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Analytical and Bioanalytical Chemistry (v.372, #5-6)

No Title by Z. Xie; S. Sielemann; H. Schmidt; F. Li; J.I. Baumbach (pp. 606-610).

A combination of a custom-designed ion mobility spectrometer (IMS) with a UV ionization source and a high speed capillary column (HSCC) has been developed as an analytical device for the sensitive detection of volatile organic compounds (VOCs), e.g. 2-propanone (acetone), 2-butanone and 3-pentanone (diethyl ketone) in the gas phase. A fast separation of the three selected substances and benzene, toluene and m-xylene (BTX) – all of which occur in human breath – has been achieved within less than four minutes at a carrier gas flow rate of 4.5 mL min^–1. Multi-dimensional correlations presented support the interpretation of the acquired spectra of mixtures. Method detection limits were 2.7 µg L^–1 for acetone and 2-butanone and 3.0 µg L^–1 for diethyl ketone in nitrogen, respectively. The assay linear dynamic range is 4–320 µg L^–1.

Keywords: Ion mobility spectrometry Photoionization High speed capillary column Ketones

No Title by Ute Herrmann; Thorsten Jonischkeit; Joachim Bargon; Uwe Hahn; Qian-Yi Li; Christoph A. Schalley; Erik Vogel; Fritz Vögtle (pp. 611-614).

"Electronic noses", i.e. arrays of differently coated quartz microbalances (QMB), have been used for selective detection of, and discrimination between, volatile organic compounds (VOC) formed during the post-harvest ripening of apples. The flavor components to be differentiated are chemically rather similar carbonyl compounds, chiefly aldehydes and esters. Because their relative ratios change during the post-harvest ripening period, appropriately selected sensor-active layers lead to characteristic patterns of the sensor responses which can be analyzed via pattern-recognition methods. This enables qualitative and quantitative identification of individual components whereby the post-harvest ripening of apples and other fruits can be monitored. Different kinds of apple differ in type and concentration of individual carbonyl compounds.

Keywords: Sensors Electronic nose Quartz microbalance Fruit ripening Aroma components

No Title by C. Zwiener; T. Glauner; F. Frimmel (pp. 615-621).

A method has been developed for quantitative determination of carbonyl disinfection by-products (DBP) from aqueous samples by derivatization with 2,4-dinitrophenylhydrazine combined with high-performance liquid chromatography (HPLC) and electrospray ionization (ESI) tandem mass spectrometry (MS–MS). The effect of excess of derivatization reagent and derivatization time, the effect of buffer and dry-gas temperature in the ESI process, and the effect of focus potential and collision energy in MS measurement are shown. Major fragment ions for compound identification on the basis of collision-induced dissociation (CID) mass spectra (MS) are given, as are common fragments for screening analyses by MS experiments such as the use of precursor ion scans. Detection limits in the µg L^–1 range could be achieved by selected ion monitoring measurements without sample preconcentration. Solid-phase extraction improved the sensitivity by a factor of 25 to 250. The applicability of the method is illustrated by DBP analyses of samples from outdoor swimming pools after chlorination. Several carbonyl compounds, e.g. aldehydes, ketones, hydroxybenzaldehyde, and dicarbonyl compounds were identified.

Keywords: Disinfection by-product Carbonyl compounds Derivatization Dinitrophenylhydrazine Tandem mass spectrometry

No Title by Stephan Brombacher; Michael Oehme; Christian Dye (pp. 622-629).

The suitability of HPLC combined with ion-trap mass spectrometry was studied for the determination of carbonyl-2,4-dintrophenylhydrazones in ambient air. MS quantification was based on two internal standards and atmospheric pressure chemical ionization in the negative-ion mode. Limits of detection for air samples of 750 L in the full-scan mode varied between 1 and 15 ng m^–3 expressed as carbonyl. Limits of quantification were approximately a factor of three higher. This is sufficient for background regions. For sample volumes of 750 L air the instrument response was linear from 10 ng m^–3 to 800 µg m^–3 for carbonyls and from 3 ng m^–3 to 250 ng m^–3 for dicarbonyls. Besides complete method validation, quantitative results for six air samples from four background sampling sites in North and Central Europe were compared with those obtained by use of HPLC–UV. Thirty-six carbonyl compounds could be identified and twenty-four were quantified. Values for major compounds, i.e. those present at levels well above the UV detection limits (9 to 18 ng m^–3), deviated by less than 20%.

