Whey peptide-encapsulated silver nanoparticles as a colorimetric and spectrophotometric probe for palladium(II).

Silver nanoparticles (AgNPs) coated with whey peptides are shown to be a useful optical nanoprobe for the highly sensitive determination of Pd(II). The peptidic surface of the AgNPs works as a molecular receptor for the rapid detection of Pd(II) via a color change from dark yellow to orange/red along with a spectral red-shift with a gap about 120 nm. The effect is caused by the formation of a coordination complex between Pd(II) and the peptide ligands. This results in the aggregation of AgNPs and an absorbance spectral shift from 410 to 530 nm. The absorbance response is linear in the range 0.1 to 1.3 µM Pd(II) with a low detection limit of 115 nM. The nanoprobe responds within a few minutes and is not interfered by other metal ions except for Mg(II). The probe potentially can be applied to the determination of Pd(II) contamination in the products of Pd(II)-catalyzed organic reactions and in pharmaceutical settings. Graphical abstractSchematic representation of the nanoprobe for Pd(II). (a) Synthesis of whey peptide-coated silver nanoparticles (AgNPs), (b) the nanoprobe design for Pd(II) detection, (c) HR-TEM imaging and elemental mapping, (d) quantitative determination of Pd(II) (Inset shows colorimetric results).

An umbelliferone-derivated fluorescent sensor for selective detection of palladium(II) from palladium(0) in living cells.

Palladium (Pd) has drawn worldwide attentions because its connections to industry, chemistry, biological material and public health. Quantitative and selective detection tools for Pd and its ion forms are in urgent necessity. Here an umbelliferone derivative Umb-Pd2 was provided as a small, steady, safe and selective sensor for detecting Pd(II). It indicated advantages including sensitive (LOD 1.1 nM), wide pH tolerance (5.0-10.0), applicable linear range (0-1.8 equivalent) and low toxicity. The most attractive point was its explicit selectivity towards Pd(II) from Pd(0) in both independent and coexistence systems. This distinguishing ability was further utilized in imaging in living cells, raising this work as a rare and important example among all the published papers on palladium sensing. Thus, Umb-Pd2 supplied a potential approach for further improvement and applications in both daily chemistry and public health.

Distribution and elimination of palladium in rats after 90-day oral administration.

This study determined the distribution in internal organs and the elimination routes in rats after oral administration of potassium hexachloro-palladate. Forty male Wistar rats were exposed for 90 days to 0, 10, 100 and 250 ng/mL of the palladium (Pd) salt in drinking water. Samples of urine and feces were collected on days 1, 30, 60 and 90, while organs (kidney, liver, lung, spleen and bones) and blood were collected at the end of the experiment. Quantification method was based on the sector-field inductively coupled plasma mass spectrometry. Results indicated that Pd ions were rapidly eliminated from the body. The principal excretion was through the feces (650 +/- 72.7 ng/g dry weight, at the Pd dose of 250 ng/mL), but at the higher dosing Pd was also eliminated through the urine (6.16 +/- 1.91 ng/mL for the Pd intake of 250 ng/mL). A clear relationship between the Pd ingested dose and the Pd excretion amount was observed mainly in the feces. Absorbed Pd was mostly found in the kidney of rats (124.4 +/- 23.0 ng/g dry weight, following the highest dose), while liver, lung, spleen and bones did not accumulate the metal. At the higher dosing, Pd content in the kidney raised proportionally with the Pd dose. Our findings may be useful to help in the understanding of the health impact of Pd dispersed in the environment as well as in identifying appropriate biological indices of Pd exposure.

Release of palladium from biomechanical prostheses in body fluids can induce or support PD-specific IFNgamma T cell responses and the clinical setting of a palladium hypersensitivity.

