Using HPLC for the determination of platinum drugs in biological matrixes after derivatization with diethyldithiocarbamate

Challenges and pitfalls in the application of diethyldithiocarbamate derivatization for LC analysis of cisplatin and oxaliplatin, as well as the suitability of this method for different biological matrices with implications for use in routine practice have been identified. The LC of platinum drugs presents a significant challenge. They are polar compounds with poor retention on reverse phase packings. Cisplatin also exhibits poor absorption in UV and ionization in mass spectrometry. Therefore, we developed and optimized a derivatization approach for the LC analysis of total platinum in plasma, plasma ultrafiltrate, peritoneal fluid, and urine. Derivatization in urine proved to be difficult due to the complexity of the matrix, and extended testing was required. Our results highlight the important issues affecting the efficiency, reliability, and suitability of platinum drug derivatization. Although precolumn derivatization is less selective than its postcolumn counterpart, the application of precolumn derivatization is a simple, rapid, and universal approach for the determination of platinum drugs by HPLC. One of its major advantages is that it allows a more affordable analysis using UV detection without the need for additional high-end instrumentation such as a MS detector.

Functionalization of melamine sponge for the efficient recovery of Pt(IV) from acid leachates

The recovery of platinum from industrial waste is of critical importance. Usually, the recovery method is to dissolve the solid waste with acid to form a solution where platinum mainly exists in the form of Pt(IV). Therefore, it is urgent to efficiently and selectively adsorb Pt(IV) ions from acid leachates. In this study, a highly efficient adsorbent was developed by grafting of carboxyl and amine groups onto melamine sponge with alginate-Ca and polyethylenimine-glutaraldehyde (ML/ACPG). Combination of SEM, FTIR and XPS showed that the ML/ACPG sponge had a tree structure and the amino, carboxyl and hydroxyl groups were successfully introduced. Maximum adsorption capacity of ML/ACPG sponge reached up to 101.1 mg/L at pH of 1 (optimum initial pH value). The Pt(IV) ions were readily desorbed (within 60-80 min) using 0.1 M HCl + 0.025 M thiourea solution. Desorption efficiency remained higher than 83.3% while adsorption capacity decreased by less than 6.0% after 5 cycles operation. The ML/ACPG sponge was stable in 3 M of HNO3, NaCl after shaking for 72 h at 300 rpm with mass loss less than 2.5%. The mechanism of Pt(IV) adsorption onto ML/ACPG sponge mainly involved coordination by electrostatic attraction and carboxyl groups by protonated amine groups. The above results confirmed that the ML/ACPG sponge has a good practical application potential for Pt(IV) recovery from acid leachates.

Design, structural, spectral, DFT and analytical studies of novel nano-palladium schiff base complex

A novel nano-palladium (II) Schiff base complex (C1) is synthesized by the reaction between palladium chloride and the Schiff base N, N'-1, 2-phenylene) bis (3 -aminobenzamide (A1). The prepared compounds were characterized by elemental analysis, Ultraviolet-Visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Thermogravimetric Analysis (TGA). A combined solvent sublation-ICP OES methodology has been studied for the preconcentration, separation and determination of trace palladium (II) in media of diverse origin using the Schiff base ligand (A1). The different experimental variables that affect the sublation efficiency (S, %) were thoroughly investigated viz.: pH of sample solution; amounts of A1, Pd (II) and TBAB; type and amounts of surfactants, types of organic solvent, temperature and stirring time. The method involves the determination of trace palladium (II) after selective separation by solvent sublation, thus eliminating the effect of foreign ions and increasing the sensitivity. Also, palladium is determined directly in the organic phase, which decreases the determination time and its loss during determination. At optimum conditions, the linear range of Pd (II) was 10.0-100.0 ngmL^-1. The coefficient of determination, the limit of detection (LOD) and limit of quantification (LOQ) were 0.9943, 21.29 ngL^-1 and 64.5 ngL^-1, respectively. This sublation method was applied to real samples and recoveries of more than 95% were obtained in the spiked samples with a preconcentration factor of 100. The mechanism of solvent sublatation of the TBA.[Pd^II-(A1)₂] ion pairs is discussed. The computational studying was estimated to approve the geometry of the isolated solid compounds.

