Current Analytical Chemistry - Volume 14, Issue 4, 2018

Introduction: Packed food can be considered as a source of contamination due to the migration of plasticizers or monomer from packaging to food. In fact, the contamination usually regards the contact with plastic containers or films that are made in a different way. This chemical migration can be considered as diffusion, in particular it was time and temperature depending. These compounds that can migrate into food are usually investigated for their toxicological aspects. Objective: This review is aimed to describe the reasons for which food are usually a main source of adipates, phthalates, alkylphenols, 2,2-bis(4-hydroxiphenyl)propane for human. In fact, international interest for the monitoring of these chemicals into food and so the human exposure is an important topic. Methods: Many studies were carried out to monitor the presence of the above cited compounds in different food also considering their toxicological profiles and to find a reason for their presence. So, many of these researches were described with regard to the presence of these compounds and the consequent human exposure. Results: The migration of these compounds into food was fully investigated in studies that employed food or food simulants as suggested by European Union (EU). In particular fatty or packed foods are observed to have higher levels of them. Toxicological studies were conducted and a lot of information for each compound was found. The use of BPA-Free packaging is not considered as safe because BPA is replaced by other bisphenols with same structural characteristic. Conclusion: Actually EU established migration limits relating to packaging and European Food Safety Authority (EFSA) continuously proposed TDIs or limiting uses of some plasticizers or monomer after acquisition of data from different countries. For this reason plastic packaging are changed, even if the use of analogues chemicals employed, such as for BPA, can be better investigated. In fact these compounds present in BPA-Free products are not always regulated and data related to them is unavailable.

Introduction: Nowadays, plastics play an important role in many industrial applications. During the production of plastics, plasticizers are added to enhance the properties of parent polymers, but some of them have shown xenoestrogen activity and their continuous exposure to humans can constitute a health risk. Sensitive and selective analytical methods are required to control the presence of these compounds and to assess the health risk. Objective: The aim of this paper is to review the analytical methodology used to determine plasticizers in food and beverages and to highlight the most important milestones and drawbacks observed in this field. Methods: The last decade literature has been reviewed. Emphasis has been placed on “blank” problems and in the application of separation techniques coupled to mass spectrometry, but the potential of ambient mass spectrometry techniques has also been addressed. Results: Separation techniques coupled to high-resolution or tandem mass spectrometry are the techniques most frequently used in this field. Nevertheless, the ubiquity of some plasticizers can contribute to background levels hindering quantitative results. The strategies applied to avoid/minimize this contamination are critically discussed in this paper. New methods based on ambient mass spectrometry have emerged to directly analyze samples avoiding sample manipulation and overcoming blank problems. Conclusion: The development of fast, simple and automatable methods to reduce analysis time and to avoid sample contamination is still needed. The future use of ambient mass spectrometry techniques for a fast screening with minimal manipulation of samples can be helpful. The evaluation of alternative ionization methods in mass spectrometry would expand the number of compounds to be identified and will help in solving possible matrix effects.

Background: Bisphenols and alkylphenols are industrial chemicals widely used in the manufacture of plastics. In addition, alkylphenols are commonly used as intermediates to produce surfactant. In the last few years, concerns about the use of these substances have increased due to their negative effects as Endocrine Disruptors. Humans may be exposed to bisphenols and alkylphenols through several sources but foods are believed to be the main exposure route. Methods: An overview of the literature concerning the analysis of the bisphenol and alkylphenol levels in foods has been reviewed. We focused on the most recent literature (2010-2016) and only articles, reporting analyses on more than ten samples were considered. Results: Concentration levels of alkylphenols in foodstuffs, reported in the literature, suggest diet to be an important route of human exposure to these contaminants. BPA is still the most detected bisphenol in food matrices. It is ubiquitous in foodstuffs prevailing in canned foods that continue to be the main route of exposure to bisphenols for humans. However, its levels are always below the current migration limits. Conclusion: Data concerning the levels of multiple bisphenols in foods are still poor as well as toxicological studies on the potential effects of the bisphenol mixtures. Based on the foregoing, further studies should be carried out in order to collect scientific findings to help governments, policy makers, and food safety authorities to amend the current legislation on bisphenols.

