High-performance Liquid chromatography-UV Research Articles

A comparative study of chemical composition, the level of fatty acids, amino acids and mineral elements between two types of catfish (Bagrus and Muraena) found in the upper Tigris River

Fish meat is considered the second most interesting to consume in Iraq hence, consumers always consider the sensory and nutritional profile of the fish meat. The study aimed to investigate the chemical composition and level of fatty acids and amino acids in Bagrus and Muraena fish fillets. These fish for this study were obtained from the upper Tigris river in the Tikrit region of Iraq, as the demand for these types of fish increased in recent years. In this work, High Performance Liquid Chromatography −UV (HPLC-UV) was used for quantification of amino acids, and atomic absorption was used for quantifying the elements. The extraction was performed by liquid –liquid extraction and purified by dispersive phase purification. Results showed that the moisture percentages in Bagrus meat were 71.36 %, while Muraena meat recorded as 71.10 %. Moreover, the protein percentages for both fish types were found as 21.36 and 21.43 % respectively. Lipid percentages in fillets of Bagrus and Muraena were 3.59 and 4.62 %, respectively. The proportion of ash was 3.01 % in Bagrus meat, while it was 2.55 % in Muraena meat. The results also presented that the Muraena has a significantly higher saturated fatty acid level (26.06 %), whereas in Bagrus meat was much less (16.6 %). The highest percentage of amino acids in Bagrus meat recorded (92.66 %), while it was 61.94 % in Muraena meat. The Bagrus meat contained essential amino acids with a higher percentage (54.04 %), compared to Muraena meat (28.55 %), non-essential Amino acids percentage also reached 47.56 % in Bagrus fish fillets. The amino acids like alanine had recorded the highest percentage among non-essential amino acids, as its level resulted in 38.62 %, while the level (33.39 %) was lower in Muraena meat.

Continuous flow membrane microextraction as a clean method for detecting codeine and papaverine in biological samples using HPLC-UV

In this study, continuous-flow membrane microextraction (CFMME) was connected online with a high-performance liquid chromatography-UV detector (HPLC-UV) for the pre-concentration and high clean-up of papaverine and codeine in biological samples. The extraction cell was designed with donor and acceptor chambers separated by a sheet membrane. By adjusting the pH of the donor phase (10 mL, pH 11), the analyte molecules were extracted into the supported liquid membrane (SLM) (15 μL of 1-octanol). The donor solution was circulated through the donor chamber using a peristaltic pump and magnetically agitated by a bar stirrer placed near the membrane, enhancing the diffusion and convection flow of the targeted drugs from the donor solution to the SLM. Subsequently, by adjusting the acceptor solution to an acidic pH of 2 (100 μL), the drugs in ionic form were reversely extracted into the acceptor phase. The procedure exhibited desirable relative standard deviation (RSD%) of less than 3.70%, linear ranges of 7-600 ng mL-1 for codeine and 2.0-600 ng mL-1 for papaverine, and limits of detection of 2.0 ng mL-1 for codeine and 0.6 ng mL-1 for papaverine. The design of the extraction cell significantly improved the performance for determining targeted drugs in complex matrices such as plasma and urine.

Electrospun of functionalized mesoporous UiO-66 as the selective coating of solid phase microextraction Arrow for the determination of nine alkylphenols.

A solid-phase microextraction (SPME) Arrow and high-performance liquid chromatography-UV detector (HPLC-UV, detection at 225nm) based method was developed for the selective determination of nine alkylphenols (APs) in milk. The functionalized mesoporous UiO-66 (4-meso-UiO-66) was utilized as the new coating material, which was synthesized by post-modification of pore-expanded UiO-66-NH2 by an esterification reaction with 4-pentylbenzoic acid. It was fully characterized by X-ray photoelectron spectroscopy (XPS), fourier transformation infrared spectrometry, nitrogen sorption-desorption test, scanning electron microscopy, transmission electron microscopy, and X-ray diffractometer. The characterization results showed the ester groups and benzene rings were introduced into the 4-meso-UiO-66, and the mesoporous structure was predominant in the 4-meso-UiO-66. The extraction mechanism of 4-meso-UiO-66 to APs is the synergistic effect of Zr-O electrostatic interaction and the size exclusion effect resulting from XPS, selectivity test, and nitrogen sorption-desorption test. The electrospinning technique was utilized to fabricate the 4-meso-UiO-66 coated SPME Arrow and polyacrylonitrile (PAN) was used as the adhesive. The mass rate of 4-meso-UiO-66 to PAN and the electrospinning time were evaluated. The extraction and desorption parameters were also studied. The linear range of this method was 0.2-1000μg L-1 with a coefficient of determination greater than 0.9989 under the optimal conditions. The detection limits were 0.05-1μg L-1, the inter-day and intra-day precision (RSD) were 2.8-11.5%, and the recovery was 83.6%-112%. The reusability study showed that the extraction performance of this new SPME Arrow could be maintained after 80 adsorption-desorption cycles. This method showed excellent applicability for the selective determination of APs in milk.

