Marcone Oliveira | Universidade Federal de Juiz de Fora (original) (raw)

Papers by Marcone Oliveira

Microchemical Journal, 2012

The preparation of photo-polymerized sol-gel monolithic stationary phases (MSP) within 100 μm int... more The preparation of photo-polymerized sol-gel monolithic stationary phases (MSP) within 100 μm internal diameter polyacrylate-coated fused-silica capillaries for use in capillary electrochromatography (CEC) was optimized. Eight mixtures containing different amounts of methacryloxypropyltrimethoxysilane (MPTMS) as the polymeric precursor, hydrochloric acid solution as the catalyst, toluene as the porogen and bis(2,4,6trimethylbenzoyl)-phenylphosphine oxide (Irgacure 819) as the photo-initiator were irradiated at 370 nm inside the capillaries in order to complete the MSP polymerization, according to a fractional factorial experimental design 2 IV 4-1. All the preparation procedure, from capillary pretreatment until the MSP is ready to use in CEC, were made in less than four hours in mild conditions. A high pressurization injection device (HPID) useful for micro-volume syringes was built in order to achieve practical, controlled and precise injections of sols, solvents and electrolytes in the capillaries. The eight MSP were equally washed, conditioned and submitted to CEC procedures via short-end injection, which showed higher efficiency and peak height taking shorter analysis time. Electrochromatographic behaviors of the MSP were corroborated with morphological characterizations by scanning electron microscopy. The optimum condition, which allowed the separation of standard mixture containing thiourea (marker compound), naphthalene, acenaphthene, fluorene, phenanthrene and anthracene in twelve minutes without external pressure assistance, showed efficiencies up to 51,460 N/m, relative standard deviation from 0.05 to 3.3% for migration/retention time and from 0.14 to 1.6% for relative area (considering thiourea as an internal standard) and also showed no statistical evidence that three MSP prepared at the same condition are different within 95% confidence interval.

Journal of Agricultural and Food Chemistry

The adverse effects of industrial trans fatty acids (TFA) consumption have prompted legislation t... more The adverse effects of industrial trans fatty acids (TFA) consumption have prompted legislation to avoid these fats in food. This work aimed to predict C18:1 TFA isomers as well as other groups of fatty acids (saturated, monounsaturated, polyunsaturated, and total TFA) in chocolates by ATR-FTIR and partial least square regression. The quantification of fatty acids in representative samples (white, dark, and milk chocolates) was rapid (<30 s) and did not require derivatization. The optimized models showed satisfactory linear correlations when compared to a reference gas chromatographic method; coefficients of correlation for prediction ranged from 0.973 to 0.998 considering C18:1 trans isomers and from 0.965 to 0.999 considering fatty acids groups. The obtained results indicate that this straightforward procedure is suitable for chocolate analysis, providing its general lipid composition and TFA isomeric profile, which would be of great interest for quality control programs in the face of the new TFA regulations.

Journal of Chromatography A, 2019

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are essential omega-3 fatty acids (FA)... more Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are essential omega-3 fatty acids (FA) in human nutrition. Dietary supplements containing these FA are available in the market and there is a need to assess their quality to prevent frauds. The purpose of this work was to optimize and validate a fast capillary electrophoresis (CE) method to determine EPA and DHA content in marine oils omega-3 supplements. Sample preparation comprised only a saponification step and analysis time was 8 min. Validation was performed according to limits of detection and quantification, linearity, accuracy and repeatability. Ten real samples of marine oil supplements were analyzed by CE and compared to conventional gas chromatography method. No significant differences between both methods were found within 95 % confidence interval. Overall, CE method was successful to FA quantification and it could be used for fast FA monitoring during omega-3 supplement manufacture, final product quality assurance and labelling.

