T P Ahammed Shabeer

Multiresidue analysis of multiclass pesticides and polyaromatic hydrocarbons in fatty fish by gas chromatography tandem mass spectrometry and evaluation of matrix effect

This paper reports a selective and sensitive method for multiresidue determination of 119 chemical residues including pesticides and polyaromatic hydrocarbons (PAH) in high fatty fish matrix. The novel sample preparation method involved extraction of the target analytes from homogenized fish meat (5 g) in acetonitrile (15 mL, 1% acetic acid) after three-phase partitioning with hexane (2 mL) and the remaining aqueous layer. An aliquot (1.5 mL) of the acetonitrile layer was aspirated and subjected to two-stage dispersive solid phase extraction (dSPE) cleanup and the residues were finally estimated by gas chromatography mass spectrometry with selected reaction monitoring (GC-MS/MS). The co-eluted matrix components were identified on the basis of their accurate mass by GC with quadrupole time of flight MS. Addition of hexane during extraction and optimized dSPE cleanup significantly minimized the matrix effects. Recoveries at 10, 25 and 50 μg/kg were within 60-120% with associated precision, RSD<11%.

Quantitative Screening of Agrochemical Residues in Fruits and Vegetables by Buffered Ethyl Acetate Extraction and LC-MS/MS Analysis

A buffered ethyl acetate extraction method is proposed for the simultaneous analysis of 296 agrochemicals in a wide range of fruit and vegetable matrices by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The optimized quantity of acetate buffer (1% acetic acid + 0.5 g of sodium acetate per 10 g of sample) adjusted the pH of each test matrix to 5-6, which in turn significantly improved recoveries of acidic and basic compounds. The role of diethylene glycol (used in the evaporation step) on signal suppression of certain compounds was evaluated, and its quantity was optimized to minimize such an effect. The method was validated in grape, mango, drumstick, bitter gourd, capsicum, curry leaf, and okra as per the DG-SANCO/12571/2013 guidelines. Recoveries in the fortification range of 1-40 μg/kg were within 70-120% with associated relative standard deviations below 20% for most of the compounds. The method has potential for regulatory and commercial applications with a generic approach.

Residue analysis of fipronil and difenoconazole in okra by liquid chromatography tandem mass spectrometry and their food safety evaluation.

A liquid chromatography tandem mass spectrometry (LC-MS/MS) based method is reported for simultaneous analysis of fipronil (plus its metabolites) and difenoconazole residues in okra. The sample preparation method involving extraction with ethyl acetate provided 80-107% recoveries for both the pesticides with precision RSD within 4-17% estimated at the limits of quantification (LOQ, fipronil=1ngg(-1), difenoconazole=5ngg(-1)) and higher fortification levels. In field, both the pesticides dissipated with half-life of 2.5days. The estimated pre-harvest intervals (PHI) for fipronil and difenoconazole were 15 and 19.5days, and 4 and 6.5days at single and double dose of field applications, respectively. Decontamination of incurred residues by washing and different cooking treatments was quite efficient in minimizing the residue load of both the chemicals. Okra samples harvested after the estimated PHIs were found safe for human consumption.

Residue dissipation and processing factor for dimethomorph, famoxadone and cymoxanil during raisin preparation.

A method was validated for the simultaneous analysis of the residues of dimethomorph, famoxadone and cymoxanil in grape and raisin matrix by ethyl acetate based extraction and liquid chromatography tandem mass spectrometric analysis. Field studies were conducted to evaluate the dissipation rate kinetics and processing factor (PF) for these pesticides during raisin making. Residue data during the drying process were best fitted to 1st+1st order rate kinetics with half-life ranging between 8-9 days for dimethomorph, 12-13 days for famoxadone and 9-10 days for cymoxanil at single dose (SD) and double dose (DD), respectively. PF values calculated were 1.03 and 1.14 for dimethomorph, 1.95 and 2.09 for famoxadone, and 1.99 and 1.35 for cymoxanil at SD and DD, respectively. PF value >1 indicates concentration of the residues during raisin making. The residues of detected pesticides in market samples of raisins were devoid of any risk of acute toxicity related to dietary exposure.

Exploitation of Nano-Bentonite, Nano-Halloysite and Organically Modified Nano-Montmorillonite as an Adsorbent and Coagulation Aid for the Removal of Multi-Pesticides from Water: A Sorption Modelling Approach

The objective of this study was to investigate the removal of multi-pesticides through a combined treatment process with coagulation–adsorption on nano-clay. Nano-clays like nano-bentonite, nano-halloysite and organically modified nano-montmorillonite were used as the adsorbent, and alum and polyaluminium chloride (PAC) were used as the coagulants. The coagulation method alone was not sufficient to purify water, whereas coagulation plus adsorption methods provided superior purification. Amongst the nano-clays used, organically modified nano-montmorillonite gave the best result in terms of pesticide removal from water. In order to evaluate the effect of coagulant addition on the removal efficiency of nano-clay, the respective adsorption isotherms were also calculated in the presence and absence of coagulants. Freundlich isotherm constants have shown that adsorption of pesticides on different nano-clay depends on the type of clay, presence and absence of coagulants as well as the properties of pesticides. The treatment combination having the maximum removal capacity was used efficiently for the removal of pesticides from natural and fortified natural water. The results indicated that alum–PAC coagulation aided by nano-clay as an adsorbent was the superior process for the simultaneous removal of multi-pesticides from water.

Validation of a Residue Analysis Method for Streptomycin and Tetracycline and Their Food Safety Evaluation in Pomegranate (Punica granatum L.)

