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Analytical and Bioanalytical Chemistry (v.375, #2)

Solvent properties of the 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid by S. Carda–Broch; A. Berthod; D. W. Armstrong (pp. 191-199).

1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF₆) was synthesized and purified to be used as a ionic liquid solvent. Its physicochemical properties were studied. The ionic liquid/water (P _il/water) and ionic liquid/heptane (P _il/heptane) distribution coefficients of a set of 40 compounds with various functionalities, including organic acids, organic bases, amino acids, antioxidants, and neutral compounds, were measured using liquid chromatography. For ionizable compounds, the P _il/water values measured at pH 2, 5.1, and 10 were very different. These allowed the determination of both the molecularP^oil_/water values and the ionP⁻il_/water value for each compound. These coefficients were compared to the corresponding P _oct/water coefficients. Marked differences in the partitioning behavior of basic, acidic, and neutral compounds were observed. The relationship between P _il/water and P _oct/water is different from that reported previously. By using the linear free energy solvation approach and the descriptors found for 12 solutes, the BMIM-PF₆ solvent parameters were calculated for the ionic liquid/water and ionic liquid/heptane biphasic systems. The regression parameters show a low basicity of the BMIM-PF₆ solvent compared to octanol. The high cohesion of the ions in the ionic liquid phase is also indicated by the regression equations obtained. Ionized phenols (phenoxide ions) associate more strongly with BMIM-PF₆ than most other ionized molecules. Amino acids were not soluble in ionic liquid; however, it is possible to extract them partially by adding a crown ether to the ionic liquid phase and working at pH 1. The positive form of amino acids is complexed by the crown ether and the complex is extracted in the ionic liquid phase.

Keywords: Ionic liquid/water distribution coefficient Ionic liquid/heptane distribution coefficient Liquid–liquid extraction Solvent properties Linear free energy relationship

The pattern of urinary acylcarnitines determined by electrospray mass spectrometry: a new tool in the diagnosis of diabetes mellitus by M. Möder; A. Kießling; H. Löster; L. Brüggemann (pp. 200-210).

l-Carnitine and its esters are products of intermediary metabolism of organisms. The distribution pattern or the favored excretion of individual acylcarnitines tells something about metabolic diseases. The determination of the urinary acylcarnitine pattern by flow injection analysis (FIA)–electrospray ionization (ESI)–mass spectrometry (MS) is presented. Groups of healthy probands and patients suffering from diabetes mellitus were investigated due to their significant acylcarnitine profile. The statistical analysis of data sets obtained clearly shows a difference in the acylcarnitine pattern of healthy and sick probands. In comparison to the controls, diabetes mellitus patients excrete more long-chain carnitine esters ranging from dodecanoyl to palmitoylcarnitine. Thus, the urinary acylcarnitine pattern determined by ESI–MS can be a useful tool in the diagnosis and therapy monitoring of diabetes mellitus.

Keywords: Urinary acylcarnitines Electrospray mass spectrometry Diabetes mellitus

Simultaneous determination of domperidone and cinnarizine in a binary mixture using derivative spectrophotometry, partial least squares and principle component regression calibration by Maissa Y. Salem; Eman S. El-Zanfaly; Mohamed F. El-Tarras; Mohamed G. El-Bardicy (pp. 211-216).

This work is concerned with the simultaneous determination of domperidone maleate (DOM) and cinnarizine (CINN) in a binary mixture form, without previous separation, by two different techniques. The first method is the application of derivative spectrophotometry where the linearity range and percentage recoveries for DOM and CINN were 2.5–30 µg mL^–1, 5–25 µg mL^–1 and 100.06±1.157, 99.93±1.377, respectively. The second method depends on the application of partial least squares (PLS) and principle component regression (PCR) models. A training set consisting of 10 mixtures containing 5–20 µg mL^–1 for each component was used for the construction of the PCR and PLS models. These models were used after their validation for the prediction of the concentration of DOM and CINN in their mixtures. The proposed procedures were successfully applied for the simultaneous determination of both drugs in laboratory prepared mixtures and in commercial tablet preparations. The validity of the proposed methods was assessed by applying the standard addition technique where the percentage recovery of the added standard was found to be 99.98±0.297 and 99.84±0.700 for DOM and CINN, respectively, using the derivative spectrophotometric method and 100.29±0.398 and 100.11±0.363 for DOM and CINN, respectively, using the PLS and PCR methods.The proposed procedures are rapid, simple, require no preliminary separation steps and can be used for routine analysis of both drugs in quality control laboratories.

