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Analytical and Bioanalytical Chemistry (v.360, #6)

Analytical methods for antimony speciation in waters at trace and ultratrace levels. A review by Patricia Smichowski; Yolanda Madrid; C. Cámara (pp. 623-629).

This review summarizes and discusses the analytical methods and techniques most frequently described in the literature for the determination of antimony species in waters (and possibly in other matrices) at ultratrace levels. The analytical methods for the separation and/or selective determination of Sb species fall into four main categories: 1. Chemical methods, which include such extraction techniques as: liquid-liquid and liquid-solid extraction, selective hydride generation and coprecipitation methods. 2. Chromatographic methods, which also includes a discussion of hyphenated techniques with different detectors. 3. Electrochemical methods based on the use of electrochemical detectors. 4. Kinetic methods The state-of-the-art of the main applications in waters and environmental samples and future trends are also reviewed.

Development and certification of reference materials for residues of organochlorine and organophosphorus pesticides in beef fat ACSL CRM 1 and 2 by P. Armishaw; J. M. Majewski; P. J. McLay; R. G. Millar (pp. 630-639).

Beef fat samples were prepared and tested as candidate reference materials for organochlorine and organophosphorus pesticides. The CRMs consisted of beef fat spiked with pesticide solutions. One sample (ACSL CRM 1) was prepared containing close to 0.2 mg/kg of each of the organochlorine pesticides dieldrin and heptachlor epoxide. A second sample (ACSL CRM 2) was prepared containing close to 0.8 mg/kg of each of the organophosphorus pesticides diazinon, chlorpyrifos and ethion. The spiking levels and homogeneity of the materials were verified. The coefficients of variation of 5 analyses carried out to test between-jar homogeneity for each reference material were dieldrin, 3.5%; heptachlor epoxide, 1.1%; diazinon, 2.1%; chlorpyrifos, 1.2% and ethion, 3.1%. No instability in any of these compounds was detected over a twelve month period. The candidate reference materials were found to be suitable for certification by interlaboratory testing.The certification process was based on a two-stage nested design described in ISO Guide 35. Analysis of results reported by collaborating laboratories provided an assessment of the homogeneity of the reference materials. The certified values together with their upper and lower 95% confidence limits are:ACSL CRM 1*Dieldrin*0.199 mg/kg**(0.188,**0.210 mg/kg)*Heptachlor epoxide*0.194 mg/kg **(0.176,**0.212 mg/kg)ACSL CRM 2*Diazinon*0.805 mg/kg**(0.755, **0.855 mg/kg)*Chlorpyrifos*0.790 mg/kg**(0.728,**0.852 mg/kg)*Ethion*0.813 mg/kg**(0.746,**0.879 mg/kg).A certificate for each material was prepared according to the guidelines set out in ISO Guide 31.

Reference materials for PAHs in foodstuffs: Results of the certification exercise of two coconut oil reference materials by T. Win; W. Luther; J. Jacob; H. A. M. G. Vaessen; A. Boenke (pp. 640-644).

This certification exercise was the final stage of a stepwise interlaboratory study approach, organized within the SMT-program of the EC, for the development of certified reference materials (CRMs) for the determination of PAHs in foodstuffs. The certification exercise was carried out by thirteen European laboratories using a variety of extraction and clean-up procedures and different analytical procedures. Two different coconut oil materials were certified for their mass fractions of six selected PAHs.

Determination of bismuth, indium and lead in geological samples by electrothermal AAS Part 2. Comparative study of palladium and molybdenum containing chemical modifiers* by Orhan Acar; A. Rehber Türker; Ziya Kılıç (pp. 645-649).

