Determination of trace platinum by supramolecular catalytic kinetic spectrofluorimetry of β–cyclodextrin–platinum–KBrO3–salicylaldehyde furfuralhydrazone

A supramolecular catalytic kinetic spectrofluorimetric method was developed for the determination of platinum(IV) and the possible mechanism of catalytic reaction was discussed. The method was based on the fluorescence-enhancing reaction of salicylaldehyde furfuralhydrazone (SAFH) with potassium bromate, which was catalysed by platinum(IV) in a water–ethanol medium. β–Cyclodextrin (β-CD) obviously sensitized the determination at pH 5.20 and 25°C. Under optimum conditions, the β-CD–platinum–KBrO₃–SAFH supramolecular kinetic catalytic reaction system had excitation and emission maxima at 372 and 461 nm, respectively. The linear range of this method was 0.60–180 ng ml⁻¹ with a relative standard deviation of 1.2%, and the detection limit was 0.18 ng ml⁻¹. Investigation of the mechanism and the effects of interferences is presented. The proposed method was applied successfully to determine trace platinum(IV) in the chemotherapeutic drug cisplatin and serum from patients with satisfactory results.      

Flow injection on-line sorption preconcentration of platinum in a knotted reactor coupled with electrothermal atomic absorption spectrometry

A flow injection on-line sorption preconcentration method for the electrothermal AAS determination of platinum has been developed. The pyrrolidine dithiocarbamate complexes of either Pt⁴⁺ or Pt²⁺, formed in 0.7 mol L^–1 HNO₃, are on-line adsorbed on the inner walls of a PTFE knotted reactor and subsequently eluted with methanol. An enhancement factor of 112 and a detection limit (3 σ) of 10 ng L^–1 along with a sampling frequency of 21 h^–1 are achieved with a 90 s preconcentration time at a sample flow rate of 8.8 mL min^–1. The relative standard deviation is 2.5% for 0.4 μg L^–1 Pt. The method has been applied to the determination of platinum in blood samples. Received: 6 October 1997 / Revised: 26 November 1997 / Accepted: 3 December 1997     

Hydration of platinum(II) complexes: a molecular mechanics study using atom-based force-field parameters

 This work is related to the interaction of water with two platinum(II) complexes, [Pt(NH₃)₄]²⁺ (denoted 1) and trans-[Pt(OH)₂(NH₃)₂] (denoted 2). We have considered two approaches of a water molecule to complexes 1 and 2 along the z-axis normal to the platinum(II) coordination plane: approach I, with the water oxygen oriented towards Pt, and approach II, with one water hydrogen directed towards Pt. Calculations have been performed within a molecular mechanics method based upon the interaction potentials proposed earlier by Claverie et al. and subsequently adjusted to results obtained with symmetry – adapted perturbational theory as well as with supermolecule (up to second-order M?ller–Plesset, MP2) methods. We discuss some possible simplifications of the potentials mentioned. The results relative to the hydration of Pt complexes 1 and 2 following approach I or II are discussed and compared to recent (MP2) ab initio energy–distance curves that we have recently determined. The MP2 calculations have shown that besides exchange–repulsion contributions, which are very similar in all hydrated complexes, approach I is mainly governed by electrostatics, whereas for approach II both electrostatic and dispersion contributions are important. Received: 16 September 1999 / Accepted: 3 February 2000 / Published online: 5 June 2000     

Inductively coupled plasma mass spectrometric analysis of the total amount of platinum in DNA extracts from peripheral blood mononuclear cells and tissue from patients treated with cisplatin

We present a highly sensitive method for the determination of platinum (Pt) in DNA extracts of peripheral blood mononuclear cells (PBMCs) and tissue samples from patients treated with cisplatin. The method is based on the measurement of Pt by inductively coupled plasma mass spectrometry (ICP-MS) and allows quantification of Pt-DNA adducts in PBMCs isolated from 10 mL blood and 1 mg tissue. The lower limit of quantification is 0.75 pg Pt or 7.5 fg Pt μg⁻¹ DNA when using 100 μg DNA. The method proved to be accurate and precise. The results obtained using the ICP-MS method were in good agreement with results from the alternative ³²P-postlabelling assay. The ICP-MS method was, however, more sensitive and proved to be less laborious. The advantages of the presented ICP-MS technique were demonstrated by the analysis of PBMCs, normal gastric tissue, and gastric tumour tissue of patients treated with cisplatin.     