Nowadays, food packaging is an indispensable element in the food manufacturing process. In the specific case of beverages, packaging is essential to contain the liquid in a cost-effective way as well as to retain the beneficial effects of processing, to retard product deterioration, and to maintain or even increase food quality and safety. During the last decades the concern about the wholesomeness and food safety has dramatically increased, since it has been observed that packaging materials are important sources of human exposure to chemicals, which can migrate into foods at different extent. Among the different compounds that have generated alarm, the most important ones are phthalates, alkylphenols, and bisphenols. There are many studies where it has been reported the presence of plasticizers in waters and the process responsible for the levels detected. However, very few studies make reference to other beverages, such as non-alcoholic and alcoholic drinks. The aim of this review is to provide an overview about the main packaging materials used for water and beverages, as well as information about the migration processes that usually take place and the compounds frequently detected. It is also indicated that the levels found are generally below the tolerable daily intake and thus, the safety of these products is guaranteed. However, some of these chemicals are endocrine disruptors for which care has to be taken to minimize human exposure. Therefore, studies that integrate migration assays and toxicological effects should be fostered to evaluate the real impact of plastic components and additives in humans.

Background: Food contact materials are regulated in the European countries through the horizontal Regulation 1935/2004, on materials and articles intended to come into contact with food, and the Regulation 2023/2006, on good manufacturing practice for materials and articles intended to come into contact with food. Specific measures have to be implemented regarding different groups of materials and presence of specific substances. Until now, only plastic, ceramic, intelligent and active materials and regenerated cellulose film, materials intended to come into contact in food, have been regulated. Methods: In an attempt to protect human health from the exposition of contaminants which might impair toxic effects, several Regulations and Directives have to be implemented to control food contact materials. Results: Plastic materials are well described in the Regulation 10/2011. This paper is intended to provide the implementation procedure of this Regulation regarding the overall and specific migration of plastic materials in contact with foodstuff. It also describes the concept and use of simulants and the assay conditions. Emphasis is given to mineral oils and Bisphenol A migration, because of their novelty or impact in the media, as a risk evaluation is still a matter of discussion. Regulations are continuously being amended according to the European Food Safety Authority (EFSA) opinions, and include authorization of new substances, according to toxicity studies. It is expected that in the near future all groups of materials are going to be regulated by specific legislations, and not only the polymeric materials. Non-intentionally added substances (NIAS) is another hot topic to consider as they represent a group of substances that are present in a material but have not been added for a technical reason during the production process. Conclusion: Whereas regulatory guidelines provide data on maximum levels of plasticizers in a specific type of food, scientific and academic studies are equally important to determine the toxicity of the different chemicals and define the effects and impact on the organisms.

Background: Since its origin, Green Chemistry has been focusing on the need for eliminating or minimizing the harmful effects of various organic solvents used, on health as well as on the environment. Analytical techniques generally compromise two very important parameters safety and environmental impact. Applying concepts of Green Chemistry and Quality by Design (QbD) solves dual purpose of being environmentally benign and robust in a single method. Objective: This review deals with the importance and advantages of using both Green analytical chemistry and QbD in analytical techniques. QbD is an organized and fastidious approach to method development in pharmaceutical analysis. It emphasizes in-depth evaluation and exploring of alternative methods in a systematic way to obtain optimal and best method performance. Method: The three main aspects of Green Analytical Chemistry (GAC) include green sample pretreatment, miniaturization of analytical devices and a reduction in the waste generated and ensuring the use of proper waste treatment methodology used. Criteria to adjudge greenness of analytical techniques include HPLC-EAT tool, AMVI approach and greener solvent selection based on solvent selection guide. Design of Experiments is an important statistical tool of QbD. Conclusion: Novel Combination of both GAC and QbD gives the dual advantage of a robust as well as environmentally benign method. The application of GAC to HPLC and various Bioanalytical techniques has proved to be a suitable approach giving additional economic benefits as well. But still a lot remains to be done and explored in this regard. QbD is the need of the future due to imparting in-built robustness to the process or method and ensuring the quality beforehand rather than after the product is obtained.

