University of North Florida
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Contact Info

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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Gerald Gubitz

Abbrev:
Gubitz, G.
Other Names:
Gerald Gübitz
Address:
Institute of Pharmaceutical Chemistry, Karl-Franzens University, Universitatsplatz 1, A-8010 Graz, Austria
Phone:
+43-316-380-5371
Fax:
+43-316-380-9846

Citations 10

"Development Of Enantioselective Chemiluminescence Flow- And Sequential-injection Immunoassays For α-amino Acids"
J. Biochem. Biophys. Methods 2002 Volume 53, Issue 1-3 Pages 1-14
Hossein Silvaieh, Martin G. Schmid, Oliver Hofstetter, Volker Schurig and Gerald Gübitz

Abstract: The development of an enantioselective flow-through chemiluminescence immunosensor for amino acids is described. The approach is based on a competitive assay using enantioselective antibodies. Two different instrumental approaches, a flow injection (FIA) and a sequential-injection system (SIA), are used. Compared to the flow injection technique, the sequential injection-mode showed better repeatability. Both systems use an immunoreactor consisting of a flow cell packed with immobilized haptens. The haptens (4-amino-L- or D-phenylalanine) are immobilized onto a hydroxysuccinimide-activated polymer (Affi-prep 10) via a tyramine spacer. Stereoselective antibodies, raised against 4-amino-L- or D-phenylalanine, are labeled with an acridinium ester. Stereoselective inhibition of binding of the acridinum-labeled antibodies to the immobilized hapten by amino acids takes place. Chiral recognition was observed not only for the hapten molecule but also for a series of different amino acids. One assay cycle including regeneration takes 6:30 min in the FIA mode and 4:40 min in the SIA mode. Using D-phenylalanine as a sample, the detection limit was found to be 6.13 pmol/ml (1.01 ng/ml) for the flow injection immunoassay (FIIA) and 1.76 pmol/ml (0.29 ng/ml ) for the sequential-injection immunoassay (SIIA) which can be lowered to 0.22 pmol/ml (0.036 ng/ml) or 0.064 pmol/ml (0.01 ng/ml) by using a stopped flow system. The intra-assay repeatability was found to be about 5% RSD and the inter-assay repeatability below 6% (within 3 days). [Journal Article; In English; Netherlands]

"Development Of An Automated Flow Injection Chemiluminescence Immunoassay For Human Immunoglobulin G"
Fresenius J. Anal. Chem. 1995 Volume 352, Issue 7-8 Pages 793-796
Andrea Hacker, Martin Hinterleitner, Curt Shellum and Gerald Gübitz

Abstract: An immunoreactor flow cell was constructed comprising a transparent PTFE tube (2 cm x 1.5 mm i.d.) packed with anti-human IgG immobilized on Affi-prep 10 support (details given). The immunoreactor was equilibrated with assay buffer of 0.01 mM sodium phosphate buffer/0.14 M NaCl/0.05% NaN3 of pH 7 at 0.3 ml/min, serum sample was injected at 0.03 ml/min and, after 1 min, the buffer was changed to the elution buffer of 32 mM 85% phosphoric acid of pH 1.8 (0.3 ml/min) and H2O2/NaOH solution was injected. Detection was by chemiluminescence. The detection limit was 7 fmol/injection of IgG in serum with intra-assay RSD (n = 7) of 1-3% and inter-assay RSD (n = 21) of 1.4%. Recoveries of 15.6 and 31.2 µM-IgG from serum were 102.2 and 103.4%, respectively.
Immunoglobulin G Serum Human Chemiluminescence Immunoassay Column Immobilized antibody

"Chemiluminescence Flow Injection Immunoassays"
Crit. Rev. Anal. Chem. 2001 Volume 31, Issue 3 Pages 167-174
Gerald Gübitz, Martin G. Schmid, Hossein Silviaeh and Hassan Y. Aboul-Enein

Abstract: The state of art in chemiluminescence flow injection immunoassays is reviewed. Different approaches and manifolds are described. Advantages of chemiluminescence flow injection immunoassays, which are discussed in detail, are speed, selectivity, and sensitivity. The major benefit of such systems is the simple and economical set up, which is easily adapted to automation.
Chemiluminescence Immunoassay Review

"Precipitation Flow Injection Immunoassay For Human Immunoglobulin G"
Biomed. Chromatogr. 1997 Volume 11, Issue 2 Pages 105-106
A. Hacker, G. Gübitz, J-M. Fernandez-Romereo, M. D. Luque de Castro, M. Valcarcel

Abstract: This paper deals with the development of a new type of FIIA based on the principle of precipitation flow-injection analysis (Valcarcel and Gallego, 1989). This approach makes use of the fact that precipitation occurs by the antigen-antibody binding reaction, which can be accelerated by the addition of polyethylene glycol. Antigens (HIgG) and fluorescence labelled antibodies are premixed by an autosampler. After injection into the flowing stream containing polyethylene glycol, the irnmuno-precipitation reaction is completed in a reaction coil. The precipitate formed is retained on a filter which is arranged on line in the flowing stream. By switching to 1 N NaOH the precipitate is dissolved and the fluorescence labelled antibodies liberated from the precipitate produce a fluorescence signal downstream at the detector.
Immunoglobulin G Immunoassay Precipitation

"Immobilized Fluorophores In Dynamic Chemiluminescence Detection Of Hydrogen Peroxide"
Anal. Chem. 1985 Volume 57, Issue 11 Pages 2071-2074
Gerald Gubitz, Piet Van Zoonen, Cees Gooijer, Nel H. Velthorst, and Roland W. Frei