A comparative and systematic study has been carried out of the effects of palladium and molybdenum containing chemical modifiers, such as Pd + Rh, Pd + Pt, Pd + Ru, Pd + Rh + Pt, Pd + Rh + Ru, Mo + Pd, Mo + Rh, Mo + Ru and Mo + Pt and additionally tartaric acid (TA) as a reducing agent together with mixed modifiers for the thermal stabilization of Bi, In and Pb in a Zeeman electrothermal atomic absorption spectrometer (ETAAS). The effect of the mass ratios of the mixed modifier components on the maximum pretreatment temperature for the analytes has been determined. The modifier mixtures of Pd + Rh + Pt, Mo + Pd + TA and Mo + Pt + TA were found to be especially powerful for the determination of Bi, In and Pb. These mixed modifiers could increase the ashing temperatures of the analytes up to 1250–1400° C. They were applied to the determination of Bi and Pb in dissolved geological reference samples and accuracy and precision of the method were thereby enhanced. The percent relative error was decreased from 20.0 to 0.4 for Bi and from 10.5 to 0.3 for Pb, depending on the sample type.

Determination of silicon using electrothermal Zeeman atomic absorption spectrometry in presence of some transition metals as modifiers by A. F. Shoukry; Y. M. Issa; R. A. Farghaly; M. Grasserbauer; H. Puxbaum; J. Rendl (pp. 650-653).

The transition metals ions Cr(III), Mn(II), Fe(III), Co(II), Ni(II), and Zn(II) in addition to Ca(II) have been used as modifiers in the determination of silicon using electrothermal Zeeman atomic absorption spectrometry. Co(II) proved to be the best. Graphite tubes treated with zirconium, in the presence of Co(II) as a modifier, exhibit higher sensitivity by a factor of five than untreated tubes. The modifier concentration and ashing and atomization temperatures have been optimized. Also interference of different inorganic cations and anions was studied.

Metal oxide-modified carbon paste electrodes and microelectrodes for the detection of amino acids and their application to capillary electrophoresis by J. Labuda; A. Meister; P. Gläser; G. Werner (pp. 654-658).

Using cyclic voltammetry and constant-potential amperometry, copper, nickel, cobalt, lead, silver, manganese, bismuth and palladium oxides in a carbon paste matrix have been investigated as redox mediators for the electro-oxidation of amino acids in the 0.05 mol/L NaOH medium. CuO and NiO have been found to be the most effective electrocatalysts. The 150 μm I.D. microelectrode with 25% CuO was applied to the amino acids detection in capillary electrophoresis.

Construction and evaluation of ion-selective electrodes for potassium and calcium with a summing operational amplifier. Application to wine analysis by R. Pérez-Olmos; A. Rios; R. A. S. Lapa; J. L. F. C. Lima (pp. 659-663).

Electrodes selective to potassium and calcium with improved senstivity were constructed like conventional electrode (ISEs), but used an operational amplifier to sum the potentials supplied by the four membranes (ESOAs). The results obtained during the evaluation of their working characteristics were compared to those obtained by conventional ISEs and were found to be similar, but with higher precision. The electrodes were used in the potentiometric determination of potassium, calcium and magnesium in wines. The results given by ESOAs were more precise than those from ISEs. The results obtained by potentiometry were in good agreement with those from AES for potassium and AAS for calcium and magnesium.

Determination of naturally occurring radionuclides in ultrapure organic liquids by R. v. Hentig; T. Goldbrunner; F. v. Feilitzsch; G. Angloher (pp. 664-668).

For the determination of trace elements in organic liquids radiochemical neutron activation analysis has been combined with counting methods geared to various decay modes of indicator radionuclides leading to a high sensitivity required for ultrapure samples. The activation parameters such as irradiation time, sample mass and neutron flux have been enlarged to the maximum possible in the available irradiation facility. Separation yields and adsorption losses have been studied in detail for a set of elements in order to rule out losses during the separation process. The attainable limits of detection are 2 · 10^–16g/g for U and Lu, in the 5 · 10^–15g/g range for Th and Sm, in the 1 · 10^–14g/g region for La, 5 · 10^–13g/g for Rb, Cd and 2 · 10^–12g/g for K and In. Although the analysis focused on traces of naturally occurring radioisotopes, results for Cr, Fe, W and Zn are presented as well.

