A novel ratiometric sensor for the fast detection of palladium species with large red-shift and high resolution both in aqueous solution and solid state

A highly selective fluorescent probe (OHBT) was designed and synthesized by linking the ESIPT fluorophore N-(3-(benzo[d]thiazol-2-yl)-4-(hydroxyphenyl) benzamide) (HBTBC) to the palladium specificity response group, allyl group, for the detection of palladium species in aqueous solution. The allyl group can be hydrolyzed by Pd⁰ species through the Pd⁰-catalyzed Tsuji–Trost reaction and thus release the fluorophore HBTBC, which shows two emission bands. The maximum emission spectra originated from the enol and keto forms at 415 and 555 nm respectively and with no overlap, which implies the high resolution of the palladium detection. The palladium species can also be detected by paper strip because of the solid-state fluorescence of probe HOBT catalyzed by palladium. This method was successfully applied in the palladium related Suzuki–Miyaura coupling reaction and the detection limit is lower than 1 μM.     

A Water‐Soluble ESIPT Fluorescent Probe with High Quantum Yield and Red Emission for Ratiometric Detection of Inorganic and Organic Palladium

A novel fluorescent probe with a high quantum yield (0.41), large Stokes shifts (255 nm), and red emission (635 nm) was designed to detect all typical oxidation states of palladium species (0, +2, +4) by palladium‐mediated terminal propargyl ethers cleavage reaction in water solution without any organic media. The probe showed a high selectivity and excellent sensitivity for palladium species, with a detection as low as 57 nM (6.2 μg L^?1).     

Exclusive Detection of Sub‐Nanomolar Levels of Palladium(II) in Water: An Excellent Probe for Multiple Applications

A new colorimetric probe has been developed for the detection and estimation of Pd^II at sub‐nanomolar concentrations. The probe consisted of rhodamine (signaling unit), which was linked with a bis‐picolyl moiety (binding site) through a phenyl ring. Pd^II induced opening of the spirolactam ring of the probe with the generation of a prominent pink color. The excellent selectivity of the probe towards Pd^II over Pd⁰ or Rh^II ensured its potential utility for the detection of residual palladium contamination in pharmaceutical drugs and in Pd‐catalyzed reactions. The probe showed a “turn‐on” (bright yellow) fluorescence upon the addition of Pd^II, which made it suitable for the detection of Pd contaminants in mammalian cells.     

A ratiometric fluorescent probe for palladium detection based on an allyl carbonate group functionalized hemicyanine dye

A novel ratiometric fluorescent probe for palladium species was synthesized based on an allyl carbonate group, a novel reaction site, and a hemicyanine dye. The probe displays relatively rapid response, high selectivity, and anti-disturbance toward palladium in HEPES buffers without additional reagents. The detection mechanism, palladium triggers the cleavage of allyl carbonate in the probe and then decarboxylation of the product to induce the ratiometric fluorescence response, was verified using UV–vis and mass spectrometry analysis. The probe was successfully applied for ratiometric fluorescent detection of palladium in tap water, river water, and in fetal bovine serum.     

A specific and selective chemiluminescent probe for Pd2+ detection

A modified 1,2-dioxetane is reported as a chemiluminescent imaging (CLI) approach for monitoring palladium(Ⅱ).     

Preconcentration of palladium in a flow-through electrochemical cell for determination by graphite furnace atomic absorption spectrometry

An electrochemical preconcentration at a controlled potential on the electrode in a flow-through mode followed by graphite furnace atomic absorption spectrometric (GFAAS) detection is proposed for determination of trace amounts of palladium. After electrolysis the polarization of the electrodes was changed and deposited metal was dissolved electrochemically in the presence of an appropriate stripping reagent. Conditions for the electrodeposition, such as pH of the solutions, a deposition potential, dissolution potential and a composition of stripping solution were optimised. The graphite electrode (GE) and glassy carbon electrode (GCE) were tested for the palladium reduction process. The detection limit of 0.05 ng ml⁻¹ Pd (1 pg) was obtained after palladium preconcentration on the GCE and dissolution with 0.2 mol l⁻¹ thiourea in 0.1 mol l⁻¹ HCl followed by GFAAS detection. The method was applied for the determination of palladium in spiked tap water and road dust samples.     

