A Fast HPLC Method for Determination of Vitamin E Acetate in Dietary Supplements Using Monolithic Column

Fabrication, characterization and release behavior of α-tocopherol acetate-loaded pH-responsive polyhydroxybutyrate/cellulose acetate phthalate microbeads

Microbeads are used in personal care and cosmetic products (PCCPs) but are produced from nondegradable materials. Biodegradable polyhydroxybutyrate (PHB) has been recognized as a promising alternative material for use in PCCPs; however, utilizing PHB to encapsulate PCCPs is challenging because PCCPs need to be protected from the environment but their release needs to be permitted under specific physiological conditions. The aim of this work was to develop and evaluate pH-responsive cellulose acetate phthalate (CAP) to formulate lipophilic α-tocopherol acetate (α-TA)-loaded pH-responsive PHB/CAP microbeads. The influences of the PHB/CAP ratio and initial α-TA loading on the microbead size, surface morphology, encapsulation efficiency (%EE), loading capacity (%LC), and α-TA release profile were studied. The microbeads exhibited a spherical shape with a size of 328.7 ± 2.9 μm. The EE and LC were 86.7 ± 2.6 % and 13.5 ± 0.4 %, respectively. The release profile exhibited pH-responsive characteristics. These α-TA-loaded pH-responsive microbeads were stable with >50 % of the α-TA remaining after 90 days at 4, 25 and 45 °C in the dark. The results from the cytotoxicity assay with PSVK1 cells demonstrated that the microbeads were nontoxic. Hence, our developed formulation has the potential to be used to encapsulate oil-based drugs to formulate lipophilic substance-loaded pH-responsive microbeads.

Development, Validation, and Application of a Novel Method for the Analysis of Vitamin E Acetate and Other Tocopherols in Aerosol Emissions of E-Cigarettes, or Vaping Products Associated With Lung Injury

E-cigarette, or vaping, product (EVP) use has increased dramatically in the United States over the last 4 years, particularly in youth and young adults. Little information is available on the chemical contents of these products. Typically, EVPs contain an active ingredient such as nicotine, CBD, or THC dissolved in a suitable solvent that facilitates aerosol generation. One EVP solvent, vitamin E acetate (VEA), has been measured in EVP liquids associated with lung injury. However, no validated analytical methods for measuring VEA in the aerosol from these devices was previously available. Therefore, we developed a high throughput isotope dilution LC-MS/MS method to simultaneously measure VEA and three other related tocopherols in aerosolized EVP samples. The assay was precise, with VEA repeatability ranging from 4.0 to 8.3% and intermediate precision ranging from 2.5 to 6.7%. Similar precision was obtained for the three other tocopherols measured. The LODs for the four analytes ranged from 8.85 × 10⁻⁶ to 2.28 × 10⁻⁵ μg analyte per mL of aerosol puff volume, and calibration curves were linear (R² > 0.99). This method was used to analyze aerosol emissions of 147 EVPs associated with EVALI case patients. We detected VEA in 46% of the case-associated EVPs with a range of 1.87 × 10⁻⁴–74.1 µg per mL of aerosol puff volume and mean of 25.1 µg per mL of aerosol puff volume. Macro-levels of VEA (>0.1% w/w total aerosol particulate matter) were not detected in nicotine or cannabidiol (CBD) products; conversely 71% of the EVALI associated tetrahydrocannabinol (THC) products contained macro-levels of VEA. Trace levels of other tocopherol isoforms were detected at lower rates and concentrations (α-tocopherol: 41% detected, mean 0.095 µg analyte per mL of aerosol puff volume; γ-tocopherol: 5% detected, mean 0.0193 µg analyte per mL of aerosol puff volume; δ-tocopherol: not detected). Our results indicate that VEA can be efficiently transferred to aerosol by EVALI-associated EVPs vaped using a standardized protocol.