A green perspective on simultaneous HPLC and UV spectrophotometric estimation of Udenafil and Dapoxetine hydrochloride in pharmaceutical formulations

Clinical research has affirmed that the combination of Udenafil and Dapoxetine hydrochloride yields greater improvement in erectile dysfunction compared to the use of individual medications. There is a requirement of precise quantitative method for accurate determination of Udenafil and Dapoxetine when taken together. Consequently, our interest lies in developing and validating analytical methods for the simultaneous estimation of Udenafil and Dapoxetine - Various strategies, such as UV spectrophotometric approaches and an innovative, straightforward, accurate, sensitive, and robust High-Performance Liquid Chromatography (HPLC) procedure, have been explored. An Isocratic HPLC approach was employed using reversed-phase CHEMSIL ODS C18 column (4.6 mm x 250 mm, 5 µm) as a stationary phase and detection wavelength (λ max) 230 nm for the two analytes in the chromatographic column. The mobile phase comprised of (70:30, v/v) mixture of Acetonitrile and 10 mM Ammonium formate buffer having pH 5, adjusted with formic acid. The elution was carried out at a constant flow rate of 1 mL/min. The UV simultaneous equation technique estimated the medicine's quantities and derived a simultaneous equation for DAP and UDN using 2 wavelengths, 230 nm and 298 nm. Furthermore, the two advanced methods underwent rigorous statistical validation, guided by the valuable ICH Q2R1 guidelines, affirming their effectiveness as a successful analytical tool for the concurrent analysis of both tablets in bulk and the synthetic mixture fabricated in the laboratory. To assess the environmental impact of contemporary UV spectrophotometric and HPLC techniques, the Green Analytical Greenness Metric (AGREE) software and the Green Analytical System Index (GAPI) were employed to evaluate the greenness profile. This examination confirmed the method's environmental friendliness concerning solvent usage, chemical ingredients, energy consumption, and waste production. The developed UV method is more sustainable and greener compare to HPLC method for simultaneous estimation of compound, which can be utilised by industry for quantification of each individual drug in their combination products.

Interaction of Perfumes with Cytochrome P-450 19

Cytochrome P450 (CYP) enzymes play a key role in the metabolism of foreign compounds and in the biosynthesis and catabolism of endogenous substances, including hormones. The activity of these enzymes can be affected by various xenobiotics, such as pollutants, food constituents, pharmaceuticals, and cosmetic products, which can disrupt the endocrine system by interfering with steroidogenic CYPs. CYP19, also known as aromatase, is a crucial enzyme for testosterone conversion into 17β-estradiol, which is the final step in estrogen biosynthesis. Endocrine disruptors have the potential to inhibit CYP19 activity, leading to an imbalance in estrogen levels in the body. This imbalance can impair reproduction and cause osteoporosis, atherosclerosis, dementia, and some types of cancer. The aim of this study was to assess the effect of commercially available perfumes on testosterone aromatization to 17β-estradiol. For this purpose, we used high-performance liquid chromatography (HPLC) with UV detection and HPLC coupled with mass spectrometry (MS) to examine CYP19 activity with and without perfume. The results showed that all perfumes tested (in a 300-fold dilution) had an inhibitory effect on this enzyme-catalyzed reaction, particularly the Montale® fragrance, ‘Intense Roses Musk’, which decreased 17β-estradiol production by 88% in comparison with the control. Upon exposure to UV light, the inhibitory effect of this perfume did not decrease. But exposure to UV light significantly increased the inhibitory capacity of another perfume with a weak baseline inhibitory effect. To ascertain whether this inhibition was caused by CYP19 interactions with perfumes, we measured the catalytic activity of NADPH:cytochrome P450 oxidoreductase (CYPOR), the CYP reaction partner, with one selected perfume, ‘Intense Roses Musk’ by Montale®, and found no significant CYPOR inhibition. Accordingly, the decrease in testosterone conversion into 17β-estradiol caused by this perfume derives solely from CYP19. Combined, our findings highlight the importance of testing perfumes rather than single ingredients to determine their potential for adverse effects and to ensure consumer safety because their mixtures can interfere with a key enzyme of estrogen biosynthesis.

