HPLC-UV Method Development and Validation of Potato Sprout Inhibitor 1,4-Dimethylnaphthalene Using Different Systems

1,4-Dimethylnaphthalene (1,4-DMN) is effective sprout suppressant used in potato stores in many countries in the world. High residue levels of this compound on the potatoes and in other environmental samples are considered for human health and environmental risks. Determination of the residue requires specific analytical methods to be developed and validated. In this study, HPLC-UV was selected for validating a separation method based on reversed phase for the analysis of 1,4-DMN using 2-methylnaphthalene (2-MeN) as internal standard testing three HPLC systems. Under the same chromatographic conditions, all three systems achieved good separation on a Jones column (Hypersil ODS 5？μm, 250？mm？×？4.6？mm) at ambient temperature isocratically using 70% acetonitrile as mobile phase at a flow rate of 1.5？mL？min？1, 20？μL injection volume, a run time of 10？min, and a detection wavelength of 228？nm. All three systems showed high precision, good linearity, and low limit of detection (LOD) and quantification (LOQ); particularly, the SpectraSERIES UV100-autosampler system offered lower values of LOD (0.001–0.004？μg？mL？1) and LOQ (0.002–0.013？μg？mL？1) for both compounds. This system can be used for the quantitative determination of 1,4-DMN residue in potato and environmental samples. 1. Introduction 1,4-Dimethylnaphthalene (1,4-DMN) is an effective chemical used for sprout control and quality management and known by the trade name DMN; it is available commercially mainly as 1,4SIGHT in USA, Canada, and New Zealand. However, the commercial use of 1,4-DMN as a naturally occurring potato sprout inhibitor [1, 2] is claiming investigation of the effective amount required for successful long-term storage and to understand the possible risks to the environment regarding waste peel, water, and soil. Therefore, validated analytical methods are required. The scientific literature for the determination of this polyaromatic hydrocarbon of 1,4-DMN is very limited. Few studies have been reported to analyse the residue of 1,4-DMN in potato samples using GC [3–5]. Nowadays, the increasing availability of HPLC analysis proved to have many advantages for pesticide residue analysis in food and environmental samples compared to GC analysis particularly polyaromatic hydrocarbons mainly owing to compounds stability, high speed, and producing reproducible response with various kinds of solvents and columns analysing large volume of samples (~500？μL) [6, 7]. The only study which has been found regarding the analysis of 1,4-DMN by HPLC-UV is separation method based on reversed phase (RP)