Manoel L. Martins

Optimization of a QuEChERS based method by means of central composite design for pesticide multiresidue determination in orange juice by UHPLC-MS/MS.

In this study, different extraction procedures based on the QuEChERS method were compared for the multiresidue determination of pesticides in orange juice by ultra high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). After choosing preliminary conditions, an experimental design was carried out with the variables C18, PSA, NaOH and CH3COONa to optimize the sample preparation step. The validation results of the validation were satisfactory, since the method presented recoveries between 70% and 118%, with RSD lower than 19% for spike levels between 10 and 100 μg L(-1). The method limit of detection (LOD) and limit of quantification (LOQ) ranged from 3.0 to 7.6 μg L(-1) and from 4.9 to 26 μg L(-1), respectively. The method developed was adequate for the determination of 74 pesticide residues in orange juice.

Evaluation of the QuEChERS method for the extraction of pharmaceuticals and personal care products from drinking-water treatment sludge with determination by UPLC-ESI-MS/MS

A modified version of the QuEChERS method has been evaluated for the determination of 21 pharmaceuticals and 6 personal care products (PPCPs) in drinking-water sludge samples by employing ultra high liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The performance of the method was evaluated through linearity, recovery, precision (intra-day), method detection and quantification limits (MDL and MQL) and matrix effect. The calibration curves prepared in acetonitrile and in the matrix extract showed a correlation coefficient ranging from 0.98 to 0.99. MQLs values were on the ng g(-1) order of magnitude for most compounds. Recoveries between 50% and 93% were reached with RSDs lower than 10% for most compounds. Matrix effect was almost absent with values lower than 16% for 93% of the compounds. By coupling a quick and simple extraction called QuEChERS with the UPLC-MS/MS analysis, a method that is both selective and sensitive was obtained. This methodology was successfully applied to real samples and caffeine and benzophenone-3 were detected in ng g(-1) levels.

Development of a multiresidue method for the determination of endocrine disrupters in fish fillet using gas chromatography–triple quadrupole tandem mass spectrometry

Endocrine Disrupter Compounds (EDCs) are responsible for alterations in the endocrine system functions. Aquatic organisms are able to accumulate EDCs residues, being the major source of contamination for top predators and human consumers. This study aimed to develop and validate a method for the determination of 40 EDCs in fish fillet using modified QuEChERS and Gas Chromatography coupled with Mass Spectrometry in tandem (GC-MS/MS). A factorial design was used to optimize the extraction procedure. Method validation presented recoveries from 70.1% to 120.0% with RSD<20% and method limit of detection ranged from 0.3 to 7.5 µg kg(-1), showing good accuracy and precision. This method was successfully applied to the analysis of fish fillet from different species and residues of bisphenol A, chlorpyrifos and bifenthrin were detected. The proposed method proved to be effective for the determination of EDCs in fish fillet at very low concentration levels.

Principais técnicas de preparo de amostra para a determinação de resíduos de agrotóxicos em água por cromatografia líquida com detecção por arranjo de diodos e por espectrometria de massas

The determination of pesticide residues in water samples by Liquid Chromatography require sample preparation for extraction and enrichment of the analytes with the minimization of interferences to achieve adequate detection limits. The Solid Phase Extraction (SPE), Solid Phase Microextraction (SPME), Stir Bar Sorptive Extraction (SBSE) and Dispersive Liquid-Liquid Microextraction (DLLME) techniques have been widely used for extraction of pesticides in water. In this review, the principles of these sample preparation techniques associated with the analysis by Liquid Chromatography with Diode Array Detection (LC-DAD) or Mass Spectrometry (LC-MS) are described and an overview of several applications were presented and discussed.

Risk assessment of surface water contamination by herbicide residues: monitoring of propanil degradation in irrigated rice field waters using HPLC-UV and confirmation by GC-MS

This study evaluates the degradation of the herbicide propanil and of its major degradation product, 3,4-dichloroaniline (3,4-DCA) in water from irrigated rice farming in the State of Rio Grande do Sul, Brazil. It also assesses the contamination risk of surrounding surface waters. After a solid phase extraction step, the concentration of both compounds was determined by high performance liquid chromatography with ultraviolet detection. Confirmation was conducted by gas chromatography-mass spectrometry. Concentrations of propanil in water samples varied from 0.1 to 3600 µg L-1. Propanil was degraded very rapidly to 3,4-DCA and high concentrations of this product were found, varying from 1.0 to 567.5 µg L-1 in water. The obtained half-life times for propanil in water under real conditions for the 2001, 2002 and 2003 harvests were 18.2, 12.5 and 12.2 h, respectively.