Silica-Based Monolithic Columns as a Tool in HPLC-An Overview of Application in Analysis of Active Compounds in Biological Samples

Monolithic fillings used in chromatography are of great interest among scientists since the first reports of their synthesis and use were published. In the 20 years since silica-based monolithic columns were introduced into the commercial market, numerous papers describing their chromatographical properties and utility in various branches of industry and scientific investigations were presented. This review is focused on possible applications of commercially available silica-based HPLC monolithic columns in the analysis of biological samples.

HPTLC Separation of a Hepatoprotective Combination in Pharmaceutical Formulation and Human Plasma

A binary mixture of Silymarin (SR) and Vitamin E (VE) acetate, of an antioxidant and a hepatoprotective effect, has been analyzed using a sensitive, selective and economic high performance thin layer chromatographic (HPTLC) method in their pure forms, pharmaceutical formulation and spiked human plasma. SR and VE were separated on 60F254 silica gel plates using hexane:acetone:formic acid (7:3:0.15, v/v/v) as a developing system with UV detection at 215 nm. The method was evaluated for linearity, accuracy, precision, selectivity, limit of detection (LOD) and limit of quantification (LOQ). SR and VE were detected in the linear range of 0.2-2.5 and 0.2-4.5 μg/band, respectively. Method validation was done as per ICH guidelines and acceptable results of accuracy of 99.86 ± 1.190 and 100.22 ± 1.609 for SR and VE, respectively were obtained. The method has been successfully applied for determination of the studied drugs in their pharmaceutical formulation without any interference from excipients, and in spiked plasma samples. Results obtained by the developed HPTLC-densitometric method were statistically compared to those obtained by the reported HPLC methods and no significant difference was found between them.

Assessment of H-β zeolite as an ochratoxin binder for poultry

Most of the cereal-based ingredients used in poultry feed are contaminated with ochratoxin-A (OTA). We have investigated H-β zeolite (HBZ) as a new OTA binder for poultry, along with widely used clay mineral-based product (CM), using in vitro and in vivo methods. In vitro binding experiment was carried out using a biphasic assay, consisting of adsorption at pH 3.2 and desorption at pH 6.8. High adsorption (>98%) with less desorption (<5%) was observed for HBZ, whereas CM showed high binding (>98%) and moderate desorption (48%). In the in vitro experiments with the different simulated gastro-intestinal pH buffers, HBZ did not desorb OTA at any of the pH. Desorption of OTA was observed with CM, as the pH increases. From the in vitro kinetic and chemisorption studies, faster, stronger, and higher adsorption was observed for HBZ. Thermodynamic studies showed positive entropy (22.76 KJ/mol K) for HBZ, signifying predominant hydrophobic interactions towards OTA, whereas CM exhibited negative entropy (-3.67 KJ/mol K). The in vivo binding efficacy of HBZ and CM was tested in 5-wk-old broiler chickens. The study consisted of 4 experimental groups, each with 6 replicates having 2 birds per replicate. The groups were control, negative control (no toxin binder), T1 (HBZ at 1 kg/ton of feed), and T2(CM at 1 kg/ton of feed). Except control, all the replicates received 20 µg of OTA in the feed. Excreta samples of T1, T2, and NC contained 11.57, 7.16, and 2.78 µg of OTA respectively, which was significantly different from each other (P < 0.05). A growth performance trial was conducted in broiler chickens for 35 D. A total of 288 one-day-old birds were randomly segregated to 3 treatment groups, each with 8 replicates of 12 birds each. Treatment groups consisted of control, T1, and T2, treated with no toxin binder, HBZ, and CM at 1 kg/ton of feed, respectively. None of the treatment groups including control, affected BW gain, and feed conversion ratio (P > 0.05).

