Towards the assessment of exposure to bisphenols in everyday items with increased accuracy by the use of integrated calibration method (ICM)-based methodology.

The most crucial purpose of the measurement is to obtain a reliable result that reflects the actual qualitative and/or quantitative features of the tested material. The overriding goal of analytical chemistry is to obtain accurate results after compensating of various interference effects as well as non-linear calibration dependence. A new approach based on an integrated calibration method (ICM) supported by H-point standard addition method (HPSAM) has been used to improve the quality of analytical results. The proposed methodological approach was extended using the step-by-step dilution procedure, and five measurement conditions were used to eliminate multiplicative, additive, and non-linear interferences. On this basis, a set of estimations is obtained to improve the quality of the analytical results. The analytical usefulness of the proposed approach was tested on the example of the determination of three compounds from the group of bisphenols (BPs) using the chromatographic technique - HPLC-DAD (high-performance liquid chromatography with diode array detection). Compared to the reference method - fluorescence spectroscopy - the obtained results were characterized by excellent accuracy (RE=3 % in most cases). The developed methodology allowed to carry out a risk assessment on BPA, BPF, and BPS present in samples of shop receipts and canned food. Store clerks have been shown to be particularly vulnerable to PBF and BPS in receipts due to skin permeation (exposure factors were equal to 308.97 µg/g for BPF and 181.89 µg/g for BPS). Consumers should also pay close attention to the BPA found in canned food samples (the average concentration was equal to 20.61 µg/mL, and the tolerable daily intake was exceeded over 165.000 times). The analytical method and the methodological approach were evaluated using the RGB model and the AGREE approach - it was shown that the method can be successfully used for other analytical purposes (the method is White) and is environmentally friendly (Significance=0.63).

Evolution of anthocyanin content during grape ripening and characterization of the phenolic profile of the resulting wine by comprehensive two-dimensional liquid chromatography.

The typical phenolic profile in grapes is characterized by its complexity both in terms of number of diverse chemical structures and their variation during ripening. Besides, the specific phenolic composition of grapes directly influences the presence of those components in the resulting wine. In this contribution, a new method based on the application of comprehensive two-dimensional liquid chromatography coupled to a diode array detector and tandem mass spectrometry has been developed to obtain the typical phenolic profile of Malbec grapes cultivated in Brazil. Moreover, the method has been demonstrated to be useful to study how the phenolic composition in grapes evolved during a 10-week ripening period. Main detected compounds in grapes and in the wine derived from them were anthocyanins, although a good number of polymeric flavan-3-ols were also tentatively identified, among other compounds. Results show how the amount of anthocyanins present in grapes was increased during ripening up to 5-6 weeks and then decreased towards week 9. The two-dimensional approach applied was demonstrated to be useful for the characterization of the complex phenolic profile of these samples, involving more than 40 different structures and has the potential to be further applied to the study of this important fraction is different grapes and wines systematically.

Spectroscopic Determination of Acetylcholine (ACh): A Representative Review.

Acetylcholine (ACh) is one of the most crucial neurotransmitters of the cholinergic system found in vertebrates and invertebrates and is responsible for many processes in living organisms. Disturbances in ACh transmission are closely related to dementia in Alzheimer's and Parkinson's disease. ACh in biological samples is most often determined using chromatographic techniques, radioenzymatic assays, enzyme-linked immunosorbent assay (ELISA), or potentiometric methods. An alternative way to detect and determine acetylcholine is applying spectroscopic techniques, due to low limits of detection and quantification, which is not possible with the methods mentioned above. In this review article, we described a detailed overview of different spectroscopic methods used to determine ACh with a collection of validation parameters as a perspective tool for routine analysis, especially in basic research on animal models on central nervous system. In addition, there is a discussion of examples of other biological materials from clinical and preclinical studies to give the whole spectrum of spectroscopic methods application. Descriptions of the developed chemical sensors, as well as the use of flow technology, were also presented. It is worth emphasizing the inclusion in the article of multi-component analysis referring to other neurotransmitters, as well as the description of the tested biological samples and extraction procedures. The motivation to use spectroscopic techniques to conduct this type of analysis and future perspectives in this field are briefly discussed.

