University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Knut Irgum

Abbrev:
Irgum, K.
Other Names:
Address:
Department of Chemistry, Umea University, S-901 87 Umea, Sweden
Phone:
+46-90-7865265
Fax:
+46-90-136310

Citations 9

"Immobilized 2-(4-hydrazinocarbonylphenyl)-4,5-diphenylimidazole As Solid-phase Luminophore In Peroxyoxalate Chemiluminescence"
Fresenius J. Anal. Chem. 1996 Volume 356, Issue 1 Pages 84-89
Einar Pontén, Patrik Appelblad, Malin Stigbrand, K. Irgum and Kenichiro Nakashima

Abstract: A new luminophore for application in peroxyoxalate chemiluminescence is presented. An analogue of the well-known chemiluminescence compound lophine, i.e. 2-(4-hydrazinocarbonylphenyl)-4,5-diphenyl-imidazole (HCPI), has been covalently immobilized to controlled pore glass and a porous methacrylate resin. By using this reagent in a solid phase detection reactor, sensitive determinations of hydrogen peroxide have been demonstrated. In homogeneous solution HCPI emits poorly as a result of 1,1'-oxalyldiimidazole excitation, but when immobilized its efficiency is almost comparable to highly efficient luminophores such as 3-aminofluoranthene. Linearity extends in the single stream flow system over several orders of magnitude with both materials. The limit of detection was 1 nmol/l (10 fmol injected), when using the porous methacrylate support.
Hydrogen peroxide Chemiluminescence HPLC Solid phase reagent Controlled pore glass Resin Immobilized reagent Solid phase detection

"Heterogeneous Hydride Generation In A Packed Membrane Cell"
Fresenius J. Anal. Chem. 1991 Volume 341, Issue 9 Pages 532-536
Solomon Tesfalidet and Knut Irgum

Abstract: Volatilization of arsenic, selenium and antimony for sample introduction in atomic absorption spectrometry has been performed by pumping an acidic sample through an anion exchanger in the tetrahydroborate (III) form packed as a bed in the liquid channel of a gas-liquid separation membrane cell. The hydrides generated in the heterogeneous reaction between bound tetrahydroborate (III) ions and the analytes are rapidly transferred with the aid of the concomitantly generated hydrogen gas through the gas-permeable membrane into the gas phase and swept to the spectrometer by an additional hydrogen gas flow. This instant transfer of the hydrides to the gas phase kinetically discriminates the reaction of the hydride with metal borides and metal colloids, whose formation by reaction with tetra-hydroborate (III) is slower than the hydride reaction. The susceptibility to interference by transition metal ions is thus markedly reduced, as compared with both batch hydride generation methods and a previously presented heterogeneous reaction scheme. The detection limits for arsenic, selenium, and antimony were 1.2, 3.7, and 10 g/l, respectively. The calibration graphs were linear from the detection limit up to 125 g/l for arsenic, 150 g/l for selenium, and 250 g/l for antimony. The relative standard deviations at concentration levels of 10 and 100 g/l were 1.8 and 0.7% for arsenic and 2.3 and 1.2% for selenium. Corresponding figures for 50 and 100 g/l antimony were 2.5 and 1.6%.
Selenium Spectrophotometry Volatile generation Interferences Membrane Volatile generation

"New Nucleophilic Catalysts For Bright And Fast Peroxyoxalate Chemiluminescence"
Anal. Chem. 2000 Volume 72, Issue 7 Pages 1373-1380
Tobias Jonsson and Knut Irgum

Abstract: Miniaturized detection applications based on chemiluminescence require fast reaction kinetics for optimum performance. in this work, high-intensity light from the analytically useful peroxyoxalate chemiluminescence reaction has been generated at high rates by employing both single-component and dual-component nucleophilic catalysis. 4-(Dimethylamino)pyridine and its derivatives were superior to all other bases in terms of reaction speed and intensity of the generated light and outshone imidazole, which hitherto has been considered as the best catalyst, The light intensity was related to the difference in pK(a) between the 4-aminopyridine catalyst and the leaving group of the reagent, and the optimum Delta pK(a) was found to be close to 0. Similarly, high light intensities were obtained when mixtures of the imidazole analogue 1,2,4-triazole and the strong, nonnucleophilic base 1,2,2,6,6-pentamethylpiperidine acted as catalysts, The mechanism behind this was concluded to be a base-induced nucleophilic catalysis, where the ancillary strong base assisted the production of the highly nucleophilic 1,2,4-triazolate anion, which as the actual catalyst then participated in the formation of a more reactive transient reagent. All the investigated catalysts reduced the light yield of the reaction due to base-catalyzed breakdown reactions of the reagents and/or intermediates. The intensity peak maximums of these bright and fast reactions typically appeared after less than 10 ms, whereafter the light decayed to darkness within a few seconds, These reaction characteristics are especially advantageous for sensitive detection applications where the observation volumes and times are limited, e.g., peaks emerging from a capillary-based separation process.

