Determination of maleic hydrazide residues in garlic bulbs by HPLC

Real-Time Monitoring of Translocation, Dissipation, and Cumulative Risk of Maleic Hydrazide in Potato Plants and Tubers by Ion Exclusion Chromatography

In this paper, a high-performance ion exclusion chromatographic (ICE) method was developed and applied for monitoring maleic hydrazide (MH) translocation in complex potato plant tissue and tuber matrices. After middle leaf uptake, most MH was trapped and dissipated in the middle leaf, and the rest was transported to other parts mainly through the phloem. Soil absorption significantly reduced the uptake efficiency of the root system, in which MH was partitioned to dissipate in root protoplasts or transfer through the xylem and persisted in the plant. Tuber uptake enabled MH to remain in the flesh and maintain stable levels under storage conditions, but during germination, MH was translocated from the flesh to the growing buds, where it dissipated through the short-day photoperiodic regime. The results demonstrated successful application of the ICE method and provided necessary insights for real-time monitoring of MH translocation behavior to effectively improve potato edible safety.

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

Maleic hydrazide has been extensively used as an effective growth regulator in tobacco sucker control. After application, maleic hydrazide distributes itself throughout the tobacco plant where it can exist as free, or forms glucoside conjugates with glucose, or becomes bound with lignin. Among them, free maleic hydrazide and its glucoside conjugates are extractable under conventional solvent extraction, while lignin bound maleic hydrazide is claimed to be non-extractable. Herein, an autoclave extraction method has been developed to extract maleic hydrazide effectively, in which tobacco samples are extracted in an autoclave at 130°C for 1 h using 4 M hydrochloric acid. Under such pressurized hot acidic water conditions, lignin bound maleic hydrazide can be released. Meanwhile, glucoside conjugates are hydrolyzed. Total maleic hydrazide is detected by liquid chromatography coupled with tandem mass spectrometry, and the quantitative results coincide well with that obtained from the international standard method. The proposed autoclave extraction with liquid chromatography and tandem mass spectrometry method exhibits excellent linearity in the range of 5-200 mg/kg (R2  = 0.9998), the matrix matched limit of detection and limit of quantification is 0.68 and 2.27 mg/kg, respectively. This method is simple and improves sample capacity, providing an effective approach to monitoring maleic hydrazide residues in tobacco.

Determination of Glyphosate, Maleic Hydrazide, Fosetyl Aluminum, and Ethephon in Grapes by Liquid Chromatography/Tandem Mass Spectrometry

A simple high-throughput liquid chromatography/tandem mass spectrometry (LC-MS-MS) method was developed for the determination of maleic hydrazide, glyphosate, fosetyl aluminum, and ethephon in grapes using a reversed-phase column with weak anion-exchange and cation-exchange mixed mode. A 5 g test portion was shaken with 50 mM HOAc and 10 mM Na2EDTA in 1/3 (v/v) MeOH/H2O for 10 min. After centrifugation, the extract was passed through an Oasis HLB cartridge to retain suspended particulates and nonpolar interferences. The final solution was injected and directly analyzed in 17 min by LC-MS-MS. Two MS-MS transitions were monitored in the method for each target compound to achieve true positive identification. Four isotopically labeled internal standards corresponding to each analyte were used to correct for matrix suppression effects and/or instrument signal drift. The linearity of the detector response was demonstrated in the range from 10 to 1000 ng/mL for each analyte with a coefficient of determination (R2) of ≥0.995. The average recovery for all analytes at 100, 500, and 2000 ng/g (n = 5) ranged from 87 to 111%, with a relative standard deviation of less than 17%. The estimated LOQs for maleic hydrazide, glyphosate, fosetyl-Al, and ethephon were 38, 19, 29, and 34 ng/g, respectively.

