Characterization of a microwave microstrip helium plasma with gas-phase sample introduction for the optical emission spectrometric determination of bromine,chlorine, sulfur and carbon using a miniaturized optical fiber spectrometer

Continuous flow generation of Br₂, Cl₂ and H₂S coupled to a low-power 2.45 GHz microwave microstrip He plasma exiting from a capillary gas channel in a micro-fabricated sapphire wafer with microstrip lines has been used for the optical emission spectrometric determination of Br, Cl and S using a miniaturized optical fiber CCD spectrometer. Under optimized conditions, detection limits (3σ) of 330, 190 and 220 μg l^− 1 for Br, Cl and S, respectively, under the use of the Br II 478.5 nm, Cl I 439.0 nm and S I 469.0 nm lines were obtained and the calibration curves were found to be linear over 2 orders of magnitude. In addition, when introducing CO₂ and using the rotational line of the CN molecular band at 385.7 nm the detection limit for C was 4.6 μg l^− 1. The procedure developed was found to be free from interferences from a number of metal cations and non-metal anions. Only the presence of CO₃²⁻ and CN⁻ was found to cause severe spectral interferences as strong CN and C₂ molecular bands occurred as a result of an introduction of co-generated CO₂ and HCN into the plasma. With the procedure described Br, Cl and S could be determined at a concentration level of 10–30 mg l^− 1 with accuracy and precision better than 2%.     

On-target sample preparation of 4-sulfophenyl isothiocyanate-derivatized peptides using AnchorChip Targets

De novo sequencing of tryptic peptides by post source decay (PSD) or collision induced dissociation (CID) analysis using MALDI TOF-TOF instruments is due to the easy interpretation facilitated by the introduction of N-terminal sulfonated derivatives. Recently, a stable and cheap reagent, 4-sulfophenyl isothiocyanate (SPITC), has been successfully used for N-terminal derivatization. Previously described methods have always used desalting and concentration by reverse-phase chromatography prior to mass spectrometric analysis. Here we present an on-target sample preparation method based on AnchorChip target technology. The method was optimized for reduction of by-products and sensitivity with SPITC-derivatized tryptic BSA peptides, and successfully applied to protein identification from silver-stained two-dimensional electrophoretic gels of fish liver extracts. The method is simple and sensitive and allowed protein identification based on de novo sequencing and BLAST search from species with limited sequence information.     

A new solid-phase extraction disk based on a sheet of single-walled carbon nanotubes

A new kind of solid-phase extraction disk based on a sheet of single-walled carbon nanotubes (SWCNTs) is developed in this study. The properties of such disks are tested, and different disks showed satisfactory reproducibility. One liter of aqueous solution can pass through the disk within 10–100 min while still allowing good recoveries. Two disks (DD-disk) can be stacked to enrich phthalate esters, bisphenol A (BPA), 4-n-nonylphenol (4-NP), 4-tert-octylphenol (4-OP) and chlorophenols from various volumes of solution. The results show that SWCNT disks have high extraction ability for all analytes. The SWCNT disk can extract polar chlorophenols more efficiently than a C₁₈ disk from water solution. Unlike the activated carbon disk, analytes adsorbed by the new disks can be eluted completely with 8–15 mL of methanol or acetonitrile. Finally, the DD-disk system is used to pretreat 1000-mL real-world water samples spiked with BPA, 4-OP and 4-NP. Detection limits of 7, 25, and 38 ng L⁻¹ for BPA, 4-OP, and 4-NP, respectively, were achieved under optimized conditions. The advantages of this new disk include its strong adsorption ability, its high flow rate and its easy preparation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Heterometallic Uranyl (Hydroxyethyl)iminodiacetic Acid (Heidi) Complexes: Molecular Models for U(VI) Uptake in Complex Media

