Raman enhancement effects of gold nanoparticles with different particle sizes on clenbuterol and ractopamine

Authors: GUO, QINGHUI - China Agricultural University; PENG, YANKUN - China Agricultural University; Chao, Kuanglin - Kevin Chao; ZHUANG, QIBIN - China Agricultural University; CHEN, YAHUI - China Agricultural University

Submitted to: Vibrational Spectroscopy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/2022
Publication Date: 12/15/2022
Citation: Guo, Q., Peng, Y., Chao, K., Zhuang, Q., Chen, Y. 2022. Raman enhancement effects of gold nanoparticles with different particle sizes on clenbuterol and ractopamine. Vibrational Spectroscopy. 123:103444. https://doi.org/10.1016/j.vibspec.2022.103444.
DOI: https://doi.org/10.1016/j.vibspec.2022.103444

Interpretive Summary: Clenbuterol and ractopamine can be used to improve leanness in swine, but since residues in pork also pose health risks, their levels in meats need to be determined. Chemical methods for detection of veterinary drug residues in meats require a strict sample collection and processing protocol, the use of very expensive analytical instrumentation, and a high technical level of expertise to both operate the equipment and to interpret the results. Spectroscopic methods once developed are less complicated to run, user friendly, and can produce practical real time analytical results useful to those raising animals for food. An EMFSL 785-nm point-scan Raman system developed for food authentication was used in the development of a detection method for clenbuterol and ractopamine. The method results in the compounds absorbed being absorbed on gold nanoparticles and detected by their spectral fingerprint. It was found that the larger particle size of gold nanoparticles, the better the signal enhancement. A linear regression model was established between Raman intensity at 390, 653, 793, 1253, 1462 and 1587 cm-1 and clenbuterol concentration. A linear regression model was also established between Raman intensity at 836, 1002, 1169, 1253, 1492 and 1578 cm-1 and ractopamine concentration. The limit of detection values of this method were 18 ng/mL and 24 ng/mL for clenbuterol and ractopamine, respectively. This rapid spectroscopic method based on gold colloid nanoparticle surface adsorption could furthermore be effective as well for other [veterinary] compounds of interest once conditions for adsorption are optimized. This benefits ARS by providing a rapid, inexpensive methodology to protect the public from specific regulated substances permitted in the human food supply. This approach can lead to assurance that levels of residues in meat and in medicated feeds for animals result in a human food supply that can be documented as safe.

Technical Abstract: Clenbuterol and ractopamine experimentally improve leanness in swine, but their residues in pork also pose human health risks requiring determining its level in meats. Surface-enhanced Raman scatter (SERS) technology establish mathematical models for to achieve rapid detection and identification of clenbuterol hydrochloride (CL) and ractopamine (RAC) in residues. Detection of CL and RAC was carried out using gold colloids with three different particle sizes as enhanced substrates. The larger particle size of gold nanoparticles used, the better the enhancement in their detection levels: gold nanoparticles with larger particle sizes adsorption more of RAC and of CL. The SERS spectra for 0.1–10 µg/mL CL and RAC solution were collected using gold colloid A with an NaCl aqueous solution (1 mol/L) as aggregating agent. Automatic Whittaker Filter (AWF) was used for preprocessing to reduce fluorescence background contained in the original Raman spectra data. Finally, models were established between spectral intensity at each characteristic peak and the concentration of CL and RAC, respectively. Mathematical models using six wavelengths for CL and for six different wavelengths for RAC were fully successful for their quantitation. The detection limit (LOD) values of this method for the detection of CL and RAC were 18 ng/mL and 24 ng/mL, respectively. Further development of a simple SERS detection method on additional compounds of interest of compounds based on using gold colloid nanoparticles are possible upon optimizing individual relevant adsorption parameters.