The increased use of Palladium (Pd) for biomedical applications, which has more than doubled in the last ten years, appears to be associated with an increased frequency of adverse reactions to Pd. The aim of this study is to investigate the relationship between the implant of a biomechanical apparatus containing Pd and the setting of a hypersensitivity to Pd by determining the levels of the metal released in biological fluids, assessing the effects of Pd on peripheral blood mononuclear cell (PBMC) cytokine production and exploring the clinical setting of skin sensitization. Of a total of 3,093 subjects examined in 2006, sensitization to Pd alone or in association with nickel (Ni) was observed in 1.6% and 13.03% of the individuals, respectively. Of these, a group of six subjects positive to Pd and negative to Ni at patch testing were selected on the basis of the oral clinical symptoms in order to measure both the levels of Pd in biological fluids and the degradation of the dental prostheses. Specific Pd measurements were carried out on salivary fluid, urine and serum samples by High Resolution Inductively Coupled Plasma-Mass Spectrometry. In addition, the degradation of the dental prostheses was assessed by both a leaching test and an analysis of the micro morphology of orthodontic prostheses. The induction of IFN-gamma production by Pd was assessed in PBMC by the ELISpot assay. Skin sensitization to Pd was evaluated by patch testing and clinical examination. Ten healthy subjects were comparatively tested as controls. We found a specific induction of an IFN-gamma response by Pd in PBMC collected from all the subjects positive to Pd at patch testing. On the contrary, control subjects did not show any response to Pd as assessed by IFN-gamma ELISpot assay or by skin testing. Remarkably, the levels of Pd in all biological samples (saliva, sera, urine) were significantly higher in Pd-sensitized patients than in those collected from controls, reaching the highest concentrations in the urine. The leaching studies gave additional evidence that the dental appliances can release measurable levels of Pd in saliva. Oral clinical symptoms in patients with Pd dental prostheses were associated with measurable levels of Pd in the biological fluids, the induction of Pd-specific IFN-gamma responses in PBMC and the clinical evidence of skin sensitization to Pd. These data suggest that dental appliances may represent an active source of Pd in the body, and this, in turn, can favour the clinical setting of a hypersensitivity to this metal.

Determination of Rh, Pd and Pt in urine samples using a pre-concentration sequential injection analysis system coupled to a quadrupole-inductively coupled plasma-mass spectrometer.

The proposed flow system was developed in order to minimize the drawbacks related to the PGEs determination by quadrupole-inductively coupled plasma-mass spectrometry (Q-ICP-MS). It was intended not only to lower the limits of detection (LODs) but also to eliminate the interferences originating from some atomic and molecular ions produced in the argon plasma. This was accomplished by means of an on-line sample clean-up/pre-concentration step, using a chelating resin (Metalfixtrade mark Chelaminetrade mark) in which Rh, Pd and Pt were preferably retained when compared with the interfering species. The results obtained by using the developed flow system in the analysis of urine samples are presented. With a sampling rate of 9 samples h(-1) (i.e., 27 determinations) and a sample consumption of ca. 10 mL, the developed flow system allowed linear calibration plots up to 100 ngL(-1) with detection limits of 1.2 ngL(-1) (Rh), 0.4 ngL(-1) (Pd) and 0.9 ngL(-1) (Pt). Repeatability studies showed good precision (R.S.D.%, n=5): 3.7% (Rh); 2.6% (Pd) and 2.4% (Pt), for 10 ngL(-1); 2.4% (Rh); 1.4% (Pd) and 1.9% (Pt), for 50 ngL(-1); and 1.3% (Rh); 0.58% (Pd) and 0.62% (Pt), for 100 ngL(-1). By spiking human urine samples, recovery tests were performed, and the values obtained ranged between 89% and 105% (Rh); 90% and 104% (Pd); and 93% and 105% (Pt).

Biomonitoring of tram drivers exposed to airborne platinum, rhodium and palladium.

OBJECT: The aim of this study was to evaluate urinary levels of Pt, Rh and Pd in occupationally exposed subjects. METHODS: A total of 122 healthy male subjects of Rome (Italy) were studied; 64 were municipal tram drivers and 58 control subjects. Metal quantification in the urine samples was carried out by sector field inductively coupled plasma mass spectrometry. RESULTS: There were statistically significant differences between urinary Pt and Rh levels of the workers and the control group (Pt median: 1.23 versus 1.03 ng/g creatinine; Rh median: 19.16 versus 11.18 ng/g creatinine), while no difference in Pd levels was observed (Pd median: 11.47 versus 8.75 ng/g creatinine). CONCLUSIONS: Urinary Pt and Rh could be useful biomarkers for monitoring population groups occupationally exposed to these elements. Urinary concentration of Pt and Rh, though still low, could be of some concern in workers heavily exposed to urban car traffic.

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.

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.

Assessment of workers' exposure to palladium in a catalyst production plant.