Química Nova

Ruminant milk is the lead source of conjugated linoleic acid (CLA) in the human diet, with cis-9,... more Ruminant milk is the lead source of conjugated linoleic acid (CLA) in the human diet, with cis-9, trans-11 CLA being the major among all. Small amounts of trans-10, cis-12 CLA are also found in synthetic supplements. Since both isomers are biologically active with potential health benefits, there is great interest in quantifying them for quality control routines. An alternative method for the analysis of the aforementioned CLAs by fast gas chromatography (GC) is discussed in the present study. The fatty acid methyl ester mixture obtained by alkaline catalysis was injected into a GC equipped with a flame ionization detector (FID) and fitted with an ionic liquid SLB-IL111 chromatographic column (15 m × 0.10 mm × 0.08 µm). Separation was achieved in less than 5 min using a 168 °C isotherm run. Both CLA isomers were quantified by using of single point standard addition statistical approach. Results were contested to those obtained using the recommended 100 m long CP-Sil88 capillary colu...

Pharmaceutics

The mixing process plays a pivotal role in the quality of pharmaceuticals and food/dietary supple... more The mixing process plays a pivotal role in the quality of pharmaceuticals and food/dietary supplements, as it can impact the homogeneity of the substances in their dosage form and affect characteristics such as dissolution and stability. Thus, the choice of the right mixing device is paramount for compounding pharmacies. In this paper, we evaluated the mixing efficacy of a new 3-axis mixer device and determined its optimal working conditions. Three different formulations were compounded with the device and a total of 540 individual assays were performed by HPLC or ICP-MS to validate its use, in addition to a direct comparison among it and two alternative mixing methods. The 3-axis mixer device was able to provide homogeneous mixtures and finished capsules with adequate content uniformity with a broad range of conditions of use (mixing times from 2 to 8 min, and speed of rotation from 10 to 100 rpm). In addition, the device was superior to classical mixing methods (such as the use of...

Nutrients

Obesity induces insulin resistance, chronic inflammation, oxidative stress, and neurocognitive im... more Obesity induces insulin resistance, chronic inflammation, oxidative stress, and neurocognitive impairment. Avocado oil (AO) has antioxidants and anti-inflammatory effects. This study evaluated the effect of AO supplementation on obese mice in the adipose tissue, muscle, liver, and hippocampus. Male C57BL/6J mice received a standard and high-fat diet (20 weeks) and then were supplemented with AO (4 mL/kg of body weight, 90 days) and divided into the following groups: control (control), control + avocado oil (control + AO), diet-induced obesity (DIO), and diet-induced obesity + avocado oil (DIO + AO) (n = 10/group). AO supplementation was found to improve insulin sensitivity and decrease hepatic fat accumulation and serum triglyceride levels in DIO mice. AO improved cognitive performance and did not affect mood parameters. Oxidative marker levels were decreased in DIO + AO mice in all the tissues and were concomitant with increased catalase and superoxide dismutase activities in the e...

Brazilian Journal of Development, 2022

The presence of many biologically active components makes pumpkins extremely attractive to the ph... more The presence of many biologically active components makes pumpkins extremely attractive to the phytochemical manufacturing industry. Studies have demonstrated that the oil extracted from the seeds has different biological activities. This study aimed to determine the fatty acid composition and total tocopherol content of the pumpkin seed oil (Cucurbita moschata – Jacarezinho cultivar) extracted by supercritical carbon dioxide (Sc-CO2) and hexane/isopropanol. The fatty acids composition and content of total tocopherols were determined by GC, GC/FID, HPLC, respectively. We also evaluated in vitro schistosomicidal activities of the crude oil, which have been described with anti-parasitic activities. Sc-CO2 extracted pumpkin seed oil, with a maximum yield of 24.3 ± 0.4%, much higher than hexane/isopropanol extraction (8.3 ± 2.7%). Was not observe differences between the non-polar compounds present in the oil extracted by both methods. In the seed oil, unsaturated acids are dominant (ole...

