The distribution and fate of chlorpropham in commercial potato stores
The thesis consists of a study of chlorpropham distribution patterns and its behaviour within tuber components in commercial potato stores in the UK. The store examined were both cold (3-4 °C) and conventional (8-10 °C) stores. As a large number of samples from different stores were taken, it was important to have a quick and reliable analytical method for chlorpropham determination. This was developed and compared against the original accepted method. Both methods were more or less similar in their precision of results, with recoveries of 83.80 2.25 and 93.14 3.51 from spiked samples by blending and reflux extracting methods respectively. When the methods were compared for extracting the amount of chlorpropham in commercially treated stored samples, it gave recoveries of 2.49 0.25 and 2.58 0.17 for the blending and reflux methods respectively. Overall the reflux extracting method was quicker and easier and it was used for further work with some slight modification. The present study showed that the level and distribution pattern of chlorpropham was significantly different within the store and as well as between different commercial stores. The overall range of chlorpropham levels in the examined stores was 2.11-236.56 mg/kg. The amount of chlorpropham varied with respect to sampling sites of the examined stores. Each store has its own distribution pattern with some similarities. However there was a common trending all the stores examined in that the maximum level of chlorpropham was on the top surface and minimum on the lower levels of the stores. In the cold store examined 'A' ( 3-4 °C) the level of chlorpropham decreased continuously from the top height towards the bottom height of the store. However the amount of chlorpropham was excessive throughout the store, even in the middle of the boxes it exceeded the MRL (Maximum Recommended Level). The level of chlorpropham dropped from 128.39 mg/kg in the middle layer samples of the top box to 49.14, 20.15, 19.01, 8.03 3.97 and 4.54 mg/kg towards the bottom boxes of a six high column of boxes in the store respectively.