Analytical evaluation of a high-throughput enzyme-linked immunosorbent assay for acrylamide determination in fried foods

The analytical performance and evaluation of a kit-based ELISA for the determination of acrylamide in fried potato and corn chip samples are described. The sample homogenate is subjected to clean-up using SPE, followed by analyte derivatization and ELISA detection. Accuracy, precision and linearity of the ELISA procedure have been validated using spiked samples. Analytical recovery ranged from 91.8% to 96.0% with coefficients of variation below 15%. Good linearity over a wide range of dilution and minimal assay drift was observed within a microtiter plate. IC50 value of the calibration curve was 110 ng/mL, with the limit of detection about 5 ng/mL and dynamic range from 10 to 1000 ng/mL. The high specificity of the ELISA was demonstrated by cross-reactivity study using 11 potential cross-reactants. A good correlation between the results obtained from the ELISA and GC-MS within the concentration range 120-1500 μg/kg was found in the chip samples (r=0.992, n=120). The data demonstrate that the evaluated and validated ELISA has a potential utility in a quick, simple and reliable acrylamide screening analysis for the medium- and large-sized food companies, as well as for residue laboratories and the food industry dealing with improving the chemical safety of foods available to the consumer.

Broad-Specificity Immunoassays for Sulfonamide Detection: Immunochemical Strategy for Generic Antibodies and Competitors

Development of antibodies with broad specificity recognition for sulfonamide drugs was found to be surprisingly difficult when conventional immunochemical strategies were applied to hapten design. To improve the cross-reactivity pattern of antibodies for the family of sulfonamide drugs, a novel strategy based on the single-ring (fragment-derived) hapten moieties with different spacer substituent lengths was employed for the preparation of immunogens, coating conjugates, and enzyme competitors. The rabbit antibodies raised against a common (one-ring) p-aminobenzenesulfonamide hapten moiety (attached to a carrier protein through the N-1 position) in combination with a homologous hapten-peroxidase tracer allowed the detection of 15 sulfonamide species at the maximum residue limit level using direct ELISA. The two-ring 6-(4-aminobenzensulfonylamino)hexanoic hapten mimics, previously reported in the literature as a weak generic antigen, generated surprisingly superior immune responses in rabbits. The antibodies raised against this two-ring hapten were capable of detecting at least 19 and 17 sulfonamides in a direct ELISA system at the regulatory level with sensitivities corresponding to 20 and 50% binding inhibition, respectively. A negligible cross-reaction with N4 metabolites makes it possible to measure responses of parent sulfonamides in the presence of their metabolized forms. In skimmed milk, the highest limit of detection (LOD) for sulfacetamide defined as 20% inhibition was 65.2 microg x L(-1) (IC20 value), whereas the additional 18 sulfonamides tested exhibited LODs in the range of 0.2-36.8 microg x L(-1). This sensitivity allows simple multisulfonamide tests to be established for use in the laboratory or on site.