The potential of lignocellulosic biomass for magnetic solid phase extraction of naproxen from saliva samples.

This paper presents a study on the application of magnetic biochars derived from three distinct biomass sources: almond (AMBC), walnut (WMBC), and peanut (PMBC) shells for magnetic solid-phase extraction (MSPE) of naproxen, a non-steroidal anti-inflammatory drug, from human saliva prior to LC-MS analysis. The three magnetic biochars were synthesized and characterized through IR, XRD, SEM, and EDX analyses. This work explored the factors influencing extraction efficiency using these three bioadsorbents through experimental design. The results obtained revealed that magnetic biochar derived from almond shells demonstrated outstanding performance in terms of naproxen extraction, achieving an impressive yield of 100.2%. This remarkable efficiency was achieved by optimizing parameters, including a 12-minute extraction time, a 3.5 mL elution volume, a 10 mg adsorbent mass, and a 4-minute elution time. Consequently, this study established almond shell as a low-cost, environmentally friendly, and efficient magnetic biochar for extracting naproxen from human saliva. This superior performance was made possible due to the abundant lignocellulosic potential inherent in almond shell structures, surpassing that of the other two biochars. The combination of magnetic extraction with LC-MS demonstrates good linearity, with an R2 value equal to 0.9987. The limits of detection (LOD) and quantification (LOQ) are 0.013 and 0.047 µg L-1, respectively.

An ICP-MS-Based Analytical Strategy for Assessing Compliance with the Ban of E 171 as a Food Additive on the EU Market.

A method was developed for the determination of total titanium in food and food supplements by inductively coupled plasma mass spectrometry (ICP-MS) after microwave-assisted acid digestion of samples. Five food supplements, including one certified reference material, and 15 food products were used for method development. Key factors affecting the analytical results, such as the composition of the acid mixture for sample digestion and the bias from spectral interferences on the different titanium isotopes, were investigated. Resolution of interferences was achieved by ICP-MS/MS with ammonia adduct formation and viable conditions for control laboratories equipped with standard quadrupole instruments were identified. The method was successfully validated and enables rapid screening of samples subject to confirmatory analysis for the presence of TiO2 particles. For the latter, single-particle ICP-MS (spICP-MS) analysis after chemical extraction of the particles was used. The two methods establish a viable analytical strategy for assessing the absence of titania particles in food products on the EU market following the E 171 ban as a food additive.

Advanced oxidation and a metrological strategy based on CLC-MS for the removal of pharmaceuticals from pore & surface water.

In this work, it is studied the photolysis, electrolysis, and photo-electrolysis of a mixture of pharmaceutics (sulfadiazine, naproxen, diclofenac, ketoprofen and ibuprofen) contained in two very different types of real water matrices (obtained from surface and porewater reservoirs), trying to clarify the role of the matrix on the degradation of the pollutants. To do this, a new metrological approach was also developed for screening of pharmaceuticals in waters by capillary liquid chromatography mass spectrometry (CLC-MS). This allows the detection at concentrations lower than 10 ng mL-1. Results obtained in the degradation tests demonstrate that inorganic composition of the water matrix directly influences on the efficiency of the drugs removal by the different EAOPs and better degradation results were obtained for experiments carried out with surface water. The most recalcitrant drug studied was ibuprofen for all processes evaluated, while diclofenac and ketoprofen were found to be the easiest drugs for being degraded. Photo-electrolysis was found to be more efficient than photolysis and electrolysis, and the increase in the current density was found to attain a slight improvement in the removal although with an associated huge increase in the energy consumption. The main reaction pathways for each drug and technology were also proposed.

Rapid determination of malondialdehyde in serum samples using a porphyrin-functionalized magnetic graphene oxide electrochemical sensor.