Spectroscopic investigations in molecularly organized solvent media. Part 3. Examination of the nitromethane selective quenching rule in aqueous anionic + cationic and anionic + nonionic mixed surfactant solutions by S. Pandey; K. A. Fletcher; W. E. Acree Jr; C. Fetzer (pp. 669-674).

Applicability of the nitromethane selective quenching rule for discriminating between alternant versus nonalternant polycyclic aromatic hydrocarbons (PAHs) is examined for 20 representative PAH solutes dissolved in micellar sodium dodecylsulfate (SDS) + cetyltrimethylammonium bromide (CTAB), SDS + dodecyltrimethylammonium bromide (DTAB), SDS + Brij-35, and SDS + sodium octanoate (SO) mixed surfactant solvent media. Experimental results show that nitromethane quenched fluorescence of all 8 alternant PAHs studied in the four different solvent systems. Unexpected quenching behavior was observed, however, in the case of nonalternant PAHs. Nitromethane quenched fluorescence emission of nonalternant PAHs dissolved in the SDS + SO solvent media, which is contrary to the selective quenching rule. In the case of the mixed anionic + cationic surfactant solvent media, nitromethane quenching selectivity was restored at concentration ratios of approximately 4 : 1 (anionic:cationic) or less.

Determination of N-acetyl-L-cysteine by flow-injection potentiometry by Nj. Radić; J. Komljenović (pp. 675-678).

A multi-purpose tubular flow-through sensor was constructed with an AgI-based membrane. The membrane was prepared by pressing silver salts (AgI, Ag₂S) and powdered Teflon. This membrane was incorporated in the tubular flow-through sensor body. A 2-mm diameter hole was drilled through the center of the tubular sensor and the membrane, thus determining the active sensor volume of about 4 μL. The tubular sensor with reference electrode was placed into a complex flow-injection system and used for the flow-through determination of N-acetyl-L-cysteine, (NAC), in perchloric acid medium, pH = l. Linear dependence was established between the recorded signal height and the concentration of NAC in the injected sample. The recorded change in potential for a decade change in concentration, 62 mV {p (NAC)}^–1, in the concentration range from 1 × 10^–4 to 1 × 10^–1 mol L^–1, was based on the formation mechanism of the sparingly soluble deposit between silver and NAC on the surface of the sensitive part of the membrane.

Separation of the reaction products of cyanazine and terbuthylazine nitrosation by thin-layer chromatography by W. Zwickenpflug; H. Weiß; N. Fürst-Hunnius; E. Richter (pp. 679-682).

N-Nitroso-triazine herbicide species were synthesized as reference standards and their reaction products were separated by TLC. The method was established for analytical as well as for preparative amounts to achieve a sufficient separation between the educts, the byproducts and the N-nitrosated moieties. Separation of the reaction mixture was performed by two-dimensional TLC, using different mobile phases for each dimension. In the second dimension two developments were executed using the same solvent mixture. To examine the quality of performance, the separation zones were scrapped off, extracted and analyzed in the HPLC-diode array detection (DAD) mode in comparison with standards of the educts and the products of their N-nitrosation. This method minimizes the contact with the resulting N-nitroso compounds. At present nothing is known about the toxicological relevance or risk assessment on human health of N-nitrosocyanazine or N-nitrosoterbuthylazine species. Therefore the practical handling of these putative mutagenic and carcinogenic substances should be seen under the aspect of precaution and prevention of contamination.

The application of butanol as dilution agent for the inductively coupled plasma-atomic emission spectrometric determination of boron and phosphorus in lubricating oils by Ricardo N. Garavaglia; Rubén E. Rodríguez; D. A. Batistoni (pp. 683-688).

