Development of a one step strip test for the detection of sulfadimidine residues†

Abstract

The one step strip test described is a competitive immunoassay in which the detector reagent consists of colloidal gold particles coated with affinity purified polyclonal anti-sulfadimidine (SDD) antibodies. The capture reagent in the assay is an SDD-ovalbumin conjugate which is immobilised on the lateral flow membrane of the test device. In the test procedure, 150 microliters (four drops) of a liquid sample (buffer, urine or milk) are brought into the sample well of the test device and allowed to migrate over the membrane. The more analyte present in the sample, the more effectively it will compete with the SDD immobilised on the membrane for binding to the limited amount of antibodies of the detector reagent. A sufficient amount of SDD in the sample will therefore prevent the binding of the detector reagent to the SDD immobilised on the membrane. Therefore, a positive sample will not show a test line in the read-out zone. With spiked buffer or calf urine this was obtained at a level of > 10 ng ml-1 of SDD and with spiked (diluted) fresh cow milk at a level > 20 ng ml-1 of SDD. At these levels, the test is applicable only as a qualitative assay. The presence or absence of a test line indicates lower or higher levels of SDD, respectively. The major advantages of the one step strip test are that results can be obtained within 10 min and that all reagents are included in the test device.

Development and evaluation of a rapid lateral flow immunochromatographic strip assay for screening 19‐nortestosterone

“…This lateral flow strip is one kind of immunochromatographic assay depending on the transport of a reactant to its binding partner immobilized on the surfaces of the membrane (Birnbaum et al, 1992;Millipore, 1999;Paek et al, 2000). It has been used as a popular rapid diagnostic tool for detecting hormones (HCG), viruses (HIV, hepatitis Band C), bacteria, parasite antigens and agonists (Verheijen et al, 1998;Zhang et al, 2006). However, in these applications, the method is based on the concept of the double-antigen sandwich assay as its targets are mostly large-molecule substances such as proteins.…”

Lateral flow (immuno)assay: its strengths, weaknesses, opportunities and threats. A literature survey

“…Labels are made of coloured or fluorescent nanoparticles with sizes of 15-800 nm, allowing an unobstructed flow through the membrane. They are often made of colloidal gold [1,[17][18][19][20] or latex [21], less often selenium [22], carbon [2,23] or liposomes [24][25][26][27][28][29] are used. Latex nanoparticles are coloured [21] for optical detection.…”

Development of an immunochromatographic assay for rapid detection of 1‐Aminohydantoin in urine specimens

“…In recent years, colloidal gold has been introduced into immunochemistry and the immunochromatographic strip assay has been a popular rapid diagnostic tool for detecting hormones (HCG), viruses (HIV, hepatitis B and C), bacteria, parasite antigens and β-agonists (Millipore, 1999;Verheijen et al, 1998;Zhang et al, 2006). These assays depend on a detector reagent which shifts to a special ligand immobilized on the surfaces of the membrane (Millipore, 1999;Birnbaum et al, 1992;Paek et al, 2000).…”