Keywords: Ambient air Quantification Carbonyls HPLC MSn

No Title by V. Van den Bergh; H. Coeckelberghs; I. Vanhees; R. De Boer; F. Compernolle; C. Vinckier (pp. 630-638).

Biogenic non-methane hydrocarbons such as isoprene, α-pinene, and β-pinene, are emitted by forests in very large quantities. To evaluate the role of α- and β-pinene and their contribution to the global production of trace gases and especially aerosol precursors, a study of the oxidation mechanism of α- and β-pinene with hydroxyl radicals must be conducted.The degradation products of both monoterpenes with hydroxyl radicals were identified and quantified in a fast-flow reactor. The products were collected on a liquid-nitrogen trap coated with a 2,4-DNPH solution to which two internal standards (benzaldehyde-2,4-DNPH and tolualdehyde-2,4-DNPH) had been added. The collection method was based on the in situ conversion of aldehyde and/or ketone compounds to their 2,4–dinitrophenylhydrazone derivatives. The derivatives were analyzed by HPLC–MS using APCI(–). TIC chromatograms and mass spectral data for the various oxidation products are presented.For α-pinene, pinonaldehyde is the most important degradation product, with smaller amounts of acetone, formaldehyde, campholenealdehyde, and acetaldehyde. For β-pinene, nopinone and formaldehyde are the most abundant products, of almost equal importance, whereas acetone and acetaldehyde are minor compounds.

Keywords: Monoterpenes DNPH HPLC–MS Product yields Fast-flow reactor

No Title by C. Kempter; T. Berkhoudt; Greve C. Tolbøl; K. Egmose; U. Karst (pp. 639-643).

Two hydrazine reagents, 4-N,N-dimethylamino-6-(4′-methoxy-1′-naphthyl)-1,3,5-triazine-2-hydrazine (DMNTH) and N-methyl-4-N′,N′-dimethylamino-6-(4′-methoxy-1′-naphthyl)-1,3,5-triazine-2-hydrazine (MDMNTH) have been synthesized and used for the determination of aldehydes in air samples. Test tubes with the reagents coated on silica gel were prepared and used for monitoring of carbonyls in air. After elution with acetonitrile the hydrazones formed were separated by reversed-phase liquid chromatography. Detection was performed by UV–visible and fluorescence spectroscopy. The results were validated by use of standard atmospheres of the carbonyls and of nitrogen dioxide and ozone, as potential interferents. In comparison with established hydrazine reagents, e.g. 2,4-dinitrophenylhydrazine (DNPH), the results from use of MDMNTH correlate well; lower recoveries were obtained by use of DMNTH. The limits of detection for the new reagents are superior to those for DNPH, because of the possibility of fluorescence detection.

Keywords: Air monitoring Aldehydes Hydrazine reagents Liquid chromatography Fluorescence detection

No Title by Erhard Schulte (pp. 644-648).

In current analytical practice, simple methods are required for assessing the quality of a deep-frying fat after some time of use. Therefore, a new procedure was developed for the fast and selective determination of higher carbonyl compounds, i.e., those triglycerides resulting from the oxidation and/or oxidative cleavage of double bonds in unsaturated fatty acids. For analysis, a fat sample is dissolved in a 1-butanol/toluene mixture containing 6-undecanone as an internal standard. Aldehydes and ketones present are allowed to react with 2,4-dinitrophenylhydrazine (DNPH) in acidic solution for at least 1 h at room temperature. The mixture is injected directly onto a reversed phase HPLC column that is eluted with a very steep gradient between methanol and tert-butylmethyl ether (TBME) and is fitted with a UV detector set at 370 nm. In this way, the DNPH derivatives of all higher carbonyl compounds are eluted as one single peak. The result is calculated as milliequivalents of carbonyls per kg of fat (meq kg^–1). The method takes a minimum of time and reagents and only requires the usual equipment.

Keywords: Carbonyls Carbonyl compounds Deep-frying fat HPLC DNPH derivatives

No Title by T. Wenzl; E. Lankmayr (pp. 649-653).