Airborne particulate matter was collected and biomonitoring of workers was performed by sampling blood, urine and hair of 84 exposed subjects, 17 occasionally exposed employees, 21 controls from administrative offices and 25 unexposed people (external controls). Determination of Pd was performed using Quadrupole and High Resolution Inductively Coupled Plasma Mass Spectrometry. The Production of Catalysts Department and the Refining Service presented the highest levels of Pd in airborne matter collected by means of an area sampler. The highest level of soluble Pd (1.66 microg m(-3)) was found in the Production of Catalysts Department. The highest concentration of Pd in airborne matter, collected by means of personal devices (7.90 microg m(-3)) was found in the Refining Service. Hair showed a clear distribution pattern among departments, with values ranging from 0.60 to 5.54 microg g(-1). Administrative workers presented blood levels of Pd between 2 and 500 times higher than external controls. Only urine levels correlated with the measurements of airborne Pd collected with personal devices. A very strong association between airborne Pd collected by personal devices and Pd levels in hair (r(2)= 0.569, with p< or = 0.01) and urine (r(2)= 0.684, with p< or = 0.01) was found. On the basis of these findings: (i) blood results appear to be an unsuitable biological marker for occupational exposure to Pd; (ii) urine could be considered as a satisfactorily responsive bio-marker for occupational monitoring; and (iii) hair cannot be considered a good index of time-related exposure.

Biomonitoring of titanium, mercury, platinum, rhodium and palladium in dental health care workers.

BACKGROUND: In dentistry, titanium, mercury, platinum, rhodium and palladium are used to produce dental fillings. Therefore, dental workers who apply such materials may be exposed to these metals. METHODS: The study concerned 40 healthy subjects-20 controls and 20 dental health care workers-to determine serum and urinary levels of the aforementioned metals by inductively coupled plasma mass spectrometry. RESULTS: Mean urinary and serum titanium did not reveal statistically significant differences in the two groups. The very low urinary and serum levels of mercury, platinum, rhodium and palladium prevented us from making a statistical evaluation between the two groups. CONCLUSIONS: We did not find a significant increase in serum and urinary titanium levels in dental health care workers. Measurement of mercury, platinum, rhodium and palladium in urine and serum was not useful in determining occupational exposure.

Association between palladium urinary concentrations and diseases of the thyroid and the immune system.

The German Environmental Specimen Bank found that students suffering from diseases of the thyroid or the immune system had increased palladium urinary values compared to healthy individuals. Since the immunotoxic features of palladium are well known, there may be a causal relationship. Sources of palladium were identified as dental alloys, the chemical industry, oil- or coal-driven power plants and the consumption of meat products.

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

The high-performance liquid chromatographic method with UV detection described below permits the selective determination of traces of palladium in human urine. After UV photolysis, during which the complete organic matrix was destroyed, the palladium was selectively enriched by solid-phase extraction (SPE). The reversed-phase C18 SPE column material was loaded with the ligand N,N-diethyl-N'-benzoylthiourea (DEBT) which shows an excellent complexing capacity for palladium in acidic solutions and at room temperature. The Pd(DEBT)2 complex was eluted with ethanol. After isocratic separation on the analytical column (MeOH/H2O 98:2 (v/v)), the complex was detected at 274 nm. The detection limit was 10 ng Pd/l. The relative standard deviations (RSD) of the within-series imprecision were in the range between 11% (75 ng Pd/l) and 7% (180 ng Pd/l). The between-day imprecision was 11% (75 ng Pd/l) and 5% (180 ng Pd/l). The recovery rates ranged between 94 and 96%. Using this method, urine samples of 44 persons from the general population were analysed. Only in one urine sample could palladium be detected. For comparison, 10 persons with occupational palladium exposure were examined. The urinary concentrations ranged from <10 to 2,538 ng/l.

Gold and palladium burden from dental restoration materials.

From 81 volunteers (16 without dental restorations, 65 with gold crowns or inlays) samples of saliva before and after chewing gum, blood, serum, urine and faeces were taken and analysed for gold (Au) and palladium (Pd). The Au concentration in all analysed biomonitors correlates significantly to the number of teeth with gold restorations. For Pd the correlations were still significant, but weaker than for Au. Persons with gold restorations show maximal Au and Pd concentrations, 10(2)-10(3) higher than the background burden. The calculated maximal daily Au load in saliva (1.38 mg Au per day) reaches the range of an oral Au therapy for rheumatoid arthritis with 6 mg Auranofin (= 1.74 mg Au per day). During this therapy severe and frequent side effects are reported. In contrast, the Au concentration in serum maximally reached from Au restorations, amounts to only approximately 1/20 of the Au level during arthritis therapy. But even under subtherapeutic doses of 1 mg Auranofin/day severe side effects have been reported (4 out of 56 cases). The mean Au blood concentration from 1 mg Auranofin daily was only 3 times higher than our maximum value. A toxicological classification of the Pd values is difficult, because no toxicological threshold limit has been established, especially for the low-level long-term burden with Pd.

