Establishment of analytical method for 6-benzylaminopurine residue, a plant growth regulator for brown rice, mandarin, pepper, potato, and soybean by using GC/NPD

Abstract

Improvement of an analytical method on 6-benzylaminopurine (BAP), a plant growth regulator, and a first-generation synthetic cytokinin for agricultural commodities was undertaken. Analytical method for BAP in the agricultural commodities by gas chromatography in cooperation with nitrogen-phosphorous detector (NPD) was adopted. BAP was extracted with acetone in all samples followed by the ion-associated partitioning method. Vapor pressure of BAP was increased by N-methylation with iodide methane [BAP→6-Benzylamino-N-methylpurine (BAMP)]. Finally, N-methylated BAMP was separated with ethylacetate. The quantitation was done by GC using Nitrogen Phosphorous Detector with DB-608, a moderate polarity column under the temperature-rising condition. The standard calibration curve presented the linearity of correlation coefficient (r2)>0.9999, analyzed from 0.2 to 4 mg/kg. The limit of quantitation in agricultural commodities showed 0.05 mg/kg. The average recoveries of intraand inter-day experiments ranged from 70.4 to 103.5% and 70.3 to 105.6%, respectively. The repeatability and reproducibility for intra- and inter-day measurements expressed as a relative standard deviation (RSD) was less than 10.7 and 8.3%, respectively. Therefore, our newly established analytical method for BAP residue in agricultural commodities was applicable to the nationwide pesticide residues monitoring program with the acceptable level of sensitivity, repeatability and reproducibility.