Determination of gold and palladium in rocks and ores by atomic absorption spectrometry using two-stage probe atomization

The efficiency of two-stage probe atomization for the determination of gold and palladium in geological samples by electrothermal atomic absorption spectrometry is studied. The effects of temperature–time program and the position of the probe in an atomizer on the fractionation of sample components and the magnitude of the analytical signal are studied. It is demonstrated that gold and palladium can be quantitatively determined by atomic absorption spectrometry in rocks and ores, using a two-stage probe atomization with the limits of detection for gold and palladium 0.01 and 0.04 g/t, respectively.     

Rational design of a NIR-emitting Pd(II) sensor via oxidative cyclization to form a benzoxazole ring

By using the substituent effect to tune the palladium(II)-involved reactivity, a new probe is found to respond quantitatively to Pd(II). Unexpectedly, the probe gave an emission band in the desirable near-infrared (NIR) region (780 nm), thus providing the first NIR sensor for palladium detection.     

Determination of Palladium by Graphite Furnace Atomic Absorption Spectrometry After Preconcentration with MCI GEL CHP 20P Resin as Sorbent

A solid phase extraction and graphite furnace atomic absorption spectrometry for the determination of palladium with MCI GEL CHP 20P resin as sorbent was studied. Trace amounts of palladium was reacted with 2-ethylhexyl octyl sulfide followed by adsorption onto MCI GEL CHP 20P solid phase extraction column, and ethanol was used as eluent. The enrichment factor of this method for palladium was reached at 250. The detection limit in the original sample for palladium was found to be 0.0048 ng mL^?1. The proposed method has been successfully applied to the determination of trace amounts of palladium in different samples.     

Development of a dispersive liquid–liquid microextraction method for determination of palladium in water samples using dicyclohexano-18- crown-6 as extracting agent

A new separation procedure for determination of palladium using dispersive liquid–liquid microextraction with dicyclohexano-18-crown-6 as complexing reagent was developed. In this method, potassium–dicyclohexano-18-crown-6 was used as a hydrophobic complex for the microextraction of palladium as PdCl₄ ^2? complex ion. The main factors affecting DLLME efficiency, such as type and volume of extractant and disperser solvent, concentration of chelating reagent, concentration of KCl and pH were optimized. Under the optimal conditions, the limit of detection for palladium was 16.0 ng mL^?1 with enrichment factor of 138. The present method was applied to the determination of palladium in water samples with satisfactory analytical results. The method was simple, rapid, cost efficient and sensitive for the extraction and preconcentration of palladium.     

Dispersive liquid-liquid microextraction preconcentration of palladium in water samples and determination by graphite furnace atomic absorption spectrometry

A new method for the determination of palladium was developed by dispersive liquid-liquid microextraction preconcentration and graphite furnace atomic absorption spectrometry detection. In the proposed approach, diethyldithiocarbamate (DDTC) was used as a chelating agent, and carbon tetrachloride and ethanol were selected as extraction and dispersive solvent. Some factors influencing the extraction efficiency of palladium and its subsequent determination, including extraction and dispersive solvent type and volume, pH of sample solution, concentration of the chelating agent and extraction time, were studied and optimized. Under the optimum conditions, the enrichment factor of this method for palladium reached at 156. The detection limit for palladium was 2.4 ng L⁻¹ (3σ), and the relative standard deviation (R.S.D.) was 4.3% (n = 7, c = 1.0 ng mL⁻¹). The method was successfully applied to the determination of trace amount of palladium in water samples.     

