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25I-NBOH is a new potent serotonin 5-HT2A receptor agonist recently identified in blotter paper seizures. This compound is a thermolabile molecule that undergoes degradation under routine gas chromatography–mass spectrometry analysis leading to misidentification. In this paper, the voltammetric behavior of 25I-NBOH and 2C-I was investigated and their electroanalytical characteristics were determined. A novel, fast and sensitive electrochemical method for the detection of 25I-NBOH using a SPCE is described and all method characteristics demonstrated the method to be analytically valuable. This method is selective and achieves full differentiation between 25I-NBOH, 2C-I and 25I-NBOMe. [ABSTRACT FROM AUTHOR]

In this work, the use of complexing acids (HF and HCl) combined with HNO3 was carefully evaluated for the digestion of several types of lipsticks and further Cd and Pb determination by inductively coupled plasma mass spectrometry (ICP-MS). Creamy, opaque and shimmering lipsticks were digested using HNO3 (6 mL) or a mixture containing HNO3 (6 mL) plus HCl (0.5 or 2 mL) or HNO3 (6 mL) plus HF (2 mL). The results indicate that complexing acids are not required for the subsequent determination of Cd in all types of lipsticks evaluated. On the other hand, complexing acids were essential for ensuring quantitative results for Pb in shimmering lipstick. Thus, by using HNO3 combined with only 0.5 mL of HCl, it was possible to obtain quantitative results for Pb and Cd in lipsticks. Under these conditions, recoveries for Cd and Pb were between 95 and 103%. No statistical difference was observed between the results obtained using the proposed method (HNO3/HCl) and those obtained using HNO3/HF, where a complete dissolution of the lipsticks' inorganic fraction occurred. Moreover, by using HCl, HF was avoided and solutions more compatible with ICP-MS analysis were obtained. The limits of detection for Cd and Pb were 3 and 77 ng g−1, respectively. This method was applied for a variety of lipsticks, and the concentration of Cd and Pb ranged from ＜3 to 31 ng g−1 and 271 to 2250 ng g−1, respectively. [ABSTRACT FROM AUTHOR]

We report the preparation of a lead free inorganic perovskite by a facile wet-chemical method using HCl as a solvent at room temperature. The cesium perovskite CsCuCl3 material was characterized by powdered X-ray diffraction (p-XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray (EDX) spectroscopy. Ultraviolet/Visible (UV-Vis) and steady state photoluminescence (PL) spectroscopy were also carried out on the material. CsCuCl3 showed promising optical properties with a band gap of 2.6 eV. The material was tested as a fluorescent sensor for the detection of metal ions and as a selective fluorescent chemodosimeter for Pb2+ ions. The substitution of Cu2+ ions by Pb2+ in CsCuCl3 proves the success of the chemodosimetry approach for the detection of Pb2+ ions. [ABSTRACT FROM AUTHOR]

A new methodology to estimate firing distance based on the direct analysis of organic components of gunshot residues (GSRs) on the bullet impact surface using Fourier transform near-infrared (FT-NIR) spectroscopy is proposed. Mathematical models relating firing distance with spectral information were developed using data obtained from a series of shots performed with a Glock model 17C (114 mm barrel length and 9 × 19 mm cartridges) at different distances, from 20 to 90 cm, against a white 40 × 40 cm square cloth (70% polyester/30% cotton) target. The study was repeated with two different types of ammunition. Spectra were obtained around the bullet entrance hole at 4 perpendicular directions and at 5 radial distances in diffuse reflectance mode with the assistance of a fiber optic probe. Principal component analysis showed that FT-NIRS displayed sensitivity in the recognition of the differences between the GSRs from the two different types of ammunition. Partial least squares regression models allowed the estimation of firing distance for both types of ammunition. Prediction errors lower than 11 cm were obtained for shots up to 90 cm. [ABSTRACT FROM AUTHOR]