Chromium Adsorption from Aqueous Solution onto Dowex Retardion 11A8 and Amberlite IRA 743 Free Base: An Insight into the Mechanism

Background:

The presence of heavy metal contaminants such as chromium, lead, mercury, cadmium, arsenic, nickel, and copper have become a major issue towards human health. Chromium is extremely toxic to living organisms as it acts as carcinogen and mutagen. High concentration of chromium may cause detrimental effects to human health in the long term. The mutagenic and carcinogenic properties, included Cr(VI) in the group “A” of human carcinogens. Cr(VI) can easily penetrate into the cell wall and exert its noxious effect due to its mobility in the environment. Cr(VI) is nearly 100 times more toxic than Cr(III). Cr(VI) causes skin and stomach irritation or ulceration, damage to liver, kidney ulceration, damage to nerve tissue, and long-term exposure above the maximum contaminated level even led to death. Therefore, it is essential to remove chromium from wastewater prior to its final discharge into the environment. This study attempts to explore the mechanism by which chromium ions had been adsorbed by these two ion exchange resins and will be extended further to investigate the uptake mechanism of other metal ions within future research.

Methods:

Equilibrium isotherms were obtained by contacting 20 mL of aqueous metal ion solution with different amounts of adsorbents in a shaker bath controlled at 25±0.5oC. The initial concentration of metal ion in the aqueous solution was varied between 40-100 mg L -1 . Equilibrium isotherms for the above metal ion were generated at pH 3, 4 and 5. The pH of the solution was varied between pH 3 to 5 using appropriate doses of buffer. Preliminary runs exhibited that the adsorption equilibrium was achieved after 1–1.30 h of contact time for both the tested resins. The adsorbents used were DOWEX and AMB resins. For estimation of adsorption enthalpy, adsorption equilibrium experiments were performed at temperatures 30, 40 and 55oC. The amount of metal ion adsorbed per unit mass of the adsorbent (mg g-1) was calculated as q= V∆C/W, where ∆C is the change in solute concentration (mg L -1 ), V is the solution volume (L) and W is the weight of the adsorbent (g). Experiments on adsorption kinetics were performed in a stirred constant volume vessel. The liquid volume was 100 cm3 with 10g of adsorbent sample. The initial concentration of metal ion was 80 mg L -1 at 25±0.5oC. The aqueous phase concentration was examined at equal time intervals till equilibration.

Results:

The electrostatic interaction of Cr(VI) with the positively charged nitrogen atom of the functional groups and chelation of Cr(III) with the electron donor groups were the possible mechanistic pathways through which the adsorption had occurred onto both the ion-exchange resins. Though electrostatic interaction was the predominant interaction in both the resins for the adsorption of anionic Cr(VI) species, but it had been observed that the mechanism of Cr(VI) adsorption was not only “anionic adsorption” but also the complexation of the reduced Cr(III) with the ammonium group of the resins. Thus, “adsorption- coupled reduction” was the main mechanism for the uptake of chromium ions.

Conclusion:

The present work demonstrated that both resins could effectively adsorb Cr(VI) ions from aqueous solution. More adsorption had taken place onto DOWEX compared to AMB. The adsorption characteristics of both the resins were studied under various equilibrium and thermodynamic conditions which proposed the spontaneous nature of the process. The adsorption capacities of both resins were influenced by the pH of the medium and exhibited high adsorption performances at pH 3. The mechanism of adsorption onto the two resins studied here was anionic adsorption of Cr (VI) and chelation of Cr (III) ion. The Cr(III) ions might have formed because of the reduction of Cr(VI) by the electron donor atoms present in the resins and interacted with the adsorbent surface. FTIR spectra also supported the interaction of chromium ions with functional groups present in the resin structures. Thus chromium uptake by DOWEX and AMB resins was mainly governed by “adsorption- coupled reduction”. Desorption studies revealed that regeneration of both the ionexchange resins are possible at basic pH and can be reused. However, the application of these two ion-exchange resins using real effluent is under consideration.