An evaluation of butanol-1 as dilution solvent for the determination of boron (B) and phosphorus (P) in lubricating oils by inductively coupled plasma-atomic emission spectrometry (ICP-AES) has been performed. Standard solutions of boric acid and tri-n-butyl phosphate (TBP) in butanol were employed as calibrants for B and P, respectively. Solutions of phosphoric acid and tris(2-ethylhexyl)phosphate (TEHP) in butanol were also tested as possible P standards. Increased concentrations of oil in the sample in the range of 0 to 20% showed no significant effects on B and P emission intensities indicating that matrix matching is not required for lubricating oils of about 2–15 cPoise. Detection limits in absence of spectral interferences were 0.06 μg B/g oil and 2 μg P/g oil. Overall estimated precision was 2.5% for B concentrations above 4 μg/g oil, and 6.5% for P concentrations above 20 μg/g oil. We evaluated the performance of a high resolution scanning spectrometer for mitigating the effects of overlapping spectral interferences from iron (Fe) and copper (Cu) on B and P emission lines. An interference from Fe 249.782 nm on the primary B line at 249.773 nm is observed for Fe concentrations higher than 100 μg/g oil, but a secondary B line at 249.678 nm is completely resolved from Fe 249.653 nm. In the case of P 213.618 nm, a contribution of the right wing of a Cu line at 213.598 nm generates a signal equivalent to P 18 μg/g oil for Cu 1000 μg/g oil.

Possibilities and limitations of an enzyme-linked immunosorbent assay for the detection of 1-nitropyrene in air particulate matter by B. Fröschl; D. Knopp; R. Niessner (pp. 689-692).

ELISAs (enzyme-linked immunosorbent assays) are generally used in environmental analytical chemistry for screening purposes. In this work the applicability of a polyclonal-based 1-nitropyrene-ELISA for the quantification of the target analyte in air particulate matter was investigated. Validation was performed using an HPLC method with fluorescence detection of the reduced form of 1-nitropyrene. It was found that the immunoassay is not only sensitive for the target analyte but to a certain extent also for other cross-reacting molecules present in the sample, such as 2-nitropyrene and 2-nitrofluoranthene, which were identified by GC-HRMS and are considered to be products of photochemically induced reactions of pyrene or fluoranthene, respectively. The degree of correlation between ELISA and HPLC results for collected samples of air particulate matter was inversely dependent on the distance between the sampling location and the source.

Pilot study: PAH fingerprints of aircraft exhaust in comparison with diesel engine exhaust by J. Krahl; H. Seidel; H.-E. Jeberien; M. Rückert; M. Bahadir (pp. 693-696).

In the course of a preliminary investigation the PAH fingerprints from diesel engines were compared with those from aircraft turbines. The goal was to determine whether PAH fingerprints permit to distinguish between the sources of air and road traffic. The results showed that the PAH spectra of both sources do not vary significantly. However, in turbine exhaust gas p-quaterphenyl was found, that is untypical for diesel engines. So this component may be a tracer for PAH pollution from aeroplanes.

Direct multiparametric determination of anions in soil samples by integrating on-line automated extraction/filtering with capillary electrophoresis by Lourdes Arce; Angel Ríos; M. Valcárcel (pp. 697-701).

An integrated continuous flow-capillary electrophoresis for the determination of soluble anions in soil samples is presented. A filtration probe coupled with the flow system, which is located before the capillary electrophoresis instrument, was designed to simplify sample pretreatment and to perform clean-up of aqueous soil suspensions. Only the manual weighing of the samples is needed. The extraction process for soil samples was optimized. The clear filtrate containing the soluble anions from soil was then passed to the capillary electrophoresis equipment by a home-made programmable arm. Chloride, sulfate, nitrite and nitrate were determined in soil samples at μg g^–1 level and the results compared to manual reference methods. The precision expressed as relative standard deviation was in the range of ± 1.6 to ± 2.5% for the set of analytes determined. The procedure is up to 4 times faster than the competitive manual methods.

Optical fiber sensor for berberine based on fluorescence quenching of 2-(4-diphenylyl)-6-phenylbenzoxazole by Ying Wang; Wanhui Liu; Kemin Wang; Guoli Shen; R. Yu (pp. 702-706).