Simultaneous square wave voltammetric determination of two anti-inflammatory drugs using a bare carbon paste electrode

Background Diclofenac (DIC) is a nonsteroidal anti-inflammatory drug (NSAID) that is more potent than indomethacin. There is an extended-release form of this drug available for long-term treatment. Diflunisal (DIF) is a NSAID with less anticoagulant activity than aspirin. It is more potent than aspirin and is not converted to salicylic acid in vivo. Objectives A simple, direct, and sensitive method for the simultaneous determination of two types of NSAIDs, namely, diclofenac ‘DIC’ and diflunisal ‘DIF’ by square wave adsorptive anodic stripping voltammetry and applied at the same time in synthetic and pharmaceutical samples. Materials and methods In this method, both cited ingredients were oxidized by a bare carbon paste electrode (CPE) forming two well-separated peaks at the potential of 0.65 and 0.85 V, respectively, in 0.04 M universal buffer solution at pH 5 with 100 mV/s scan rate by square wave adsorptive anodic stripping voltammetry technique with an Autolab system of potentiostat/galvanostat. Results and conclusion The prepared sensor showed good linear regression curves over the concentration ranges of 1–6 and 5–25 μg/ml for DIC and DIF, respectively, while the detection limit ‘LOD’ and quantification limit ‘LOQ’ and were 0.204 and 0.68 μg/ml for DIC and 1.366 and 4.553 μg/ml for DIF, in turn. The cited sensor was applied with accurate and precise results for determining DIC and DIF at the same time in synthetic and pharmaceutical samples and gave close results in comparison with the official method, specifically by UV-high performance liquid chromatography.

Effect of Dexketoprofen on the Disposition Kinetics of Moxifloxacin in Plasma and Lung in Male and Female Rats.

The simultaneous use of NSAIDs and antibiotics is recommended for bacterial diseases in human and veterinary medicine. Moxifloxacin (MFX) and dexketoprofen (DEX) can be used simultaneously in bacterial infections. However, there are no studies on how the simultaneous use of DEX affects the pharmacokinetics of MFX in rats. The aim of this study was to determine the effect of DEX on plasma and lung pharmacokinetics of MFX in male and female rats. A total of 132 rats were randomly divided into 2 groups: MFX (n=66, 33 males/33 females) and MFX+DEX (n=66, 33 females/33 males). MFX at a dose of 20 mg/kg and DEX at a dose of 25 mg/kg were administered intraperitoneally. Plasma and lung concentrations of MFX were determined using the highperformance liquid chromatography-UV and pharmacokinetic parameters were evaluated by noncompartmental analysis. Simultaneous administration of DEX increased the plasma and lung area under the curve from 0 to 8 h (AUC0-8) and peak concentration (Cmax) of MFX in rats, while it significantly decreased the total body clearance (CL/F). When female and male rats were compared, significant differences were detected in AUC0-8, Cmax, CL/F and volume of distribution. The AUC0-8lung/AUC0-8plasma ratios of MFX were calculated as 1.68 and 1.65 in female rats and 5.15 and 4.90 in male rats after single and combined use, respectively. MFX was highly transferred to the lung tissue and this passage was remarkably higher in male rats. However, DEX administration increased the plasma concentration of MFX in both male and female rats but did not change its passage to the lung. However, there is a need for a more detailed investigation of the difference in the pharmacokinetics of MFX in male and female rats.