Miniaturization of Anthracene-Containing Nonapeptides for Selective Precipitation/Recovery of Metallic Gold from Aqueous Solutions Containing Gold and Platinum Ions

The separation and recovery of noble metals is increasingly of interest, in particular the recovery of gold nanocrystals, which have applications in medicine and industry. Typically, metal recovery is performed using liquid–liquid extraction or electrowinning. However, it is necessary to develop noble metal recovery systems providing high selectivity in conjunction with a one-pot setup, ready product recovery, and the use of dilute aqueous solutions. In prior work, our group developed a selective gold recovery process using peptides. This previous research showed that RU065, a nonapeptide containing an anthracene moiety (at a concentration of 2.0 × 10−4 M), is capable of selective reduction of HAuCl4 to recover gold from a solution of HAuCl4 and H2PtCl6, each at 5.0 × 10−5 M. However, peptide molecules are generally costly to synthesize, and therefore it is important to determine the minimum required structural features to design non-peptide anthracene derivatives that could reduce operational costs. In this study, we used RU065 together with 23 of its fragment peptides and investigated the selective precipitation/recovery of metallic gold. RU0654–8, a fragment peptide comprising five amino acid residues (having two lysine, one L-isoleusine, and one L-alanine residue (representing six amide groups) along with an L-2-anthrylalanine residue) provided an Au/Pt atomic ratio of approximately 8, which was comparable to that for the full-length original RU065. The structural features identified in this study are expected to contribute to the design of non-peptide anthracene derivatives for low-cost, one-pot selective gold recovery.

Elimination of interferences in the determination of platinum, palladium and rhodium by diffusive gradients in thin films (DGT) and inductively coupled plasma mass spectrometry (ICP MS) using selective elution

The analysis of platinum (Pt), palladium (Pd) and rhodium (Rh) in aquatic samples by the diffusive gradients in thin films (DGT) technique using chelating resins, specific designed for the accumulation of PGEs, namely Purolite S914, S920 and Italmatch Chemicals IONQUEST® MPX-317. may however, still be influenced by the accumulation of other elements such (Cu, Zn, Pb, etc.) which will be extracted simultaneously by the hot aqua regia extraction and interfere with the Inductively Coupled Plasma Mass Spectrometry (ICPMS) analysis of the Platinum Group Elements (PGEs). Selective extractions were investigated to release the interfering elements without loss of the Platinum Group Elements (PGEs) from the resin gels. . A rinse with deionized water removes over 95% of Sr and Rb and a second rinse with 0.05 mol L^-1 H₂SO₄ can be used to as a common eluent to remove an important fraction of the interfering elements from S920 and S914 without loss of PGEs but this results in loss of around 15% of the PGEs from MPX-317. It was shown that selective extractions can be used to remove specific interferences from each resin gel.

Chelating polymers with valuable sorption potential for development of precious metal recycling technologies

A special attention is currently focused on the recovery of Au, Ag, Pt, Pd and Rh from both primary and secondary sources. From the wide range of sorbents that have been used in this respect, the required selectivity is proved only by the chelating polymers containing donor N, O and S atoms in their functional groups. This work presents the recent published researches on this topic, pointing out the capabilities of chelating sorbents based on organic synthetic polymers for a sustainable development. The chelating sorbents are differentiated and reviewed according to their synthesis strategy and compatibility with synthetic and real matrices. First, an overview on the novel functionalized polymers and impregnated resins with good selectivity for the recovery of most valuable precious metals from synthetic leach solutions is given. Subsequently, the performances of these materials in the selective and preconcentrative recovery of Au, Ag, Pt, Pd and Rh from simulated and real leachates are discussed. The viability of an integrated approach for the determination of precious metals from simulated solutions by solid phase spectrometry is highlighted. The transposition of chelating polymers’ potential in challenging technologies for precious metal recovery-reuse-recycling needs further research on directions that are proposed.

New sulfur-containing polymeric sorbents based on 2,2′-thiobisethanol dimethacrylate

The first step in obtaining of a specific polymer sorbent containing sulfur atoms was the synthesis of a functional monomer – 2,2′-thiobisethanol dimethacrylate (TEDM). Synthesis consists of the reaction of 2,2′-thiobisethanol with methacryloyl chloride in the presence of triethylamine in methylene chloride. The new poly(dimethacrylate)s materials containing sulfur atoms were synthesized in radical suspension polymerization. Homopolymerization of 2,2′-thiobisethanol dimethacrylate and its copolymerization with ethylene glycol dimethacrylate or pentaerythritol tetraacrylate were carried out. The selection of synthesis conditions determines the parameters of the polymer structure and its properties. The presence of sulfur atoms in polymer chains resulted in specific donor-acceptor interactions, which can intensify sorption ability towards metal ions belonging to the group of soft acids. Therefore, the sorption properties of the obtained materials have been determined based on the recovery of precious metal ions, such as gold(III) and silver(I).