25X-NBOMe compounds - chemistry, pharmacology and toxicology. A comprehensive review.

Recently, a growing number of reports have indicated a positive effect of hallucinogenic-based therapies in different neuropsychiatric disorders. However, hallucinogens belonging to the group of new psychoactive substances (NPS) may produce high toxicity. NPS, due to their multi-receptors affinity, are extremely dangerous for the human body and mental health. An example of hallucinogens that have been lately responsible for many severe intoxications and deaths are 25X-NBOMes - N-(2-methoxybenzyl)-2,5-dimethoxy-4-substituted phenethylamines, synthetic compounds with strong hallucinogenic properties. 25X-NBOMes exhibit a high binding affinity to serotonin receptors but also to dopamine, adrenergic and histamine receptors. Apart from their influence on perception, many case reports point out systemic and neurological poisoning with these compounds. In humans, the most frequent side effects are tachycardia, anxiety, hypertension and seizures. Moreover, preclinical studies confirm that 25X-NBOMes cause developmental impairments, cytotoxicity, cardiovascular toxicity and changes in behavior of animals. Metabolism of NBOMes seems to be very complex and involves many metabolic pathways. This fact may explain the observed high toxicity. In addition, many analytical methods have been applied in order to identify these compounds and their metabolites. The presented review summarized the current knowledge about 25X-NBOMes, especially in the context of toxicity.

Investigation of the origin and concentration of polycyclic aromatic hydrocarbon with improved accuracy by the use of a multi-component integrated calibration method in the Katowice region, Poland.

The basic variant of the integrated calibration method (ICM), based on a combination of external calibration (EC) and standard addition method (SAM), was applied to multi-component (MC) analysis to obtain a new methodological approach to improve the quality of analytical results. The analytical performance of the proposed method was evaluated on indicated by EPA polycyclic aromatic hydrocarbons (PAHs) determination in various environmental samples (air, house dust, tap water, river water, river sediment, and snow) from the Katowice region (Poland). HPLC-FLD was used during all analyses. The main aim was to show the origin of PAHs in different places in the urban and industrialized region of Poland. MC-ICM allowed for the elimination of interference from the coelution of other substances. Several diagnostic coefficients were calculated for the results free from systematic errors and interferences. The obtained results were consistent with the chemometric analysis (PCA). The method was assessed regarding analytical usefulness using the RGB model (the color method is White) and environmental friendliness using the AGREE approach.

Recent Advances in Sandwich SERS Immunosensors for Cancer Detection.

Cancer has been one of the most prevalent diseases around the world for many years. Its biomarkers are biological molecules found in the blood or other body fluids of people with cancer diseases. These biomarkers play a crucial role not only in the diagnosis of cancer diseases, but also in risk assessment, selection of treatment methods, and tracking its progress. Therefore, highly sensitive and selective detection and determination of cancer biomarkers are essential from the perspective of oncological diagnostics and planning the treatment process. Immunosensors are special types of biosensors that are based on the recognition of an analyte (antigen) by an antibody. Sandwich immunosensors apply two antibodies: a capture antibody and a detection antibody, with the antigen 'sandwiched' between them. Immunosensors' advantages include not only high sensitivity and selectivity, but also flexible application and reusability. Surface-enhanced Raman spectroscopy, known also as the sensitive and selective method, uses the enhancement of light scattering by analyte molecules adsorbed on a nanostructured surface. The combination of immunosensors with the SERS technique further improves their analytical parameters. In this article, we followed the recent achievements in the field of sandwich SERS immunosensors for cancer biomarker detection and/or determination.