Preparation of a highly specific and sensitive monoclonal antibody against tilmicosin and its application in lateral flow immunoassay

To reduce the false positive results caused by cross reactivity of the antibodies with other structural analogues, it is crucial to prepare a high specificity and sensitivity antibody against target for developing an accurate immunoassay. In this study, tilmicosin (TM) was selected as a model molecule. Firstly, two-dimensional similarity, electrostatic potential energy, mulliken atomic charges and overlapping of different haptens with TM were calculated using Gaussian 09W and Discovery studio, and the newly designed TM-HS was selected as the optimal hapten. Furthermore, a monoclonal antibody (mAb 12C8) was produced with the half maximal inhibitory concentration (IC50) of 0.36 ng/mL, and negligible cross-reactivity (CR) with other antibiotics. Finally, a lateral flow immunoassay (LFA) for the detection of TM based on amorphous carbon nanoparticles (ACNPs) labeled mAb 12C8 was developed by the reflectance value under natural light. The recoveries of TM ranged from 83.18% to 103.25% with a coefficient of variation (CV) < 12.47%. The results showed that the cut-off value of TM in milk samples was 1 ng/mL, and the limits of detection (LODs) for chicken muscle, bovine muscle, porcine muscle and porcine liver samples were 5.23, 5.98, 6.85 and 7.31 μg/kg, respectively. In addition, 40 real samples were tested by the LFA, and the detection results were consisted with that of high-performance liquid chromatography-UV detector (HPLC–UV). Those results indicated that the developed LFA is an accurate and useful tool for on-site screening of TM in milk and animal tissues.

Establishing an integrated, four-dimensional quality assessment system for traditional Chinese medicine: A case study of Shuanghuanglian oral liquid

The quality of traditional Chinese medicine (TCM) is the premise to ensure its safety and effectiveness in clinical application. In this study, a complete quality control system for four-dimensional fingerprinting of TCM was innovatively constructed based on multiple detection techniques, and the quality of Shuanghuanglian oral liquid (SHL) was evaluated. Electrochemical fingerprinting (ECFP) as an emerging method without pretreatment provides rich and quantifiable information for SHL samples. The first quantitative ECFP of SHL was developed by the B-Z oscillation system. Eight characteristic parameters were analyzed and a good linear relationship was found between the oscillation lifetime and sample volume, by which the calculated values of the added sample volume (VL) showed different fluctuations between samples. What is more, high-performance liquid chromatography five-wavelength fusion fingerprint (HPLC-FWFP), GC fingerprint (GC-FP), and UV quantum fingerprint (UV-QFP) was established. Meanwhile, the purity of the peaks of the HPLC-FWFP was verified by the dual-wavelength absorption coefficient ratio spectrum (DWAR). Equal weighted ratio quantitative fingerprinting method (EWRQFM) was successfully proposed to extract all potential features for the overall quality assessment of the samples. Finally, a comprehensive evaluation strategy was proposed, namely the variation coefficient weighting algorithm (VCWA). The results of qualitative and quantitative evaluation of HPLC-FWFP, GC-FP, electrochemical quantum fingerprints (EC-QFP), and UV-QFP were integrated by this method. The established evaluation system is also a suitable strategy to control the quality of other TCM preparations.

Optimisation study on the flavonoid extraction process from Abrus precatorius leaves and the comparison of total flavonoid content by HPLC and UV

Abrus precatorius is a leguminous plant with high medicinal value. Its leaves are rich in flavonoids. There only are limited reports on the extraction process and quality assessment of total flavonoids in Abrus precatorius leaves (APL). This study presents the extraction process of total flavonoids in APL and its optimisation by response surface methodology (RSM). High-performance liquid chromatography (HPLC) and UV methods were used to determine the total flavonoid content and their differences were compared. The feasible extraction parameters of total flavonoids from APL were found to be 50% ethanol, a liquid-solid ratio of 50:1, an extraction time of 60 ​min and two extraction cycles. The number of extraction cycles was the main influencing factor. The total flavonoid content as determined by this optimised process was 69.0 ​mg/g by HPLC and 41.7 ​mg/g by UV. There was a significant difference between the total flavonoid content determined by the UV method and HPLC. A comparative analysis of 29 samples in RSM and 14 batches of APL showed that the total flavonoid content as determined by UV was only about half of that determined by HPLC. The factors that influence this difference and potential solutions to this challenge were discussed. The results of this study could lay a foundation for the quality assessment, standardisation, development and utilisation of flavonoids in APL.