Amidoximated absorbents (AO-PAN) effectively remove U(VI) from aqueous solution, but previous studies reported more variability for complex natural waters that contain additional confounding ions and molecules. Ternary phases containing U(VI), M(III) (M=Fe(III), Al(III), Ga(III)), and organic molecules exist under these conditions and cause heterogeneous U(VI) uptake on AO-PAN. The goal of the current study is to provide additional insights into the structural features ternary complexes using N-(2-hydroxyethyl)-iminodiacetic acid (HEIDI) as the model organic chelator and explore the relevance of these species on U(VI) capture. Three model compounds ([(UO₂)(Fe)₂(μ₃-O)(C₆NO₅H₈)₂(H₂O)₄] ( UFe₂ ), ([(UO₂)(Al)₂(μ₂-OH)(C₆NO₅H₈)₂(H₂O)₃] ( UAl₂ ) and [(UO₂)(Ga)₂(μ₂-OH)(C₆NO₅H₈)₂(H₂O)₃] ( UGa₂ )) were characterized by single-crystal X-ray diffraction. Raman spectra of the model compounds were compared with solution data and the ternary phases were noted in the case of Al(III) and Ga(III), but not in the Fe(III) system. U(VI) adsorption onto AO-PAN was not impacted by the presence of HEIDI or the trivalent metal species.     

Magnetic molecularly imprinted polymer based on dynamically established metal-mediated binding sites for the determination of trace captopril in rat plasma

Therapeutic drug monitoring of captopril, which is a commonly used antihypertensive agent in clinical practice, is necessary. However, matrix effect-induced pretreatment is the bottleneck for determination. Metal-mediated molecularly imprinted polymers, an essential branch of molecularly imprinted polymers with better specificity and selectivity, have been used to separate/enrich analytes from complex matrices. In this work, Cu²⁺ was introduced to dynamically establish the binding sites of metal-mediated molecularly imprinted polymer towards captopril. All evidence demonstrated that the metal-mediated molecularly imprinted polymer based on Cu²⁺ coordination obtained a higher adsorption capacity (81.23 mg/g), faster adsorption rate (adsorption equilibrium within 50 min), and better selectivity (with the unrecognized analog). Subsequently, the Cu²⁺-mediated molecularly imprinted polymer was used as dispersive molecularly imprinted solid-phase extraction to successfully establish an analytical platform for the determination of trace captopril in rat plasma. The enrichment factor was up to 20, the detection limit was as low as 0.16 μg/ml, and the average recovery was in the range of 87.51%–98.28% with a relative standard deviation of less than 3.29%. This study provides a promising reference for the preparation of selective adsorbents to improve pretreatment.     

Determination of ticagrelol in rat plasma and tablets by micellar electrokinetic chromatography coupled with large volume sample stacking: Application to a pharmacokinetic study

A method using micellar electrokinetic chromatography coupled with large-volume sample stacking for the determination of ticagrelol was developed and validated. The analysis was performed in a fused silica capillary (41.5 cm effective length, 50 μm diameter) with ultraviolet detection at 195 nm. The background electrolytes were 30 mM phosphate buffer of pH 3.0 with 120 mM sodium dodecylsulfate and 10 % (v/v) acetonitrile (120 s X 50 mbar; 20°C; -18 kV) and 30 mM borate buffer of pH 8.5 with 75 mM sodium dodecylsulfate (120 s X 50 mbar; 20°C; 25 kV); under acidic and alkaline conditions, respectively. The method was found to be reliable with respect to specificity, linearity of the calibration line (R² > 0.99), repeatability (relative standard deviation 2.56%–3.34%), and accuracy (recovery in the range 101.21%–102.67%). The limits of detection and quantitation were 0.032, 0.071, and 0.087, 0.188 μg/mL, respectively. The method was successfully applied for the determination of ticagrelol concentrations in rat plasma and tablets with good recoveries and reproducibility. The presented method proved to be suitable for monitoring ticagrelor in rat plasma.     

Advanced porous organic materials for sample preparation in pharmaceutical analysis

The development of novel sample preparation media plays a crucial role in pharmaceutical analysis. To facilitate the extraction and enrichment of pharmaceutical molecules in complex samples, various functionalized materials have been developed and prepared as adsorbents. Recently, some functionalized porous organic materials have become adsorbents for pharmaceutical analysis due to their unique properties of adsorption and recognition. These advanced porous organic materials, combined with consequent analytical techniques, have been successfully used for pharmaceutical analysis in complex samples such as environmental and biological samples. This review encapsulates the progress of advanced porous materials for pharmaceutical analysis including pesticides, antibiotics, chiral drugs, and other compounds in the past decade. In addition, we also address the limitations and future trends of these porous organic materials in pharmaceutical analysis.