Determination of palladium in human urine by high-performance liquid chromatography and ultraviolet detection after ultraviolet photolysis and selective solid-phase extraction

Palladium nanoparticles as emerging pollutants from motor vehicles: An in-depth review on distribution, uptake and toxicological effects in occupational and living environment

Palladium nanoparticles (PdNPs) play an integral role in motor vehicles as the primary vehicle exhaust catalyst (VEC) for tackling environmental pollution. Automobiles equipped with Pd-based catalytic converters were introduced in the mid-1970s and ever since the demand for Pd has steadily increased due to stringent emission standards imposed in many developed and developing countries. However, at the same time, the increasing usage of Pd in VECs has led to the release of nano-sized Pd particles in the environment, thus, emerging as a new source of environmental pollution. The present reports in the literature have shown gradual increasing levels of Pd particles in different urban environmental compartments and internalization of Pd particles in living organisms such as plants, aquatic species and animals. Occupational workers and the general population living in urban areas and near major highways are the most vulnerable as they may be chronically exposed to PdNPs. Risk assessment studies have shown acute and chronic toxicity exerted by PdNPs in both in-vitro and in-vivo models but the underlying mechanism of PdNPs toxicity is still not fully understood. The review intends to provide readers with an in-depth account on the demand and supply of Pd, global distribution of PdNPs in various environmental matrices, their migration and uptake by living species and lastly, their health risks, so as to serve as a useful reference to facilitate further research and development for safe and sustainable technology.

A novel UV-photolysis approach with acetone and isopropyl alcohol for the rapid determination of fluoride in organofluorine-containing drugs by spectrophotometry

A UV photolysis decomposition (UVPD) method for the determination of fluoride in fluorine containing pharmaceuticals by spectrophotometry is reported. It is based on the use of high intensity UV-irradiation in the presence of a digesting solution comprising a mixture of acetone and isopropanol. For the optimization of the UVPD procedure, three bulk drugs (levofloxacin, nebivolol and efavirenz) were chosen as representatives of three diverse compounds containing a single fluorine atom, two fluorine atoms, and trifluoromethyl groups respectively. Operational conditions of the UVPD method, such as concentration and volume of reagents (acetone and isopropyl alcohol), and UV irradiation time (1–6 minutes) were optimized. The efficiency of digestion was evaluated by the determination of fluoride in sample digests. Using the developed method, it was possible for complete conversion of the organofluoride to free fluoride ion for its subsequent determination by spectrophotometry based on bleaching of Zr–xylenol orange-color complex. Quantitative recovery (>98%) of the fluorine in the drug samples could be achieved using a mixture of 2% acetone + 2% isopropyl alcohol + 0.003% Na₂CO₃ in just 5 minutes of UV irradiation, which can be considered an important aspect considering the difficulties involved in the cleavage of the C–F bond. Accuracy was evaluated by comparison of results obtained by the UVPD method with the values estimated using formula weight of the compound and no statistical difference was observed between the results. Therefore, the proposed method is suitable for application in routine analysis of fluoride in organofluorine-containing drugs.

Leaves of Phragmites australis as potential atmospheric biomonitors of Platinum Group Elements

The increasing emissions of Platinum Group Elements (PGEs), namely Pt, Pd and Rh, may pose a significant risk to ecosystem processes and human health. A periodic assessment of PGEs distribution in the environment is thus of the utmost importance for the implementation of timely measures of mitigation. Although several studies have quantified PGEs in different life forms such as mammals, birds, fish, crustaceans, algae, mosses and even human beings, data about vascular plants need further surveys. This study aimed to test the suitability of the grass Phragmites australis (common reed) as a biomonitor of PGEs atmospheric pollution. The results showed that Pd and Pt concentrations in leaves are significantly higher in urban areas. In particular, Pd showed the highest range of values in line with current studies that consider palladium as the main element of traffic-related pollution. Overall, the leaves of Phragmites australis reflected the different gradient of PGEs emissions, and may thus be considered as potential biomonitors of atmospheric pollution.

Solid phase extractive preconcentration of silver from aqueous samples

N,N-dibutyl-N1-benzoylthiourea (DBBT) impregnated onto a polymeric matrix, Amberlite XAD-16 was prepared. The separation and enrichment of Ag(I) from solution was investigated. Effective extraction conditions were optimized in column methods prior to determination by atomic absorption spectrometry. The optimum pH range for quantitative adsorption is 2-5. Quantitative recovery of Ag was achieved by stripping with 1 mol L(-1) thiourea in 1 mol L(-1) HCl. The sorption capacity of resin is 0.115 mmol Ag+ g(-1) resin. The relative standard deviation and detection limit was 3.1% for 1 microg Ag+ mL(-1) solution and 0.11 microg L(-1), respectively. The method was used for the determination of silver in geological water samples.