An electrochemical sensor based on a screen-printed carbon electrode (SPCE) modified with porphyrin-functionalized magnetic graphene oxide (TCPP-MGO) was developed for the sensitive and selective determination of malondialdehyde (MDA), an important biomarker of oxidative damage, in serum samples. The coupling of TCPP with MGO allows the exploitation of the magnetic properties of the material for separation, preconcentration, and manipulation of analyte, which is selectively captured onto the TCPP-MGO surface. The electron-transfer capability in the SPCE was improved through derivatization of MDA with diaminonaphthalene (DAN) (MDA-DAN). TCPP-MGO-SPCEs have been employed to monitor the differential pulse voltammetry (DVP) levels of the whole material, which is related to the amount of the captured analyte. Under optimum conditions, the nanocomposite-based sensing system has proved to be suitable for the monitoring of MDA, presenting a wide linear range (0.01-100 µM) with a correlation coefficient of 0.9996. The practical limit of quantification (P-LOQ) of the analyte was 0.010 µM, and the relative standard deviation (RSD) was 6.87% for 30 µM MDA concentration. Finally, the developed electrochemical sensor has demonstrated to be adequate for bioanalytical applications, presenting an excellent analytical performance for the routine monitoring of MDA in serum samples.

SERS-Based Methodology for the Quantification of Ultratrace Graphene Oxide in Water Samples.

The extensive use of graphene materials in real-world applications has increased their potential release into the environment. To evaluate their possible health and ecological risks, there is a need for analytical methods that can quantify these materials at very low concentrations in environmental media such as water. In this work, a simple, reproducible, and sensitive method to detect graphene oxide (GO) in water samples using the surface-enhanced Raman spectroscopy (SERS) technique is presented. The Raman signal of graphene is enhanced when deposited on a substrate of gold nanoparticles (AuNPs), thus enabling its determination at low concentrations with no need for any preconcentration step. The practical limit of quantification achieved with the proposed method was 0.1 ng mL-1, which is lower than the predicted concentrations for graphene in effluent water reported to date. The optimized procedure has been successively applied to the determination of ultratraces of GO in water samples.

Detection of Porphyrins in Hair Using Capillary Liquid Chromatography-Mass Spectrometry.

Unlike humans, some animals have evolved a physiological ability to deposit porphyrins, which are pigments produced during heme synthesis in cells, in the skin and associated integument such as hair. Given the inert nature and easiness of collection of hair, animals that present porphyrin-based pigmentation constitute unique models for porphyrin analysis in biological samples. Here we present the development of a simple, rapid, and efficient analytical method for four natural porphyrins (uroporphyrin I, coproporphyrin I, coproporphyrin III and protoporphyrin IX) in the Southern flying squirrel Glaucomys volans, a mammal with hair that fluoresces and that we suspected has porphyrin-based pigmentation. The method is based on capillary liquid chromatography-mass spectrometry (CLC-MS), after an extraction procedure with formic acid and acetonitrile. The resulting limits of detection (LOD) and quantification (LOQ) were 0.006-0.199 and 0.021-0.665 µg mL-1, respectively. This approach enabled us to quantify porphyrins in flying squirrel hairs at concentrations of 3.6-353.2 µg g-1 with 86.4-98.6% extraction yields. This method provides higher simplicity, precision, selectivity, and sensitivity than other methods used to date, presenting the potential to become the standard technique for porphyrin analysis.

Rapid Sample Screening Method for Authenticity Controlling of Vanilla Flavours Using Liquid Chromatography with Electrochemical Detection Using Aluminium-Doped Zirconia Nanoparticles-Modified Electrode.

A rapid and sensitive technique for frauds determination in vanilla flavors was developed. The method comprises separation by liquid chromatography followed by an electrochemical detection using a homemade screen-printed carbon electrode modified with aluminium-doped zirconia nanoparticles (Al-ZrO2-NPs/SPCE). The prepared nanomaterials (Al-ZrO2-NPs) were characterized by using X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX). This method allows for the determination of six phenolic compounds of vanilla flavors, namely, vanillin, p-hydroxybenzoic acid, p-hydroxybenzaldehyde, vanillyl alcohol, vanillic acid and ethyl vanillin in a linear range between 0.5 and 25 µg g-1, with relative standard deviation values from 2.89 to 4.76%. Meanwhile, the limits of detection and quantification were in the range of 0.10 to 0.14 µg g-1 and 0.33 to 0.48 µg g-1, respectively. In addition, the Al-ZrO2-NPs/SPCE method displayed a good reproducibility, high sensitivity, and good selectivity towards the determination of the vanilla phenolic compounds, making it suitable for the determination of vanilla phenolic compounds in vanilla real extracts products.

