University of North Florida
Browse the Citations
-OR-

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

View Stuart Chalk's profile on LinkedIn

Petra M. Kramer

Abbrev:
Kramer, P.M.
Other Names:
Petra M. Krämer
Address:
GBF – Gesellschaft für Biotechnologische Forschung mbH, Mascheroder Weg 1, 38124 Braunschweig, Germany
Phone:
+49-89-3187-4529
Fax:
+49-89-3187-3371
Email:
kramer@gsf.de

Citations 5

"Comparison Of Two Express Immunotechniques With Polyelectrolyte Carriers, ELISA And FIIAA, For The Analysis Of Atrazine"
Talanta 2005 Volume 65, Issue 2 Pages 324-330
Petra M. Krämer, Annette Franke, Anatoly V. Zherdev, Elena V. Yazynina and Boris B. Dzantiev

Abstract: Conventional immunoassays on microtiterplates are very useful analytical tools in environmental analysis, but the long assay times, usually in the range of hours, are a drawback. To overcome this disadvantage, the development of fast (express) assay formats is described, which use polyelectrolytes as carriers. Two semi-homogeneous immunochemical methods, namely the polyelectrolyte-ELISA (enzyme-linked immunosorbent assay) and the express-FIIAA (flow injection immunoaffinity analysis) for the analysis of the herbicide atrazine were set-up. Using polyclonal antisera for atrazine, the following results were obtained. Standard curves for atrazine showed a linear range from 3 to 100 ?g l -1 in polyelectrolyte-ELISA and 0.3-100 ?g L-1 in express-FIIAA. The test midpoints in polyelectrolyte-ELISA and express-FIIAA were 12 and 5 ?g l-1, respectively. The duration time of the immunochemical reaction was in both assays 15 min, but the total assay time differed (30 min (polyelectrolyte-ELISA) and 18 min (express-FIIAA)). A significant difference between the formats could be observed in the number of samples that can be determined per day. The polyelectrolyte-ELISA can handle samples in parallel on a microtiterplate (usually 20/plate), whereas in the express-FIIAA the samples are automatically analyzed one after another. This first demonstration of these techniques shows the potential of these methods, but also their limitations. © 2004 Elsevier B.V. All rights reserved.

"Automated Immunochemical Analysis Of Specific S-triazine And Phenylurea Herbicides In Drinking Water Supplies"
Food Technol. Biotechnol. 1998 Volume 36, Issue 2 Pages 111-118
Petra M. Krämer

Abstract: Automated immunochemical analysis offers an inexpensive online monitoring or off-line screening of different drinking water sources without extensive sample preparation and without using organic solvents. Two prototype system instruments, one online the other off-line, were studied within the European project, Program Life. Results discussed were performed with the off-line device, where standards and samples are supplied in sep. vials. Automated anal. depends on an extended time of operation without attendants; therefore, all reagents, especially immunoreagents (antibody and enzyme-tracer), should have a stability of at least 14 days. Different stabilization methods were studied. Best stability (at least 14 days) was achieved by adding 0.5% BSA (bovine serum albumin) and 0.5% micro-O-protect, together with storage at 4°C. To reduce buffer salts, which would be discharged to the environment during continuous FIIAA (flow injection immunoaffinity anal.), a comparison of 40 and 4 mM PBS (phosphate buffered saline) as carrier buffer was made. Results showed there was no difference in performance between the 2 carrier buffers. As an example, the system was applied to determine diuron in actual water samples which contained high concentrations of humic substances (9.5 mg/L DOC [dissolved organic carbon]). Samples were collected from groundwater and different water treatment stages of the water supply station in Fuhrberg, Germany, and afterwards spiked with diuron. As a reference method, samples were analyzed by conventional micro-titer plate ELISA, using the same immunoreagents. Determined amounts were generally in good agreement with spiked amts.; FIIAA produced better results.
Herbicides, phenylurea Herbicides, triazine Water Immunoaffinity Process monitoring Apparatus Instrumentation Optimization Method comparison