Background: Kashmir is an area rich in medicinal plants; the inhabitants use frequently diverse parts of these plants to cure diseases such as fever, headache, liver, and stomach disorders etc. According to our best knowledge this is new study in the area. In this study, commonly used medicinal plants including Viola odorata were selected for analysis. Objective: The aim of this study was to explore the antioxidant potential and trace metals levels of medicinal plants in the targeted area and to introduce the readers about potential impact of plants to cure the diseases. Methods: Soil and plant samples were collected, digested and extracted as per requirement using standard procedures for the analysis. Protocols for the extraction and analysis of selected parameters are provided. Results: The outcome of current study indicates that the Acacia nilotica bark in water extract showed significantly high total phenolic contents. The highest flavonoid contents documented as rutin equivalents were found in Acacia nilotica bark demonstrating the greatest antioxidant activity. The higher scavenging assets of Cassia fistula may be due to hydroxyl groups that can deliver the essential constituents as radical scavenger. Fe, Zn and Mn appeared as leading contributors. Conclusion: This study concludes that the investigation on medicinal plants used in treating numerous diseases on the concern of their pharmacological exploit is supportive in regulating their use. Due to having good quantity of essential elements such as Fe, Mn, Zn the water extracts of these medicinal plants could be taken as supplements by the consumers. The extracts of Viola odorata (leaves and flowers) demonstrated the greatest antioxidant activity.

Background: A simple and novel electrochemical sensor was developed for the determination of pyrazinamide (PZM) in various pharmaceutical samples. The sensor was developed by modifying the glassy carbon electrode (GCE) in 3 different stages; GCE modified with multi walled carbon nano tubes MWCNTs (GCE/MWCNTs), further it was coated with copper oxide nanoparticles (CuONPs). Finally Cytochrome c (Cyt c) was immobilized on the surface of the pre-coated electrode. Cyclic voltammry and differential pulse voltammetric techniques were employed for the electrochemical investigations. The CV results obtained showed well-defined anodic and cathodic peaks at the peak potentials -0.77 V and -0.80 V respectively, and also revealed good electrocatalytic activity of Cyt c/CuONPs/MWCNTs/GCE towards PZM. From the measured DPV results, the limit of detection and limit of quantification of the developed sensor were calculated, and found to be 0.0038 μM and 0.0129 μM respectively. Furthermore, the proposed sensor was successfully applied to the analysis of PZM in the various commercial pharmaceutical samples. Pyrazinamide (PZM) is an antimycobacterial and a chief component of multidrug therapy for tuberculosis (TB). It is crucial for the prevention or treatment of TB infections. PZM has become an important component of short-term (6 months) multiple-drug therapy for tuberculosis. Owing to the high medical significance of PZM, it is necessary to develop a simple and rapid methodology for the analysis of PZM in various pharmaceutical is crucial. Ectrochemical methods with modified sensors have been exhibiting greater advantages in the current progressive scientific world. In the present manuscript a novel high sensitive electrochemical sensor was developed for the determination of PZM in various pharmaceutical samples. The developed sensor shows realistic behaviour towards pharmaceutical samples which is successfully monitored and tabulated in the present work. Methodology: Voltammetric measurements were carried out with 797 VA Computrace system with version 1.3.1 software from Metrohm (Switzerland). PZM stock and standard solutions were made with 0.1 M phosphate buffer solution (PBS). The CuONPs were synthesized according to the previous report with slight modification. Electrode modification was performed in three different stages with MWCNTs, CuONPs and Cyt c to develop the finalized sensor. 10 ml of the PBS (pH 7) was introduced into the electrochemical cell. Thereafter a bare and modified GCE was dipped into the electrochemical cell followed by purging nitrogen gas for about 10 min and then the CV/DPV experiment was performed. An aliquot of the PZM solution was then introduced into the electrochemical cell, at 1000 rpm of rotating disc speed and the optimized pre-concentration potential was fixed for the voltammetric measurements. The cyclic and differential pulses voltammograms were monitored at the scan rate of 0.1 V s-1 with the potentials increasing towards the positive direction. In addition the real pharmaceutical samples were also analysed via standard addition method. Results: Infrared spectroscopy and X-ray diffraction study characterization reveals the confirmation of formed CuONPs. Transmission electron microscopic studies confirmed the surface characterization of finalized sensor. Additionally, thermogravimetric analyses support the confirmation of the formed nanocomposite coated on the surface of GCE. Randles-Sevick equation reveals the high surface area of the modified sensor. This indicates the development of a suitable platform for electrochemical redox mechanism of PZM on the surface of the final sensor. The utmost electrochemical parameters like pH, scan rate, and deposition time were optimized. The developed sensor showed enhanced electrochemical sensing peak currents in cyclic voltammetry. The differential pulse voltammetry showed the linear range 3-30 μM with good LOD and LOQ of 0.0038 μM and 0.0129 μM respectively. The developed sensor showed good percentages of recovery viz., 99.5% and 98.2% respectively. Conclusion: In the present work the developed sensor showed good catalytic activity towards PZM, due to the increased electrochemical sensing mechanism for PZM. The modified electrode was successfully characterized by the TEM, FT-IR, TGA and XRD techniques. The fabricated sensor showed enhanced peak currents and low detection limits with PZM. The proposed sensor showed excellent sensitivity, selectivity and low detection limits. In addition the developed sensor was applied for the determination of PZM in real pharmaceutical samples, and reflects good recovery percentages. It is evident that the proposed method will serve as a standard protocol for the determination of PZM in various pharmaceutical samples, and would be of great help to pharmaceutical industries in the future.