Contributions of Capillary Electrophoresis in Analytical Nanometrology: A Critical View.

An overview on the increasing role of capillary electrophoresis in characterization and direct analysis of nanomaterials is herein presented. The niche of electrophoretic approaches in nanometrology is so relevant that nonmetallic, metal, metal oxide nanoparticles, and quantum dots have been analyzed to be targeted via capillary electrophoresis with conventional detection systems or coupling arrangements aimed at increasing selectivity and sensitivity toward either pristine or conjugated nanoparticles. Moreover, parameters altering intrinsic properties of nanoparticles may be optimized to gather the desired results and identify nanomaterials according to their size, shape, or associations with binding agents. The usefulness and quickness of capillary electrophoresis for quantifying or screening ultrasmall-sized particles enables this technique to set an example for analysis of standards or previously synthesized nanostructures in research or routine laboratories. Abundant evidence of the suitability of electrophoretic approaches for characterization and direct determination of nanomaterials in actual samples has been provided in this review, together with a discussion about hyphenation with state-of-the art detectors and comparison between capillary electrophoresis with other separation approaches. This permits scientific community to be optimistic in the short term.

Surface Polymers on Multiwalled Carbon Nanotubes for Selective Extraction and Electrochemical Determination of Rhodamine B in Food Samples.

In this study, we combine magnetic solid phase extraction (MSPE), with the screen-printed carbon electrode (SPCE) modified by a molecular imprinted polymer (MIP) for sensitive and selective extraction and electrochemical determination of Rhodamine B in food samples. A magnetic solid phase extraction (MSPE) was carried out using magnetic poly(styrene-co-divinylbenzene) (PS-DVB) and magnetic nanoparticles (MNPs) synthetized on the surface of multiwalled carbon nanotubes (MWCNTs). An MIP was prepared on the surface of MWCNTs in the presence of titanium oxide nanoparticles (TiO2NPs) modifying the SPCE for the rapid electrochemical detection of Rhodamine B. The MIPs synthesis was optimized by varying the activated titanium oxide (TiO2) and multiwalled carbon nanotubes (MWCNTs) amounts. The MSPE and electrochemical detection conditions were optimized as well. The present method exhibited good selectivity, high sensitivity, and good reproducibility towards the determination of Rhodamine B, making it a suitable method for the determination of Rhodamine B in food samples.

Ionic liquid and magnetic multiwalled carbon nanotubes for extraction of N-methylcarbamate pesticides from water samples prior their determination by capillary electrophoresis.

A simple and rapid microextraction procedure is reported on the use of ionic liquid (IL) in combination with magnetic multiwalled carbon nanotubes (MMWCNTs). The procedure is based on temperature-controlled IL dispersive liquid phase microextraction (DLPME) and MMWCNTs, for selective preconcentration of N-methylcarbamate pesticides in water samples, followed by their hydrolysis in alkaline buffer, prior to being analyzed by capillary electrophoresis. The extraction procedure uses small volume of organic solvents, and there is no need for centrifugation. In the experimental approach the IL was quickly disrupted by an ultrasonic probe, heated with the temperature controlled at 90 °C and dispersed in water samples in a homogenous form. At this stage, N-methylcarbamate pesticides migrate into the IL. Then the solution was cooled and small amounts of MMWCNTs were dispersed into the sample solutions to adsorb the ionic liquid containing the analytes and phase separation was completed. The ionic liquid allowed the microextraction of the analytes and a small volume of dichloromethane (DCM) was used for elution. MMWCNTs favored the adsorption of the ionic liquid with the analytes and improved the final recovery with respect to the use of simple magnetic nanoparticles as a sorbent material. Under the optimum conditions, limit of quantifications (LOQ) were achieved in the 5.6-9.3 ng mL-1 range, with recoveries between 85.0% and 102.4%.

