by HPLC-VWD.