Simultaneous Determination of Palladium, Platinum and Rhodium by On-Line Column Enrichment and HPLC with 5-(2,4-Dihydroxyphenylazo)-Rhodanine as Pre-Column Derivatization Reagent

In this paper, a new method for the simultaneous determination of palladium, platinum and rhodium ions was developed using a rapid column high performance liquid chromatography equipped with on-line enrichment technique. The palladium, platinum and rhodium ions were pre-column derivatized with DHAR to form colored chelates. The Pb-DHAR, Pt-DHAR and Rh-DHAR chelates could be absorbed onto the front of the enrichment column when they were injected into the injector and sent to the enrichment column [ZORBAX Stable Bound, 4.6 x 10 mm, 1.8 microm] with a 0.05 mol L(-1) of phosphoric acid solution as mobile phase. After enrichment, and by switching the six ports switching valve, the retained chelates were back-flushed by mobile phase and traveling towards the analytical column. The separation of these chelates on the analytical column [ZORBAX Stable Bound, 4.6 x 50 mm, 1.8 microm] was satisfactory with 54% acetonitrile (containing 0.05 mol L(-1) of phosphoric acid and 0.1% of tritonX-100) as mobile phase. Palladium, platinum and rhodium were separated completely within 2 min. By on-line enrichment technique, the enrichment factor of 100 was achieved, and the detection limits (S/N = 3) of palladium, platinum and rhodium reaches 1.4 ng L(-1), 1.6 ng L(-1) and 2.0 ng L(-1), respectively. This method was applied to the determination of palladium, platinum and rhodium in water, urine and soil samples with good results.

Microwave-assisted UV-digestion procedure for the accurate determination of Pd in natural waters

A procedure was developed for the selective determination of Pd in environmental aquatic solutions. The method is based on a preliminary microwave-assisted UV-digestion for the degradation of dissolved organic material, and the subsequent determination of Pd using a recently presented enrichment procedure with ETAAS detection. Due to the simultaneous use of microwave and UV irradiation only extremely small quantities of hydrogen peroxide were necessary to yield a quantitative degradation of interfering organic ligands. Thus the on-line pre-concentration of Pd in the digested samples using the complexing agent N,N-diethyl-N'-benzoylthiourea was possible without any further sample pre-treatment. Using a sample volume of 1.57 ml for FI-ETAAS analysis a limit of detection of 15 ng l(-1) was obtained for the combined procedure, with a relative standard deviation being not more than 4.9%. The method was applied to quantify the water-soluble fraction of Pd in urban road dust. Extractions with a rain sample of pH 5.9 revealed that an average of 2.2% (n=8) of the total Pd present in urban road dust was water soluble.

Simultaneous determination of palladium, platinum, rhodium and gold by on-line solid phase extraction and high performance liquid chromatography with 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine as pre-column derivatization regents

In this paper, 5-(2-hydroxy-5-nitrophenylazo)thiorhodanine (HNATR) was synthesized. A new method for the simultaneous determination of palladium, platinum, rhodium and gold ions as metal-HNATR chelates was developed using a rapid analysis column high performance liquid chromatography equipped with on-line solid phase extraction technique. The samples (Water, human urine, geological samples and soil) were digested by microwave acid-digestion. The palladium, platinum, rhodium and gold ions in the digested samples were pre-column derivatized with HNATR to form colored chelates. The Pd-HNATR, Pt-HNATR, Rh-HNATR and Au-HNATR chelates can be absorbed onto the front of the enrichment column when they were injected into the injector and sent to the enrichment column [Zorbax Stable Bound, 10 mm x 4.6 mm, 1.8 microm] with a buffer solution of 0.05 mol L(-1) phosphoric acid as mobile phase. After the enrichment had finished, by switching the six ports switching valve, the retained chelates were back-flushed by mobile phase and travelling towards the analytical column. These chelates separation on the analytical column [Zorbax Stable Bound, 10 mm x 4.6 mm, 1.8 microm] was satisfactory with 72% acetonitrile (containing 0.05 mol L(-1) of phosphoric acid and 0.1% of Triton X-100) as mobile phase. The palladium, platinum, rhodium and gold chelates were separated completely within 2.5 min. Compared to the routine chromatographic method, more then 80% of separation time was shortened. By on-line solid phase extraction system, a large volume of sample (10 mL) can be injected, and the sensitivity of the method was greatly improved. The detection limits (S/N=3, the sample injection volume is 10 mL) of palladium, platinum, rhodium and gold in the original samples reaches 1.4, 1.8, 2.0 and 1.2 ng L(-1), respectively. The relative standard deviations for five replicate samples were 2.4-3.6%. The standard recoveries were 88-95%. This method was applied to the determination of palladium, platinum, rhodium and gold in human urine, water and geological samples with good results.