Keywords: Domperidone Cinnarizine Binary mixture Derivative spectrophotometry Partial least squares Principle component regression Chemometrics

New approach in the treatment of data from an acid–base potentiometric titration by Vania Maslarska; Jasmina Tencheva; Omortag Budevsky (pp. 217-222).

Based on precise analysis of the acid–base equilibrium, a new approach in the treatment of experimental data from a potentiometric titration is proposed. A new general formula giving explicitly the relation V=f([H⁺]) is derived, valid for every acid–base titration, which includes mono- and polyfunctional protolytes and their mixtures. The present study is the first practical application of this formula for the simplest case, the analysis of one monofunctional protolyte. The collected mV data during the titration are converted into pH-values by means of an auto pH-calibration procedure, thus avoiding preliminary preparation of the measuring system. The mentioned pH-calibration method is applicable also in water–organic mixtures and allows the quantitative determination of sparingly soluble substances (particularly pharmaceuticals). The treatment of the data is performed by means of ready-to-use software products, which makes the proposed approach accessible for a wide range of applications.

Keywords: Analysis of acids and bases Potentiometry Auto pcH-calibration Acid–base constants.

Determination of polychlorinated biphenyl congeners and chlorinated pesticides in a fish tissue standard reference material by Dianne L. Poster; John R. Kucklick; Michele M. Schantz; Barbara J. Porter; Stefan D. Leigh; Stephen A. Wise (pp. 223-241).

The concentrations of a wide range of polychlorinated biphenyl congeners (PCBs) and chlorinated pesticides in a fish tissue Standard Reference Material (SRM) have been determined using multiple methods of analysis. This material, SRM 1946, Lake Superior Fish Tissue, was recently issued by the National Institute of Standards and Technology (NIST) and complements a suite of marine environmental natural-matrix SRMs that are currently available from NIST for the determination of organic contaminants such as aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), PCBs, and chlorinated pesticides. SRM 1946 is a fresh tissue homogenate (frozen) prepared from filleted adult lake trout (Salvelinus namaycush namaycush) collected from the Apostle Islands region of Lake Superior. SRM 1946 has certified and reference concentrations for PCB congeners, including the three non-ortho PCB congeners, and chlorinated pesticides. Certified concentrations are available for 30 PCB congeners and 15 chlorinated pesticides. Reference concentrations are available for 12 PCB congeners and 2 chlorinated pesticides. In addition, SRM 1946 is characterized for additional chemical constituents and properties: fatty acids, extractable fat, methylmercury, total mercury, selected trace elements, proximates, and caloric content. The characterization of chlorinated compounds is described in this paper with an emphasis on the approach used for the certification of the concentrations of PCB congeners and chlorinated pesticides. The PCB congener and chlorinated pesticide data are also compared to concentrations in other marine natural-matrix reference materials available from NIST (fish oil, mussel tissue, whale blubber, and a second fresh frozen fish tissue homogenate prepared from filleted adult lake trout collected from Lake Michigan) and from other organizations such as the National Research Council Canada (ground whole carp), the International Atomic Energy Agency (fish homogenate), and the European Commission Joint Research Centre [fish oils (cod and mackerel) and mussel tissue].

Keywords: Standard Reference Materials SRMs PCBs Pesticides Fish

Determination of ultratrace elements in natural waters by solid-phase extraction and atomic spectrometry methods by Marco Grotti; Maria Luisa Abelmoschi; Francesco Soggia; Roberto Frache (pp. 242-247).

