Abstract

We present a video-densitometric high-performance thin-layer chromatography (HPTLC) quantification method for patulin in apple juice, developed in a vertical chamber from the starting point to a distance of 50 mm, using MTBE, n-pentane (9 + 5, v/v) as mobile phase. After separation the plate is sprayed with methyl-benzothiazolinone hydrazone hydrochloride monohydrate (MBTH) solution (40 mg in 20 mL methanol) and heated at 105 °C for 15 min. Patulin zones are transformed into yellow spots. The quantification is based on direct measurements using an inexpensive 48-bit flatbed scanner for color measurements (in red, green, and blue). Evaluation of the blue channel makes the measurements very specific. Quantification in fluorescence was also done by use of a 16-bit CCD-camera and UV-366 nm illumination as well as using a HPTLC DAD-scanner. For linearization the extended Kubelka–Munk expression for data transformation was used. The range of linearity covers more than two magnitudes and lies between 5 and 800 ng patulin. The extraction of 20 g apple juice and an extract application on plate up to 50 µL allows statistically defined checking the limit of detection (LOD) of 50 ng patulin per track, which is equivalent to 50 µg patulin per kg apple juice.

摘要

我们提出了一种用于苹果汁中展青霉素的视频密度计高效薄层色谱 (HPTLC) 定量方法，该方法在垂直室中从起点到 50 mm 的距离开发，使用 MTBE、正戊烷 (9 + 5 , v/v) 作为流动相。分离后，用甲基苯并噻唑啉酮腙盐酸盐一水合物 (MBTH) 溶液（40 毫克在 20 毫升甲醇中）喷洒该板，并在 105°C 下加热 15 分钟。棒曲霉素区转变为黄色斑点。量化基于使用廉价的 48 位平板扫描仪进行颜色测量（红色、绿色和蓝色）的直接测量。蓝色通道的评估使测量非常具体。荧光定量也通过使用 16 位 CCD 相机和 UV-366 nm 照明以及使用 HPTLC DAD 扫描仪进行。对于线性化，扩展的Kubelka-Munk使用了数据转换的表达式。线性范围涵盖两个以上的量级，介于 5 到 800 ng 棒曲霉素之间。提取 20 g 苹果汁并在平板上应用高达 50 µL 的提取物，可以通过统计定义检查每条轨迹 50 ng 棒曲霉素的检测限 (LOD)，这相当于每公斤苹果汁 50 µg 棒曲霉素。