Aldehydes in cellulose-based materials such as cardboard are derived from lipid degradation. Depending on the production- and storage conditions of the cardboard, the aldehyde content changes. Owing to their sensorial properties, accurate control of their content is obligatory. The cardboard usually exhibits strong and even varying matrix effects and considerable inhomogeneity.The comparability of results of analysis after static and dynamic headspace extraction of short chained saturated aldehydes from cellulose-based matrices was studied. In the case of the static extraction technique, special attention was given to the establishment of the headspace equilibrium, which could be reached by the addition of water as a displacer.For dynamic headspace extraction, the volatiles were purged from the matrix by an inert gas and enriched on an adsorbent trap. In theory, the extraction yield should be 100%. Since there are no certified reference materials for verification of the extraction efficiency available, confirmation was achieved by determining the total amount of analytes in the sample by means of multiple headspace extraction.In comparison to the static operation mode, the major drawbacks of the dynamic technique were found to be based on a more complex parameter string and on limitations to the extractable sample quantities, which may result in enhanced uncertainty of the measurements. Nevertheless, the results of analysis pointed out that both headspace extraction techniques are suitable for the determination of volatile aldehydes from cellulose-based materials.

Keywords: Static headspace extraction Dynamic headspace extraction Gas chromatography Displacer Cardboard Aldehydes

No Title by Cong-Khanh Huynh; Trinh Vu-Duc (pp. 654-657).

Within the framework of a European interlaboratory exercise, the Vito facility for the generation of controlled atmospheres was used to test the suitability of four sampling techniques for priority aldehydes namely formaldehyde, acrolein, acetaldehyde, and glutaraldehyde at the ranges of 0.5 to 150 µg m^–3. The samplers are DNPH-containing impingers, DNPH-impregnated cartridges and filters, and 2-HMP coated XAD-2 tubes. The three first DNPH samplers are to be analyzed by HPLC and the latter by GC-MS for the oxazolidine derivatives. The intermethod comparison comprises two to five sets of experiments depending on the compounds of interest. The aim of the exercise was also to assess the chemical interferences caused by ozone, nitrogen dioxide, and ammonia when using different techniques for sampling and analysis. The active DNPH method (with minor modifications such as shorter sampling time, immediate elution after sampling, and/or eventually wetting of samplers) delivered results within the 30% overall relative uncertainty for formaldehyde, acetaldehyde, and acrolein at the upper µg m^–3 levels. However, the results suggest that the current DNPH methods for aldehydes do not comply with the 30% minimum performance criteria at the sub µg m^–3 level. Sampling of aldehydes in the presence of ozone and NO₂ interferences by using a "scrubber" cartridge appears to be beneficial to the quality of results.

Keywords: Sampling, active Aldehydes Environmental samples

No Title by Theo L. Hafkenscheid; Joos A. van Oosten (pp. 658-663).

Within the framework of the SMT "Aldehydes" project (SMT4-CT97-2910) three laboratory comparisons have been organized in which artificial aldehyde hydrazone samples have been distributed among participating laboratories. To these samples potentially interfering compounds have been added to simulate as closely as possible real air or air emission samples.In addition to the "Aldehydes" project partners external EU laboratories have participated. It may, therefore, be assumed that the results of these comparisons reflect the state-of-the-art in the analytical determination of aldehydes in air samples using the 2,4-dinitrophenylhydrazine (DNPH)-method. In this paper several aspects of the organization of these comparisons and the overall results obtained are presented. These demonstrate that results obtained using liquid chromatographic techniques are usually comparable between laboratories within ±2 times the coefficient of variation (~6–15%), indicating the robustness of the methodology. In addition, laboratory (liquid chromatography) mean results can be made to agree with preparation concentrations at the 95% confidence levels after optimization of separation and integration conditions; these are mainly related to the measurement of formaldehyde in the presence of interferents and the measurement of low concentrations of acrolein and acetone. Some problem areas still remain, however – namely the measurement of glutaraldehyde and the measurement of low levels of acetone.

Keywords: Aldehydes DNPH method Laboratory comparisons

No Title by María Marazuela; María Moreno-Bondi (pp. 664-682).

This article reviews progress and developments during the past five years in the field of optical fiber biosensors. Because of the expense and time constraints associated with modern laboratory analysis, there is a growing need for real-time, low-cost technology that can be used industrially, environmentally, and clinically, and to monitor food processing. Miniaturization, integrated systems, and multianalyte determination have become key aspects of sensor development and efforts in this direction will also be discussed, with some pointers to likely directions of future research in the area. The review will provide information about the analytical characteristics and applications of fiber-optic biosensors classified depending on the biorecognition element employed – enzymes, whole cells, antibodies, nucleic acids, and biomimetic polymers.