A single-step methanol extraction based method was developed and validated for simultaneous estimation of the residues of streptomycin and tetracycline group compounds in pomegranate fruits by LC-MS/MS. The limits of quantification for all target compounds were ≤0.005 mg kg(-1) with recoveries (%) at fortification levels of 0.005, 0.01, and 0.05 mg kg(-1) being within 90-116% (RSD ≤ 9%) and interday precision RSD ≤ 12% at 0.01 mg kg(-1). A field experiment on the dissipation of streptomycin and tetracycline (including 4-epimers) residues in pomegranate fruits with regards to field applications of the commercial formulation Streptocycline SP (streptomycin sulfate 90% + tetracycline hydrochloride 10%) at 200 and 400 g a.i. ha(-1) indicated preharvest intervals of 45 and 55 days for streptomycin and 12 and 15 days for tetracycline, respectively. The study will be useful in promoting effective residue monitoring and ensuring safe use of these antibiotics in managing bacterial diseases of pomegranate.

Kresoxim methyl dissipation kinetics and its residue effect on soil extra-cellular and intra-cellular enzymatic activity in four different soils of India

The rate of degradation of kresoxim methyl and its effect on soil extra-cellular (acid phosphatase, alkaline phosphatase and β-glucosidase) and intra-cellular (dehydrogenase) enzymes were explored in four different soils of India. In all the tested soils, the degradation rate was faster at the beginning, which slowed down with time indicating a non-linear pattern of degradation. Rate of degradation in black soil was fastest followed by saline, brown and red soils, respectively and followed 1st or 1st + 1st order kinetics with half-life ranging between 1–6 days for natural soil and 1–19 days for sterile soils. The rate of degradation in natural against sterilized soils suggests that microbial degradation might be the major pathway of residue dissipation. Although small changes in enzyme activities were observed, kresoxim methyl did not have any significant deleterious effect on the enzymatic activity of the various test soils in long run. Simple correlation studies between degradation percentage and individual enzyme activities did not establish any significant relationships. The pattern and change of enzyme activity was primarily due to the effect of the incubation period rather than the effect of kresoxim methyl itself.

A unified approach for high-throughput quantitative analysis of the residues of multi-class veterinary drugs and pesticides in bovine milk using LC-MS/MS and GC-MS/MS.

This paper reports a unified sample preparation approach for high-throughput multi-residue analysis of veterinary drugs and pesticides in a single sub-sample of bovine milk. The sample (5 g) was deproteinized with acetonitrile before an aliquot (I) was withdrawn, and the remainder was phase-separated using MgSO4 and NaCl. The acetonitrile layer (II) was recovered and the extracts combined, cleaned, and solvent-exchanged before the concentrations of veterinary drugs and pesticides were measured by ultra-fast liquid chromatography tandem mass spectrometry (UFLC-MS/MS). As a unique approach, extract II was analyzed simultaneously using gas chromatography tandem mass spectrometry (GC-MS/MS). Method performance for 78 drugs and 238 pesticides complied with CD 2002/657/EC and SANTE/11813/2017 guidelines, respectively, with significant savings in time and cost. Thus, it would be ideal for regulatory analysis of analytes ranging from non-polar organochlorine pesticides to polar drugs, including penicillins, quinolones, and tetracyclines.

Estimation of polyphenols by using HPLC–DAD in red and white wine grape varieties grown under tropical conditions of India

Abstract Grapes are well known for their high content of phenolic compounds. Polyphenols are classified into flavonoids and non-flavonoids by their primary chemical structures of hydroxybenzene. Flavonoids mainly consist of anthocyanins, flavonoids, and flavonols whereas non-flavonoids include hydroxycinnamic and hydroxybenzoic acids. In the present study, sixteen phenolic compounds from ten red and nine white grape wine varieties were quantified using high-performance liquid chromatography. Gallic acid, Vanillic acid, Rutin hydrate, Ellagic acid, Chlorogenic acid, Sorbic acid, Catechin hydrate, Epicatechin, p-coumaric acid, Quercetin, Myricetin, Kaempferol, Piceatannol, and Resveratrol were major compounds found in red wine grapes. Among the varieties, Petit Verdot, Cabernet Franc showed maximum quantitative phenolics, whereas Cabernet Sauvignon, Niellucio, Cinsaut, and Syrah showed least quantitative phenolics in grape berries. Phenolic profile of white wine grapes showed lower concentration of phenolics than that of red wine grapes. The variety Gros Meseng showed maximum phenolics followed by Sauvignon, while the variety Colombard and Chenin Blanc showed least phenolics.

Comprehensive multiresidue determination of pesticides and plant growth regulators in grapevine leaves using liquid- and gas chromatography with tandem mass spectrometry

Grape leaf, which is known for its nutritional and medicinal properties, is finding increased applications for cuisine and remedial purposes. This article reports a comprehensive analytical method for the identification and quantification of a broad range of pesticides and plant growth regulators (PGRs) in the grape leaf matrix. The sample preparation method for pesticides involved an optimized QuEChERS-based extraction protocol, with subsequent clean-up by the dispersive solid phase extraction (dSPE) using a mixture of sorbents (25 mg PSA + 5 mg GCB + 150 mg MgSO4). The PGRs were extracted with methanol. The performance of the method was investigated and validated for a mixture of 363 pesticides (148 in GC-MS/MS and 203 in LC-MS/MS) and 12 PGRs (LC-MS/MS) in compliance with the analytical quality control criteria of the SANTE/11813/2017 guidelines. The matrix effects were comparatively higher against grape berries. The findings indicated satisfactory recoveries at 10 ng/g and higher levels with precision RSDs less than 20%. This method has potential applications in commercial residue testing laboratories and also for the regulatory compliance check purposes for its lower LOQs compared to the corresponding EU-MRLs.