Carbohydrate-based quality consistency evaluation of Saposhnikoviae Radix

This study aims to evaluate the quality consistency of Saposhnikoviae Radix based on carbohydrates, and explore the potential of carbohydrates as the internal quality control indicators of Saposhnikoviae Radix. The total polysaccharides were quantified by UV-Vis spectrophotometry and the molecular weight range of the polysaccharides was determined by high performance gel-permeation chromatography-evaporative light scattering detection(HPGPC-ELSD). The monosaccharides in polysaccharides and the free monosaccharides were quantified by high performance liquid chromatography-UV detection(HPLC-UV), and the oligosaccharides and fructose were quantified by high performance liquid chromatography-evaporative light scattering detection(HPLC-ELSD). The carbohydrate-based quality of Saposhnikoviae Radix was compared among 45 batches of commercial samples and 13 batches of self-collected samples. The results showed that the molecular weight distribution, monosaccharide composition, oligosaccharide, and free monosaccharide composition were similar in the 58 batches of samples. The average content of total polysaccharides, oligosaccharides, and total free monosaccharides in commercial samples were 39.66, 148.79, and 68.62 mg·g~(-1), respectively. The content showed significant differences among batches, with the highest differences of 3.51, 1.75, and 2.58 times, respectively. The RSD of the relative ratios of monosaccharides in the polysaccharides in commercial samples reached 28%-45%. The average content of total polysaccharides, oligosaccharides, and total free monosaccharides in self-collected samples were 68.07, 145.76, and 42.04 mg·g~(-1), respectively, with the inter-region differences of 2.88, 1.88, and 1.07 times, respectively. The RSD of the relative ratios of monosaccharides in polysaccharides in self-collected samples ranged from 8.2% to 59%. The total polysaccharides and total free monosaccharides in self-collected samples were 1.72 times higher and 1.63 times lower, respectively, than those in commercial samples. The content of oligosaccharides was similar between self-collected samples and commercial samples. To sum up, carbohydrates are one of the material bases for the internal quality consistency of Saposhnikoviae Radix. The qualitative characteristics of polysaccharides and the quantitative characteristics of polysaccharides and oligosaccharides are related to the origin of medicinal materials. Moreover, the quantitative characteristics of polysaccharides and free monosaccharides may be related to the storage conditions. Carbohydrates are potential indicators for the quality control of Saposhnikoviae Radix and deserve attention.

In Vitro Filaricidal Properties of Hydro-Methanolic Extracts of Powdery Fractions of Khaya senegalensis (Meliaceae) on Onchocerca ochengi.

Onchocerciasis is a neglected tropical disease that remains endemic in sub-Saharan African countries. Unfortunately, only a few microfilaricidal agents have been approved so far. This study aimed to assess the in vitro macro and microfilaricidal potentialities of the hydro-methanolic extracts of the different powdery fractions of Khaya senegalensis against Onchocerca ochengi. Adult male worms and microfilariae (mf) of O. ochengi were isolated from cowhides in Ngaoundere II, Cameroon. Parasites were incubated for 4h (mf) or 48h (adult worms) in RPMI-1640 medium in the presence or absence of ivermectin, flubendazole, or hydro-methanolic extracts of different plant powdery fractions obtained by controlled differential sieving. The filaricidal effect was evaluated using motility (mfs) and mortality tests (worms) and oxidative stress parameters. Cytotoxicity and acute toxicity tests were performed on monkey-derived kidney cell lines (LLC-MK2) and Swiss albino mice, respectively, and selectivity indexes were determined. Phytochemical screening was also carried out using high-performance liquid chromatography/UV (HPLC/UV), molecular networking, and through quantification of phenolic contents. The hydro-methanolic extracts of 0-63µm fractions from leaves and barks exhibited the strongest macrofilaricidal activities with lethal concentrations 50 of 162.4 and 208.8µg/mL respectively versus 22.78µg/mL for flubendazole. These two fractions also showed the fastest microfilaricidal activities (T1/2 of 1h), although it was low when compared to ivermectin (T1/2 < 1h). Their macrofilaricidal effects were accompanied by a significant inhibition of nitric oxide secretion and a significant increase of glutathione and catalase activity compared to the untreated group. However, no effect was found on superoxide dismutase activity, the GABAergic and glutamatergic receptors. Although neither extract was toxic to Swiss mice until a dose of 2000mg/kg body weight, the 0-63µm leaf fraction hydro-methanolic extract was selectively more effective on worms than bark extract (SI = 1.28 versus 0.34). Both extracts were found to contain some flavonoids including procyanidin-, rutin-, myricetin-, and naringenin derivatives as well as new unknown compounds. However, the total polyphenol, flavonoid and tannin contents of the leaf extract were significantly greater (P < 0.05) than that of the bark extract. These results support the anti-filarial effect of K. senegalensis leaves and highlight stress oxidative markers as new therapeutic targets in O. ochengi. Further, in vivo experiments are required in understanding their anti-parasitic properties, and testing combinations of fine fractions.