Environmental routes for platinum group elements to biological materials--a review

The increased use of platinum group elements (PGE) in automobile catalysts has led to concern over potential environmental and biological accumulation. Platinum (Pt), palladium (Pd) and rhodium (Rh) concentrations have increased in the environment since the introduction of automobile catalysts. This review summarises current knowledge concerning the environmental mobility, speciation and bioavailability of Pt, Pd and Rh. The greater proportion of PGE emissions is from automobile catalysts, in the form of nanometer-sized catalyst particles, which deposit on roadside surfaces, as evidenced in samples of road dust, grass and soil. In soil, PGE can be transformed into more mobile species through complexation with organic matter and can be solubilised in low pH rainwater. There are indications that environmentally formed Pd species are more soluble and hence more mobile in the environment than Rh and Pt. PGE can reach waterbodies through stormwater transport and deposition in sediments. Besides external contamination of grass close to roads, internal PGE uptake has been observed for plants growing on soil contaminated with automobile catalyst PGE. Fine particles of PGE were also detected on the surface of feathers sampled from passerines and raptors in their natural habitat, and internal organs of these birds also contained PGE. Uptake has been observed in sediment-dwelling invertebrates, and laboratory studies have shown an uptake of PGE in eel and fish exposed to water containing road dust. The available evidence indicates that the PGE, especially Pd, are transported to biological materials through deposition in roots by binding to sulphur-rich low molecular weight species in plants. PGE uptake to exposed animals have uptake rates in the following order: Pd>Pt>Rh. The liver and kidney accumulate the highest levels of PGE, especially Pd. Urinary Pd and Rh, but not Pt, levels are correlated with traffic intensity. Dental alloys may lead to elevated urinary Pt levels. Platinum is a well-known allergen and Pd also shows a strong sensitisation potential.

Platinum group elements in raptor eggs, faeces, blood, liver and kidney

The increased use of platinum group elements (PGEs) in automobile catalysts and their emission into the environment has led to a concern over environmental and particularly biological accumulation. Specimens of samples from raptors are useful for the investigation of the impact of PGEs because these birds are found in both urban and rural environments and are invariably at the top of the food chain. Platinum (Pt), palladium (Pd) and rhodium (Rh) concentrations were determined by quadrupole Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) in eggs of the sparrowhawk (Accipiter nisus) and the peregrine falcon (Falco peregrinus), and in blood, liver and kidney of the peregrine falcon, while only Pt was determined in faeces of the peregrine falcon and the gyrfalcon (Falco rusticolus). PGE concentrations were higher in blood compared to both faeces and eggs, while liver and kidney concentrations were not elevated indicating no bioaccumulation through metallothionein pathways. A significant spatial trend could only be established for Pt in faeces. The general lack of a spatial trend is probably due to the widespread distribution of automobiles and the long-range transport of nanoparticles containing PGEs, and because birds migrate and forage over large areas. No significant temporal trend could be established. Higher relative concentrations of Pd, followed by Rh and Pt, indicate a mobility gradient of Pd>>Rh>Pt.

Improved separation of palladium species in biological matrices by using a combination of gel permeation chromatography and isotachophoresis

The binding of palladium to high-molecular-mass compounds in palladium-treated lettuce is investigated as an example for a biological matrix. The total palladium concentration in lettuce leaves is 10.3 ng/g wet weight. After homogenization, high-molecular-mass compounds (> 10 kDa) are isolated by ultrafiltration. For separation of these palladium species a combination of preparative gel permeation chromatography (GPC) and preparative isotachophoresis (ITP) is used. Palladium is determined in separated fractions by using a highly sensitive total reflection X-ray fluorescence (TXRF) method after preconcentration. After GPC separation, four main fractions of palladium species are collected, each containing palladium in ng quantities (3-10 ng). Two of these fractions are further separated by ITP, yielding at least three main peaks per GPC fraction, each containing palladium in the range of 0.3-3 ng. These palladium containing peaks are characterized by high-performance size exclusion chromatography (HPSEC) and capillary isotachophoresis (cITP) in parallel. HPSEC enables the estimation of the molecular mass of six main palladium peaks, covering a molecular mass range of 69-200 kDa. It is also shown that the estimation of molecular mass after separation is more reliable than the respective estimation directly in the first GPC run. However, cITP reveals that each of the separated peaks is still a mixture of at least five different compounds.

Platinum group elements in the environment and their health risk

Accumulation of platinum group elements (PGEs) in the environment has been increased over the time. Catalytic converters of modern vehicles are considered to be the main sources of PGE pollution, since the correlation is between the Pt:Rh ratios in various environmental compartments and in converter units. The present literature survey shows that the concentration of these metals has increased significantly in the last decades in diverse environmental matrices; like airborne particulate matter, soil, roadside dust and vegetation, river, coastal and oceanic environment. Generally, PGEs are referred to behave in an inert manner and to be immobile. However, there is an evidence of spread and bioaccumulation of these elements in the environment. Platinum content of road dusts can be soluble, consequently, it enters the waters, sediments, soil and finally, the food chain. The effect of chronic occupational exposure to Pt compounds is well-documented, and certain Pt species are known to exhibit allergenic potential. However, the toxicity of biologically available anthropogenic Pt is not clear. Hence, there is a need to study the effect on human health of long-term chronic exposure to low levels of Pt compounds.