A new nanometrological strategy for titanium dioxide nanoparticles screening and confirmation in personal care products by CE-spICP-MS.

A new nanometrological approach was developed for screening of titania nanoparticles by capillary electrophoresis after adsorption of a target analyte namely l-cysteine onto the nanoparticles in a sodium phosphate buffer, followed by titanium elemental analysis by means of inductively-coupled plasma-mass spectrometry and size distribution measurements by single-particle mode. This analytical strategy involved a first screening of nanotitania in actual samples by electrophoresis, sensitivity being enhanced by cysteine which acts as a nanoparticles stabiliser. Detection and quantitation limits were 0.31 ng µL-1 and 1.03 ng µL-1 respectively for anatase nanoparticles in capillary electrophoresis, and a high amount of titanium was found in the samples subject to study (lip balm and two types of toothpaste) by total elemental analysis. Besides, the potential of single-particle modality for inductively-coupled plasma-mass spectrometry was exploited for a verification of particle size distribution, then confirming the presence of titanium dioxide nanoparticles as an ingredient in the composition of the real samples and validating the overall strategy herein presented.

LC-MS determination of catecholamines and related metabolites in red deer urine and hair extracted using magnetic multi-walled carbon nanotube poly(styrene-co-divinylbenzene) composite.

A novel analytical methodology for the extraction and determination of catecholamines (dopamine, epinephrine and norepinephrine) and their metabolites DL-3,4-dihydroxyphenyl glycol and DL-3,4-dihydroxymandelic acid by LC-MS is developed and validated for its application to human and animal urine and hair samples. The method is based on the preliminary extraction of the analytes by a magnetic multi-walled carbon nanotube poly(styrene-co-divinylbenzene) composite. This is followed by a <9 min chromatographic separation of the target compounds in an Onyx Monolithic C18 column using a mixture of 0.01% (v/v) heptafluorobutyric acid in water and methanol at 500 µL min-1 flow rate. Detection limits within range from 0.055 to 0.093 µg mL-1, and precision values of the response and retention times of analytes were >90%. Accuracy values comprised the range 79.5-109.5% when the analytes were extracted from deer urine samples using the selected MMWCNT-poly(STY-DVB) sorbent. This methodology was applied to real red deer urine and hair samples, and concentrations within range from 0.05 to 0.5 µg mL-1 for norepinephrine and from 1.0 to 44.5 µg mL-1 for its metabolite 3,4-dihydroxyphenyl glycol were calculated. Analyses of red deer hair resulted in high amounts of 3,4-dihydroxyphenyl glycol (0.9-266.9 µg mL-1).

Analytical control of Rhodamine B by SERS using reduced graphene decorated with copper selenide.

A novel approach for the decoration of reduced graphene oxide with copper selenide (CuSe-rGO), using supercritical carbon dioxide (sc-CO2) as a medium, was developed and proposed as a new substrate for surface-enhanced Raman spectroscopy (SERS) to determine Rhodamine B in chili powder. The synthesized materials graphene oxide (GO), reduced graphene oxide (rGO) and CuSe-rGO were characterized by Raman spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). All SERS spectra were obtained by using a portable Raman spectrometer. The procedure presented involves a simple and rapid sample pretreatment in order to determine Rhodamine B in chili powder, with a limit of quantification of 44.5 ng g-1. The recovery values of the proposed method resulted in the 96% to 99% range, with RSD values from 2.4% to 3.0%. The developed SERS active hybrid substrate has an enhancement factor higher than those using gold or silver nanoparticles, providing a clear improvement in the sensitivity.

Graphene quantum dots for enhancement of fluorimetric detection coupled to capillary electrophoresis for detection of ofloxacin.

