Flow-injection estimation of 2-aminophenol in pharmaceutical agents using piezoquartz immunosensors

Abstract

A flow piezoquartz immunosensor was developed for the rapid estimation of 4-aminophenol in pharmaceutical formulations based on paracetamol. The bioreceptor coating was a 4-aminophenol-protein conjugate (4-AP-GA-BSA), immobilized on the silanized surface of a silver electrode. The effects of the concentration of polyclonal antibodies on the analytical signal of the sensor were studied: the activities of immunological reagents were assessed in terms of the binding constant K b . A method for flow-injection estimation of 4-aminophenol in pharmaceutical formulations using the piezoquartz immunosensor as the detector was developed. The calibration curve was linear over the concentration range 2 -120 ng/ml and the detection limit for 4-aminophenol was 1.1 ng/ml. 220 0091-150X/08/4204-0220

Heterogeneous Thermal-Lens Immunoassay for Small Organic Compounds: Determination of 4-Aminophenol

“…[4][5][6][7] Nevertheless, even in the variant developed here, TLIA provides a good screening opportunity for small molecules in combination with another immunoassay. 22 In our opinion, further enhancements in the analytical parameters can be achieved by developing more traceable procedures for antibody immobilization at a polymer surface including dual-surface treatment, 25 which could provide at least two-fold enhancement in sensitivity. As well, tracers with higher absorptivity/lower quantum yields, which are almost not in use today due to the low sensitivity of spectrophotometric measurements, may prove very expedient in TLIA.…”

“…Finally, from the viewpoint of trace analysis, TLIA combines the well-known advantages of ELISA and flowinjection immunoassays 22,24,25 and provides online preconcentration of the target hapten, both for the batch and flow modes. Therefore, TLS-based immunoassays for small molecules may widen the applications of immunochemical analysis.…”

“…12), the sensitivity of the TLIA procedure is mainly governed by the calibration slope rather than the background signal. Hence, it is inferior only to our recent development of a 4-AP immunoassay using the same antibodies with a piezoquartz immunosensor, 22 although the latter procedure for flow analysis involves preconcentration and shows a shorter calibration range.…”

“…12,14,15 The linearity range is 0.1 to 500 lg mL À1 , which is wider than that for immunoassays for 4-aminophenol. 10,[16][17][18][20][21][22]34 Concentrations above 500 lg mL À1 give signals insignificantly different from a blank (Table III). Thus, the labeled antigen is completely removed from the surface and it does not directly interact with the matrix.…”

“…Recently, 4-aminophenol determination has been carried out using liquid chromatography with photometric 16 or fluorimetric detection, [17][18][19] which do not always provide enough sensitivity or selectivity, 19 or using mass-spectrometric detection, 20,21 which is complicated, expensive, and sometimes lacks reproducibility in paracetamol samples. Immunoassays 11,[22][23][24][25] show good sensitivity for phenolic compounds including 4-AP, and thermal-lens spectrometry was used to improve the sensitivity of photometric methods for the determination of phenolic compounds in solution including 4-aminophenol; 26 limits of detection of 50 ng mL À1 were achieved, which led us to expect good sensitivity from TLIA.…”