Separation and enrichment of palladium and gold in biological and environmental samples, adapted to the determination by total reflection X-ray fluorescence.

The reductive co-precipitation of trace and ultra-trace elements together with mercury followed by complete evaporation of the mercury makes it possible to determine palladium and gold by total reflection X-ray fluorescence. Both elements can be detected without interferences at optimal sensitivity in the pg range. Thus, detection limits of, e.g., 2.5 ng L-1 for palladium and 2.0 ng L-1 for gold, in urine, were obtained. The precision was determined to 0.04 at a palladium concentration of about 200 ng L-1 urine and to 0.19 at a gold concentration of only 18 ng L-1. The recovery for a urine sample spiked with known amounts of palladium and gold amounted to > 95%. Results of the combined procedure are given for the determination of palladium and gold in the urine of non-exposed and occupationally exposed persons and in some other environmentally relevant samples.

Internal platinum, palladium, and gold exposure in environmentally and occupationally exposed persons.

In a pilot study the urinary platinum (Pt), palladium (Pd), and gold (Au) excretion was analyzed in 27 dental technicians, 17 road construction workers and 17 school-leavers using sector field inductively coupled plasma mass spectrometry (SF-ICP-MS). Detection limits in urine were 0.24 ng/l for Pt and Au and 0.17 ng/l regarding Pd. A standardized questionnaire was used to assess information about kind and degree of contact to these metals, the physical condition of the volunteers and confounding factors. Significant differences between the three study groups were found. The mean Pt, Pd, and Au excretions of the dental technicians were significantly higher than those of the road construction workers and school-leavers. This indicates that the occupational treatment of dental alloys leads to an internal exposure to these metals which is distinctly higher than that from automobile exhaust exposure. Significant differences between Monday morning (pre-shift) and Thursday afternoon (post-shift) urine samples of the dental technicians were not found. The Pt excretion of road construction workers working near a much traveled highway was comparable with that of school-leavers being less (only environmentally) exposed to automobile exhaust. Regarding Pd and Au the road construction workers showed a tendency to higher levels in urine when compared with the school-leavers, but statistically significant differences were not found. The tendency to higher urinary Pd and Au levels in the road-construction workers may be explained by their slightly greater number of noble metal containing artificial dentures, which may cause an additional exposure. A statistically significant effect of age on the urinary noble metal excretion was not detectable.

The determination of metals (antimony, bismuth, lead, cadmium, mercury, palladium, platinum, tellurium, thallium, tin and tungsten) in urine samples by inductively coupled plasma-mass spectrometry.

OBJECTIVE: An analytical method has been established to determine the concentration of antimony (Sb), bismuth (Bi), lead (Pb), cadmium (Cd), mercury (Hg), Palladium (Pd), platinum (Pt), tellurium (Te), tin (Sn), thallium (Tl) and tungsten (W) in urine. The aim was to develop a method which is equally suitable for the determination of environmentally as well as occupationally caused metal excretion. METHODS: Inductively coupled plasma-mass spectroscopy (ICP-MS) was used for the determination of metals. Calibration was done using aqueous solutions and standard addition respectively. RESULTS: Urine samples of 14 persons occupationally non-exposed to metals were analysed. With the exception of Pt and Bi all the metals were found in these urine samples. The detection limits for these metals lie between 5 and 50 ng/l. CONCLUSIONS: For some metals, which are important from an occupational as well as an environmental viewpoint, ICP-MS is more sensitive than atomic absorption spectrometry (AAS). ICP-MS, moreover, is welcome as a reference method for AAS with the additional advantage of multi-element measurement.

Determination of platinum, palladium, and lead in biological samples by atomic absorption spectrophotometry.

A flameless atomic absorption method for the coextraction of platinum and palladium from biological and environmental samples by high molecular weight amine (HMWA) is given. Also, methods for lead determination in biological samples by use of extraction flameless analysis and direct aspiration-flame analysis are reported. A study of lead contamination of Vacutainer tubes is given.