Sorption-luminescence determination of gold,silver, and platinum with the use of silica gel chemically modified with <Emphasis Type="Italic">N</Emphasis>-(1,3,4-thiodiazole-2-thiol)-<Emphasis Type="Italic">N</Emphasis>′-propylurea groups

Silica gel chemically modified with N-(1,3,4-thiodiazole-2-thiol)-N′-propylurea extracted gold(III) from solutions in the range of 6 M HCl-pH 8 and silver(I) from nitric acid solutions in the range of 6 M HNO₃-pH 8 and 1–2 M HCl at 20°C with 99.0–99.9% recovery and a sorption equilibration time of 5 min. Platinum(II) was quantitatively extracted at room temperature from solutions in the range of 4 M HCl-pH 8; the sorption equilibration time was 20 min. For the quantitative extraction of platinum(IV), it should be reduced to platinum(II). The intense yellowish orange luminescence (λ_max (Au) = 575 nm, λ_max (Ag) = 550 nm, and λ_max(Pt) = 620 nm) of surface complexes at 77 K under UV irradiation was used in the development of procedures for the low-temperature sorption-luminescence determination of gold, silver, and platinum. The detection limits were 0.15 (Au), 0.1 (Ag), and 0.05 μg (Pt) per 0.1 g sorbent. The calibration function was linear to 50 (Au, Ag) or 80 μg (Pt) per 0.1 g sorbent. The relative standard deviation in the determination of more than 5 μg of a metal was no higher than 6%. The sorption-luminescence determination procedures were tested in the determination of gold in gold-containing concentrates and their processing products and platinum in alumina-platinum catalysts.     

Simple and rapid determination of piperacillin and ceftazidime in human plasma samples by HPLC

Summary A simple and rapid liquid chromatographic method has been developed for the determination of therapeutic levels of piperacillin (I) and ceftazidime (II) in human plasma. Plasma and p-propionamidophenol (internal standard) were precipitated with methanol (I) or 20% trichloroacetic acid (II). The supernatant was analysed on a 5 μm Spherisorb ODS C₁₈ column with acetonitrile-0.05 M phosphate buffer pH 3.8 as mobile phase and ultraviolet detection at 254 nm. The calibration graph was linear from 10 to 250 μg mL⁻¹, for (I), and from 5 to 200 μg mL⁻¹ for (II). Intra and inter-day CV did no exceed 2.29% for (I), and were 10.76–11.13%–2.00–5.62 for (II) at concentrations of 10 μg mL⁻¹ and 250 μg mL⁻¹.     

Growth and characterization of Mn- and Co-doped ZnO nanowires

A flow injection chemiluminescence method is proposed for the determination of cobalt, based on the strong catalytic effect of Cobalt(II) (1,10-phenanthroline)₃ complex on the lucigenin-periodate reaction in alkaline medium. Under the optimum experimental conditions, the chemiluminescence signal responded linearly to the concentration of cobalt(II) in the 1.0 × 10⁻⁹–3.0 × 10⁻⁷ g mL⁻¹ range with a detection limit of 4.4 × 10⁻¹⁰ g mL⁻¹ cobalt(II). The relative standard deviation for the determination of 5.0 × 10⁻⁸ g mL⁻¹ of cobalt was 2.3% in eleven replicated measurements. The method was successfully applied to the determination of cobalt(II) in pharmaceutical preparations.     

Copper Incorporated [Me2(15)dieneN4] Macrocyclic Complex for Fabrication of PVC based Membrane Electrode for Copper

Copper (II) complex of 2,4-dimethyl-1,5,9,12-tetraazacyclopentadeca-1,4-diene, [Me₂(15)dieneN₄] was synthesized and used in the fabrication of Cu²⁺ – selective ISE membrane in PVC matrix. The membrane having Cu(II) macrocyclic complex as electroactive material along with sodium tetraphenyl borate (NaTPB) as anion discriminator. Dibutyl phthalate (DBP) as plasticizer in poly(vinyl chloride) (PVC) matrix was prepared for the determination of Cu²⁺. The best performance was observed by the membrane having Cu(II) complex–PVC–NaTPB–DBP with composition 1:5:1:3. The sensor worked well over a concentration range 1.12 × 10⁻⁶ M–1.0 × 10⁻¹ M between pH 2.1–6.2 and a fast response time 10±2 s and a lifetime of 6 months. Their performance in partially non-aqueous medium was found satisfactory. Electrodes exhibited excellent selectivity for Cu²⁺ ion over other mono-, di-, trivalent cations. It can also be used as indicator electrode in the potentiometric titration of Cu²⁺ against EDTA as well as in the determination of Cu²⁺ in real samples.     