Developing a Method for Quantifying Meropenem in Children-Volumetric Adsorptive Microsampling Versus Plasma Sampling.

Meropenem is a carbapenem antibiotic often used in pediatric intensive care units due to its broad spectrum of activity. Therapeutic drug monitoring (TDM) is a useful tool to increase the effectiveness of meropenem by adjusting the dose based on plasma levels; however, the relatively large sample volume required for TDM can limit its use in children. Therefore, this study aimed to determine meropenem concentrations and consequently perform TDM effectively using the smallest possible sample volume. Volumetric absorptive microsampling (VAMS) is a sampling technology developed to collect a small, precise volume of blood. For the applicability of VAMS in TDM, plasma concentrations must be reliably calculated from whole blood (WB) collected by VAMS. VAMS technology using 10 µL of WB was evaluated and compared with EDTA-plasma sampling. High-performance liquid chromatography with UV detection was applied to quantify meropenem in VAMS and plasma samples after the removal of proteins by precipitation. Ertapenem was used as the internal standard. Samples were collected simultaneously from critically ill children receiving meropenem using VAMS and traditional sampling. It was found that no consistent factor could be determined to calculate meropenem plasma concentrations from the WB, indicating that VAMS was not reliable in the TDM of meropenem. Therefore, to reduce the required sample amount in pediatric patients, a method for quantifying meropenem from 50 µL of plasma with a lower limit of quantification of 1 mg/L was developed and successfully validated. A simple, reliable, and low-cost method was established using high-performance liquid chromatography-UV to determine the concentration of meropenem in 50 µL of plasma. VAMS using WB does not seem to be suitable for TDM of meropenem.

Keggin type phosphotungstic acid intercalated copper-chromium-layered double hydroxide reinforced porous hollow fiber as a sorbent for hollow fiber solid phase microextraction of selected chlorophenols besides their quantification via high performance liquid chromatography

Herein, a copper-chromium-layered double hydroxide (Cu/Cr-LDH) was synthesized by the co-precipitation method. The Cu/Cr-LDH was intercalated to the Keggin-type polyoxometalate (H3PW12O40). The modified LDH accommodated in the pores of hollow fiber (HF), to prepare the extracting device for the HF-solid phase microextraction method (HF-SPME). The method was used for the extraction of 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6- trichlorophenol from tap water, river water, and tea sample. The extracted target analytes were quantified via high-performance liquid chromatography-UV detection. The figures of merit of the method such as, linear dynamic ranges (LDRs), limit of detections (LODs) and, limit of quantifications (LOQs), were determined based on the obtained optimum condition. Based on the results, the LDR was between 1 and 500 μg L − 1 and r2 higher than 0.9960. The LODs and LOQs were obtained in the ranges of 0.28–0.36 µg L − 1 and 0.92–1.1 µg L − 1, respectively. The relative standard deviations ((RSDs% for inter-and intra-day) of the method for the extraction of target analytes were calculated in two different concentrations of (2 and 10 μg L − 1) and (5 and 10 μg L − 1) between 3.70% - 5.30% and 3.50% - 5.70%-respectively. The enrichment factors were obtained between 57 and 61. In order to investigate the accuracy of the method, also the relative recovery was obtained, between 93 and 105%. Finally, the proposed method was used for the extraction of the selected analytes in different water and tea samples.