Oscillopolarography of Palladium(II)–Tropeolin 0 Complexes

The electrochemical behavior of palladium(II) complexes of Tropeolin 0 (Tr0) was studied by linear-potential-sweep voltammetry in acetate–ammonia buffer solutions. The optimum conditions for determining palladium(II) with Tr0 were found. The composition of the complex was found to be Pd : Tr0 = 1 : 2. A procedure was proposed for determining palladium(II) with a detection limit of 2.54 × 10^–7M. The procedure was used for determining palladium(II) in capacitors.     

A highly selective fluorescent probe for the detection of palladium(II) ion in cells and aqueous media

We report on a fluorescent probe for the optical (and even bare eye) detection of palladium(II) ion which causes the probe to undergo a strong increase in absorbance and fluorescence. The probe is easily synthesized from rhodamine B hydrazide and 9-anthraldehyde and displays high selectivity over other metal ions. Fluorescence intensity and absorbance are linearly proportional to the concentration of Pd(II) in the 0–7 μM and 0–1 μM concentration range, respectively, with detection limits of 0.21 μM and 0.03 μM. The probe can detect Pd(II) with virtually no interferences by other metal ions and anions. It was applied to intracellular imaging of Pd(II) in living cells and to its determination in a palladium-containing catalyst and in spiked water samples.

Determination of palladium in gasoline by neutron activation analysis and automated column extraction

^? Palladium in gasoline was determined by means of neutron activation analysis (NAA) and selective sorbent extraction. Unleaded gasoline consistent with DIN EN 228, RON 95 was irradiated at a thermal neutron flux of Φ_th = 1.68 · 10¹³s^–1cm^–2 and an epithermal neutron flux of 3.32 · 10¹¹s^–1cm^–2 for t_irr = 12 h. The irradiated gasoline was digested with nitric acid and palladium was then separated as N,N-diethyl-N’-benzoylthiourea complex by an automated column pre-concentration procedure. The eluate of 50 μL was dried on a filter paper and the 88.03 keV photons resulting from the decay of ¹⁰⁹Pd were detected in a low level HPGe spectrometer with an efficiency of 35.5%. Severe interferences with other matrix constituents, especially ⁸²Br could be overcome and the detection limit for palladium was improved to 3.4 ng/L at a confidence level of 90%. Although the analytical procedure applied yielded the lowest detection limit for palladium obtained in gasoline up to now, no indications for the presence of palladium were found.     

Laser ablation doping of poly crystalline tin dioxide films with palladium

Laser ablation of palladium was studied and velocity (energy) distributions of palladium ions evaporated by an Kr-F laser in a vacuum were obtained. The optimum values of energy fluence (fluence rate) of laser radiation for doping tin dioxide films, at which neither multiply charged Pd^N+ ions nor ionized clusters Pd _N ⁺ , occur in a plasma, were determined. From time-of-flight probe measurement data, Pd⁺ implantation depths in SnO₂ films were calculated, which qualitatively agree with the results obtained by secondary neutral mass spectrometry. Electric conductivity measurements on the obtained films in a gas phase showed that introduction of palladium into polycrystalline SnO₂ films by laser ablation significantly enhanced their gas sensitivity to hydrogen.     

Determination of palladium by a new preconcentration method (Mg-W cell)-electrothermal atomic absorption spectrometry

A new concentration method for palladium using Mg-W cell-electrodeposition has been developed. The method was combined with electrothermal atomic absorption spectrometry (ETAAS) with a tungsten tube atomizer. The detection limit of palladium by this method was 0.37 ng ml^–1 (3 S/N). The severe interferences on the AAS signal of palladium caused by large amounts of Al, Ca, Cu, Fe, K, Na, Pb and Zn were eliminated by the Mg-W cell-electrodeposition method. The method was adapted for the determination of palladium in environmental samples. The recovery of palladium spiked environmental samples was in the range of 102 to 114%. Received: 12 August 1996 / Revised: 16 October 1996 / Accepted: 7 November     

