Unmodified cellulose filter paper, a sustainable and affordable sorbent for the isolation of biogenic amines from beer samples.

While current trends in Green Analytical Chemistry aim at reducing or simplifying sample treatment, food usually comprises complex matrices where direct analysis is not possible in most cases. In this context, sample treatment plays a pivotal role. Biogenic amines are naturally formed in many foodstuffs due to the action of microorganisms, while their presence has been associated with adverse health effects. In this work, the extraction of seven biogenic amines (cadaverine, histamine, phenylethylamine, putrescine, spermidine, spermine, and tyramine) from beer samples has been simplified using laboratory filter paper as sorbent without any further modification. The analysis of the eluates by direct infusion mass spectrometry reduces the time of analysis, increasing the sample throughput. This simple but effective method enabled the determination of the analytes with limits of detection as low as 0.06 mg L-1 and relative standard deviations better than 11.9%. The suitability of the method has been assessed by analyzing eight different types of beers by the standard addition method.

Paper-based sorptive phases for microextraction and sensing.

The simplification of the analytical procedures, including cost-effective materials and detectors, is a current research trend. In this context, paper has been identified as a useful material thanks to its low price and high availability in different compositions (office, filter, chromatographic). Its porosity, flexibility, and planar geometry permit the design of flow-through devices compatible with most instrumental techniques. This article provides a general overview of the potential of paper, as substrate, on the simplification of analytical chemistry methodologies. The design of paper-based sorptive phases is considered in-depth, and the different functionalization strategies are described. Considering our experience in sample preparation, special attention has been paid to the use of these phases under the classical microextraction-analysis workflow, which usually includes a chromatographic separation of the analytes before their determination. However, the interest of these materials extends beyond this field as they can be easily implemented into spectroscopic and electrochemical sensors. Finally, the direct analysis of paper substrates in mass spectrometry, in the so-called paper-spray technique is also discussed. This review is more focused on presenting ideas rather than the description of specific applications to draw a general picture of the potential of these materials.

Nano-depletion of acrosome-damaged donkey sperm by using lectin peanut agglutinin (PNA)-magnetic nanoparticles.

Lectin is considered as a suitable biomarker for nano-depletion of acrosome-damaged sperm. The aim of this study was to synthetize magnetic nanoparticles (MNPs) coated by peanut (Arachis hypogaea) agglutinin lectin (PNA) and investigate its beneficial effect in improving of sperm characteristics. MNPs were obtained by co-precipitation method, functionalized with chitosan and coated by PNA at a concentration of 0.04 mg/mL. Semen was frozen either with glycerol-based or sucrose-based extenders. Frozen-thawed straws from five donkeys (three ejaculates per donkey) were incubated with lectin-MNPs (2 mg/mL), and then exposed to an external magnet enabling the non-bound sperm to be collected as nanopurified sperm. Sperm were evaluated post-thawing (control) and after nanopurification for motility, plasma membrane integrity, acrosome integrity, morphology, DNA fragmentation and concentration. The statistical analyses were extended to investigate the correlation between the initial quality of the frozen-thawed semen samples and the effect of nanopurification after thawing. The obtained MNPs were biocompatible to the sperm and significantly improved the progressive motility (P < 0.05) for the glycerol nanopurified group (43.08 ± 3.52%) in comparison to control (33.70 ± 2.64%). Acrosome-damaged sperm were reduced (P < 0.05) in both nanopurified groups (19.92 ± 2.69 for G and 21.57 ± 2.77 for S) in comparison to control (36.07 ± 3.82 for G and 35.35 ± 3.88 for S). There were no significant changes in sperm morphology and membrane integrity after nanopurification. The average sperm recovery after nanopurification was 80.1%. Sperm quality index was significantly higher (P < 0.001) in nanopurified groups regardless of the initial quality of the frozen thawed semen samples. However, in the high sperm quality group, nanopurification significantly improved the progressive motility and membrane integrity besides the increasing of acrosome-intact sperm. Sperm nanopurification using lectin-magnetic nanoparticles can be considered as a suitable method to reduce the proportion of acrosome-damaged sperm and to increase the quality of frozen thawed donkey semen.

Silver nanoflower-coated paper as dual substrate for surface-enhanced Raman spectroscopy and ambient pressure mass spectrometry analysis.

Paper-based analytical devices (PADs) have encountered a wealth of applications in recent years thanks to the numerous advantages of paper as a support. A silver nanoflower (AgNF) modified paper-based dual substrate for both surface-enhanced Raman spectroscopy (SERS) and ambient pressure paper spray mass spectrometry (PS-MS) was developed. AgNFs were immobilized on nylon-coated paper modified with silver and ethylenediamine. The developed substrate was characterized via scanning electron microscopy and infrared spectroscopy. The densely packed nanoscale petals of the AgNFs lead to a large number of so-called hot spots at their overlapping points, which result in an enhancement of the Raman signal. In addition, the presence of the AgNFs produces an increase in the sensitivity of the mass spectrometric analysis as compared with bare paper and nylon/Ag-coated paper. The dual substrate was evaluated for the identification and quantification of ketoprofen in aqueous standards as well as human saliva from healthy volunteers. The method enables the determination of ketoprofen with a limit of detection and limit of quantification via PS-MS of 0.023 and 0.076 mg L-1, respectively, with a relative standard deviation (RSD) of 3.4% at a concentration of 0.1 mg L-1. This dual substrate enables the simple and fast detection of ketoprofen with minimal sample preparation, providing complementary Raman and mass spectrometric information. Graphical abstract.