Dual-enhancement and dual-tag design for SERS-based sandwich immunoassays: evaluation of a metal-metal effect in 3D architecture.

The design of a sandwich-type SERS immunoassay (surface-enhanced Raman spectroscopy) is demonstrated operating in dual surface enhancement and dual-tag paradigm. The capture and detection antibodies are linked to two SERS-active substrates and form together the three-dimensional (3D) structure after specific binding to interleukin 6. A variety of metal combinations is tested (Au-Ag, Au-Au, and Ag-Ag), but an enhanced electromagnetic field is generated only due to coupling of Ag and Au nanoparticles with an Au hexagonal nanoarray. The amplified in that way Raman signals improve the limit of detection over 3 times in comparison to the assay with only one SERS-active substrate. It is also shown that the proper readout of the true-positive signal can be achieved in assays with two Raman tags, and this approach also improves LOD. For the optimal combination of the metal-metal junction and Raman tags, a linear relationship between the Raman signal and the concentration of IL-6 is obtained in the range 0-1000 pg⋅mL-1with LOD of 25.2 pg mL-1and RSD < 10%. The presented proof-of-concept of the SERS immunoassay with the dual-enhancement and dual-tag opens additional opportunities for engineering reliable SERS biosensing.

Comparison of Quantitative Detection Methods Based on Molecular Fluorescence Spectroscopy and Chromatographic Techniques Used for the Determination of Bisphenol Compounds.

Analytical methods using the fluorescence properties of bisphenols (BPA, BPF and BPS) and their complexes with ß-cyclodextrin and methyl-ß-cyclodextrin were developed. The methods were applied for the analysis of thermal paper and canned food. Their performance was compared with a standard HPLC approach with a diode array and fluorescence detections. For comparison purposes, basic validation parameters (linear range, limit of detection, sensitivity, precision) were evaluated. It was concluded the developed methods facilitate fast and cost-effective determination of three bisphenol species in liquid samples, similar to the HPLC performance. They are also environmentally friendly. BPA, BPF and BPS can be routinely determined with the presented approach.

2-(4-Iodo-2,5-dimethoxyphenyl)-N-[(2-methoxyphenyl)methyl]ethanamine (25I-NBOME): A Harmful Hallucinogen Review.

NBOMes are N-benzylmethoxy derivatives of the 2C family compounds with N-2-methoxybenzyl moiety substituted by the methoxy group at the 2- and 5-position and the halogen group at the 4-position of the phenyl ring. These substances are a new class of potent serotonin 5-HT2A receptor agonist hallucinogens with potential harmful effects. The substitution with halogen of the already psychoactive phenethylamine produces a derivative (2C-I) with increased hallucinogenic effects. This class of hallucinogens has chemical structures very similar to natural hallucinogenic alkaloid mescaline and these are sold mainly via internet as a 'legal' alternative to other hallucinogenic drug-lysergic acid diethylamide (LSD). 25I-NBOMe is the first synthesized and one of the most common compound from NBOMes. Knowledge of pharmacological properties of 25I-NBOMe is very limited so far. There are only a few in vivo and in vitro so far published studies. The behavioral experiments are mainly related with the hallucinogenic effect of 25I-NBOMe while the in vitro studies concerning mainly the affinity for 5-HT2A receptors. The 25I-NBOMe Critical Review 2016 reported 51 non-fatal intoxications and 21 deaths associated with 25I-NBOMe across Europe. Case reports describe various toxic effects of 25I-NBOMe usage including tachycardia, hypertension, hallucinations, rhabdomyolysis, acute kidney injury and death. The growing number of fatal and non-fatal intoxication cases indicates that 25I-NBOMe should be considered as a serious danger to public health. This review aims to present the current state of knowledge on pharmacological effects and chemical properties of 25I-NBOMe and to describe reported clinical cases and analytical methods available for identification of this agent in biological material.