Application of oxidized multi-walled carbon nanotubes and zeolite nanoparticles for simultaneous preconcentration of codeine and tramadol in saliva prior to HPLC determination

In this work, a dispersive micro-solid phase extraction technique along with high-performance liquid chromatography-UV detection was developed for simultaneous preconcentraion and determination of trace levels of codeine and tramadol in human saliva. This method is based on the adsorption of codeine and tramadol on a mixture of oxidized multi-walled carbon nanotubes and zeolite Y nanoparticles with 1:1 ratio as an efficient nanosorbent. Various analytical parameters influencing the adsorption step including the amount of adsorbent, the pH of the sample solution, the temperature, the stirring rate, the contact time of the sample solution, and the adsorption capacity were investigated. Based on the results, 10 mg adsorbent, sample solutions with pH = 7.6, temperature of 25 °C, stirring rate 750 rpm and contact time 15 min, in the adsorption step shows the best results for both drugs. Then the effective parameters on the analyte desorption stage such as the type of desorption solution, pH of the desorption solution, desorption time and desorption volume were investigated. Studies have shown that water/methanol (50:50 v/v) as desorption solution, pH = 2.0, desorption time of 5 min and desorption volume of 2 ml gives the best results.Chromatographic separation was performed on a RP-Shim-pack CLC-ODS-C18 column (250 mm × 4.6 mm, 5 µm) with isocratic mode. The mobile phase contained of acetonitrile:phosphate buffer (18:82, v/v) at pH = 4.5 and the flow rate was 1 ml.min−1. The wavelength of UV detector was adjusted at 210 nm and 198 nm for codeine and tramadol, respectively.Under optimum conditions, the extraction efficiencies of 98.5% and 99.2% were achieved for codeine and tramadol respectively. Enrichment factor of 13, detection limit of 0.3 μg L−1, relative standard deviation of 4.07 for codeine; and an enrichment factor of 15, a detection limit of 0.15 μg L−1, and standard deviation of 2.06 for tramadol were calculated. The linear range of the procedure for each drug was 1.0 to 1000 μg L−1. This method was successfully applied for the analysis of codeine and tramadol in saliva samples.

Effect of Encapsulation Material on Lipid Bioaccessibility and Oxidation during In Vitro Digestion of Black Seed Oil.

Different encapsulation materials might not only affect lipid hydrolysis but also lipid oxidation during in vitro digestion. Thus, this study aimed to investigate the effect of two commonly used shell materials, starch and gelatin, on the extent of lipolysis and bioaccessibility of the main and some minor lipid compounds, as well as on the oxidative status in encapsulated black seed oil (Nigella sativa) during in vitro digestion. The study was carried out using 1H nuclear magnetic resonance spectroscopy, liquid chromatography-mass spectrometry and high-performance liquid chromatography-UV. It was shown that starch increased the level of lipid hydrolysis in black seed oil during gastric in vitro digestion, while no differences were observed in the intestinal digestates between starch-encapsulated oil and gelatin-encapsulated oil. Similarly, the bioaccessibility of minor compounds (tocopherols, sterols and thymoquinone) was not influenced by the shell materials. However, regarding lipid oxidation, a 20- and 10-fold rise of free oxylipins was obtained in oils encapsulated by starch and gelatin, respectively, after intestinal in vitro digestion. This study evidenced that gelatin rather than starch should be used for the encapsulation of oils to minimize the digestion-induced formation of bioactive oxylipins.

A SIMPLE AND SELECTIVE METHOD FOR SIMULTANEOUS DETERMINATION OF PATULIN AND 5- HMF IN HONEY AND APPLE JUICE BY HPLC-UV

A selective and sensitive method using a high-performance liquid chromatography-UV detector (HPLC-UV) for the simultaneous determination of Patulin (PAT) and 5-(hydroxymethyl)furfural (5-HMF) in honey and apple juice was developed. The sample preparation technique QuEChERS was applied to increase the sensitivity and selectivity. The linear ranges for PAT and 5-HMF detected by the method were 2.0 ppb ÷ 200.0 ppb and 2.0 ppm ÷ 20 ppm. The results of method validation show that the recovery efficiency for PAT ranged from 92.8% ÷ 98.2% with % RSDr from 0.56% ÷ 0.63% and from 97.9% ÷ 101.2% with %RSD 0.39% ÷ 0.67% for 5-HMF and LOD and LOQ values of the method for PAT and 5-HMF detection were respectively: 0.6 and 2.0 ppb; 0.6 and 2.0 ppm. The influence of the matrix effect on the accuracy, repeatability, and recovery of the method was insignificant. The proposed method was applied to quantify the content of PAT, and 5-HMF in actual samples, collected in Ho Chi Minh City, Vietnam. The result showed that PAT was not found in honey samples but was detected in 5 of 10 apple juice samples. In addition, 5-HMF was detected in 3 of 10 honey samples and 10 of 10 apple juice samples.