Differences in the kinematics of booster-seated pediatric occupants using two different car seats.

OBJECTIVE: The objective of this article is to compare the performance of forward-facing child restraint systems (CRS) mounted on 2 different seats. METHODS: Two different anthropomorphic test device (ATD) sizes (P3 and P6), using the same child restraint system (a non-ISOFIX high-back booster seat), were exposed to the ECE R44 regulatory deceleration pulse in a deceleration sled. Two different seats (seat A, seat B) were used. Three repetitions per ATD and mounting seat were done, resulting in a total of 12 sled crashes. Dummy sensors measured the head tri-axial acceleration and angular rate and the thorax tri-axial acceleration, all acquired at 10,000 Hz. A high-speed video camera recorded the impact at 1,000 frames per second. The 3D kinematics of the head and torso of the ATDs were captured using a high-speed motion capture system (1,000 Hz). A pair-matched statistical analysis compared the outcomes of the tests using the 2 different seats. RESULTS: Statistically significant differences in the kinematic response of the ATDs associated with the type of seat were observed. The maximum 3 ms peak of the resultant head acceleration was higher on seat A for the P3 dummy (54.5 ± 1.9 g vs. 44.2 ± 0.5 g; P =.012) and for the P6 dummy (56.0 ± 0.8 g vs. 51.7 ± 1.2 g; P =.015). The peak belt force was higher on seat A than on seat B for the P3 dummy (5,488.0 ± 198.0 N vs. 4,160.6 ± 63.6 N; P =.008) and for the P6 dummy (7,014.0 ± 271.0 N vs. 5,719.3 ± 37.4 N; P =.015). The trajectory of the ATD head was different between the 2 seats in the sagittal, transverse, and frontal planes. CONCLUSION: The results suggest that the overall response of the booster-seated occupant exposed to the same impact conditions was different depending on the seat used regardless of the size of the ATD. The differences observed in the response of the occupants between the 2 seats can be attributed to the differences in cushion stiffness, seat pan geometry, and belt geometry. However, these results were obtained for 2 particular seat models and a specific CRS and therefore cannot be directly extrapolated to the generality of vehicle seats and CRS.

Towards enhanced optical sensor performance: SEIRA and SERS with plasmonic nanostars.

We report the preparation and characterization of plasmonic chip-based systems comprising self-assembled gold nanostars at silicon substrates that enable concomitantly enhanced Raman (surface enhanced Raman spectroscopy; SERS) and mid-infrared (surface enhanced infrared reflection or absorption spectroscopy; SEIRA) spectral signatures. The high-aspect-ratio structure of gold nanostars provides an increased number of hot spots at their surface, which results in an electric field enhancement around the nanomaterial. Gold nanostars were immobilized at a silicon substrate via a thin gold layer, and α-ω-dimercapto polyethylene glycol (SH-PEG-SH) linkers. The Raman and IR spectra of crystal violet (CV) revealed a noticeable enhancement of the analyte vibrational signal intensity in SERS and SEIRA studies resulting from the presence of the nanostars. Enhancement factors of 2.5 × 103 and 2.3 × 103 were calculated in SERS considering the CV bands at 1374.9 cm-1 and 1181 cm-1, respectively; for SEIRA, an enhancement factor of 5.36 was achieved considering the CV band at 1585 cm-1.

Characterization of stainless steel assisted bare gold nanoparticles and their analytical potential.

A simple, environmentally friendly, one-pot method to synthesize highly stable bare gold nanoparticles (AuNPs) has been developed. AuNPs have been synthesized from tetrachloroauric acid solution using steel or stainless steel as solid reducing agent, which can be reused. The proposed method yields bare gold nanoparticles at atmospheric pressure and room temperature for potentially producing large quantities. The obtained AuNPs have been characterized by SEM, TEM and AFM finding an average diameter of around 20 nm, polygonal yet nearly spherical shape and a narrow size distribution. The mechanism of reaction has been investigated by UV-vis spectroscopy, ICP-OES and EDX analysis. The obtained dispersed gold nanoparticles proved to be stable if stored a 4 °C for over four months without the addition of a stabilizing agent. Their analytical potential as SERS substrate has been demonstrated and their performance compared with that showed by citrate-coated gold nanoparticles. Thanks to their unique properties, their use as analytical tools provides analytical processes with enhanced selectivity and precision.

Raman spectroscopic characterization of single walled carbon nanotubes: influence of the sample aggregation state.