DNAzyme based electrochemical biosensors have the characteristics of high sensitivity and selectivity, but traditional DNAzyme based electrochemical biosensors need the immobilization of DNAzyme on the electrode surface first, and the procedures are time consuming and tedious, which limit their real application. In this study, a simple but sensitive immobilization free DNAzyme based electrochemical biosensor has been proposed and lead has been chosen as a model target because of the severe effects of lead toxicity. The different diffusivity and electrostatic repulsion between long and short DNA on the negatively charged ITO electrode can be used to discriminate the short and long DNA. Lead dependent DNAzyme was hybridized with its substrate (which was modified with methylene blue at the 3′ terminal) beforehand. Since the DNAzyme/substrate complex contains a large negative charge, it cannot diffuse easily to the negatively charged ITO electrode surface and little electrochemical signal has been detected. The presence of lead would trigger the cleavage of the DNAzyme/substrate complex and cause the release of a methylene blue-labeled short-oligonucleotide into the solution. The methylene blue-labeled short-oligonucleotide can diffuse easily to the surface of the negatively charged ITO electrode and results in the enhanced electrochemical response being detected. Each lead can cleave a lot of DNAzyme/substrate complex to realize signal amplification. The enhanced electrochemical signal has a linear relationship with the Pb2+ concentration in the range of 0.05–1 μM with a detection limit of 0.018 μM (S/N = 3). The proposed biosensor has been applied to detect Pb2+ in water samples with satisfactory results. [ABSTRACT FROM AUTHOR]

A turn-on fluorescent chemosensor of Pb2+ in the near-infrared (NIR) region, which is based on the Pb2+-tuned restored fluorescence of a weakly fluorescent fluorophore–gold nanoparticle (AuNPs) assembly, has been reported. In this fluorophore–AuNP assembly, NIR fluorescent dye brilliant cresyl blue (BCB) molecules act as fluorophores and are used for signal transduction of fluorescence, while AuNPs act as quenchers to quench the nearby fluorescent BCB molecules via electron transfer. In the presence of Pb2+, fluorescent BCB molecules detached from AuNPs and restored their fluorescence due to the formation of a chelating complex between Pb2+ and glutathione confined on AuNPs. Under the optimal conditions, the present BCB–AuNP assembly is capable of detecting Pb2+ with a concentration ranging from 7.5 × 10−10 to 1 × 10−8 mol L−1 (0.16–2.1 ng mL−1) and a detection limit of 0.51 nM (0.11 ng mL−1). The present BCB–AuNP assembly can be used in aqueous media for the determination of Pb2+ unlike common organic fluorescent reagents, and also shows advantages of NIR fluorescence spectrophotometry such as less interference, lower detection limit, and higher sensitivity. Moreover, the present method was successfully applied for the detection of Pb2+ in water samples with satisfactory results. [ABSTRACT FROM AUTHOR]

Using a guanine-rich sequence (AGRO100) and N-methyl mesoporphyrin IX (NMM), a turn-on and label-free fluorescent Pb2+ sensor with high sensitivity and low background fluorescence was presented as a representative of five turn-on sensing systems. [ABSTRACT FROM AUTHOR]

A multicommuted system has been developed for lead (Pb) isolation, pre-concentration and determination using an atomic fluorescence spectrometer as the detector. The lab-on-valve (LOV) technique allows automatic separation and pre-concentration of lead by means of solid phase extraction. The Pb resin was conditioned with nitric acid (1 mol L−1) and the analyte was eluted with 1.3 mol L−1 glycine solution. Chemical and flow variables affecting the extraction/pre-concentration of Pb2+ were investigated by a multivariate approach. First, screening of the independent variables and their interactions was carried out by a two level full factorial design (2k). Then, a face centered central composite design was performed in order to find the optimal values of the significant variables. Because a wide range of sample volumes can be loaded on the microcolumn (1–100 mL), a mass calibration curve was obtained in order to quantify Pb in sample batches with a wide variability in lead concentration. Under optimal conditions, the limit of detection and the quantification limit were 0.004 and 0.014 ng of Pb2+, respectively. The linear response range was 0.014–20 ng of Pb2+. The repeatability, expressed as relative standard deviation (RSD), is 2.4% for 4 μg L−1 Pb2+ (n = 10). A small amount (0.6 g) of Pb resin is enough to fill the microcolumn of the LOV device. The durability of the resin reached 154 injections. The injection frequency permitted between a sample frequency of 1–10 h−1 depending on the sample pre-concentration volume. This method was validated using certified reference materials such as SRM-1400 (bone ash), SRM-2976 (mussel tissue) and BCR-610 (groundwater), and the results obtained showed good agreement with the certified values. The proposed LOV system was successfully applied to different samples of environmental and biological interest (water, fish and human teeth) with satisfactory recoveries, between 90–110%. The proposed system has some advantages such as minimization of sample handling, sensitivity, good precision, reduction of reagent volumes, high durability of the column and the versatility achieved by a variety of managed sample volumes. [ABSTRACT FROM AUTHOR]