Background: Saliva is a clear and complex biological fluid with pH value in the range of 6.0 – 7.0 that is produced from three main salivary glands. Recently, saliva has been recognized as a noninvasive diagnostic tool for surveillance of disease and in healthcare research and promotion since saliva is able to indicate a wide range of health and disease conditions with distinctive advantages over serum. In this study, we have fabricated an electrochemical immunosensor for sensitive detection of salivary immunoglobulin A (sIgA) based on indirect competitive format and using magnetic beads (MBs) as reaction carrier. Methods: Firstly, carboxylic modified MBs were covalently attached to sIgA with N-(3- dimethylaminopropyl)- N'-ethylcarbodiimide and N-hydroxysulfosuccinimide. Then, the sIgA immobilized on MBs and free sIgA in solution was allowed to compete with each other for fixed amount of primary antibody. Upon the formation of immunocomplex, biotin-conjugated secondary antibody was incubated with the modified MBs following affinity binding with streptavidin-hydrogen peroxidase. For amperometric measurement, the resulting MBs were immobilized onto the surface of single-walled carbon nanotube working electrode with a strong external magnet and subsequently 3,3',5,5',- tetramethylbenzidine and hydrogen peroxide were introduced that functioned as electron transfer mediator and as enzyme substrate, respectively. Results: The proposed MB-based immunosensor demonstrated a wide linear range of 5 pg/mL – 10 ng/mL and a low detection limit of 5 pg/mL with excellent reproducibility. Conclusion: The developed immunosensor has great potential for clinical diagnostic application to monitor sIgA in field setting.

Background: Fullerene-based compounds are being developed for an extensive range of biomedical applications, and may provide a completely new class of biologically useful reagents. In support of our continuing investigation and characterization of one such compound, e,e,e-fullerene(60)- 63-tris malonic acid (1) we optimized the conditions for obtaining mass spectra. Methods: Both positive and negative ion mass spectra are obtained using electrospray ionization (ESI). However, the spectra are dramatically different in the different ionization modes. We studied the effect of solvent media, acid content as well as the concentration of the compound (1) on mass fragmentation pattern both in positive and negative mode. We also analyzed the ion current as function of capillary voltage for selected ion. Results: The best mass spectra were obtained when 1 was sprayed from a solution containing a weak organic acid added to aqueous methanol (1:1) in positive mode. Fragment ions formed by the direct loss of carboxyl groups from the doubly-charged dimer occur for the loss of one, two and six carboxyl groups. Of these, the loss of one carboxyl is the most abundant. The dominant mechanism for the formation of singly-charged fragment ions arises from splitting of the doubly-charged dimers into singlycharged monomers with subsequent carboxyl losses. Conclusion: In positive ion mode, the spectra are simple with minimal fragmentation and the molecular ion region increases linearly with analyte concentration over the range studied. In negative ion mode, the spectra are more complex with the formation of dimer and fragment ions and the molecular ion region increases in a non-linear way with concentration. Further, in negative ion mode, fragment ions are affected by nearly every instrumental parameter controlling the ionization process.