"Immobilized Amino Aromatics For Solid-phase Detection Using Imidazole-mediated Bis(trichlorophenyl) Oxalate Chemiluminescence"
Anal. Chem. 1995 Volume 67, Issue 23 Pages 4302-4308
Einar Ponten, Malin Stigbrand, and Knut Irgum

Abstract: This investigation examines six amino polycyclic aromatic hydrocarbons, covalently immobilized onto non-porous and porous methacrylate, controlled-pore glass, and Merrifield (S-DVB) beads, for their suitability in solid phase peroxyoxalate chemiluminescence detection, The solid phase luminophores were packed in a now cell mounted adjacent to a photomultiplier tube, and the properties of the different reagents were evaluated by injecting aqueous hydrogen peroxide into a stream of premixed bis(trichlorophenyl) oxalate and imidazole in acetonitrile, The highest sensitivity was obtained with 3-aminoperylene and 3-aminofluoranthene, A high degree of functionalization as well as a large surface area of the support increased the efficiency, The porous methacrylate material was found to give better sensitivity and precision than a non-porous material of similar composition, In this respect, the porous methacrylate support was also superior to controlled-pore glass, although these materials gave similar detection limits. The microporous S-DVB copolymer with the same overall degree of functionalization as the porous methacrylate support showed a lower sensitivity, since its subsurface functionalization did not contribute to the efficiency. (49 references)
Hydrogen peroxide Chemiluminescence Controlled pore glass Immobilized reagent Solid phase detection

"1,1'-oxalyldi-imidazole As Chemiluminescence Reagent In The Determination Of Low Hydrogen Peroxide Concentrations Of Flow Injection Analysis"
Anal. Chem. 1994 Volume 66, Issue 10 Pages 1766-1770
Malin Stigbrand, Einar Ponten, and Knut Irgum

Abstract: Sample solution (50 µL) were injected into a reagent stream (1 ml/min) of 5 mM 1,1'-oxalyldi-imidazole in acetonitrile. After mixing, the solution passed through a flow cell (2.2 cm x 2.4 mm i.d.) packed with polymethacrylate beads on which the fluorophore 3-aminofluoranthrene had been immobilized. The flow cell was mounted as close as possible to the window of a side-view photomultiplier tube, with a piece of specular Al foil above the cell as a reflector. Calibration graphs were linear for 1.5-6 µM-H2O2, with a detection limit of 10 nM. This detection limit and the non-zero intercept arise from traces of background H2O2 present in water, which are difficult to remove. The signal from 6 µM-H2O2 repeatedly injected decreased 7% after 1 h. The new reagent was 10 times more sensitive than trichlorophenyl oxalate, which also required a separate imidazole catalyst reagent stream.
Hydrogen peroxide Environmental Chemiluminescence

"Polymer-bound Tetrahydroborate For Arsine Generation In A Flow Injection System"
Anal. Chem. 1989 Volume 61, Issue 18 Pages 2079-2082
Solomon Tesfalidet and Knut Irgum

Abstract: Generation of arsine for subsequent AAS determination was carried out in a flow system using a column (10 cm x 6 mm) of Amberlyst A-26 (20 to 50 mesh) in the tetraborate form as a polymer-supported reducing agent. The analysis cycle comprised regeneration, washing and injection of HCl-acidified sample, and could be repeated every 4 min. The detection limit for As(III) was 1.5 µg L-1 (40 µL sample) and the calibration graph was rectilinear up to 100 µg l-1. Nickel, Co, Cu and Fe ions caused 10% signal degradation when present at concentration. of 2500 to 5000 mg L-1 when L-cystine was added as masking agent. The column could be used for at least 3 months without performance degradation.
Arsenic Spectrophotometry Interferences Calibration Immobilized reagent Volatile generation Reduction column Volatile generation

"Very Fast Peroxyoxalate Chemiluminescence"
Anal. Chim. Acta 1999 Volume 400, Issue 1-3 Pages 257-264
Tobias Jonsson and Knut Irgum