"A New, Versatile Field Immunosensor For Environmental Pollutants: Development And Proof Of Principle With TNT, Diuron, And Atrazine"
Biosens. Bioelectron. 2005 Volume 21, Issue 2 Pages 354-364
Ioan M. Ciumasu, Petra M. Krämer, Cristina M. Weber, Gunther Kolb, David Tiemann, Stefan Windisch, Ines Frese and Antonius A. Kettrup

Abstract: This paper presents a new, versatile, portable miniaturized flow-injection immunosensor which is designed for field analysis. The temperature-controlled field prototype can run for 6 h without external power supply. The bio-recognition element is an analyte-specific antibody immobilized on a gold surface of pyramidal structures inside an exchangeable single-use chip, which hosts also the enzyme-tracer and the sample reservoirs. The competition between the enzyme-tracer and the analyte for the antigen-binding sites of the antibodies yields in the final step a chemiluminescence signal that is inversely proportional to the concentration of analyte in the given range of detection. A proof of principle is shown for nitroaromatics and pesticides. The detection limits (DL; IC20) reached with the field prototype in the laboratory was below 0.1 ?g L-1 for 2,4,6-trinitrotoluene (TNT), and about 0.2 ?g L-1 for diuron and atrazine, respectively. Important aspects in this development were the design of the competition between analyte and enzyme-tracer, the unspecific signal due to unspecific binding and/or luminescence background signal, and the flow pattern inside the chip. © 2004 Elsevier B.V. All rights reserved.

"Flow Injection Immunoaffinity Analysis (FIIAA) -A Screening Technology For Atrazine And Diuron In Water Samples"
Anal. Chim. Acta 1999 Volume 399, Issue 1-2 Pages 89-97
Petra M. Krämer, Annette Franke and Christine Standfuss-Gabisch

Abstract: An automated, computer controlled flow injection immunoaffinity analysis (FIIAA) system was used for screening water samples of different origin, e.g., groundwater, surface water for the presence of diuron and atrazine, respectively. Here, an in-house prepared column material with Protein A was used in the affinity column, which showed very similar features compared to the commercial material used previously. The in-house prepared material could be regenerated for more than 1000 times. The results obtained by FIIAA were compared with conventional analysis (gas or liquid chromatography, respectively) and with enzyme-linked immunosorbent assay (ELISA). The later used the same immunoreagents as the FIIAA. All three methods showed comparable results. ELISA and FIIAA. showed in a few cases higher concentrations than those determined by chromatography, which are mainly caused by the cross-reactivities of the antibodies and probably some matrix effects. In a few cases false negative results were observed, which should not be present in a screening method. For the majority of samples though, the FIIAA system proved to be a very good screening tool for different water matrices.

"Prototype Of A Newly Developed Immunochemical Detection System For The Determination Of Pesticide Residues In Water"
Anal. Chim. Acta 1997 Volume 347, Issue 1-2 Pages 187-198
Petra M. Krämer*, Bert A. Baumann and Peter G. Stoks

Abstract: Methods based on flow injection immunoaffinity analysis (FIIAA) are described for determining atrazine and diuron in water. The analyzes were performed on a prototype instrument consisting of an affinity column packed with protein A immobilized on polymethacrylate and a flow-through fluorimeter. The sequential experimental procedure was carried out by subjecting the affinity column to the following treatments; (i) incubating with anti-pesticide antibodies, (ii) rinsing, (iii) incubating with pesticide solution, (iv) rinsing, (v) incubating with peroxidase tracer for 3 min, (vi) rinsing and (vii) incubating with 3-hydroxyphenyl propionic acid/H2O2 substrate solution. The product of the enzyme reaction was detected at 415 nm (excitation at 320 nm). Between each determination the protein A affinity column was regenerated with 100 mM sodium citrate buffer. The linear range of the assays was 0.02-0.5 µg/l for both atrazine and diuron and the concentration producing 50% inhibition of the maximum response for atrazine was 0.1 µg/l. Diuron and isoproturon had no effect on the atrazine determination but simazine caused a decline in the atrazine signal. Recoveries for 0.02-0.5 µg/l atrazine were satisfactory.
Atrazine Diuron Environmental LC Immunoassay Fluorescence Interferences Buffer Column