Background: Malondialdehyde is a product of lipid peroxidation of polyunsaturated fatty acids in foods and biological samples and widely used as biomarker of oxidative stress in various diseases. We describe the validation of a new microextraction-LC-UV method for the determination of malondialdehyde (MDA) in the form of 2,4-dinitrophenylhydrazine (DNPH) derivatization in plasma samples. Objective: A new microextraction technique called vortex and N2 assisted liquid-liquid microextraction has been developed for the determination MDA in plasma samples. Method: The DNPH-derivatized MDA was extracted into ethyl acetate as an extraction solvent and measured by LC-UV at 310 nm after evaporation of ethyl acetate and re-dissolving in mobile phase composed of 0.2% acetic acid–acetonitrile (50:50; v/v). This method validated according to U.S. Food and Drug Administration guidelines. Results: The limit of detection of MDA was 0.038 μmol L-1 (2.74 μg L-1) and the intra and interday relative standard deviations were in the range of 3.8-5.0% and 5.5-9.4%, respectively for different concentrations of MDA. Conclusion: A precise and valid method to measure MDA as DNPH derivatization in plasma samples using LC was proposed.

Background: Salicinoids (a type of phenolic glycoside) are plant secondary metabolites with chemical structures based on salicyl alcohol conjugated to b-D-glucopyranose, with demonstrated antiherbivore activity. These compounds have been purified and quantified in a variety of contexts. Validation of published methods is often incomplete, and there is no broadly-applicable reference procedure. Objective: To develop and validate a robust, versatile procedure for purification and quantification of salicinoids in salicaceous plants. Method: We extracted salicinoids from dried, ground Populus foliage into methanol:water, and purified them by sequential liquid-liquid extraction, flash chromatography and preparative scale HPLC. To evaluate potential source material for purification of salicinoids, we quantified salicortin, hydroxycyclohexen- on-oyl salicortin (HCH-salicortin), and tremulacin in methanolic extracts of Populus tremuloides, P. fremontii, and P. deltoides using ultra-high performance liquid chromatography (UHPLC) with diode array (DAD) and negative electrospray ionization single quadrupole mass spectrometry (MS) detection. Results: Recovery efficiencies and purities of salicinoids extracted from Populus ranged from 6-63% and 58->99%, respectively. Both detectors provided accurate quantification of salicinoids; MS was 100more sensitive than DAD, permitting detection of plant tissue salicinoid concentrations ≥0.0006% dry weight. Conclusion: By consolidating and refining existing methods, we developed a reliable, versatile, and more environmentally-friendly procedure for purification and quantification of salicinoids.

Background: Elevated levels of Carcinoembryonic antigen (CEA) have been documented in different types of cancers, including ovarian, breast, cervical, small intestine, gastric, pancreatic, colon, rectal, and non-small-cell lung cancers. In addition, higher CEA levels have been found also in heavy smokers. CEA provides important evidence regarding the patient prognosis, recurrence of tumors postsurgical removal, and efficacy of treatment. For these reasons, a sensitive method is needed for determination of CEA levels. Objective: This study was devoted to the development of a new highly efficient kinetic exclusion analysis (KinExA) immunosensor-based assay for measurement of CEA in serum, and to overcome several drawbacks confronted in the conventional existing immunoassays for CEA. Methods: Polymethylmethacrylate (PMMA) beads were coated with CEA and charged into a microbead column in the observation cell of the KinExATM 3200 instrument. A pre-equilibrated mixture of CEA and its specific antibody was passed through the beads column, followed by passing a secondary fluorescently-labeled antibody through the beads column. The fluorescence signals were monitored by a camera installed inside the flow cell of the instrument, and used for generating the calibration curve of the assay. Results: The limit of detection for CEA with this assay was 0.2 μg/L. The advantage of KinExA platform was the instrument automation and high sensitivity that resulted in rapid and reliable quantification of CEA without any matrix effect. The analytical recovery of serum-spiked CEA was 93.3 – 106.9% and the relative standard deviation (%RSD) for the recovery ranged from 1.6 – 9.0%. The precisions of the assay were satisfactory; %RSD were 7.6 – 9.5 and 4.3 – 9.6% for the intra- and interassay precision, respectively. Conclusion: The automated analysis by the KinExA-based assay described herein facilitated the processing of a large number of specimens, and the new sensor-based assay is anticipated to have a great value in measurement of CEA. The proposed sensor-based assay provides a format to overcome the problems encountered in conventional immunoassays for CEA.