• Food Science and Biotechnology
• /
• v.15 no.6
• /
• pp.990-992
• /
• 2006

In a previous study, we obtained polyclonal antibodies against the organophosphorus insecticide fenitrothion and developed an enzyme-linked immunosorbent assay (ELISA) for this pesticide. Using these antibodies and an enzyme tracer, a direct competitive ELISA method specific for fenitrothion using a dipstick format was developed. Dipstick ELISA using antibodies to fenitrothion immobilized on an Immunodyne membrane allowed the quick visual detection of fenitrothion at concentrations above $10\;{\mu}g/L$. The $IC_{50}$ value of dipstick ELISA using reflectance detection was $27\;{\mu}g/L$ with a detection limit of $2\;{\mu}g/L$. The recovery of fenitrothion from spiked lettuce and rice samples using the dipstick ELISA ranged from 87-107%.

• Journal of Food Hygiene and Safety
• /
• v.11 no.4
• /
• pp.287-290
• /
• 1996

To control the maximum residue level (MRL) for sulfamethazine (SMZ) residues in pork tissue, a microbial inhibition method is a regulatory screening assay method in Korea. Microwell plate-based competitive enzyme immunoassay (ELISA) kit is avalable for routine screening of SMZ residues in pork tissue. One ELISA kit is evaluated. Phosphate buffer extracts of samples fortified with SMZ at 0, 1, 5, and 10 ng/g were used in a recovery test of the kit. Market pork samples were assayed by the kit. Recovery of sulfamethazine was 104% at 10 ng/g. Intraassay variations and interassay variations for the kit were 7.70% and 5.76%, respectively. Concentration causing 50% inhibition of color development compared with blanks was 16.4ng. The violative pork samples with over MRL (0.1 $\mu\textrm{g}$/g) was 4 of 32 cases (12.5%) by used ELISA kit. This result indicates a possibility of the ELISA kit for screening test of SMZ residues in pork tissue, and still needs a comfirmatory assay for mandatory purposes.

• Microbiology and Biotechnology Letters
• /
• v.25 no.4
• /
• pp.414-419
• /
• 1997

In order to develop an enzyme-linked immunosorbent assay (ELISA) for deoxynivalenol (DON) in com, we produced a specific monocl- onal antibody and established ELISA conditions. After the spleen cells from mice immunized with DON-bovine serum albumin conjugate were fused with S$_{p}$2/0 myeloma cells, a hybridoma cell 3G7 producing anti-DON antibody was screened by ELISA. From the standard curve of competitive direct ELISA (cdELISA) using 3G7 monoclonal antibody and DON-HRP conjugate, the detection range of DON showed 3-3,000 ng/ml (ppb). The monoclonal antibody showed some cross-reactivities against DON analogues such as 15 acetyl-DON (110%), nivalenol (5.0%), 3 acetyl-DON (1.7%), fusarenon-x (0.72%), and T-2 (0.59%). When the cdELISA was applied to the spiked coms after extracting with 60% methanol and diluting 5- fold with washing buffer, the assay recoveries of DON were 313, 163, 106, and 88.9% (av., 168%) in the levels of 200, 600, 2,000, and 6,000ng/g, respectively. For the quantitation of DON in coms, 30 samples kept under two different storage conditions of cold and room temperature were assayed by cdELISA. The mean detection concentrations were 595 (detection range, 0-2,750) and 2,448 (detection range, 0-4,500) ppb, respectively.

• Applied Biological Chemistry
• /
• v.42 no.4
• /
• pp.310-316
• /
• 1999

BBPI contents in domestic soybean and soybean products were investigated by the measurement of chymotrypsin inhibiting activity(C.I.A) and competitive ELISA method. In order to produce polyclonal antibody, BBPI was purified from soybean trypsin-chymotrypsin inhibitor by ion exchange chromatography and electrophoretic gel slicing. Rabbit anti-BBPI polyclonal antibody was produced with the purified BBPI as immunogen. This antibody showed relatively specific binding to BBPI and then used for the establishment of competitive ELISA method to measure BBPI contents in extracts of soybean and soybean products. The standard curve for the measurement of BBPI in soybean extracts was drawn up within the range 0.03 to $30\;{\mu}g/ml$ of BBPI. The C.I.A. and BBPI contents of 12 soybean cultivars were $8,462{\sim}12,428\;U/g$ and $482{\sim}692\;mg%$, respectively. The C.I.A. and BBPI contents were not detected in most of soybean products except soybean sprouts, which contained $10,695{\sim}13,249\;U/g$ of C.I.A. and $529{\sim}803\;mg%$ of BBPI.

• The Korean Journal of Pesticide Science
• /
• v.5 no.2
• /
• pp.1-12
• /
• 2001

A competitive indirect enzyme-linked immunosorbent assay (ci ELISA) for the organophosphorus insecticide acephate, O,S-dimethyl acetylphosphoramidothioate, was developed using a polyclonal antibody. Three different haptens mimicking the analyze and containing hexanoic acid moiety as a linker were synthesized, and then conjugated with the carrier proteins bovine serum albumin and keyhole limpet hemocyanin by the N-hydroxysuccinimide active ester method. Polyclonal antibodies raised against hapten-KLH conjugates in rabbits and the hapten-BSA conjugates as coating antigens were screened and selected for the assay in the homologous and/or heterologous ELISA system. The effects of various assay conditions, including blocking reagents, detergent content, organic solvents, pH, and preincubation of tile mixture of the polyclonal antibody and the analyze on the sensitivity were evaluated. The $IC_{50}$ value of acephate of 110 ng/mL was obtained in an optimized heterologous system using hapten-3-BSA as a coating antigen and a polyclonal antibody 8377, showing the detection range of 10-1000 ng/mL and the lowest detection limit of 4 ng/mL. The cross-reactivities of the structurally related insecticides, including methamidophos were less than 0.02%. These results indicate that the ELISA could be a convenient and alternative tool for monitoring acephate residues in agricultural products and environmental samples.