Gold and silver nanoparticles in resonance Rayleigh scattering techniques for chemical sensing and biosensing: a review

This review (with 116 refs.) summarizes the state of the art in resonance Rayleigh scattering (RRS)-based analytical methods. Following an introduction into the fundamentals of RRS and on the preparation of metal nanoparticles, a first large section covers RRS detection methods based on the use of gold nanoparticles, with subsections on proteins (albumin, bovine serum albumin and ovalbumin, glycoproteins, folate receptors, iron binding-proteins, G-proteins-coupled receptors, transmembrane proteins, epidermal growth factor receptors), on pesticides, saccharides, vitamins, heavy metal ions (such as mercury, silver, chromium), and on cationic dyes. This is followed by a section on RRS methods based on the use of silver nanoparticles, with subsections on the detection of nucleic acids and insecticides. Several Tables are presented where an RRS method is compared to the performance of other methods. A concluding section summarizes the current status, addresses current challenges, and gives an outlook on potential future trends. Graphical Abstract Change in the resonance Rayleigh scattering (RRS) intensity when mixing the nanoparticles with the specific analyte.

Amplification of resonance Rayleigh scattering of gold nanoparticles by tweaking into nanowires: Bio-sensing of α-tocopherol by enhanced resonance Rayleigh scattering of curcumin capped gold nanowires through non-covalent interaction

Tuning optical properties by controlling size and shape of the metallic nanoparticles has been of great interest to design novel bio-sensing techniques. Here, as a first example we illustrate that resonance Rayleigh scattering (RRS) signal of Au nanoparticles (NPs) can be amplified >10-fold by growing into Au nanowires (NWs). These thin and long NWs of ~20-25nm diameter and >1µm length can be achieved by suitably manipulating the temperature during green synthesis using curcumin. Interestingly, mixture of Au NWs and NPs or shorter NWs gives a moderate increase in RRS signal suggesting formation of longer NWs is crucial for optimal enhancement of RRS signal. Curcumin along with CTAB act as capping and stabilizing agent for Au NWs/NPs in different temperatures, which is confirmed by XRD, TGA, DSC, EDX and FT-IR data. This amplified RRS signal of Au NWs has been employed to design a new optical biosensor for α-tocopherol (α-TOH), which is among the most biologically active form of vitamin E. Association of α-TOH with Au NWs further enhances the RRS signal of Au NWs, ~10 fold through non-covalent interaction. No interference from other antioxidant substances like ascorbic acid and 6-O-Palmitoyl-L-ascorbic acid is observed. The sensing method is simple, fast and offers remarkable linear dynamic ranges, 12.8-1004µmolL^-1, which is larger than reported values. The detection limit for α-TOH estimation has been found to be 50nmolL^-1. The biosensor is found to be stable both in the absence and presence of α-TOH and provides an excellent recovery for synthetic samples.

A new approach to the rapid separation of isomeric compounds in a Silybum marianum extract using UHPLC core-shell column with F5 stationary phase

In this paper, a new ultra-high performance liquid chromatography (UHPLC) method using a core-shell column with a pentafluorophenyl stationary phase for separation of seven active compounds of a Silybum marianum extract was developed and validated. Silymarin, an extract of Silybum marianum, is known for its abilities to protect the liver from toxic substances, hepatitis therapy, and anti-tumour activity. Silymarin is currently being widely used in commercial preparations and herbal teas. Separation of seven compounds contained in the Silybum marianum extract (taxifolin, silychristin, silydianin, silybin A, silybin B, isosilybin A, isosilybin B) and other substances occurring in real samples was performed on the Kinetex 1.7μ F5 100A (150×2.1mm), 1.7μm particle size core-shell column, with a mobile phase methanol/100mM phosphate buffer pH 2.0 according to the gradient program. A mobile phase 0.35mLmin-1 flow rate and 50°C temperature was used for the separation. The detection wavelength was set at 288nm. Under optimal chromatographic conditions, good linearity with a correlation coefficient of R2 >0.999 for all compounds was achieved. The available commercial samples of herbal teas and food supplements were extracted with methanol using an ultrasonic bath. After dilution with water and centrifugation, a 2μL sample of the filtered supernatant was directly injected into the UHPLC system. The use of a pentafluorophenyl stationary phase with methanol as the organic component of the mobile phase showed new ways to effectively separate isomeric compounds in herbal extracts, which could not be done with the conventional C18 stationary phase.