Química Nova, 2021

In December 2019, the World Health Organization officially announced the discovery and fast sprea... more In December 2019, the World Health Organization officially announced the discovery and fast spread of the new coronavirus disease (COVID-19), which is caused by the SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2), discovered in Wuhan, China. Since the beginning of the pandemic, there has been a global search for the discovery of antiviral candidates capable of treating the infection caused by SARS-CoV-2. However, none of them has shown proved efficacy and low toxicity for an effective dose. In view of this, research with plants based in natural products has been highlighted by the low toxicity of its metabolites and reduced side effects, since plants have been used for millennia in the treatment of various diseases. In this review, we highlight some plant species and plant metabolites belonging to the structural class of phenolic, alkaloids and terpenes with promising antiviral potential agains coronavirus that could be explored as potential candidates for drug prototyp...

ELECTROPHORESIS, 2021

The advent of policies that incentivize or require alternative diesel fuels has increased the dem... more The advent of policies that incentivize or require alternative diesel fuels has increased the demand for the development of fast analytical methods aiming for the quality control of these fuels. This study approached an alternative method for the determination of biodiesel acidity employing capillary zone electrophoresis based on free fatty acids screening and quantification. Sample preparation comprised vortex‐assisted liquid‐liquid extraction of free fatty acids and was a crucial step for analysis. It was studied through a 32 full factorial design considering sample mass and the stirring time. Then, solvent suitability was evaluated univariately. The free fatty acid screening was carried out employing a capillary zone electrophoresis method able to separate C16:0, C18:0, C18:1 n‐9, C18:2 n‐6, and C18:3 n‐3, major fatty acids in a variety of vegetable oils used for biodiesel synthesis. In addition to the straightforward sample preparation protocol, the running time of the developed method was only 12 min. Moreover, ultraviolet absorption indirect detection of analytes was approached to avoid analytes derivatization, considering the lack of chromophore groups in saturated fatty acids. Statistical tests did not evidence any significant differences in the biodiesel acidity determination expressed in percentage of free fatty acids when comparing the proposed capillary zone electrophoresis method and the traditional potentiometric titration approach within the 95% confidence interval, which demonstrates the suitability of this alternative method for the biodiesel quality control in routine.

ELECTROPHORESIS, 2020

Fatty acids determination is of paramount importance for quality control and suitable labeling of... more Fatty acids determination is of paramount importance for quality control and suitable labeling of edible oils, required by regulatory agencies in several countries, and fast methods for this determination are worldly desired. This review article aimed to explore the available analytical methods for vegetable and marine oils analyses employing CE, which can be a straightforward and faster alternative than GC methods for fatty acid determination, considering some purposes. CE usually offers the possibility of a rapid analysis with a simple preparation of the sample, without requiring specific columns, which are inherent advantages of the technique. Instrumental conditions and the key points about fatty acids determination employing the technique are highlighted, and the main challenges and perspectives are also approached. Potential use of CE for edible oil analyses has been demonstrated for research and routine, which can be of interest for industries, regulatory agencies, and edible oil researchers. Therefore, we have explored the analytical approaches described in the last decades, intending to spread the interest of CE methods for fatty acid monitoring, label accuracy assessment, and food authenticity evaluation of edible oils.

Analytical Methods, 2020

A novel method was proposed for simultaneous determination of artesunate (ATS) and mefloquine (MF... more A novel method was proposed for simultaneous determination of artesunate (ATS) and mefloquine (MFQ) in fixed-dose combination tablets by capillary zone electrophoresis with simultaneous direct and indirect detection by ultraviolet (CZE-UV).

Food Analytical Methods, 2020

Capillary electrophoresis (CE) is a technique that may offer high-resolution separations in compl... more Capillary electrophoresis (CE) is a technique that may offer high-resolution separations in complex matrices with a short analysis time. It generally employs straightforward sample preparation protocols and requires low amounts of sample and reagents, which follows the green chemistry concept. This review presents several methods developed within the 2010s decade, aiming simpler and faster food analyses in the determination of lipids applying CE. It summarizes sample preparation protocols, background electrolyte, and instrumental conditions optimized in each method. Different CE modes and detection systems are discussed, as well as figures of merit of the developed analytical methods. Moreover, it approaches significant challenges involved with lipid assay by CE and opportunities for innovation in the lipid research.