A study was carried out on the preconcentration of ultratrace amounts of cadmium, lead, manganese, copper and iron from high-salinity aqueous samples and determination by atomic spectrometry methods. Sample volume, amount of resin, loading flow rate, and elution volume were optimized in order to obtain the simultaneous preconcentration of all the analytes. Quantitative recoveries were obtained by using 200 mg of iminodiacetic resin with a loading flow rate of 2 mL min⁻¹, elution volume of 3 mL and sample volume of 50–450 mL. Only copper in seawater samples was not completely retained by the resin (60–70% recovery), due to unfavorable competition of iminodiacetic-active groups with organically bound metal.To quantify the metals in the eluates, two atomic spectrometry techniques were compared: electrothermal atomization atomic absorption spectrometry (ETAAS) and inductively coupled plasma–optical emission spectrometry (ICP–OES) with simultaneous CCD detection system. Both techniques are suitable for sample analysis with detection limits of 1.0, 4.7, 3.3, 6.8, and 53 ng L⁻¹ using ETAAS and 12, 122, 3.4, 17, and 21 ng L⁻¹ using ICP–OES for Cd, Pb, Mn, Cu, and Fe, respectively. Relative standard deviations of the procedures ranged from 1.7 to 14% at the sub-μg L⁻¹ concentration level. The accuracy of both methods was verified by analyzing various certified reference materials (river water, estuarine water, coastal and off-shore seawater).

Keywords: Preconcentration Iminodiacetic resin Electrothermal atomic absorption spectrometry Inductively coupled plasma–optical emission spectrometry Natural waters

Variable selection by an evolution algorithm using modified Cp based on MLR and PLS modeling: QSAR studies of carcinogenicity of aromatic amines by Qi Shen; Jian-Hui Jiang; Guo-li Shen; Ru-Qin Yu (pp. 248-254).

The variable selection in QSAR studies by MLR and PLS modeling has been performed using the evolution algorithm (EA). The Cp statistic has been modified and used as the objective function in the EA search for different combinations of molecular descriptors. For MLR modeling a few information-rich descriptors are selected for model formulation. In PLS modeling, the proposed procedure selects a relatively large number of information-containing descriptors, and a PLS model is formulated based on a few latent variables, which are linear combinations of the selected descriptors. The proposed procedures were used for the prediction of carcinogenicity of aromatic amines.

Keywords: Modified Cp statistic Variable selection Evolution algorithm QSAR MLR PLS

Triton X-100-stabilized "oil-in-water" emulsions as suitable media for alkalimetric determination of hydrophobic organic acids by S. Kulichenko; G. Shevchenko (pp. 255-258).

The protolytic properties of fat row carbonic acids in Triton X-100-stabilized "oil-in-water" (O/W) emulsions were studied. The differential influence of emulsions on the force of acids was shown to depend on the length of the hydrocarbon radical. The conditions for separate alkalimetric determinations of acids with different hydrophobicities in their mixtures using emulsions stabilized by non-ionic surfactant were suggested. The procedure for the determination of 4-chloro-N-(2-furilmethyl)-5-sulfamoylanthranilic acid (furosemide) main substance content in pharmaceuticals using Triton X-100-stabilized emulsion was proposed.

Keywords: O/W emulsions Non-ionic surfactant Triton X-100 Carbonic acids Protolytic properties Alkalimetric determination Furosemide

Electrostatic ion chromatography using a carboxybetaine-type zwitterionic surfactant as the stationary phase by Wenzhi Hu; Paul R. Haddad; Kazuhiko Tanaka; Kiyoshi Hasebe (pp. 259-263).