Potentiometric Determination of Menadione (Vitamin K3)

 The construction and electrochemical response characteristics of poly(vinyl) chloride matrix membrane sensors for menadione (vitamin K₃) are described. Membranes incorporating the ion association complexes of menadione anion with bathophenanthroline nickel(II) and iron(II) as electroactive materials show linear response for menadione over the range 10⁻¹–10⁻⁵ M with anionic slopes of 58.2–51.4 mV per concentration decade. Both sensors exhibit fast response time (20–30 s), low detection limit (2 × 10⁻⁵ M), good stability (4–6 weeks) and selectivity coefficient (10⁻¹–10⁻³). Direct potentiometric determination of menadione under static and hydrodynamic mode of operations shows average accuracies of 98.8 and 98.5% with relative standard deviations of 0.6% and 1.3%, respectively. Application of the method for the determination of menadione in human plasma gives favourable results compared with those obtained by the standard spectrophotometric method. Received February 26, 2001. Revision October 1, 2001.     

Determination of total iron in fresh waters using flow injection with potassium permanganate chemiluminescence detection

A flow injection method is described for the determination of iron in fresh water based on potassium permanganate chemiluminescence detection via oxidation of formaldehyde in aqueous hydrochloric acid. Total iron concentrations are determined after reducing Fe(III) to Fe(II) using hydroxylamine hydrochloride. The detection limit (three standard deviations of blank) is 1.0 nM, with a sample throughput of 120 h⁻¹. The calibration graph was linear over the range (2–10) × 10⁻⁷ M (r ² = 0.9985) with relative standard deviations (n = 5) in the range 1.0–2.3%. The effect of interfering cations (Ca(II), Mg(II), Zn(II), Ni(II), Co(II), Fe(III), Mn(II), Pb(II), and Cu(II)) and common anions (Cl⁻, SO ₄ ²⁻ , PO ₄ ³⁻ , NO ₃ ⁻ , NO ₂ ⁻ , I⁻, F⁻, and SO ₃ ²⁻ ) was studied at their maximum admissible concentrations in fresh water. The method was applied to fresh-water samples from the Quetta Valley, and the results obtained (0.04 ± 0.001–0.11 ± 0.01 mg/L Fe(II)) were in reasonable agreement with those obtained using the spectrophotometric reference method (0.05 ± 0.01–0.12 ± 0.02 mg/L Fe(II)). The text was submitted by the authors in English.     

Mechanism of the catalytic action of the mechanoactivated salt K2PTCL4 in the gas-phase hydrochlorination of acetylene

A heterogeneous catalyst for the hydrochlorination of acetylene by gaseous HCl is formed as a result of mechanical treatment of the solid salt K₂PtCl₄ in an atmosphere of acetylene, ethylene, or propylene by the formation of π complexes of platinum(II) as active centers in the surface layer under these conditions. The controlling stage of the catalytic reaction is chloroplatination of the π-coordinated acetylene by the HCl molecule. The reaction takes place as a concerted process, in which an intermediate β-chlorovinyl derivative of platinum(II), a complex of platinum with a coordination vacancy[PtCl ₃ ^* ]⁻, and a new molecule of HCl are formed simultaneously with cleavage of the H—Cl and Pt—Cl bonds in the metal complex adjacent to the π-acetylene complex. The catalytic cycle closes with rapid dissociation of the organoplatinum intermediate by the action of HCl, giving the final product and the initial complex [PtCl₄]²⁻. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 5, pp. 306–311, September–October, 2006.     