Bioanalytical methodology for determination of glutamate and aspartate for use in pharmacological sciences with application of Integrated Calibration Method.

A new calibration approach based on the adaptation of Integrated Calibration Method (ICM) to consecutive two components analysis in separation science is presented. Consecutive ICM method (C-ICM) was conceptually developed and applied to determination of two excitatory amino acids - glutamate and aspartate in cerebrospinal fluids collected by the use of brain microdialysis from freely-moving animals. Both analytes as a neurotransmitters play an important role in formation of the memory trace, and thus the processes of learning and memory. Due to their low concentration and presence of interferences, considered analytical system - animal brain - was a big challenge. High-performance liquid chromatography (HPLC) with electrochemical detection (ECD) was used in all experimental work. The most important feature of proposed method is integration of interpolative and extrapolative ways to calculate analyte concentration in single calibration procedure, which consequently leads to obtain series of six estimations of analytical result. Comparison of individual estimations with each other allows for a more in-depth analysis of systematic errors. It was proved that C-ICM approach enables diagnosis and compensation of systematic errors induced by occurrence of interference effects and improvement of accuracy of analytical results. Most of all, it was demonstrated that application of this method is efficient and useful analytical tool in analysis of complicated biological samples in pharmacology and neuroscience.

Hallucinogen-Like Action of the Novel Designer Drug 25I-NBOMe and Its Effect on Cortical Neurotransmitters in Rats.

NBOMes are N-benzylmethoxy derivatives of the 2C family hallucinogens. 4-Iodo-2,5-dimethoxy-N-(2-methoxybenzyl)phenethylamine (25I-NBOMe) is one of the commonly used illicit drugs. It exhibits high binding affinity for 5-HT2A/C and 5-HT1A serotonin receptors. Activation of 5-HT2A receptor induces head-twitch response (HTR) in rodents, a behavioral marker of hallucinogen effect in humans. There is not much data on neurochemical properties of NBOMes. Therefore, we aimed to investigate the effect of 25I-NBOMe on extracellular level of dopamine (DA), serotonin (5-HT), and glutamate (GLU) in the rat frontal cortex, tissue contents of monoamines, and hallucinogenic activity in rats. The extracellular levels of DA, 5-HT, and GLU were studied using microdialysis in freely moving animals. The tissue contents of DA, 5-HT and their metabolites 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) were determined in the rat frontal cortex. We also tested a drug-elicited HTR. 25I-NBOMe at doses 1, 3, and 10 mg/kg (sc) increased extracellular DA, 5-HT, and GLU levels, enhanced tissue content of 5-HT and 5-HIAA, but did not affect tissue level of DA and its metabolites. The compound exhibited an inverted U-shaped dose-response curve with respect to the effect on extracellular DA and 5-HT levels, but a U-shaped dose-response curve was observed for its effect on GLU release and HTR. The data from our study suggest that hallucinogenic activity of 25I-NBOMe seems to be related with the increase in extracellular GLU level-mediated via cortical 5-HT2A receptors. The influence of 25I-NBOMe on 5-HT2C and 5-HT1A receptors may modulate its effect on neurotransmitters and HTR.

Reliable calibration by nonlinear standard addition method in the presence of additive interference effects.

ABSTRACT: The possibility of adapting the Standard Addition Method (SAM) to calibration in very difficult analytical conditions, namely when there is a need to determine an analyte with the use of nonlinear calibration graph and in the presence of matrix components causing additive interference effect, is investigated. To this aim the SAM in the common version and the Chemical H-point Standard Addition Method (C-HPSAM) realized by the flow injection technique were applied. Specifically, a flow manifold was used for construction of a set of nonlinear calibration graphs in different chemical conditions. As the graphs were intersected indicating both the additive interference effect and the analytical result free of this effect, the analyte concentration in the sample was able to be obtained with improved accuracy. The applicability of this approach was verified on the example of spectrophotometric determination of paracetamol in pharmaceuticals and of total acidity in wines. The C-HPSAM method enabled complete compensation of the additive effect and obtaining analytical results at a relative error not exceeding 6.0%.

