The first method developed for detection of patulin and adopted as an AOAC official method (AOAC Official Method 974.18) involved the use of normal phase TLC . Apple juice is extracted with ethyl acetate, and the extract partially purified on a silica gel column. Patulin is eluted, concentrated, and detected by TLC using normal phase silica gel plates which are typically developed in toluene/ethyl acetate/formic acid and then sprayed with 3-methyl-2-benzothiazolinone hydrochloride (MBTH). Patulin appears as a yellow-brown fluorescent spot under UV light at 366 nm. The method has a limit of detection of ~20 ^ patulin/l apple juice. More recently, Prieta et al.  described an analytical method for patulin using diphasic dialysis for extraction of patulin from juice, followed by separation on TLC silica gel plates, detection with MBTH, and quantification by densitometry. The authors reported a detection limit of 50 ^ patulin/l juice and extraction recovery of 65% . TLC remains the method of choice for detection of patulin in many parts of the world, especially in developing countries.
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