A new CE method with fluorescence detection is reported on the determination of ofloxacin in milk samples using graphene quantum dots (GQDs) for sensitivity enhancement. Injection of GQDs prior the standards/sample is crucial to increase the antibiotic fluorescence response. Clean-up and preconcentration steps allowed for a good linear correlation in a concentration range between 50 and 1000 ng/mL for the ofloxacin, detection and quantification limits being 10.7 and 35.5 ng/mL, respectively. Optimal CE conditions for the seven-fluoroquinolone separation method were assessed in terms of buffer type, pH, and voltage. The selective interaction of GQDs with ofloxacin as model analyte was subsequently studied finding a significant sensitivity improvement; therefore, the analytes would be detected at low concentrations by means of a commercial CE device equipped with a multi-wavelength photoluminescence detector. Due to the different maximum emission wavelengths of the target compounds and the limitations shown by the single-wavelength photoluminescence detector coupled to the CE system, we demonstrated the usefulness of the GQD-assisted sensitivity-enhanced CE method to determine ofloxacin in milk samples. This work opens an interesting possibility of using GQDs in separation techniques combined with photoluminescence detectors for lowering sensitivity levels typically provided by the mere device.

Unique evolution of vitamin A as an external pigment in tropical starlings.

Pigments are largely responsible for the appearance of organisms. Most biological pigments derive from the metabolism of shikimic acid (melanins), mevalonic acid (carotenoids) or levulinic acid (porphyrins), which thus generate the observed diversity of external phenotypes. Starlings are generally dark birds despite iridescence in feathers, but 10% of species have evolved plumage pigmentation comprising bright colors that are known to be produced only by carotenoids. However, using micro-Raman spectroscopy, we have discovered that the bright yellow plumage coloration of one of these species, the Afrotropical golden-breasted starling Cosmopsarus regius, is not produced by carotenoids, but by vitamin A (all-trans-retinol). This is the first organism reported to deposit significant amounts of vitamin A in its integument and use it as a body pigment. Phylogenetic reconstructions reveal that the retinol-based pigmentation of the golden-breasted starling has independently appeared in the starling family from dark ancestors. Our study thus unveils a unique evolution of a new class of external pigments consisting of retinoids.

Nanostructured hybrid surface enhancement Raman scattering substrate for the rapid determination of sulfapyridine in milk samples.

The fabrication of surface-enhanced Raman spectroscopy (SERS) substrates, which can offer the advantages of strong Raman signal enhancement with good reproducibility, is still a challenge for practical applications. In this work, a simple and reproducible SERS substrate combining the properties of multi-walled carbon nanotubes (MWCNTs) and gold nanoparticles (AuNPs), is proposed for the determination and quantification of sulfapyridine in milk samples with a concentration range of 10-100 ng mL-1. The Raman signals of sulfapyridine is enhanced at factor of 4394. The procedure presented is capable of detecting and quantifying small quantities of sulfapyridine without implying any preconcentration step, just using an affordable and portable Raman spectrometer. The precision, in terms of repeatability and inter and intermediate precision, was lower than 8% in all cases.

Analytical nanometrological approach for screening and confirmation of titanium dioxide nano/micro-particles in sugary samples based on Raman spectroscopy - Capillary electrophoresis.

Analytical nanometrology is a present challenge in today's analytical science, particularly from a practical point of view and when it is addressed to routine/control laboratories. In this way, a screening-confirmation approach is described for the characterization and distinction between titanium dioxide nano/micro-particles in sugary food samples. The first step involves the confirmation of the presence of TiO2 in the sample (used as additive E171 in sugary samples), using a portable Raman spectrometer, in which the crystalline structure of TiO2 (anatase or rutile) in the positive samples can be also obtained in this step. Then, the second step was only applied to positive samples, and it involves the use of Capillary Electrophoresis (CE), which allows to distinguish between TiO2-nanoparticles (<100 nm) from TiO2-microparticles (>100 nm). Additionally, nanoparticles (TiO2 anatase (5 nm diameter) and TiO2 rutile (60 nm diameter) and rutile microparticles (0.1-0.2 µm diameter) can be electrophoretically separated. The general procedure is simple, fast, and low cost, providing a valuable analytical tool in the field of food safety and control, thus contributing to the development of the analytical nanometrology.