A comparative study of ICH validated novel spectrophotometric techniques for resolving completely overlapping spectra of quaternary mixtures

A pharmaceutically marketed mixture of Yohimbine, Alpha-tocopheryl acetate, Niacin, and Caffeine co-formulated as a promising therapy for erectile dysfunction. Simultaneous determination of the aforementioned pharmaceutical formulation without prior separation steps was applied using mean centering of ratio spectra and triple divisor spectrophotometric methods. Mean centering of ratio spectra method depended on using the mean centered ratio spectra in three successive steps which eliminated the derivative steps and so the signal to noise ratio was improved. The absorption spectra of the prepared solutions were measured in the wavelength range of 215-300 nm in the concentration ranges of 1-15, 3-15, 1-20, and 3-15 μg mL(-1) for Yohimbine, Alpha-tocopheryl acetate, Niacin, and Caffeine, respectively. The amplitudes of the mean centered third ratio spectra were measured at 250 nm and 268 nm for Yohimbine and Alpha-tocopheryl acetate, respectively and at peak to peak 272-273 and 262-263 nm for Niacin and Caffeine, respectively. In triple divisor method each drug in the quaternary mixture was determined by dividing the spectrum of the quaternary mixture by a standard spectrum of a mixture containing equal concentrations of the other three drugs. First derivative of these ratio spectra was obtained where determination could be achieved without any interference from the other three drugs. Amplitudes of 1-15, 3-15, 1-15, and 3-15 μg mL(-1) were used for selective determination of Yohimbine, Alpha-tocopheryl acetate, Niacin, and Caffeine, respectively. Laboratory prepared mixtures were analyzed by the developed novel methods to investigate their selectivity also, Super Act® capsules were successfully analyzed to ensure absence of interference from additives. The developed methods were validated according to the ICH guidelines. The proposed methods were statistically compared with each other and with the reported methods; using student t-test, F-test, and one way ANOVA, where no significant difference was found with respect to accuracy and precision.

Simultaneous determination of tylosin and josamycin residues in muscles, liver, eggs and milk by MLC with a monolithic column and time-programmed UV detection: application to baby food and formulae

Background

Tylosin and Josamycin are macrolide antibiotics. They are used in the treatment of pneumonia, arthritis and mastitis in cattle, and mycoplasma infections in poultry. The incorrect use of antibiotics has lead to the presence of antibiotic residues in foods. The residues cause toxic effects on consumers.

Results

A simple and sensitive method was optimized and validated for the analysis of tylosin and josamycin residues in food samples. Analytical separation was performed in less than 10 min using a RP C₁₈ monolithic column with time-programmed UV detection at 287 nm and 232 nm and a micellar solution of 0.17 M sodium dodecyl sulphate, 14% methanol and 0.3% triethylamine in 0.02 M phosphoric acid buffered at pH 4 as the mobile phase. The method was fully validated in accordance with ICH guidelines. The micellar method was successfully applied to quantitatively determine tylosin and josamycin residues in spiked chicken muscles, chicken liver, bovine muscles, liver, milk and eggs. It was also extended to the determination of tylosin and josamycin residues in chicken-based baby food and baby formulae. The compounds were separated by a monolithic column which, on account of its particular structure, could bear higher flow rates than usually found for this kind of analysis. High extraction efficiency for tylosin and josamycin was obtained without matrix interference in the extraction process and in the subsequent chromatographic determination. No organic solvent was used during the pretreatment step. Hence, it is considered an interesting technique for “green” chemistry.

Conclusion

The proposed method was validated and successfully applied for the determination of tylosin and josamycin residues in spiked chicken muscles, chicken liver, bovine muscles, liver, milk and eggs. It was also extended to the determination of tylosin and josamycin residues in chicken-based baby food and baby formulae.