FI spectrophotometric determination of Pd with DBOK-chlorophosphonazo

A flow injection method was developed for the determination of palladium, based on the reaction of palladium with DBOK-chlorophosphonazo with a detection limit of 0.07 μg/mL and a linear calibration range from 0.1 to 3.2 μg/mL of palladium. The reaction product has a maximum absorption at 630 nm. The method was applied to determine Pd²⁺ in catalysts and in anode mud samples. The relative error is less than 3% and the recovery of palladium is in the range 95% to 105% Received: 27 April 1998 / Revised: 24 August 1998 / Accepted: 26 August 1998     

Switchable solvent based liquid phase microextraction of palladium coupled with determination by flame atomic absorption spectrometry

A switchable solvent-based micro-extraction method for pre-concentration and separation of ultratrace palladium was developed prior to its flame atomic absorption spectrometric detection. Reverse change of hydrophilicity of N,N-dimethylcyclohexylamine (DMA) was achieved by reaction with carbonated water. The hydrophilic bicarbonate salt of the protonated DMA was used as extractant for palladium complexed with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP). Formation of the hydrophobic form of switchable solvent from hydrophilic form of switchable solvent phase was achieved by addition of sodium hydroxide into the extractant-sample solution. The effect of key parameters affected extraction recovery was studied and optimised by using Plackett–Burman design, central composite design and three dimension (3D) surfaces response. The calibration plot was linear in the range 0.015–1.6 mg L^?1 of palladium with a correlation coefficient of 0.999. The limit of detections values of palladium for liquid and solid samples were 4.28 μg L^?1 and 0.54 µg g^?1, respectively. The pre-concentration factor was 37.5. The accuracy was confirmed by determination of palladium in certified reference material. The procedure was also applied for determination of palladium content of real samples as automotive catalytic converter, roadside dust, sea water and river water.     

Modified analcime loaded with zincon as a useful material for the separation and preconcentration of trace palladium and its determination by third-derivative spectrophotometry

This work assesses the potential of natural analcime zeolite as a sorbent for the preconcentration of palladium. Palladium is quantitatively retained on modified analcime zeolite loaded with zincon using the column method in the pH range from 2.5 to 3.5 at a flow rate of 1 mL/min. The palladium complex was removed from the column with 5.0 mL of dimethylsulfoxide (DMSO) and determined by third-derivative spectrophotometry. The detection limit is 0.03 μg/mL (signal-to-noise ratio = 3) in the final solution. Since it is possible to retain 0.15 μg of palladium from 600 mL of solution passing through the column, elution with 5.0 mL of DMSO gives a detection limit of 0.25 ng/mL for palladium in the initial aqueous solution. The calibration curve is linear over the range 0.1 to 5.0 μg/mL of palladium(II) in the final solution with a correlation coefficient of 0.9996. Seven replicated determinations of 5.0 μg of palladium in 5.0 mL dimethylsulfoxide gave a mean d ³ A/dλ³ (peak-to-peak signal between λ₂ = 625 and λ₁ = 654 nm) of 0.64 with a relative standard deviation of 1.2%. The sensitivity of the method (d ³ A/dλ³) is 0.5843 mL/μg of palladium(II) from the slope of the calibration curve. The interference of a large number of anions and cations has been studied and the optimized conditions developed were utilized for the determination of trace palladium in various synthetic and water samples. The text was submitted by the authors in English.     

FI spectrophotometric determination of Pd with DBOK-chlorophosphonazo

A flow injection method was developed for the determination of palladium, based on the reaction of palladium with DBOK-chlorophosphonazo with a detection limit of 0.07 μg/mL and a linear calibration range from 0.1 to 3.2 μg/mL of palladium. The reaction product has a maximum absorption at 630 nm. The method was applied to determine Pd²⁺ in catalysts and in anode mud samples. The relative error is less than 3% and the recovery of palladium is in the range 95% to 105% Received: 27 April 1998 / Revised: 24 August 1998 / Accepted: 26 August 1998