Studies on a novel method for the determination of nitrosamines in food by HPLC-UV-FLD coupling with terbium-doped carbon dots

In this paper, a novel, selective and sensitive high performance liquid chromatography-UV photolysis-fluorescence detection (HPLC-UV-FLD) method for nitrosamines (NAs) is proposed based on terbium-doped carbon dots (Tb-CDs). Experimental studies have shown that nitrosamines can be degraded by UV photolysis with wavelength at 254 nm to produce NO2−, while NO2− can rapidly and specifically quench the fluorescence of Tb-CDs. Based on this principle, N-nitrosodimethylamine (NDMA), Nnitrosomorpholine (NMor), N-nitrosopyrrolidine (NPYR), N-nitrosodiethylamine (NDEA) and N-nitrosopiperidine (NPIP) are separated within 8 min by HPLC. These five kinds of NAs showed a good linear relationship in the range of 10–2000 μg/L, and the limit of detection was as low as 2.25 μg/L. The proposed method is successfully applied to the detection of sweet potato, lotus root, potato, water chestnut, tomato and cucumber. The sample recoveries range from 77.35 % to 119.3 %.

Degradation of Patulin in Pear Juice and Apple Juice by Ascorbic Acid and the Combination of Ascorbic Acid and Ferrous Iron.

Patulin (PAT) is a toxic secondary metabolite produced by certain species of Penicillium sp. and Aspergillus sp. on apples and pears. In this study, we investigated the effects of ascorbic acid and the combination of ascorbic acid and ferrous iron on degradation of PAT in 100% pure pear juice and apple juice using high-performance liquid chromatography UV detector (HPLC-UVD). The addition of 2 different levels of ascorbic acid (143 or 286 μg/mL) into pear juice or apple juice containing 0.08 or 0.4 μg/mL of PAT showed 87.7-100% and 67.3-68.7% of PAT degradation rates, respectively, after 24 h incubation at 25 °C. Moreover, the addition of both ascorbic acid (143 or 286 μg/mL) and ferrous iron (0.033 or 0.11 μmol/mL) into pear juice or apple juice containing the same level of PAT exhibited higher PAT degradation rates (100 and 75-94%, respectively) than the addition of only ascorbic acid after 24 h incubation at 25 °C. Our data demonstrated that ascorbic acid plus ferrous iron as well as ascorbic acid were highly effective on degradation of PAT in pear juice and apple juice and that addition of both ascorbic acid and ferrous iron produced higher PAT degradation rates than addition of only ascorbic acid.

The effects of hypothermia on glutamate and γ-aminobutyric acid metabolism during ischemia in monkeys: a repeated-measures ANOVA study

During an ischemic stroke, the brain releases various factors, including glutamate and γ-aminobutyric acid. Glutamate can cause neurotoxic effects through certain receptors and exacerbate neurological damage, while γ-aminobutyric acid as an inhibitory neurotransmitter can antagonize the excitotoxic effects of glutamate and enhance the tolerance of neurons to ischemia. Therefore, in this study, the content of amino acid neurotransmitters in brain tissue before ischemia, after 10 min of ischemia, hypothermic perfusion, and rewarming were analyzed by high-performance liquid chromatography-UV in an animal model of ischemic stroke generated by blocking the bilateral common carotid arteries of rhesus monkeys. The changes in amino acid neurotransmitters in the rhesus monkey brain during post-ischemia hypothermic perfusion and rewarming were investigated by statistical methods of repeated measures ANOVA, showing that the concentration change of glutamate had not only a temporal factor but also was influenced by temperature, and there was an interaction effect between the two. Time but not temperature affected the change in γ-aminobutyric acid concentration, and there was an interaction effect between the two. Accordingly, hypoperfusion exerts a protective effect during ischemia by inhibiting the release of excitatory amino acid neurotransmitters, while the antagonistic effect of GABA on Glu is not significant.