Abstract: Various procedures are described for the immobilization of 3-aminofluoranthene(I) on solid carriers such as cellulose, silica gel and glass beads for use in the chemiluminescence detection of H2O2 in aqueous solution. Controlled pore glass, the most suitable carrier, with immobilized I, was packed in a silica cell and used in a flow injection system also containing a bed reactor of solid bis-(2,4,6-trichlorophenyl) oxalate. A detection limit of 10 nM-H2O2 was obtained, and the calibration graph was rectilinear for 100 µM.
Hydrogen peroxide Chemiluminescence Cellulose Controlled pore glass Glass beads Immobilized enzyme Silica gel

"Enantioselective Sequential-injection Chemiluminescence Immunoassays For 3,3,5-triiodothyronine (T3) And Thyroxine (T4)"
Anal. Chim. Acta 2002 Volume 463, Issue 1 Pages 5-14
Hossein Silvaieh, Reinhold Wintersteiger, Martin G. Schmid, Oliver Hofstetter, Volker Schurig and Gerald Gübitz

Abstract: This study deals with the development of enantioselective flow-through immunosensors for triiodothyronine (T3) and tetraiodothyronine (thyroxine, T4) on the basis of a competitive assay using enantioselective antibodies. The instrumental set-up is based on a simple sequential-injection system equipped with a chemiluminescence detector and an immunoreactor, which consists of a flow-cell packed with immobilized haptens. As haptens, 4-amino-L-phenylalanine (4-amino-L-Phe), 4-amino-D-Phe or L-T3 were used. Antibodies directed against 4-amino-L- or D-Phe or L-T3 were labeled with an acridinium ester. Three different approaches for immobilizing the haptens were investigated including simple adsorption on polystyrene, chemical binding to an activated methacrylate polymer and binding via the biotin-streptavidin binding (BSB) system. The latter approach showed the best results regarding repeatability and sensitivity. Using biotinylated L-T3 immobilized onto a streptavidin-derivatized trisacryl support and labeled anti-L-T3 antibodies, a detection limit of 15.5 fmol/ml for -T3 was obtained. One assay cycle including regeneration takes only about 5 min. This approach was applied to detect L-T3 in plasma samples without any sample pre-treatment. The average recovery from spiked plasma sample was about 93% with a RSD below 5%.

"Flow Injection-and Sequential Injection Immunoassay For Triiodothyronine Using Acridinium Ester Chemiluminescence Detection"
Anal. Chim. Acta 1999 Volume 398, Issue 2-3 Pages 183-190
Dieter Dreveny, Christine Klammer, Jacek Michalowsky and Gerald Gübitz

Abstract: This study describes the development of a competitive immunoassay for triiodothyronine (T3) comparing a flow injection and a modified sequential injection technique. The detection is carried out by chemiluminescence using an acridinium ester as a label for the antigen. Both immunoreaction and chemiluminescence reaction take place in a flow-cell packed with immobilized antibodies. The sequential injection technique was applied with and without flow-reversal. The detection limits for all types of assays were in the low fmol range (0.4 ng ml-1), whereby, with the flow-reversal mode, a slight improvement of the detection limit was observed. The relative standard deviation for the flow injection-and the sequential-injection mode were 4.4-7.9% and 2.2-5.5%, respectively. The total assay time was 7-9 min, depending on the mode.
Triiodothyronine Immunoassay Chemiluminescence Sequential injection Immobilized antibody Flow reversal Manifold comparison

"Flow Injection Immunoassays"
Anal. Chim. Acta 1993 Volume 283, Issue 1 Pages 421-428
G. Gübitz*, C. Shellum

Abstract: This review concentrates on heterogeneous immunoassays, and is illustrated by examples of flow injection EIA with electrochemical detection, and flow injection immunoassays with spectrophotometric, fluorimetric or chemiluminescence detection. (26 references).
Immunoassay Electrochemical analysis Fluorescence Chemiluminescence Review Enzyme

"Flow Injection Immunoassays With Acridinium Ester-based Chemiluminescence Detection"
Anal. Chim. Acta 1989 Volume 227, Issue 1 Pages 97-107
C. Shellum and G. Gübitz

Abstract: The cited method was demonstrated by determination of mouse IgG. Anti-mouse IgG was labelled with acridinium N-hydroxysuccinimide ester and immobilized on a column of Trisacryl GF-2000. Samples (20 µL) of IgG, labelled IgG and a mixture of H2O2 and NaOH solution were consecutively injected into a buffered carrier stream to the column and the emitted light was measured with a Kratos fluorimeter. The response was rectilinear up to 20 fmol with a limit of detection of 0.2 fmol. The coefficient of variation (n = 10) were 4.3%.
Immunoglobulin G Immunoassay Chemiluminescence Buffer Immobilized protein Column

"Development Of Solid Phase Chemiluminescence Immunoassays For Digoxin Comparing Flow Injection And Sequential Injection Techniques"
Analyst 1998 Volume 123, Issue 11 Pages 2271-2276
Dieter Dreveny, Jacek Michalowski, Renate Seidl and Gerald Gübitz

Abstract: The development of a competitive solid phase immunoassay for digoxin making use of the acridinium chemiluminescence system is described. Two different instrumental approaches are compared. One is based on a continuous-flow system using a peristaltic flow injection analysis pump; the other uses a new sequential injection technique. In both systems a flow cell, consisting of transparent PTFE tubing packed with immobilized antibodies, acts as an immunoreactor. The entire assay, including both the immunoreaction and the chemiluminescence reaction, takes place in this immunoreactor cell. Compared with the flow injection technique, the sequential injection mode showed higher precision, ranging from 2.16 to 5.5% RSD depending on concentration. The total assay time, including regeneration, is less than 8 min with the sequential injection technique. The detection limit for both techniques is in the low femtomole range.
Digoxin Blood Chemiluminescence Method comparison Sequential injection Immobilized antibody Solid phase detection