A carboxybetaine-type zwitterionic stationary phase obtained by immobilizing Mitsubishi Reagent EF-700 (C₈F₁₇SO₂NHC₃H₆N⁺ (CH₃)₂-C₂H₄-COO^–) onto a reversed-phase column was used for chromatographic separation of ions. When aqueous electrolyte solutions having higher pH values (>8) were used as eluents, the model analyte ions (NO₂ ^–, H₂PO₄ ^–, Cl^–, Br^–, NO₃ ^–, ClO₃ ^–, I^– and SCN^–) were co-eluted and appeared at the void volume of this HPLC system. However, when aqueous electrolyte solutions having lower pH values (<5.5) were used as eluents, these anions were well retained and separated. Furthermore, when acetate buffers (NaAc/HAc) were used as eluents, plots of log k′ (k′, retention factor) versus pH of eluents (at constant [NaAc+HAc]), and log k′ versus log [NaAc+HAc] (at constant pH), were linear with negative slopes. Breakthrough curves for acid solutions obtained using conductivity detection showed that H⁺ ions and their conjugate anions were both retained on the stationary phase and the degree of binding was found to be independent of the acid species used. The degree to which the eluent cation was bound onto the carboxylate functionality of the zwitterion was found to exert a major effect on the retention of analyte anions. A strongly bound cation, such as H⁺, reduced electrostatic repulsion effects exerted by the carboxylate functionality on analyte anions, so that they could freely access the quaternary ammonium sites on the zwitterion. It is concluded based on these experimental results that both the charges on the zwitterionic stationary phase make meaningful contributions to the separation of the analyte ions.

Keywords: Zwitterionic chromatography Carboxybetaine stationary phase Capacity modulation Anion separation

Preparative separation and determination of matrine from the Chinese medicinal plant Sophora flavescens Ait by molecularly imprinted solid-phase extraction by Jia-Ping Lai; Xi-Wen He; Yue Jiang; Feng Chen (pp. 264-269).

Molecularly imprinted microspheres (MIMs) were synthesized by micro-suspension polymerization using matrine (MT) as template. The MIMs were employed for solid-phase extraction (SPE) and as chromatographic stationary phase for the determination of MT from the Chinese medicinal plant Sophora flavescens. The effects of the various eluents, their concentrations and volumes on the retention behavior were investigated. The selectivity and capacity of the imprinted microspheres against MT was also discussed. The results showed that the MIMs exhibited stronger specific affinity to MT than to oxymatrine (OMT). Methanol–water (3:7, v/v) was used for washing impurities from the MIMs-SPE cartridge loaded with the herb extracts, while methanol–glacial acetic acid (9:1, v/v) was used for eluting MT. The maximum load of MT and the recovery of MIMs cartridge towards MT were 38.7 μg g^–1 and 71.4%, respectively. The method developed might be used to separate and extract effective constituents from Chinese medicinal plants on a large scale.

Keywords: Molecularly imprinted microspheres Solid-phase extraction Matrine Sophora flavescens

On-line complexation/cloud point preconcentration for the sensitive determination of dysprosium in urine by flow injection inductively coupled plasma–optical emission spectrometry by Claudia Ortega; Soledad Cerutti; Roberto A. Olsina; María F. Silva; Luis D. Martinez (pp. 270-274).

An on-line dysprosium preconcentration and determination system based on the hyphenation of cloud point extraction (CPE) to flow injection analysis (FIA) associated with ICP–OES was studied. For the preconcentration of dysprosium, a Dy(III)–2-(5-bromo-2-pyridylazo)-5-diethylaminophenol complex was formed on-line at pH 9.22 in the presence of nonionic micelles of PONPE-7.5. The micellar system containing the complex was thermostated at 30 °C in order to promote phase separation, and the surfactant-rich phase was retained in a microcolumn packed with cotton at pH 9.2. The surfactant-rich phase was eluted with 4 mol L⁻¹ nitric acid at a flow rate of 1.5 mL min⁻¹, directly in the nebulizer of the plasma. An enhancement factor of 50 was obtained for the preconcentration of 50 mL of sample solution. The detection limit value for the preconcentration of 50 mL of aqueous solution of Dy was 0.03 μg L⁻¹. The precision for 10 replicate determinations at the 2.0 μg L⁻¹Dy level was 2.2% relative standard deviation (RSD), calculated from the peak heights obtained. The calibration graph using the preconcentration system for dysprosium was linear with a correlation coefficient of 0.9994 at levels near the detection limits up to at least 100 μg L⁻¹. The method was successfully applied to the determination of dysprosium in urine.

Keywords: On-line preconcentration Dysprosium Cloud point extraction

A novel analytical low-cost flow system based on a 0.6 MPa (84 psi) diaphragm pump applied to on-line trace pre-concentration in flame AAS and ICP-OES by Annelen Ratka; Harald Berndt (pp. 275-280).