A new optical fiber sensor was prepared for the determination of berberine in aqueous solution using a micrometer-sized flow-cell and a bifurcated optical fiber. The sensing is based on fluorescence quenching of 2-(4-diphenylyl)-6-phenylbenzoxazole (PBBO) in the PVC membrane. This process is accompanied by non-fluorescent ground-state complex formation. With this sensor, berberine can be determined in sample solutions from 2.42 × 10^–5 mol L^–1 to 6.04 × 10^–7 mol L^–1. Satisfactory reproducibility, reversibility, and short response times of less than 1 min are realized. The sensor also shows good selectivity over some common pharmaceutical species and alkali and alkali-earth metal salts, and can be used for the direct assay of berberine in commercial tablets. The results are in correspondence with those obtained by the pharmacopoeia method.

Acid predigestion as a slurry pretreatment for the determination of Ca, Cu, K, Mg, Na and Zn in human scalp hair by flame atomic absorption/emission spectrometry with a high-performance nebulizer by P. Bermejo-Barrera; Antonio Moreda-Piñeiro; Jorge Moreda-Piñeiro; Adela Bermejo-Barrera (pp. 707-711).

A comparison was carried out between the use of wetting agents, Viscalex HV30 or glycerol, and an acid predigestion of the slurry for the determination of major metals (Ca, Cu, K, Mg, Na and Zn) in human scalp hair by FAAS/FAES with a high-performance nebulizer. Human scalp hair was pulverized in a Zr vibrating ball mill over a period of 20 min (mean particle size about 0.8 μm measured by laser diffraction). The use of wetting agents was only found adequate for dilute slurries; thus, Viscalex HV30 can be proposed for the determination of Zn in scalp hair slurries (relative atomization efficiency close to unit). For all cases, the use of acidified slurries with nitric acid at a concentration of 1.0% offers adequate analytical performance: LODs of 5.0, 3.5, 3.1 and 20.0 mg kg^–1 for Ca, Cu, Fe and K, respectively, and 1.7, 0.6 and 3.5 μg kg^–1 for Mg, Na and Zn. The repeatability of the overall method (n = 11), acid predigestion-slurry pretreatment and FAAS/FAES determination expressed as RSD (%), was between 8.7 for Zn and 18.6 for K. The developed methods were applied to 25 human scalp hair samples from healthy adults.

Comparative study on the use of Ir, W and Zr-coated graphite tubes for the determination of chromium in slurries of human scalp hair by electrothermal atomic absorption spectrometry by P. Bermejo-Barrera; Antonio Moreda-Piñeiro; Jorge Moreda-Piñeiro; Adela Bermejo-Barrera (pp. 712-716).

The use of Ir, W and Zr-coated graphite tubes, as permanent chemical modifiers, was studied for the determination of chromium in human scalp hair by ETAAS using the slurry sampling technique. The use of Mg(NO₃)₂ and Pd, as aqueous chemical modifiers, was also investigated and compared to the use of the permanent chemical modifiers. Scalp hair samples were pulverized using a Zr vibrational ball mill, (mean particle diameter of 0.8 μm) and suspended in ultrapure water. The lowest limit of detection, 44.5 μg kg^–1,was achieved for the use of W-coated graphite tubes. The repeatability of the overall procedures (slurry preparation and ETAAS determination) were 15.7, 14.5 and 16.7% for W- and Zr-coated graphite tubes and Mg(NO₃)₂, respectively. The methods were applied to several reference materials, CRM 397 (human hair), DOLT-1 (dogfish liver) and DORM-1 (dogfish muscle), and the results obtained were in agreement to the certified values. Finally, the methods were applied to several human scalp hair samples from healthy adults.

Determination of alkaline phosphatase activity in human sera by mid-FTIR spectroscopy by B. Lendl; P. Krieg; R. Kellner† (pp. 717-720).