Study of the Degradation of the Herbicide Clomazone in Distilled and in Irrigated Rice Field Waters using HPLC-DAD and GC-MS

This study evaluated the degradation of the herbicide clomazone in distilled water and from irrigated rice fields, through UV irradiation and under natural conditions. After a solid phase extraction (SPE) as preconcentration step, the remained concentration of clomazone was determined by high performance liquid chromatography with diode array detection (HPLC-DAD) and the identification of the degradation products was achieved by gas chromatography-mass spectrometry (GC-MS). Under UV irradiation, the clomazone was degraded faster in distilled water than in surface water. In irrigated rice water, under sunlight irradiation, clomazone presented a half-life time average of 3.2 days in three consecutive harvests, and after application the concentration in water remained higher than 0.1 μg L-1 for 20 days. Several by-products, like 2-chlorobenzaldehyde and 2-chlorobenzene methanol, were identified by GC-MS, which evidenced that the concentration of intermediates at the begining increase and then they also undergo degradation.

Multiresidue determination of pesticide residues in honey by modified QuEChERS method and gas chromatography with electron capture detection

Honey can present pesticide residues due to the contamination of bees during the collection of pollen and nectar or by treatment of hives. Thus, the determination of pesticide residues in honey is of great importance, despite the difficulty due to the complexity of the matrix. In this study a new method for the determination of pesticides from different chemical groups in honey was developed and validated. Honey samples were extracted by modified QuEChERS method and analyzed by gas chromatography with electron capture detection (GC-ECD). Recovery results, evaluated at three spike levels, were between 71 and 119% for most of the compounds, with relative standard deviation (RSD) < 20%. The proposed method enables the determination at limits of detection between 3 and 6 µg kg-1, combining effective extraction and clean-up steps with good sensitivity and selectivity, and was successfully applied to the analysis of commercial honey samples.

Determination of pesticides and related compounds in water by dispersive liquid–liquid microextraction and gas chromatography-triple quadrupole mass spectrometry

The declining quality of drinking water supplies due to industrial waste is the result of highly diverse industrial processes. In this context, the establishment of analytical methods focused on monitoring organic compounds related to environmental and health problems is very important. In this study, a quick and effective method based on dispersive liquid–liquid microextraction (DLLME) and gas chromatography coupled with triple quadrupole tandem mass spectrometry (GC-QqQ-MS/MS) was developed and validated for the simultaneous determination of pesticide residues and related compounds in water. The proposed DLLME method uses water sample aliquots of 5 mL, 2 mL of acetone as a dispersive solvent and 50 μL of carbon tetrachloride as an extraction solvent at low temperature. This method was successfully applied for the determination of pesticide residues and related compounds in water at quantification limits between 0.03 and 0.10 μg L−1. The method showed a linear range from 0.05 to 10.0 μg L−1 with r2 > 0.998. Recovery assays presented mean recoveries between 70 and 120% for most of the compounds with good precision, despite different chemical natures of the compounds analyzed.

O estado da arte na determinação de resíduos de medicamentos veterinários em alimentos de origem animal empregando técnicas cromatográficas acopladas à espectrometria de massas

The determination of veterinary drug residues in foods of animal origin is an important issue because of the risk these compounds pose to human health in addition to their persistence and tendency to bioaccumulate. In recent years, significant progress has been made in the area and this review presents the state of the art in sample preparation procedures associated with chromatographic techniques coupled to mass spectrometry for multiresidue determination of veterinary drugs in food of animal origin at concentration levels suitable for the control of residues and contaminants in food.

Development of a Multiresidue Method for Pesticide Analysis in Drinking Water by Solid Phase Extraction and Determination by Gas and Liquid Chromatography with Triple Quadrupole Tandem Mass Spectrometry

In this work, a method for multiclass determination of 70 pesticides residues with different properties in drinking water using solid phase extraction (SPE) with polymeric sorbent and determination by gas and liquid chromatography coupled to tandem mass spectrometry (GC-MS/MS and LC-MS/MS) was developed and validated. Different sample volumes, sorbents and elution solvents were evaluated. The best results were obtained using the sorbent Oasis® HLB, sample acidified at pH 2.5 and a mixture of dichloromethane/methanol as eluent. The limit of quantification (LOD) of the method was 0.02 µg L-1 for aldrin, dieldrin and chlordane and 0.5 µg L-1 for the other compounds. Satisfactory accuracy, with recoveries between 70 and 117.3%, and good precision, with relative standard deviation (RSD) values below 19.7% for most of the compounds, were achieved. The validated method was applied to real water samples and results indicated that the proposed method is suitable for the determination of pesticide residues in water samples.