Theophylline-bearing microspheres with dual features as a coordinative adsorbent and catalytic support for palladium ions

Polystyrenic microspheres in the sub 5 micrometer size range (micro-gel) with –CH₂Cl active sites were synthesized via the dispersion polymerization of 4-chloromethylstyrene, divinyl benzene and methoxy polyethylene glycol acrylate. Then, theophylline residues were introduced onto the polystyrenic microspheres via the substitution of the chloride in the –CH₂Cl group to prepare chelate type microspheres of μ-T2. It was found that the microspheres have co-continuous structures, monodispersed particle sizes, and excellent solvent and water wettability. Using the μ-T2 microspheres possessing theophylline residues, adsorption experiments involving the adsorption of palladium(ii), copper(ii) and platinum(iv) from acidic chloride media under both individual and mixed conditions were carried out and it was found that the μ-T2 microspheres exhibited excellent adsorption selectivity for palladium(ii) over copper(ii) and platinum(iv). It was also revealed that thiourea or ammonia solutions are the most effective in desorbing palladium ions from the microspheres. Despite being used in four adsorption–desorption cycles, the μ-T2 microspheres were still able to strongly adsorb palladium ions, with an adsorption of over 85%. In addition, the μ-T2 microspheres also showed palladium capturing ability even in very dilute palladium solutions (below 1.0 ppm). Interestingly, the μ-T2 microsphere-adsorbed palladium ions exhibited excellent catalytic activity in the Suzuki–Miyaura coupling reaction of bromobenzene and phenylboronic acid, yielding biphenyl in 100% under the conditions within 1 hour at 50 °C in water.

Sub 5 micrometer sized polystyrenic microspheres bearing theophylline residues were synthesized and used as adsorbent and catalytic support for palladium ions.

A perspective on diverse adsorbent materials to recover precious palladium and the way forward

A perspective on diverse adsorbent materials for the recovery of palladium.

Chitosan and Its Derivatives as Highly Efficient Polymer Ligands

The polyfunctional nature of chitosan enables its application as a polymer ligand not only for the recovery, separation, and concentration of metal ions, but for the fabrication of a wide spectrum of functional materials. Although unmodified chitosan itself is the unique cationic polysaccharide with very good complexing properties toward numerous metal ions, its sorption capacity and selectivity can be sufficiently increased and turned via chemical modification to meet requirements of the specific applications. In this review, which covers results of the last decade, we demonstrate how different strategies of chitosan chemical modification effect metal ions binding by O-, N-, S-, and P-containing chitosan derivatives, and which mechanisms are involved in binding of metal cation and anions by chitosan derivatives.

Application of multivariate optimization procedures for preconcentration and determination of Au(III) and Pt(IV) in aqueous samples with graphene oxide by X-ray fluorescence spectrometry

A simple method was developed for the determination of Au(III) and Pt(IV) contents in aqueous samples after preconcentration. The method was based on the sorption of analytes as 2-amino-5-mercapto-1,3,4-thiadiazol complexes onto graphene oxide and subsequent direct determination by wavelength dispersive X-ray fluorescence (WDXRF). The optimization step was carried out using two-level full-factorial and Box-Behnken designs. The effects of four variables (pH, ligand mass, sonication time, and temperature) were studied by a full-factorial design to find significant variables and their interactions. Results of two-level full-factorial design for Au extraction showed that the factors: pH, ligand mass, temperature of sonication beside the interaction of pH-ligand mass, and interaction sonication temperature-ligand mass were significant. For Pt, the results revealed pH, ligand mass, sonication time, and interaction of pH-ligand mass were statistically significant. Box-Behnken matrix design was applied to determine the optimum level of significant parameters for extraction of two analytes simultaneously. The optimum values of the factors were pH 2.5, 0.9 mL ligand solution, 56 min sonication time and 15 °C temperature. The limits of detection (LOD) were found to be 8 ng mL(-1) for Au and 6 ng mL(-1) for Pt. The adsorption capacity for Au and Pt were 115 and 169 μg mg(-1), respectively. The relative standard deviation (RSD) was lower than 1.4 % (n = 5), and the extraction percentage was more than 95 % for both elements. The method was validated by determination of Au and Pt in spiked water samples and certified reference standard materials.

Supramolecular solvent microextraction of gold prior to its determination by microsample injection system coupled with flame atomic absorption spectrometry

A supramolecular solvent based liquid–liquid microextraction (SsLLME) system for gold was developed prior to its determination by a microsample injection system coupled with flame atomic absorption spectrometric (MS-FAAS).