Keywords: Biosensor Optical sensors Fiber-optic

No Title by N. Faber (pp. 683-687).

The trilinear PARAFAC model occupies a central place in multiway analysis, because the components of a data array can often be uniquely resolved. This paper compares the resolution for a large variety of methods, namely the generalized rank annihilation method (GRAM), alternating least squares (ALS), alternating trilinear decomposition (ATLD), alternating coupled vectors resolution (ACOVER), alternating slice-wise diagonalization (ASD), alternating coupled matrices resolution (ACOMAR), self-weighted alternating trilinear decomposition (SWATLD), and pseudo alternating least squares (PALS). The comparison was conducted using Monte Carlo simulations. It was shown that GRAM performs well for moderately and highly overlapped data. These results argue strongly against the previously claimed superiority of the alternatives listed above.

Keywords: Chemometrics PARAFAC Second-order bilinear calibration GRAM DTLD ALS ATLD ACOVER ASD ACOMAR SWATLD PALS

No Title by Axel Dürkop; Frank Lehmann; Otto S. Wolfbeis (pp. 688-694).

The first competitive fluorescence polarization immunoassay using ruthenium metal-ligand complexes (5-MC and 55-DC) as labels is described. These were newly synthesized and characterized in terms of their spectra, their covalent linkage to proteins, and their use in both homogeneous and competitive immunoassays. Linkage to proteins was achieved by the N-hydroxysuccinimide ester method, which was demonstrated for the systems HSA–anti-HSA and myoglobin–anti-myoglobin. The values of the fundamental polarization are 0.18 for 5-MC and 0.33 for 55-DC. Polarization immunoassays with labeled HSA and myoglobin were performed in the homogeneous format and resulted in an increase of the fluorescence polarization of up to 100%. In the competitive assay, a decrease in polarization of >90% was detectable. When the competitive HSA immunoassay was validated against an independent test both methods gave almost the same results.

Keywords: Ruthenium metal-ligand complex Polarization probe Fluorescence polarization immunoassay

No Title by Attila Gáspár; Harald Berndt (pp. 695-699).

Flame-furnace AAS (FF–AAS) comprises two individual, recently developed FAAS techniques remarkable for their high power of detection and the small amounts of sample required. One of these techniques is beam-injection flame-furnace AAS (BIFF–AAS), whereby the sample is introduced into a flame-heated atomization cell as a high-speed liquid jet. For the first time this sample-introduction beam has been generated at low pressure by use of a peristaltic pump and a special micro channel smooth jet nozzle developed for this application. Compared with standard FAAS a 7- to 17-fold improvement in the power of detection was obtained for six elements (Ag, Cd, Hg, Pb, Se, and Zn). The relative standard deviation (N=15) was between 0.7% and 3.4%. Sample volumes between 10 µL and 1 mL have been investigated. The applicability of the peristaltic pump for beam generation enables an optimum sampling mode for a variety of analytical tasks (continuous sample uptake, manual or automated, or different flow-injection modes). The method can also be regarded as a simple, effective interface between FIA techniques and flame AAS.

Keywords: Flame AAS Flame furnace AAS Beam injection Micro samples Sample-jet generation

No Title by L. Schloske; H. Waldner; F. Marx (pp. 700-704).

A fast and accurate method of pre-treatment for biological materials in the hydride generation-atomic absorption spectroscopy (HG-AAS) selenium determination is described. All procedures of sample pre-treatment were performed in closed-vessels in a microwave oven. After sample decomposition using a HNO₃/H₂O₂ mixture, the pre-reduction and a 'denitrification' step (reduction of interfering nitrogen intermediates) with amidosulfuric acid were combined. Hence, analysis time and the risk of element losses or the emergence of possible contamination are minimised.

Keywords: Selenium analysis Microwave digestion FI-HG-AAS Pre-reduction Denitrification Sample pre-treatment

No Title by Rainer Füßler; Helwig Schäfer; Andreas Seubert (pp. 705-711).