We present a straightforward method for accurate and precise U/Pb dating of baddeleyite using quadrupole LA-ICP-MS. To establish the validity of our ICP-MS data we used FC-4b baddeleyite from the Duluth complex as external standard, whereas baddeleyite from the Phalaborwa (South Africa) and the Sorkka (SW Finland) intrusions were treated as unknowns. The analytical protocol includes the use of a matrix matched standard, which allows for an accurate downhole-fractionation and laser-induced interelement fractionation correction. The quadrupole ICP-MS results for the Phalaborwa and Sorkka samples analyzed are accurate within error of the published ID-TIMS U/Pb ages and with a precision of 0.3–0.7% (2σ) from concordia ages of ten to twenty analyses per sample. No orientation effects were observed. [ABSTRACT FROM AUTHOR]

Stable germanium(II) and lead(II) amido complexes {LOi}M(N(SiMe3)2) (M= GeII, PbII) bearing amino(ether)- phenolate ligands are readily available using the proteo-ligands {LOi}H of general formula 2-CH2NR2-4,6-tBu2-C6H2OH (i = 1, NR2 = N((CH2)2OCH3)2; i = 2, NR2 = NEt2; i = 3, NR2 = aza-15-crown-5) and M- (N(SiMe3)2)2 precursors. The molecular structures of these germylenes and plumbylenes, as well as those of {LO3}GeCl, {LO3}SnCl and of the congeneric {LO4}SnII(N(SiMe3)2) where NR2 = aza-12-crown-4, have been determined crystallographically. All complexes are monomeric, with 3-coordinate metal centres. The phenolate systematically acts as a N^Ophenolate bidentate ligand, with no interactions between the metal and the Oside-arm atoms in these cases (for {LO1}-, {LO3}- and {LO4}-) where they could potentially arise. For each family, the lone pair of electrons essentially features ns2 character, and there is little, if any, hybridization of the valence orbitals. Heterobimetallic complexes {LO3}M(N(SiMe3)2).LiOTf, where the Li+ cation sits inside the tethered crown-ether, were prepared by reaction of {LO3}M(N(SiMe3)2) and LiOTf (M = GeII, SnII). The inclusion of Li+ (featuring a close contact with the triflate anion) in the macrocycle bears no influence on the coordination sphere of the divalent tetrel element. In association with iPrOH, the amido germylenes, stannylenes and plumbylenes catalyse the controlled polymerisation of L- and racemic lactide. The activity increases linearly according to GeII ⪡ SnII ⪡ PbII. The simple germylenes generate very sluggish catalysts, but the activity is significantly boosted if the heterobimetallic complex {LO3}Ge(N(SiMe3)2).LiOTf is used instead. On the other hand, with 10-25 equiv. of iPrOH, the plumbylenes afford highly active binary catalysts, converting 1000 or 5000 equiv. of monomer at 60 °C within 3 or 45 min, respectively, in a controlled fashion. [ABSTRACT FROM AUTHOR]

Aqueous solution containing two additives, chloroauric acid (HAuCl4) and trisodium citrate (Na3C6H5O7), was irradiated by sunlight, without any additional stimulus such as electric power, to form high-yield Au decahedra. Those Au nanodecahedra were thermodynamically stable and exhibited high performance sensing of lead (Pb2+) ions. [ABSTRACT FROM AUTHOR]