Fourier transform infrared spectroscopy is applied to the determination of alkaline phosphatase (ALP) activity in human sera. 4-nitrophenylphosphate was found to be an excellent ALP substrate for FT-IR spectroscopic detection. The developed method is based on the acquisition of two FT-IR spectra: one recorded immediately after mixing the sample and assay solution and the other after an incubation time of 10 min. Spectral changes in the mid IR range due to the enzymatic reaction could be correlated to the ALP activity in the sample. Experimental conditions were established such that the clinically relevant range for determination of ALP activity in human sera (50 to 900 U/L) was covered. The method was applied to the analysis of ALP activities in standard solutions as well as in human sera yielding results which agreed well with those obtained by a standard reference method.

Study and application of a method for the determination of metallic elements by ICP-AES with preconcentration on an active carbon-silica gel microcolumn in a FI system by Hongnian Ji; Zhenhuan Liao; Junmei Sun; Zucheng Jiang; Hongnian Ji; Zhenhuan Liao; Junmei Sun; Zucheng Jiang (pp. 721-723).

Using active carbon-silica gel as adsorbent and sodium diethyldithiocarbamate (NaDDTC) as chelating reagent in a flow injection system, an ICP-AES method has been developed for preconcentration and determination of trace metallic elements in high purity rare earth oxides. The experimental parameters such as pH, flow rate, amount of adsorbent, length of reaction coil and eluent acidity were optimized. At pH 4.6 Al,Cr,Cu,Fe,Pb,V,Zn could be preconcentrated, and subsequently determined by ICP-AES. This method can eliminate matrix effects. Its enrichment factors were 8.1–12.6 with detection limits in the ng/mL range and RSD of 2.3–5.0. This method was applied to the analysis of high purity of La₂O₃ and Eu₂O₃ with satisfactory results.

Selenium determination using ethylation and on-line trapping/detection by graphite furnace atomic absorption spectrometry by R. Allabashi; J. Rendl; M. Grasserbauer (pp. 723-725).

An on-line system for the continuous ethylation of selenium (IV) in combination with trapping and detection of the produced diethylselenide in the coated AAS graphite furnace was developed. Due to the slow kinetics of the ethylation the volume of the reaction coil and the reaction time had to be increased to 5.5 mL and 80 s, respectively. The sensitivity of the method was comparable with that of the hydride generation in the same system and the relative standard deviation was 6–10%. The determination of Se(IV) in real samples after the most widely used digestion with nitric acid could not be accomplished, because of the drastic signal depression caused by this acid.

Determination of copper in sulfide minerals by Zeeman electrothermal atomic absorption spectrometry by Anna Lazaru; Trajče Stafilov (pp. 726-728).

A method for the determination of copper in some sulfide minerals (lorandite, realgar, orpiment, marcasite, stibnite, galenite and sphalerite) by Zeeman electrothermal atomic absorption spectrometry is presented. After the dissolution of samples, copper was extracted with sodium diethyldithiocarbamate into different organic solvents (carbon tetrachloride, chloroform and methylisobutyl ketone) at pH 11.0–12.0. The procedure was verified by standard addition. The standard deviation (SD) for 0.5 ng Cu is 0.01 ng, the relative standard deviation ranges from 3.5 to 5.5% and the detection limit of the method, calculated as 3 SD of the blank, was found to be 0.05 μg · g^–1.

Separation of mixed hexafluorochloro- and hexafluorobromo-rhenates(IV), ReFnX6–n2– (X = Cl, Br; n = 0–6) including the cis/trans and fac/mer isomers by HPLC and their characterization by a photodiode array detection system by H. Müller; M. Idilbi (pp. 729-731).

HPLC with Nucleosil 10 Anion has been used for the separation of mixed hexafluorochloro- and hexafluorobromo-rhenates(IV) and for their characterization by UV-vis spectra.