Small and highly pressure-stable PS–DVB copolymers of different porosity had been prepared by a two-step swelling procedure which enabled variation of diluent composition, an important characteristic affecting the porosity. The polymers were characterized by inverse size-exclusion chromatography and scanning electron microscopy. Subsequent chloromethylation and amination resulted in anion exchangers suitable for ion chromatography.The pore volume and the pore-size distribution is substantially affected by the fraction of the solvens component in the diluent. It was apparent from scanning electron microscopy that surface structure and the size of the polymer particles was not affected by diluent composition. The functionalization process led to a decrease in pore volume. The pore-size distribution remained unchanged during functionalization, which can be explained in terms of partial closing of all pore sizes. The chromatographic efficiency of the functionalized polymers in ion chromatography was highly dependent on diluent composition and the extent of functionalization was determined by the total pore volume.The composition of the diluent is an excellent tool for optimization of polymers used for the synthesis of surface-functionalized anion exchangers.

Keywords: Ion chromatography Inverse size-exclusion chromatography Polystyrene Porosity

No Title by Yi Yuan; Peng Wang; Guoyi Zhu (pp. 712-717).

Methylene blue-intercalated α-zirconium phosphate (MBZrP) micro particles in deionized water were deposited onto the surface of graphite powder to prepare graphite powder-supported MBZrP, which was subsequently dispersed into methyltrimethoxysilane-derived gels to yield a conductive composite. The composite was used as electrode material to fabricate a surface-renewable, rigid, leak-free carbon ceramic composite electrode, bulk-modified with methylene blue (MB). In the configuration, α-zirconium phosphate was employed as a solid host for MB, which acted as a catalyst. Graphite powder ensured conductivity by percolation, the silicate provided a rigid porous backbone and the methyl groups endowed hydrophobicity and thus limited the wetting section of the modified electrode. Peak currents of the MBZrP-modified electrode were surface-confined at low scan rates but diffusion-controlled at high scan rates. Square-wave voltammetric study revealed that MBZrP immobilized in carbon ceramic matrix presented a two-electron, three-proton redox process in acidic aqueous solution with pH ranged from 0.44 to 2.94. In addition, the chemically modified electrode showed an electrocatalytic activity toward nitrite reduction at +0.15 V (vs. Ag/AgCl) in acidic aqueous solution (pH=0.44). The linear range and detection limit are 1×10^–6–4×10^–3 mol L^–1 and 1.5×10^–7 mol L^–1, respectively.

Keywords: Sol-gel carbon ceramic electrode Methylene blue-intercalated α-zirconium phosphate micro particles Micro particles

No Title by A. Firooz; M. Mazloum; J. Safari; M. Amini (pp. 718-722).

A copper(II) ion-selective electrode based on a recently synthesized 2-quinolyl-2-phenylglyoxal-2-oxime (phenylglyoxal-α-monoxime) has been developed. The PVC-based membrane containing phenylglyoxal-α-monoxime, dibutyl phthalate as plasticizer, and sodium tetraphenylborate as anion excluder and membrane modifier, was directly coated on the surface of a platinum-wire electrode. The response of the electrode was linear with a near-Nernstian slope of 28.2 mV decade^–1 within the Cu²⁺ ion concentration range 1×10^–6–1×10^–1 mol L^–1. The response time for the proposed electrode to achieve a 95% steady potential for Cu²⁺ concentrations ranging from 1×10^–1 to 1×10^–6 mol L^–1 is between 10 and 50 s, and the electrode is suitable for use within the pH range of 3 to 6.5. The electrode has a detection limit of 5×10^–7 mol L^–1 Cu²⁺ and its selectivity relative to several alkali, alkaline earth, transition, and heavy metal ions was good. The coated-wire electrode could be used for at least two months without a considerable alteration of its potential. Applications of the electrode for determination of copper in milk powder samples and as an indicator electrode for potentiometric titration of Cu²⁺ ion using EDTA are reported.

Keywords: Copper-selective electrode Sensors Coated-wire electrode Potentiometric sensors Phenylglyoxal-α-monoxime Ion-selective electrode

No Title by K. Torrence; R. McDaniel; D. Self; M. Chang (pp. 723-731).