Application of gradient ratio flow-injection technique to implementation of the Chemical H-point Standard Addition Method.

A new gradient ratio approach to Chemical H-point Standard Addition Method (C-HPSAM) was developed in flow injection analysis with spectrophotometric detection. C-HPSAM is based on an idea to use SAM for calibration in several different chemical conditions in order to correct unspecific (additive) interferences in samples with unknown matrix. The approach proposed in this paper employs the gradient ratio flow-injection technique to generate a continuous change of chemical conditions. By doing so a set of two-point SAM calibration curves with different slopes are possible of registering that are intersected in a common point indicating the values of both unspecific interferences and analyte concentration in a sample. The applicability of the approach was verified on the examples of spectrophotometric determinations of ascorbic acid and paracetamol. Ascorbic acid was determined in soft drinks and juices basing on reduction of Fe(III) to Fe(II) and reaction of the latter ion with o-phenantroline to form the ferroin complex absorbing at 512 nm. Paracetamol determined in pharmaceuticals was nitrificated in reaction with sodium nitrite in acidic medium and then the formed derivative species was converted into a more stable compound in reaction with sodium hydroxide, for which absorbance was recorded at 430 nm. All analytical results were obtained within the confidence interval of the values obtained by capillary electrophoresis and the relative errors were below 6%. It was proved that the developed method is readily applicable to analysis of real samples of complex unknown matrices. As it is additionally effective, low-cost and green, it can be considered as a helpful analytical tool.

New approach to H-point standard addition method for detection and elimination of unspecific interferences in samples with unknown matrix.

A novel method for correction of unknown unspecific (additive) interferences was developed in sequential injection analysis (SIA) using a Lab on Valve module (LOV) with spectrophotometric detection. The method implements a novel idea to calibrate by the standard addition method in several different chemical conditions created in such a way to measure different signal for an analyte and unchanged signal for interferents causing additive effect. This approach, being an enhancement of the H-point standard addition method (HPSAM), enables to quantify unbiased concentration of an analyte in the presence of unknown interferences. The method was tested on the example of the determination of ascorbic acid in soft drinks and juices basing on reduction of Fe(III) to Fe(II) and reaction of the latter with o-phenanthroline to the ferroin complex absorbing at 512.0nm. The analytical utility of the method has been verified and confirmed by the spectrophotometric determination of total acidity in rose and red wines in the presence of bromothymol blue absorbing at 616.0nm. Calibration solutions were prepared automatically in the designed flow system. Ascorbic acid was determined with LOD of 1.4mgL-1 and LOQ of 4.2mgL-1 within linear working range up to 80mgL-1, while in case of the determination of total acidity the values of 4.2, 11.8 and 100, respectively, were obtained. A sample was consumed in volumes of 400 and 1000µL in both cases. The analyses are simple, "green", and non-expensive. The developed method is readily applicable to analysis of real samples of complex unknown matrices and adaptable to different analytical methods.

Solenoid micropump-based flow system for generalized calibration strategy.

Generalized calibration strategy (GCS) is one of the innovative approaches aimed at verification and improvement of accuracy of analytical determinations. It combines in a single procedure the interpolative and the extrapolative calibration approaches along with stepwise dilution of a sample with the use of a dedicated flow system. In the paper a simple solenoid micropump-based flow system designed for implementation of GCS has been described. The manifold consists of several modules fully operated by a computer and connected with each other in a properly designed network. Its performance and usefulness were tested on determination of calcium by FAAS in synthetic and natural samples containing strong interferents. It was shown how GCS can serve for detection, examination and elimination of the interference effects. It was demonstrated that the designed manifold enabled to perform GCS procedure with very good precision, in short time and with very low standard, sample and reagent consumption.