A novel inexpensive 0.6 MPa (84 psi) flow system based on a low-cost diaphragm pump has been developed. The unfavourable strong pulsation of the pump has been overcome by using highly flexible silicone tubing as a pulse suppression coil. This results in a smooth pulse-free continuous flow of 100 mL min^–1 in circulation. This flow rate is much too high for a flow-injection system; however, with a restrictor capillary the flow rate required can be tapped off down to a range of 0.1–50 mL min^–1. By employing diaphragm pumps in an analytical flow system the pressure gap between HPLC pumps (2–40 MPa) and peristaltic pumps (<0.2 MPa), mainly used in FIA systems, can be filled. Due to the higher pressure delivered by diaphragm pumps relative to peristaltic pumps, the new flow system can be applied to on-line sample pre-concentration and matrix separation in flame AAS and ICP-OES by using standard HPLC pre-columns or small ion-exchange columns, respectively. In this way, very low detection limits in flame AAS have been reached (Cd 0.07 µg L^–1, Cu 0.05 µg L^–1, Co 0.9 µg L^–1, Ni 0.8 µg L^–1, Mn 0.7 µg L^–1, Pb 0.8 µg L^–1 and Tl 0.2 µg L^–1).

Keywords: Flow-injection systems Diaphragm pump flow system On-line pre-concentration Damped diaphragm pump

Flow injection determination of papaverine based on its sensitizing effect on the chemiluminescence reaction of permanganate-sulfite by Ya-Feng Zhuang; Si-Chun Zhang; Jun-Sheng Yu; Huang-Xian Ju (pp. 281-286).

A novel chemiluminescence (CL) method for the determination of papaverine (PAP) has been developed by combining the flow injection technique and its sensitizing effect on the weak CL reaction between sulfite and acidic permanganate. A mechanism for the CL reaction has been proposed on the basis of fluorescent and chemiluminescence spectra. The CL response is proportional to the concentration of PAP over the range 0.2–10 µmol L^–1. The detection limit of PAP is 0.10 µmol L^–1 (3 s) with a relative standard deviation (RSD) of 2.0% for 10 repetitive determinations of 1.0 µmol L^–1 PAP. Interferences from other alkaloids in the opium, such as morphine and codeine, are negligible except that of narcotine. The method has been satisfactorily used for the determination of PAP in injections and compound liquorice tablets.

Keywords: Chemiluminescence Papaverine Permanganate Sulfite Flow injection analysis

Carbon nanotube-enhanced electrochemical DNA biosensor for DNA hybridization detection by Hong Cai; Xuni Cao; Ying Jiang; Pingang He; Yuzhi Fang (pp. 287-293).

A novel and sensitive electrochemical DNA biosensor based on multi-walled carbon nanotubes functionalized with a carboxylic acid group (MWNTs–COOH) for covalent DNA immobilization and enhanced hybridization detection is described. The MWNTs–COOH-modified glassy carbon electrode (GCE) was fabricated and oligonucleotides with the 5'-amino group were covalently bonded to the carboxyl group of carbon nanotubes. The hybridization reaction on the electrode was monitored by differential pulse voltammetry (DPV) analysis using an electroactive intercalator daunomycin as an indicator. Compared with previous DNA sensors with oligonucleotides directly incorporated on carbon electrodes, this carbon nanotube-based assay with its large surface area and good charge-transport characteristics dramatically increased DNA attachment quantity and complementary DNA detection sensitivity. This is the first application of carbon nanotubes to the fabrication of an electrochemical DNA biosensor with a favorable performance for the rapid detection of specific hybridization.

Keywords: Functionalized multi-walled carbon nanotubes DNA immobilization Hybridization Electrochemical DNA biosensor Daunomycin

Electrocatalytic oxidation of nitric oxide at indium hexacyanoferrate film-modified electrodes by E. Casero; F. Pariente; E. Lorenzo (pp. 294-299).