Brazilian Journal of Analytical Chemistry, 2020

Journal of Food Science and Technology, 2020

Lactose-free products are more susceptible to chemical and physical modifications during heating ... more Lactose-free products are more susceptible to chemical and physical modifications during heating and storage, due to the release of glucose and galactose during enzymatic processing, both more reactive than lactose. The present study demonstrates the effect of enzymatic lactose hydrolysis on 5-hydroxymethylfurfural (HMF), whey protein nitrogen index (WPNI) and lactulose used as thermal markers for UHT milk process monitoring. Six milk leading brands which provided regular and lactose-free UHT milk were selected, giving a total of 12 UHT milk samples analyzed in authentic duplicates. All lactose-free samples showed high levels of HMF index (42.15 lmol L-1 , against 13.11 lmol L-1 for regular samples) and low lactulose contents (13.03 mg 100 mL-1 , against 35.59 mg 100 mL-1 of regular ones). High variations in HMF (55-85%) and lactulose (42-91%) intra-brand analysis indicated that both markers are influenced by the lactose hydrolysis process. The paired t test indicated there was no difference among WPNI indexes of regular and lactosefree milks suggesting that this thermal marker is suitable to infer about heat damage in lactose-free dairy matrices.

ELECTROPHORESIS, 2019

An alternative method for simultaneous baseline separation of α and β-acids homologues and isomer... more An alternative method for simultaneous baseline separation of α and β-acids homologues and isomers in hop by cyclodextrin-modified micellar electrokinetic chromatography with UV detection was proposed. The optimized background electrolyte was composed of 30 mmol/L sodium tetraborate solution, 45 mmol/L sodium dodecyl sulfate, 20 mmol/L β-cyclodextrin and 10% v/v acetonitrile. The instrumental conditions were evaluated by using a 3 3 Box-Benhken experimental design. In order to demonstrate the applicability of the method, twenty-one hop samples from different varieties were analyzed. The repeatability intraday and interday tests were performed and relative standard deviations lower than 7% for area and migration times were observed. The present method comprehended 8 min analysis time and revealed to be faster and more efficient when compared to previous reports from literature.

Journal of Separation Science, 2018

A validated sub minute capillary zone electrophoresis method with direct ultraviolet absorption d... more A validated sub minute capillary zone electrophoresis method with direct ultraviolet absorption detection for simultaneous determination of isoniazid and rifampicin in fixed-dose combination tablets was developed. Background electrolyte was defined based on the analytes effective mobility curve and it was composed by 20 mmol L-1 of sodium carbonate/sodium bicarbonate at pH 10.2. A careful validation procedure considering the main figures of merit was performed. Regression models were satisfactory for isoniazid and rifampicin, showing no lack of fit within 95% significance interval. Interday and intraday precision were evaluated in standard and sample and slight relative standard deviations were achieved for concentration, area and migration time. Recovery values for accuracy in two levels were 99.97 and 90.08% for isoniazid and 95.45 and 95.12% for rifampicin. The limits of detection for isoniazid and rifampicin were 0.22 and 0.34 mg L-1 respectively, and the limits of quantification were 0.74 and 1.13 mg L-1 , respectively. Method selectivity was verified by injecting diluent, background electrolyte, a standard mixture and a sample, confirming no interferent peaks. The method proved to be simple, environmental friendly, sensitive and was successfully applied for simultaneous quantification of isoniazid and rifampicin in fixed-dose combination tablets.

Electrophoresis, Jan 6, 2018

The precursor compounds related to the bitterness of beer are called α-acids. These compounds are... more The precursor compounds related to the bitterness of beer are called α-acids. These compounds are extracted from the hop, which is an important ingredient in the brewing process. These compounds were analyzed by capillary electrophoresis. The electrophoretic method used 160 mmol/L of ammonium carbonate (pH 9) as BGE (background electrolyte), a voltage of +20 kV in a capillary with 50 μm of internal diameter and with a 62.5 cm of total length (54 cm effective). The samples were injected in hydrodynamic mode applying a pressure of 25 mbar for 5 s and the analytes were detected at 230 nm. A hydromethanolic extraction during 3 h was considered as the optimum condition for the sample preparation using MeOH/HO 80:20 v/v as the extract solution. From the optimized conditions the electropherograms were evaluated for their use as input for chemometric modeling. Preprocessing investigation for electrophoretic data taking into account the alignment, denoising and baseline correction, and varia...