Raman spectroscopy has been employed in analytical sciences for purity determination of carbon nanotube samples based on the consideration of G-/D-band intensity ratios. This work demonstrates the role of aggregation in these feature bands, which, in the case of single walled carbon nanotubes (SWNTs), has proved to be crucial for G-/D-band intensity ratio measurements. We have found variation in the relative intensities of G- and D-bands across a sample of SWNTs without any other treatment, discarding the possible influence of the laser beam or sample focusing. In the case of multiwalled carbon nanotubes (MWNTs), this effect is less notorious. Thus, to achieve a good representativeness of Raman measurements, it is important to consider the sample preparation procedure in order to avoid aggregation, which has an effect over the signals, making difficult the subsequent interpretation of results.

Bare gold nanoparticles mediated surface-enhanced Raman spectroscopic determination and quantification of carboxylated single-walled carbon nanotubes.

The paper proposes a simple and portable approach for the surface enhanced Raman scattering (SERS) spectroscopy in situ determination of carboxylated single walled carbon nanotubes (SWNTs) in river water samples. The method is based on the subsequent microfiltration of a bare gold nanoparticles solution and the water sample containing soluble carbon nanotubes by using a home-made filtration device with a small filtration diameter. An acetate cellulose membrane with a pore size of 0.2 µm first traps gold nanoparticles to form the SERS-active substrate and then concentrates the carbon nanotubes. The measured SERS intensity data were closely fit with a Langmuir isotherm. A portable Raman spectrometer was employed to measure SERS spectra, which enables in situ determination of SWNTs in river waters. The limit of detection was 10 µg L(-1). The precision, for a 10 mg L(-1) concentration of carbon nanotubes, is 1.19% intra-membrane and 10.5% inter-membrane.

Determination of carboxylic SWCNTs in river water by microextraction in ionic liquid and determination by Raman spectroscopy.

The paper proposes a simple approach for the preconcentration of carboxylated single-walled carbon nanotubes and their determination in river water samples. The method is based on a microliquid-liquid extraction into an ionic liquid (bmim PF6) in the presence of a cationic surfactant (CTAC). 10 µL of the ionic liquid phase are microfiltrated by using a home-made filtration device having a small diameter. The membrane was of cellulose with a pore size of 5 µm. Finally, the carbon nanotubes retained in the membrane are directly analyzed by Raman spectroscopy, which allows their direct characterization and quantification. The limit of detection was 0.050 mg L(-1). The precision, for a 1.4 mg L(-1) concentration of carbon nanotubes, is 3.2%.

Qualitative detection and quantitative determination of single-walled carbon nanotubes in mixtures of carbon nanotubes with a portable Raman spectrometer.

The main aim of this work is to develop a one-step method for the characterization of mixtures of single- and multi-walled carbon nanotubes using a simple and inexpensive tool, a portable Raman spectrometer. In order to overcome the problem of heat dissipation in solid samples, the suitability of three surfactants-SDS, Triton X-100 and CTAB-to disperse nanotubes has been evaluated. A systematic study of the wavelength and relative intensity of the D and G bands has been carried out with six samples of multiwalled carbon nanotubes (MWNTs) and one of single-walled carbon nanotubes (SWNTs) dispersed in these surfactants, and this has been compared with solid samples. Finally, the possibility has been demonstrated to identify and (semi)quantify the presence of SWNTs in a mixture containing MWNTs.

Rapid analysis of gold nanoparticles in liver and river water samples.

This paper describes a simple approach to determine gold nanoparticles in liver and river water samples. The method of purification of nanoparticles from the matrix is based on the stabilization of gold nanoparticles with a cationic surfactant followed by a microliquid-liquid extraction in ionic liquid. Finally, the extracted nanoparticles can be analysed by UV/Vis detection or Raman spectroscopy. The precision of the proposed method for the analysis of liver tissue and river water samples was 9.7% and 18% respectively for UV/Vis analysis. The sensitivity was 1.17 × 10(-12) M for the analysis of 3 mL of liver homogenate or river water sample.

Analytical potential of hybrid nanoparticles.

The growing use of nanoparticles in the analytical process in recent years has set a new trend towards the simplification of analytical methods and improvement of their performance. Miniaturization and nanotechnology have allowed new analytical challenges to be met. Hybrid nanoparticles in particular possess exceptional properties enabling further improvement of analytical methods. Despite the continuous developments in their synthesis and characterization, hybrid nanomaterials have scarcely been used in analytical chemistry, however. This paper discusses the analytical potential of hybrid nanoparticles in terms of their special characteristics and properties, and describes their analytical applications.

The potential of carbon nanotube membranes for analytical separations.

Advances in nanotechnology have enabled the development of nanoporous membranes based on carbon nanotubes, which, by virtue of their exceptional properties, constitute excellent supports for analytical processes, including the selective separation of some molecules.

[Alpha-1-antitrypsin deficiency associated with ruptured aneurysm of the splenic artery]. / Déficit de alfa-1-antitripsina asociado a rotura de aneurisma de la arteria esplénica.

We show a patient with a rupture of splenic artery aneurysm, seven days after liver transplantation for hepatic cirrhosis and portal hypertension secondary to alfa-1-antitrypsin deficiency. We analyse the aneurysm pathology and its relationship with the blood flow through the aneurysm.