The electrocatalytic oxidation of nitric oxide (NO) by indium (III) hexacyanoferrate (III) films has been studied. These films are electrodeposited onto glassy carbon electrodes through potential cycling in acidic solutions containing a potassium electrolyte, indium (III), and potassium hexacyanoferrate. The resulting modified electrodes exhibit a reversible redox response ascribed to the oxidation/reduction of iron atoms presents in the electrodeposited film. The films have a potent and persistent electrocatalytic activity towards NO oxidation at neutral pH. The electrocatalytic oxidation of NO takes place at potentials around +0.75 V which represents a moderate diminution in the overpotential. In addition, interferences due to the presence of nitrate and nitrite have been significantly reduced. According to these results, the described modified electrodes have been used as sensors for the determination of NO generated by decomposition of a typical NO-donor, such as S -nitroso- N -acetyl- d, l -penicillamine (SNAP).

Keywords: Nitric oxide Indium (III) hexacyanoferrate (III) films Modified electrodes Sensors

Copper–mercury film electrode for cathodic stripping voltammetric determination of Se(IV) by Vladimir Sladkov; François David; Blandine Fourest (pp. 300-305).

The copper–mercury film electrode has been suggested for the determination of Se(IV) in a wide range of concentration from 1×10^–9 to 1×10^–6 mol L^–1by square-wave cathodic stripping voltammetry. Insufficient reproducibility and sensitivity of the mercury film electrode have been overcome by using copper(II) ions during the plating procedure. Copper(II) has been found to be reduced and form a reproducible copper–mercury film on a glassy carbon electrode surface. The plating potential and time, the concentration of copper(II) and the concentration of the supporting electrolyte have been optimised. Microscopy has been used for a study of the morphology of the copper–mercury film. It has been found that it is the same as for the mercury one. The preconcentration step consists in electrodeposition of copper selenide on the copper–mercury film. The relative standard deviation is 4.3% for 1×10^–6 mol L^–1 of Se(IV). The limit of detection is 8×10^–10 mol L^–1 for 5 min of accumulation.

Keywords: Cathodic stripping voltammetry Selenium Film electrode Glassy carbon

Determination of copper in coal fly ash in the presence of excess titanium by dynamic reaction cell inductively coupled plasma mass spectrometry by Hui-Tao Liu; Shiuh-Jen Jiang (pp. 306-309).

Inductively coupled plasma quadrupole mass spectrometry (ICP–QMS) was used for the accurate determination of copper in coal fly ash samples in the presence of excess titanium, using the reaction of Cu⁺ ions with NH₃ in the cell. The method eliminated the effect of polyatomic isobaric interferences at m/z 63 and 65 caused by the formation of ⁴⁷Ti¹⁶O⁺, ⁴⁹Ti¹⁶O⁺ and ⁴⁷Ti¹⁸O⁺ on ⁶³Cu⁺ and ⁶⁵Cu⁺ by detecting Cu⁺ as the product cluster ion Cu(NH₃)₂ ⁺. As the signal of ⁶³Cu(NH₃)₂ ⁺ overlapped with that of ⁹⁷Mo⁺ which existed in the samples, ⁶⁵Cu(NH₃)₂ ⁺ was detected at m/z 99. The effect of the operating conditions of DRC system was studied in order to obtain the best signal to noise ratio for Cu(NH₃)₂ ⁺ at m/z 99. The formation of Cu(NH₃)₂ ⁺ was through the clustering reaction Cu⁺+2NH₃→Cu(NH₃)₂ ⁺ which resulted in the separation of analyte from the interfering oxide. The detection limit for Cu(NH₃)₂ ⁺ was 0.015 ng mL^–1 as Cu. The method was applied to the determination of copper in NIST SRM 1633a and 1633b coal fly ash reference materials. The precision between sample replicates was better than 2.0% and the analysis results were in good agreement with the certified values.

Keywords: Inductively coupled plasma mass spectrometry Dynamic reaction cell Coal fly ash Copper Titanium

A core–shell structured BaTiO₃ precursor preparation, characterization and potential by Michael Rössel; Silvio Gablenz; Thomas Müller; Andreas Röder; Hans-Peter Abicht (pp. 310-314).

