ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Molecularly imprinted dispersive solid-phase extraction coupled with high-performance liquid chromatography for the determination of pyraclostrobin in ginseng

Jun Wang, Yan Wang, Xin-Xin Liu, De-Ming Li, and Sui-Xin Li

College of Resources and Environment, Jilin Agricultural University, Changchun, People’s Republic of China

E-mail: wy@jlau.edu.cn

Received: 2 July 2019  Accepted: 4 November 2019

Abstract:

Determination of pyraclostrobin in ginseng samples by molecularly imprinted dispersive solid-phase extraction (MIDSPE) coupled with high-performance liquid chromatography (HPLC) method was developed. Molecularly imprinted polymers (MIPs) were prepared by precipitation polymerization using pyraclostrobin as template, methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) and azobisisobutyronitrile (AIBN) as cross-linker and initiator, respectively. The mixture of butanone (MEK) and n-heptane (7:3, V:V) was used as solvent and porogen. The microspheres were characterized by laser particle size analyzer, scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR). Binding experiments showed high binding capacity of polymers, and that the maximum adsorption of MIPs and NIPs to pyraclostrobin was 73.01 mg g⁻¹ and 59.14 mg g⁻¹. Selective adsorption experiments verified that polymers had specific and selective recognition site for pyraclostrobin. Comparing MIPs with C₁₈, the recoveries of pyraclostrobin from blank ginseng samples spiked at 0.05, 0.1, and 1.0 mg kg⁻¹ ranged between 77.6% and 93.5% with the standard deviation of 2.18–6.07 and the relative standard deviations (RSDs) between 2.47 and 6.99% (n = 5). The recoveries of pyraclostrobin that used C₁₈ as sorbent were found to be 53.04–63.86% with the standard deviation of 1.13–2.83 and the relative standard deviations of 1.07–4.99%. The data indicated that the method for the analysis of the pyraclostrobin in ginseng samples can achieve good recoveries, repeatability and reproducibility. The linear regression equation was calculated as y = 2.09935e−006x + 0.0176235 (R² = 0.998656). The limit of detection (LOD, S/N = 3) was 0.01 mg kg⁻¹. The confidence interval for the slope at the 95% confidence level was [356084.1828, 899542.8563], and the confidence interval for the intercept was [− 755349.2710, 72645.0856]. The MIDSPE-HPLC method showed specific selective separation and enrichment of trace pyraclostrobin in ginseng samples. The raw samples were tested and results were all below the maximum Residue Limit (MRL) 0.1 mg kg⁻¹ in the European Union.

Keywords: Dispersive solid-phase extraction; Ginseng; High-performance liquid chromatography; Molecularly imprinted microspheres; Pyraclostrobin

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-019-00990-9

Chemical Papers 74 (6) 1717–1727 (2020)