• Biomedical Science Letters
• /
• v.5 no.1
• /
• pp.11-15
• /
• 1999

Thyroxine (3,5,3',5'-L-tetraiodothyronine; T$_4$) is the most commonly measured thyroid hermono for the diagnosis of various thyroid disorders. Although radioimmunoassay (RIA) is still considered as the reference technique for the measurement of T$_4$, it is generally regarded that RIA has its primary disadventages in handling the wastes and controling the human and material resources. Therefore, establishment of enzyme-linked immunosorbent assay (ELISA) has of great significance. To verify the usefulness of our enzyme immunoassay, we have obtained the standard dose response curve of T$_4$ in patient's sera which is inversely proportional to the amount of herseradish peroxidase (HRP) conjugated monoclonal antibody of T$_4$ bound to the wells. The correlation coefficient (r) between the ELISA and chemiluminescent assay was 0.444 (n=38). Thus we have investigated the establishment of rapid and sensitive competitive ELISA assay method for detection of T$_4$ in patient's sera.

• Korean Journal of Environmental Agriculture
• /
• v.13 no.1
• /
• pp.76-82
• /
• 1994

A competitive indirect enzyme-linked immunosorbent assay(ELISA) was developed to detect and quantify levels of the fungicide metalaxyl in crops. Antiserum against metalaxyl was demonstrated in rabbits immunized with metalaxyl-human serum albumin(HSA) conjugate. Metalaxyl-protein conjugate was prepared by mixed anhydride and peptide coupling method with EDC. In this assay, metalaxyl-ovalbumin(OA) was $coated(8{\mu}g/ml)$ on the microtiter plate, which was incubated for 1 hr at $4^{\circ}C$ or 4 hr at $37^{\circ}C$ with diluted antiserum(1:2,000). The optimum volume ratio of antigen and antibody mixture was 0.5: 1, which was incubated for 1 hr at $20^{\circ}C$. The detection of metalaxyl bound on the surface of wells was determined by the reaction(30 min) of antirabbit Ig G-peroxidase conjugate with its substrate.

• Korean Journal of Veterinary Research
• /
• v.40 no.1
• /
• pp.81-85
• /
• 2000

Coxiella burnetii (C burnetii) is the causative agent of Q fever in animal and human. The distribution of the disease has been documented around world. In this study we developed the competitive enzyme linked immunosorbent assay(cELISA) and compared it with indirect immunofluorescent assay(IFA). A monoclonal antibody(Mab) against C burnetii and a peroxidase-conjugated anti-mouse IgM were used as an indicator system competing against antibody in animal serum or as an indicater of the absence of antibody. Sera were considered antibody positive when the percentage inhibition index(PI index) is upper than 30. PI index is calculated as 100-[sample OD/Mab OD)${\times}100$]. Among 162 bovine serum samples, 23 samples were antibody positive both in cELISA and IFA. And 156 samples showed same results. From goat with experimentally induced infection with C burnetii the antibody was detected 20 days early in cELISA compared to IFA. On the basis of present findings, it was demonstrated that cELISA is a reliable diagnostic method for The detection of specific antibodies against C burnetii infection.

• The Korean Journal of Food And Nutrition
• /
• v.19 no.3
• /
• pp.296-300
• /
• 2006

Immunoblotting and competitive indirect enzyme-liked immunosorbent assay(Ci-ELISA) was used for detection of ${\beta}$-lactoglobulin(BLG) in dairy products, such as milk, dried milk and fermented milk. In immunoblotting, human IgE weakly recognized proteins of fermented milk, but still responded to dried milk even though become weak. Rabbit polyclonal antibody to BLG, used as a model of antigen, and milk allergic patients' IgE was used in the ELISA. Reactivities of Abs were the highest in market milk. BLG in fermented milk was detected in a low content. This result indicates the fermented milk have the lowest BLG content and could be used as hypo-allergenic food for milk-allergic individual.

• Bulletin of the Korean Chemical Society
• /
• v.22 no.9
• /
• pp.953-957
• /
• 2001

The specificity of conjugation site for coating ligands was investigated using toluene-bovine serum albumin (BSA) conjugates in which BSA was conjugated at the position of o-, m-, and ${\rho}-toluic$ acid. Toluene-BSA conjugated at ${\rho}-position$ showed a binding activity of about 89-95%, whereas, those conjugated at o- and m-position of toluene exhibited a binding activity of 5 and 11%, respectively. On the basis of the above result, coating ligands with various proteins (OVA, BSA, KLH) were compared by conjugating with $\rho-toluic$ acid, and toluene-KLH was considered as the best coating ligand for this ELISA. Indirect competitive ELISA method was developed using anti-toluene antibody and $\rho-position$ conjugated toluene-KLH. The dose-response curve constructed after kinetic and optimization studies showed a 1${\times}$10-4 - 1${\times}$102 mM detectable response range with 0.1 ${\mu}M$ detectability. In specificity test of the antibody, the binding capabilities of aromatic compounds substituted with nitro-, alkyl-, chloro-, and hydroxyl group were larger rather than those of aromatic compounds (benzene, toluene and xylene) themselves. Also, tests with soil and water samples that had been spiked with toluene resulted in 102.7-113.7% recovery.