A new procedure for the preparation of a core–shell-structured BaTiO₃ precursor (core=TiO₂; shell=BaCO₃) will be described. The structure of this precursor is characterized by electron microscopy (environmental scanning electron microscopy; energy disperse X-ray spectroscopy), whereas the development of phases during thermal treatment is followed by X-ray powder diffraction.

Keywords: Barium titanate precursor Core–shell structure Electron microscopy Formation mechanism

Copper(II)-catalysed oxidative coupling reaction of 3-hydroxyacetanilide with 3-methyl-2-benzothiazolinone hydrazone for the spectrophotometric determination of traces of copper(II) by M. S. Hemantha Kumar; P. Nagaraja; H. S. Yathirajan (pp. 315-318).

A spectrophotometric method is developed for the determination of traces of copper(II), based on the catalytic oxidative coupling reaction of 3-hydroxyacetanilide with 3-methyl-2-benzothiazolinone hydrazone in the presence of ammonia and hydrochloric acid. Beer's law is obeyed in the copper(II) concentration range of 0.008–0.16 μg mL⁻¹, and the molar absorptivity at 530 nm is 2.5×10⁵ L mol⁻¹ cm⁻¹. The Sandell's sensitivity of the product is 0.000254 μg cm⁻². The optimum reaction conditions and other important analytical parameters have been investigated. The proposed method is applied to the analysis of water and soil samples and the results are compared with the literature method.

Keywords: Copper(II) 3-Hydroxyacetanilide 3-Methyl-2-benzothiazolinone hydrazone Spectrophotometry

A highly sensitive spectrophotometric determination of platinum(IV) using leuco xylene cyanol FF by H. Revanasiddappa; Kiran T. Kumar (pp. 319-323).

A new, simple, highly sensitive and rapid spectrophotometric method has been described for the determination of platinum(IV). The method is based on the oxidation of leuco xylene cyanol FF (LXCFF) to its blue form of xylene cyanol FF by platinum(IV) in sulfuric acid medium (pH 1.0–2.5), the formed dye shows an absorption maximum at 620 nm in acetate buffer medium (pH 3.0–4.5). The method obeys Beer's law over a concentration range of 0.3 to 2.6 µg mL^–1 platinum, having molar absorptivity and Sandell's sensitivity of 5.1×10⁴ L mol^– ¹ cm^–1 and 0.0038 µg cm^–2, respectively. The optimum reaction conditions and other analytical parameters have been evaluated. The developed method has been successfully applied to the determination of platinum in pharmaceutical preparations, soil, natural water, plant material, platinum-containing catalyst, and synthetic alloy samples.

Keywords: Spectrophotometry Platinum(IV) determination Leuco xylene cyanol FF

Application of reflectance micro-infrared spectroscopy in coal structure studies by A. Hacura; R. Wrzalik; A. Matuszewska (pp. 324-326).

Fourier transform infrared micro-scale analysis of organic matter has been applied to characterise individual petrographic components of coal. The use of an infrared microscope made it possible to study and compare different parts of a single individual grain of vitrinite. This method enables analysis of particular macerals without the need for previous separation from coals. For this purpose the polished grainy micro-sections of coal have been prepared. The results obtained indicated the progression of aromatisation in the vitrinite structure with an increase of coalification degree of the parent coals.

Keywords: Micro-FTIR spectrometry Reflectance Structure of coal Vitrinite

Application of chemiluminescence for the detection of peroxy compounds in high-performance liquid chromatography by Stefan Baj; Anna Chrobok; Mariola Cieślik; Tomasz Krawczyk (pp. 327-330).

The possibility of applying post-column reaction and chemiluminescence to determine organic peroxy compounds by RP-HPLC was investigated. Conditions of qualitative and quantitative analyses have been established. The applicability of the method has been demonstrated for a series of compounds representative of the most important groups of peroxy-type compounds, that is, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters, and peroxyacids.

Keywords: Luminol Chemiluminescence Peroxy compounds High-performance liquid chromatography

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Analytical and Bioanalytical Chemistry (v.375, #2)