The slurry sampling technique has been applied for the determination of As, Cd, and Pb in mainstream cigarette smoke condensate (MS CSC) by graphite furnace–atomic absorption spectrometry (GF–AAS) and inductively coupled plasma–mass spectrometry (ICP–MS). The MS CSC of the 1R4F Reference Cigarette was collected by electrostatic precipitation and was subsequently prepared as two slurry samples with and without the dispersing agent Triton X-100. Comparison of results determined by ICP–MS analyses of the 1R4F MS CSC slurry samples with those from the conventional microwave digestion method revealed good agreement. The precision of Triton X-100 slurry sampling and of microwave-assisted digestion was better than 10% RSD, and both were superior to slurry sampling without use of Triton X-100. The accuracy of the analytical results for the Triton X-100 slurry sample was further verified by graphite furnace–atomic absorption spectrometry (GF–AAS). For GF–AAS, the method limits of detection are 1.6, 0.04, and 0.5 µg L^–1 for As, Cd, and Pb, respectively. For ICP–MS, the method limits of detection are 0.06, 0.01, and 0.38 µg L^–1 for As, Cd, and Pb, respectively. The MS CSC of the 1R4F Reference Cigarette was collected in accordance with the Federal Trade Commission (FTC) smoking regime (35 mL puff volume of 2-s puff duration at an interval of 60 s) and the concentrations of As, Cd and Pb were 6.0±0.5, 69.3±2.8, and 42.0±2.1 ng/cigarette, respectively.

Keywords: Mainstream cigarette smoke condensate Slurry samples Trace metal analysis

No Title by T. Hyötyläinen; T. Tuutijärvi; K. Kuosmanen; M.-L. Riekkola (pp. 732-736).

A sample pretreatment method based on microporous membrane liquid–liquid extraction (MMLLE) was developed for the subsequent gas chromatographic determination of pesticides in wine. MMLLE provided efficient and selective extraction with enrichment factors in the range 3–13. The gas chromatographic separation was carried out using on-column injection and flame ionization detection. The method was linear, repeatable and sensitive. The limits of quantification were better than 0.006 mg/L for all the analytes except for iprodione (0.37 mg/L). The method was applied to the determination of pesticides in several red wines of different origin.

Keywords: Microporous membrane liquid–liquid extraction Pesticides Red wine

No Title by Dandan Chen; Yibin Cao; Baohong Liu; Jilie Kong (pp. 737-739).

A novel BOD biosensor has been fabricated from a microbial membrane on an oxygen electrode; a porous inorganic Al₂O₃ sol–gel matrix was used to immobilize the yeast. Use of the sensor is convenient and rapid compared with the official BOD₅ method. The gelation time required to form the microorganism membrane was less than 15 min. There was linear relationship between the response (sensor current) and BOD values ranging from 10–50 mg L^–1. The lifetime of the BOD biosensor was more than 30 days at ambient temperature.

Keywords: BOD biosensors Microorganism Sol–gel

No Title by Donglan Ma; Guosheng Ding; Jinye Wang (pp. 740-743).

The preparation and characteristics of a new water-soluble reagent, N-phenyl-N′-(sodium p-aminobenzenesulfonate)thiourea (PPT) are described. In the presence of cetyltrimethylammonium bromide (CTMAB) PPT reacts with Au(III), Pd(II), and Pt(IV) to form colored complexes with absorption maxima at 317 nm, 306.1 nm, 778.4 nm, respectively. Optimum conditions for color development were studied. The reagent was used for the simultaneous determination of Au(III), Pd(II), and Pt(IV); Amberlyst A-26 macropore anion-exchange resin was used as a means of rapid separation. The method was applied to the determination of Au(III), Pd(II), and Pt(IV) in catalyst materials and anode mud with satisfactory results.

Keywords: Simultaneous determination Gold(III) Palladium(II) Platinum(IV) Spectrophotometry

No Title by G. Drochioiu (pp. 744-747).

A novel reaction of cyanide with 2,2-dihydroxy-1,3-indanedione in the presence of sodium carbonate is described. It is highly selective and sensitive, and suitable for the determination of hydrogen cyanide in the environment and free cyanide ions in water, blood, urine, serum, etc. As little as 1.25×10^–7 mol L^–1 CN^– (3.25×10^–9 g mL^– ¹ cyanide) can be determined by use of this reaction. The color system obeys Beer's law in the range 10 ng mL^– ¹ to 1.0 µg mL^– ¹ at 510 nm. The molar absorptivity was 8.0×10⁴ L mol^–1 cm^–1 for a solution of concentration 0.2 µg mL^– ¹. All other important analytical properties of the reaction have been studied. It is proposed that the purple color produced under these reaction conditions is that of 2-cyano-1,2,3-trihydroxy-2H indene.

Keywords: Cyanide 2,2-Dihydroxy-1,3-indanedione 2-Cyano-1,2,3-trihydroxy-2H indene

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Analytical and Bioanalytical Chemistry (v.372, #5-6)

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Analytical and Bioanalytical Chemistry (v.372, #5-6)