Residues of free and bound maleic hydrazide in potato tubers

Abstract

SummaryThe method of Vadukul (1991) for determining maleic hydrazide (MH) was modified and gave recoveries of free MH of 89% _+ 4%. The values recorded on individual tubers ranged from 2-14 mg kg -I. Maleic hydrazide was evenly distributed throughout the tuber (peel, outer and inner flesh) but concentration increased slightly as tuber size increased. The concentration of free MH decreased from 7 to 3 mg kg -t over the storage period of 51/2 months. Acid hydrolysis released substantial amounts of MH particularly from older potatoes (13 mg kg -I) compared with 6 mg kg -I from new potatoes, implying that free MH is gradually converted to a bound form with time after treatment. No evidence was found for the presence of a [5-glucoside of MH.

Use of autoclave extraction and liquid chromatography with tandem mass spectrometry for determination of maleic hydrazide residues in tobacco

“…Since MH presents as free MH, glucose‐MH conjugates, and lignin bound MH in tobacco, aggressive extraction conditions are required to fully extract MH. Both caustic and acidic conditions at elevated temperatures have shown to work well and also have the added benefit of hydrolyzing the glucoside conjugates in the process. However, in the reported acidic extraction procedures, various extraction approaches were employed, including heating reflux, sonication, and microwave assisted extraction.…”

“…reported the determination of free and bound MH residues in tobacco with HCl hydrolysis by GC–NPD, HPLC–UV, and LC–MS/MS, respectively. Dias and Duncan investigated free and bound MH in potato tubers with HCl and β‐D‐glucosidase treatment . However, when comparing these methods that analyzing free and bound form of MH simultaneously, we have found that concentration of HCl, temperature, time, and extraction approach used in these methods differ a lot.…”

“…Various techniques have been established for the determination of MH, including colorimetric methods, chromatographic methods, electrochemical methods, etc. Among them, as the powerful separation technique, chromatographic methods are the most widely employed approaches for MH analysis in different matrices such as garlic, potato, and tobacco.…”

“…In GC based methods, the extracted MH residues in tobacco were firstly derivatized with either N,O ‐bis(trimethylsilyl) acetamide or dimethyl sulfate, and the obtained MH derivatives were measured by GC coupled with flame ionization detector or GC coupled with nitrogen‐phosphorus detector. In HPLC based methods, MH residues were usually extracted with methanol or HCl by multiple partition steps, and finally analyzed using HPLC with UV detector at wavelengths ranged from 303 to 330 nm. In recent years, with the advancement of instrumentation, LC–MS/MS based methods have been established for determination of MH only or MH and other pesticides simultaneously …”