Unprecedented high catecholamine production causing hair pigmentation after urinary excretion in red deer.

Hormones have not been found in concentrations of orders of magnitude higher than nanograms per milliliter. Here, we report urine concentrations of a catecholamine (norepinephrine) ranging from 0.05 to 0.5 g/l, and concentrations of its metabolite DL-3,4-dihydroxyphenyl glycol (DOPEG) ranging from 1.0 to 44.5 g/l, in wild male red deer Cervus elaphus hispanicus after LC-MS analyses. The dark ventral patch of male red deer, a recently described sexually selected signal, contains high amounts of DOPEG (0.9-266.9 mg/l) stuck in the hairs, while DOPEG is not present in non-darkened hair. The formation of this dark patch is explained by the chemical structure of DOPEG, which is a catecholamine-derived o-diphenol susceptible to be oxidized by air and form allomelanins, nitrogen-free pigments similar to cutaneous melanins; by its high concentration in urine; and by the urine spraying behavior of red deer by which urine is spread through the ventral body area. Accordingly, the size of the dark ventral patch was positively correlated with the concentration of DOPEG in urine, which was in turn correlated with DOPEG absorbed in ventral hair. These findings represent catecholamine concentrations about one million higher than those previously reported for any hormone in an organism. This may have favored the evolution of the dark ventral patch of red deer by transferring information on the fighting capacity to rivals and mates. Physiological limits for hormone production in animals are thus considerably higher than previously thought. These results also unveil a novel mechanism of pigmentation based on the self-application of urine over the fur.

Magnetic multi-walled carbon nanotube poly(styrene-co-divinylbenzene) for propranolol extraction and separation by capillary electrophoresis.

AIM: The preparation of magnetic multi-walled carbon nanotube poly(styrene-co-divinylbenzene) for propranolol magnetic solid-phase extraction is described. MATERIALS & METHODS: A study comparing propranolol adsorption and desorption was performed with only magnetic multi-walled carbon nanotubes, and different poly(styrene-co-divinylbenzene) with and without magnetic multi-walled carbon nanotubes. Enantiomeric separation of propranolol took place by cyclodextrin-modified capillary electrophoresis and the method was validated in spiked human urine samples. RESULTS: Recovery values raised when styrene/divinylbenzene millimoles ratio was 19.57:15.80. Enrichment factors increased up to approximately 100, detection limits were 13.8 and 10.5 ng ml-1 for R- and S-propranolol respectively, quantitation limits were 46.0 and 34.8 ng ml-1 for R- and S-propranolol respectively, recoveries from spiked samples ranged from 90.9 to 109.0%, and relative standard deviations were <6.3%. CONCLUSION: This methodology was proven to be more effective than classical solid-phase extraction strategies and may be applied to other kind of biological samples.

Innovative coupling of supercritical fluid extraction with ion mobility spectrometry.

This paper describes a pioneer on-line hyphenation between a supercritical fluid extraction (SFE) and an ion mobility spectrometry (IMS) detector through a Tenax TA sorbent trap as retention interface. By means of a simple design, taking advantage of both techniques, this new coupling allows us to extract and preconcentrate analytes and in a second step to determine them. As result, an increase in the accuracy of the analytical process was achieved by elimination of sample transfer from one device to another. In addition, this new coupling reduces the time needed for the optimization of a new SFE method, since the detector can monitor on-line the efficiency of the extraction. The parameters affecting the coupling and its success have been studied in detail via the extraction of benzene and toluene from soil samples. Finally, the suitability of IMS as on-line detector to monitor compounds of industrial interest extracted by SFE was evaluated taking as a model, the extraction and detection of 1,8-cineole (eucalyptol) in rosemary aromatic plants, which could be extrapolated on an industrial scale.