Sensitive spectrophotometric determination of ascorbic acid in fruit juices and pharmaceutical formulations using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP)

A simple and very sensitive method has been developed for the determination of ascorbic acid based on the oxidation of ascorbic acid to dehydroascorbic acid by iron(III), followed by a complexation of iron(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol(Br-PADAP). The iron(II) complex is formed immediately, with absorption maxima at 560 and 748 nm and a molar absorptivity of 1.31 × 10⁵ l mole^–1cm^–1 and 5.69 × 10⁴ l mole^–1cm^–1, respectively. The ascorbic acid determination is possible with a linear range up to 2.4 μg ml^–1, a calibration sensitivity of 0.744 ml μg^–1 at 560 nm and 0.323 ml μg^–1 at 748 nm, and a detection limit of 15 ng ml^–1 and 44 ng ml^–1, respectively. The procedure was used for the ascorbic acid determination in several fruit juices and pharmaceutical formulations. The results demonstrated a good precision (R.S.D. < 1%) and are in agreement with those obtained with others methods. The Br-PADAP method proposed is six times more sensitive than the method using the iron(II)-1,10-phenanthroline system. Received: 7 May 1996 / Revised: 1 July 1996 / Accepted: 8 August 1996     

Sensitive spectrophotometric determination of ascorbic acid in fruit juices and pharmaceutical formulations using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP)

A simple and very sensitive method has been developed for the determination of ascorbic acid based on the oxidation of ascorbic acid to dehydroascorbic acid by iron(III), followed by a complexation of iron(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol(Br-PADAP). The iron(II) complex is formed immediately, with absorption maxima at 560 and 748 nm and a molar absorptivity of 1.31 × 10⁵ l mole^–1cm^–1 and 5.69 × 10⁴ l mole^–1cm^–1, respectively. The ascorbic acid determination is possible with a linear range up to 2.4 μg ml^–1, a calibration sensitivity of 0.744 ml μg^–1 at 560 nm and 0.323 ml μg^–1 at 748 nm, and a detection limit of 15 ng ml^–1 and 44 ng ml^–1, respectively. The procedure was used for the ascorbic acid determination in several fruit juices and pharmaceutical formulations. The results demonstrated a good precision (R.S.D. < 1%) and are in agreement with those obtained with others methods. The Br-PADAP method proposed is six times more sensitive than the method using the iron(II)-1,10-phenanthroline system. Received: 7 May 1996 / Revised: 1 July 1996 / Accepted: 8 August 1996     

Role of dimethylformamide in generating the active form of platinum for catalyzing the synthesis of diaryls from aryl iodides

A mechanism is proposed for the reaction of aryl iodides with platinum(II) tetrachloride complexes in dimethylformamide including formation of PtCl₃(CONMe₂)²⁻ in the first step through activation of a dimethylformamide C−H bond by platinum(II) and subsequent oxidative addition of ArI to this species. L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 Lyuksemburg ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 34, No. 4, pp. 244–246, July–August, 1998.     

Determination of organic micro-pollutants such as personal care products, plasticizers and flame retardants in sludge

In this study, a method for the determination of organic micro-pollutants, i.e. personal care products such as synthetic musk fragrances, household bactericides, organophosphate flame retardants and plasticizers, as well as phthalates in sludge, has been developed. This method is based on lyophilisation and accelerated solvent extraction followed by clean-up steps, i.e. solid phase extraction and size exclusion chromatography. The determination is performed by gas chromatography coupled to mass spectrometry. Stable isotope-labelled compounds such as musk xylene (MX D₁₅), tri-n-butylphosphate (TnBP D₂₇) and triphenylphosphate (TPP D₁₅) were used as internal standards. Recovery rates were determined to be 36–114% (with typical relative standard deviation of 5% to 23%) for the target compounds. The limit of detection was 3–30 ng g⁻¹, and the limit of quantification was 10–100 ng g⁻¹ dry matter.     

Chelating resin preconcentration and Hg(II) assisted elution followed by differential-pulse anodic stripping voltammetry for the determination of Cd, Cu, and Pb in seawater

A new and efficient Hg(II) back-elution method for the desorption of Cd, Cu, and Pb from Chelex-100 chelating resin was developed. A smaller eluent volume and shorter elution time can be achieved using an Hg(II) containing eluent rather than pure nitric acid. Owing to the remaining Hg(II) ion in the effluent, a mercury thin-film electrode is formed in-situ during the anodic stripping voltammetric determination without any further addition of Hg(II). The results indicate that all the analytes in seawater matrix can be completely adsorbed on Chelex-100 resin from the sample at pH 6.5, and subsequently eluted from the resin with an acid solution of 5 × 10^–4 mol/L Hg²⁺ + 1 mol/L HClO₄. The detection limits obtained from the differential-pulse anodic (μg L^–1 to ng L^–1) stripping voltammetry are at sub-ppb to ppt (μg L^–1 to ng L^–1) levels permitting to determine Cd, Cu and Pb traces in seawater. The analytical reliability was confirmed by the analysis of the certified reference material CASS-II (open ocean seawater). Received: 22 April 1997 / Revised: 5 August 1997 / Accepted: 7 August 1997     