The europium/samarium-2-benzoyl-indane-1,3-dione-cetyltrimethylammonium bromide fluorescence system and its analytical application by Zhikum Si; Wei Jiang; Yuanju Ding; Jingtian Hu (pp. 731-734).

The fluorescence system of the Eu³⁺ (or/and Sm³⁺)-2-benzoyl-indane-1,3-dione(BID)-cetyltrimethylammonium bromide (CTMAB) was investigated at excitation wavelengths of 350 nm, and emission wavelengths at 612 nm for europium and 565, 606 and 650 nm for samarium, respectively. The system was used for the determination of Eu and Sm in rare earth oxides and of BID in water. Europium or/and samarium could be determined in the range of 1.0 × 10^–9–1.0 × 10^–5 mol/L and 2.0 × 10^–8–5.0 × 10^–5 mol/L, respectively; 1.0 × 10^–6–2.0 × 10^–5 mol/L of BID could also be determined.

Indirect atomic absorption spectroscopic determination of SiO2 in copper composite coatings by V. Terzieva; L. Jordanova; S. Arpadjan (pp. 734-736).

A fast, sensitive and reliable method for the indirect atomic absorption determination of SiO₂ in copper composite coatings after extraction of silicomolybdic acid in a mixture of isobutyl methyl ketone and butanol (volume ratio 5 : 1) and measurement of the molybdenum absorbance in an air/acetylene flame is described. The experimental conditions are optimized for (i) prevention of the silicon polymerization during sample preparation and storage; (ii) for overcoming of the Cu(SiF₆) – complex formation and (iii) for quantitative extraction of the yellow complex into the organic phase for a wide silicon concentration range. The method permits the determination of 0.5–10 mg/g Si in copper. The analytical performance of the proposed method is compared with direct Si determination using ICP-AES.

ICP-OES determination of traces of Ru, Au, V and Ti preconcentrated and separated by a new poly(epoxy-melamine) chelating resin from solutions by Xi-Jung Chang; Bo-Lin Gong; Zhi-Xing Su; Dong Yang; Xing-Yin Luo (pp. 736-739).

A new poly(epoxy-melamine) chelating resin is synthesized from epoxy resin and used for the preconcentration and separation of traces of Ru(III), Au(III), V(V) and Ti(IV) ions from sample solutions. The ions analyzed can be quantitatively enriched by the resin at a flow-rate of 2 mL/min at pH 4, and quantitatively desorbed with 10 mL of 1 mol/L HCl + 0.2 g CS(NH₂)₂ at a flow-rate of 1 mL/min with recoveries of over 97%. The chelating resin can be reused 7 times without obvious loss of efficiency. Thousand-fold excesses of coexistent ions caused little interference during the enrichment and determination steps. The RSDs for the determination of 50 ng/mL Ru(III) and Au(III), 5.0 ng/mL V(V) and Ti(IV) were in the range of 1.5–4.5%. The recoveries of added standards in a real sample solution are between 96% and 100%, and the results for the ions analyzed in a nickel alloy sample are in good agreement with their reported values.

Investigations on the applicability of two ELISA types for the determination of chlorpyrifos in soil samples compared with a gas chromatographic method by V. Heber; J. Siebers; H.-G. Nolting; H.-J. Vetten; R. Kreuzig; M. Bahadir (pp. 739-741).

Two commercially available ELISA kits for water analysis, a microtiter plate-ELISA based on polyclonal antibodies (p-ELISA) and a magnetic particle tube-ELISA based on monoclonal antibodies (t-ELISA), were used to determine chlorpyrifos residues in soils. Comparison with a gas chromatographic method frequently applied was carried out by fortification experiments and by analyses of real soil samples. At concentration levels of 1.0, 0.1, 0.05 and 0.01 mg/kg, chlorpyrifos was reliably determined by the GC method. Application of the p-ELISA did not permit a reliable quantitation, while the t-ELISA was applicable in a concentration range of 0.05–1.0 mg chlorpyrifos/kg dry soil.

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Analytical and Bioanalytical Chemistry (v.360, #6)