Fast determination of four polar contaminants in soy nutraceutical products by liquid chromatography coupled to tandem mass spectrometry

An analytical method based on a modified QuPPe (quick polar pesticide) extraction procedure coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was evaluated for the determination of four polar compounds (chlorate, fosetyl-Al, maleic hydrazide, and perchlorate) in nutraceutical products obtained from soy. Experimental conditions including extraction such as solvent, acidification, time, and clean-up sorbents were varied. Acidified acetonitrile (1 % formic acid, v/v) was used as extraction solvent instead of methanol (conventional QuPPe), which provides a doughy mixture which cannot be injected into the LC. Clean-up or derivatization steps were avoided. For analysis, several stationary phases were evaluated and Hypercarb (porous graphitic carbon) provided the best results. The optimized method was validated and recoveries ranged between 46 and 119 %, and correction factors can be used for quantification purposes bearing in mind that inter-day precision was equal to or lower than 17 %. Limits of quantification (LOQs) ranged from 4 to 100 μg kg-1. Soy-based nutraceutical products were analyzed and chlorate was detected in five samples at concentrations between 63 and 1642 μg kg-1. Graphical Abstract Analysis of polar compounds in soy-based nutraceutical products.

Reduced graphene oxide/gold tetraphenyl porphyrin (RGO/Au–TPP) nanocomposite as an ultrasensitive amperometric sensor for environmentally toxic hydrazine

A gold tetra phenyl porphyrin/reduced graphene oxide (RGO/Au–TPP) nanocomposite film modified glassy carbon electrode (GCE) was prepared for the trace level detection of hydrazine.

Sprout suppression on potato: need to look beyond CIPC for more effective and safer alternatives

World over, potatoes are being stored at 8-12 °C (85-90 % RH). This is the most common way of long-term (up to 6 to 9 months) storage of potatoes. The benefit of storing the potatoes within the temperature range of 8-12 °C is minimum accumulation of sugars in stored potato tubers. In sub-temperate, sub-tropical and tropical countries of the world, short-term (3 to 4 months) storage of potatoes is being done by non-refrigerated traditional/on-farm methods. These short- and long-term storage methods keep the stored potatoes suitable not only for table purpose but also for processing. However, once the natural dormancy period of potato is over, the prevailing temperatures in these storage methods favour sprouting and sprout growth. Therefore, use of some sprout suppressant to check the sprout growth becomes essential under these methods of potato storage. CIPC [Isopropyl N-(3-chlorophenyl) carbamate] is the most wide spread and commonly used sprout suppressant on potatoes. CIPC has been in use for more than 50 years and research carried out over such a long period use of CIPC has not only enhanced our understanding of its properties and chemistry but also about the production and toxicological status of its metabolites/degradation products. Today, various safety issues and concerns have surfaced primarily due to continuous and long-term use of CIPC. This review presents an appraisal on CIPC and explains the reasons for the long-time dependence on this chemical as a potato sprout suppressant. Issues like maximum residue limit and acceptable daily intake limit are being discussed for CIPC. This article brings an update on practical aspects of potato storage, residue levels of CIPC, efficacy of CIPC as sprout suppressant and health and environmental safety issues linked with CIPC and its metabolites. The aim of this article is to find possible solutions, way outs and future plans that can make the sprout suppression of potatoes safer and more risk free.

Surface-enhanced Raman spectroscopic analysis of maleic hydrazide adsorbed on gold surface

In this paper, surface-enhanced Raman scattering (SERS) spectra of maleic hydrazide (MH, 6-hydroxy-3(2H)-pyridazinone) were studied by using citrate-reduced gold colloidal nanoparticles. Comparisons between the prominent SERS bands and the precise mode descriptions predicted through density functional theory (DFT) simulations at the B3LYP/6-311++g(d,p) level allowed an in-depth orientation analysis of the adsorbed species on gold surfaces. And main forms of hydrogen bonds in the solid state of MH were also determined to be O-H⋯O. Furthermore, the effects of concentration and pH on the SERS spectra of the molecule were discussed. It is found that with the different adsorbate concentration, the SERS spectra of MH show significant changes in their features, indicating different orientations and adsorption sites of the molecule on the gold colloidal surface. The SERS and absorption spectra under different pH conditions show that a basic environment leads to the deprotonation of N2 and the nearly parallel orientation of the MH molecule on the gold surface. Moreover, the enhanced characteristic bands were observed at MH concentrations down to about 1 ppm with the gold colloids, demonstrating a potential of the technique in the analysis of MH residues.