Abstract: Peroxyoxalate chemiluminescence (PO-CL) detection offers an advantage in chromatographic detection, by the virtue of its multiple unique selectivities and high sensitivity. However, many of the analytical separation techniques available today require observation times in the millisecond range to preserve the band resolution, and as the reaction kinetics of the PO-CL reaction is considerably slower, extra flow elements are needed to observe the reaction in a time window at maximum emission intensity. Since these flow elements increase the complexity of the system and contribute to band-broadening, the rational way to adapt PO-CL detection to miniaturised separation systems is to speed up the reaction, so that it emits an initial burst of light within the acceptable detection time-frame. Although this may result in a lower overall quantum yield, the actual detection sensitivity could be equal to, or better than slower PO-CL systems. By making careful selections of oxalic reagent and catalyst(s) the reaction can be fine-tuned to maximise the intensity. In this work, the time-dependent light emission from the reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO) was studied under the catalytic influence of imidazole, 1,2,4-triazole, 4-dimethylaminopyridine (DMAP), and 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU) in acetonitrile. Both DMAP and DBU accelerated the reaction substantially, but the best combination of reaction speed and intensity was found for a mixture of 0.5 mM DBU and 5 mM 1,2,4-triazole, which reached its maximum emission after only 40 ms and had an emission intensity comparable to that seen with 5 mM imidazole as catalyst.
Fountain cell

"Heterocyclic Compounds As Catalysts In The Peroxyoxalate Chemiluminescence Reaction Of Bis(2,4,6-trichlorophenyl)oxalate"
Anal. Chim. Acta 1998 Volume 361, Issue 3 Pages 205-215
Tobias Jonsson, Malin Emteborg (b. Stigbrand) and Knut Irgum*

Abstract: Substituted imidazoles and leaving groups known from other areas of chemistry have been tested for catalytic efficiency in the peroxyoxalate chemiluminescence (PO-CL) reaction, using bis(2,4,6-trichlorophenyl)oxalate (TCPO) as reagent. Catalytic activity was found for 1,2,4-triazole, 1-methylimidazole, 2-methylimidazole, 4-methylimidazole and 4,5-dichloroimidazole, while 2-mercaptioimidazole, 2-nitroimidazole, 4-nitroimidazole, benzimidazole, benzotriazole, thiazole, o-benzoic sulfimide, phthalimide, succinimide, 2(1H)-pyridone and 1,2,3-benzotriazine-4(3H)-one yielded no detectable chemiluminescence under the conditions used. None of the tested compounds was more efficient than imidazole in catalyzing the PO-CL reaction. Spectrophotometric measurements of the catalytic breakdown of TCPO showed that an intermediate was formed with almost all catalysts, and that intermediates that were more stable or present at lower concentration led to a reduced catalytic efficiency in the PO-CL reaction of TCPO.
1,2,4-Triazole 1-Methylimidazole 2-Methylimidazole 4-Methylimidazole 4,5-Dichloroimidazole Chemiluminescence Indirect Reaction intermediates Catalysis

"Peroxyoxalate Chemiluminescence In Aqueous Solutions: Coupling Of Immobilized Enzyme Reactors And 1,1'-oxalydiimidazole Chemiluminescence Reaction To Flow Injection Analysis And Liquid Chromatographic Systems"
Anal. Chim. Acta 1997 Volume 357, Issue 1-2 Pages 111-118
Malin Emteborg (b. Stigbrand)a, Knut Irguma,*, Cees Gooijerb and Udo A. Th. Brinkmanb

Abstract: A highly sensitive method for the determination of enzymatically generated hydrogen peroxide in flow-injection analysis (FIA) and liquid chromatography (LC) has been developed. A dual-line flow system is used, one carrier (or eluent) delivering the analyte and the other one the chemiluminescent reagent 1,1'-oxalyldiimidazole (ODI). The results show that the composition of the analyte flow line is not critical for the chemiluminescence detection step; even purely aqueous buffers, as generally applied if immobilized enzyme reactors (IMERs) are involved in FLA and LC, can be used without loss of sensitivity. IMERs containing either glucose oxidase or acetylcholine esterase/choline oxidase were incorporated in this flow line and favourable detection limits (S/N = 3) were obtained, i.e. 3 nM for glucose and 50 nM for acetylcholine and choline. The performance of the approach in real-sample analysis was tested by determining glucose and choline in urine samples.
Glucose Choline Urine Chemiluminescence LC Immobilized enzyme Post-column derivatization Reactor