Analytical Methods, 2017

These advantages make the technique be very attractive to attend demand of governmental agencies ... more These advantages make the technique be very attractive to attend demand of governmental agencies and industries facing the global concern in respect of the harmful health effects caused by increasing intake of TFA, as EA.

Journal of AOAC International, 2017

Tuberculosis is the second most deadly infectious disease, surpassed only by HIV/AIDS, and has re... more Tuberculosis is the second most deadly infectious disease, surpassed only by HIV/AIDS, and has resulted in over 1 billion deaths in the last 200 years. The World Health Organization estimates that in 2014, 9.6 million people were infected by this disease and 1.5 million had died. First-choice treatment consists of fixed-dose combination tablets containing rifampicin, isoniazid, pyrazinamide, and ethambutol hydrochloride (4-FDC). There are pharmacopeial protocols available to test 4-FDC, but they are prolonged, two-step methods. One single-step method in the literature performs the simultaneous determination by HPLC, but requires a long acquisition time. In this context, an ultra-HPLC (UHPLC) method was developed based on the HPLC method with the objective of reducing analysis time. A C18 column (1.9 µm particle size) was used with UV-diode-array detection at 238 and 282 nm. The method was found to be selective, linear, exact, precise, and robust. Samples from two batches were analyzed and the results compared with those obtained by the HPLC method, with no statistically significant differences observed (P > 0.05). This UHPLC method reduced the analysis time from 17 to 4 min, with a more than 90% reduction in sample and reagent consumption and a financial economy of almost 50-fold. T uberculosis is an infectious and contagious disease that, despite being preventable and treatable, has been responsible for 1.5 million deaths around the world in 2014; 9.6 million people had acquired the disease in that same year (1). The treatment recommended by the World Health Organization for adults and youths consists of fixed-dose combination tablets containing rifampicin (RIF), isoniazid (INH), pyrazinamide (PYZ), and ethambutol hydrochloride (EMB; 4-FDC) for 2 months, followed by 4 months of RIF and INH. Polypharmacotherapy has an 86% cure rate without relapse and results in a reduction in the development of resistant microorganisms. In addition, 4-FDC tablets improve adherence to long-term treatment and reduce posology errors that may compromise treatment (1, 2). Figure 1 shows the chemical structure of the four drugs present in 4-FDC. Assay methods for the combination of RIF, INH, PYZ, and EMB are found in United States Pharmacopeia (USP; 3) and International Pharmacopoeia (4). However, both pharmacopeias describe the methods in two steps that require a long analysis time and demand large amounts of solvents. Chellini et al. (5) developed a method for the simultaneous determination of 4-FDC using a single chromatographic procedure and have shown its advantages compared with pharmacopeial methods. Several authors described the problems that arose from the acetonitrile supply crisis of 2009 (6-8). Moreover, green chemistry experts have recommended the adoption of miniaturized or ultra-HPLC (UHPLC) methods to reduce the consumption of organic solvents in the laboratory because a reduced amount of solvent waste could have positive effects on the environment (9). Comparing UHPLC and traditional HPLC methods, the most mentionable advantages are the possibility of assessing separate multiple analytes in a short period of time, more efficiency, a higher resolution, and a reasonably diminished consumption of organic solvents (10). Within this context, in the present study, a novel method for the simultaneous determination of 4-FDC in tablets by UHPLC-UV was developed, optimized, and validated. This method was compared with the traditional HPLC-UV method that is considered the most interesting in the literature up to now. The parameters of comparison were mainly to assess the advantages of the proposed method in relation to time consumption and solvent waste.