Estimation of platinum in environmental water samples with solid phase extraction technique using inductively coupled plasma mass spectrometry

A solid phase extraction technique for the determination of platinum(IV) at trace levels by inductively coupled plasma mass spectromA solid phase extraction technique for the determination of platinum(IV) at trace levels by inductively coupled plasma mass spectrometry (ICP-MS) was developed. The method was based on retention of platinum in a sample on silica gel modified with aminepropyl groups. The retention of platinum(IV) from the sample solution and the recovery of platinum with 1.0 mol L⁻¹ thiourea solution were quantitative. The relative standard deviation (RSD) was calculated as 5% (n = 7) at the 10 ng L⁻¹ level. The enrichment factor was found to be (50-fold) for 250 mL of water sample. Under optimum conditions, the method detection limit (MDL) was found to be 1 ng L⁻¹ for platinum in water matrices. Recoveries of Pt from spike addition to atmospheric water samples were quantitative (80–95%). The present method was used for the determination of platinum in precipitation, throughfall and runoff water samples.      

Organic solvent-soluble membrane filters for the preconcentration and spectrophotometric determination of iron(II) traces in water with Ferrozine

An organic solvent-soluble membrane filter (MF) is proposed for the simple and rapid reconcentration with subsequent spectrophotometric determination of trace levels of iron (II) in water. Iron (II) is collected on a nitrocellulose membrane filter as ion associate of an anionic complex, which is formed by iron (II) and Ferrozine and a cation-surfactant. The ion-pair compound and the MF can be dissolved in small volumes of 2-ethoxyethanol and the absorbance of the resulting solution is measured at 560 nm against a reagent blank with molar absorptivity of 4.01 × 10⁴ L mol^–1 cm^–1. Beer’s law is obeyed over the concentration range 0–10 μg L^–1 of iron (II) in water and the detection limit is 0.03 μg L^–1 with a 50-fold enrichment factor. The proposed method can satisfactorily be applied to the determination of iron (II) in natural water and sea water. Received: 23 June 1998 / Revised: 21 July 1998 / Accepted: 25 August 1998     

Anodic stripping voltammetric determination of total lead, copper and selenium in whole blood and blood serum

A two-step procedure including appropriate wet-digestions, separation of selenium from interfering ions such as heavy metal ions with pentyl alcohol and anodic stripping voltammetric (ASV) determination of Pb²⁺, Cu²⁺ and SeO₃ ^2– is developed. The elements in digested whole blood and serum sample solutions were determined by using a standard addition method. 1 × 10^–9 mol/L SeO^2– ₃, Cu²⁺ and Pb²⁺ were successfully determined with relative standard deviations of approximately 1–2% (n = 6–8). Received: 19 August 1996 / Revised: 24 February 1997 / Accepted: 28 February 1997     

Simultaneous determination of trace levels of ethylmercury and methylmercury in biological samples and vaccines using sodium tetra(<Emphasis Type="Italic">n</Emphasis>-propyl)borate as derivatizing agent

Because of increasing awareness of the potential neurotoxicity of even low levels of organomercury compounds, analytical techniques are required for determination of low concentrations of ethylmercury (EtHg) and methylmercury (MeHg) in biological samples. An accurate and sensitive method has been developed for simultaneous determination of methylmercury and ethylmercury in vaccines and biological samples. MeHg and EtHg were isolated by acid leaching (H₂SO₄–KBr–CuSO₄), extraction of MeHg and EtHg bromides into an organic solvent (CH₂Cl₂), then back-extraction into Milli-Q water. MeHg and EtHg bromides were derivatized with sodium tetrapropylborate (NaBPr₄), collected at room temperature on Tenax, separated by isothermal gas chromatography (GC), pyrolysed, and detected by cold-vapour atomic fluorescence spectrometry (CV AFS). The repeatability of results from the method was approximately 5–10% for EtHg and 5–15% for MeHg. Detection limits achieved were 0.01 ng g⁻¹ for EtHg and MeHg in blood, saliva, and vaccines and 5 ng g⁻¹ for EtHg and MeHg in hair. The method presented has been shown to be suitable for determination of background levels of these contaminants in biological samples and can be used in studies related to the health effects of mercury and its species in man. This work illustrates the possibility of using hair and blood as potential biomarkers of exposure to thiomersal.