MAISE PASTORE GIMENEZ

MAISE PASTORE GIMENEZ

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Optimizations on Lithium ion exchange separation and isotopic measurements
2022 - OTOMO, JULIANA I.; GIMENEZ, MAISE P.; ANDRADE, MARIANA N. de; MONTEIRO, LUCILENA R.; NASCIMENTO, LETICIA da S.; BATAGLIA, HENRIQUE; LEAO, PAULO H.B.; CECILIO, PRISCILA de S.; BERGAMASCHI, VANDERLEI; COUTINHO, JOAO F.; BUSTILLOS, JOSE O.W.V.
Introduction: The Lithium-7 is of interest for nuclear application, being used for primary cooling of PWR (Pressurized Water Reactor) reactors [1]. An environmentally friendly technique is required to replace the Mercury amalgam technique used worldwide [1,2]. This work aims to present the preliminary results of the development of 7Li separation by ion exchange. Methods: A 120 mm x1.0 cm i.d. glass column filled with Dowex 50W-x16 resin was used. A total of 3.0 liters of 0.2 M CH3COOLi solution percolated the column in order to saturate and displace the formed band of 6Li and 7Li. Fractions were collected every 50 mL, then the resin was washed with 5M HNO3 and ultrapure water. The fractions were filtered and evaporated at 80°C, finally taken up with HNO3 1%. Samples were analyzed by ICP-OES – SPECTRO ARCOS. The fractions were analyzed by ICP-MS, model ELAN 6000 – SCIEX. For isotopic ratio measurement, with the parameters of gas flow of approximately 1.1 L min-1, RF 600 W, gas flow rate 1.2 L min-1, Peak Hopping mode, dwell time 80 and 480 for 6Li and 7Li (respectively), 50 sweeps per reading, 1 read per replicate and 10 replicates. Results: A total of 63 samples were collected from the separation experiment. The Li isotopic ratio measured for each fraction was assessed by ANOVA one-way considering the differences among fractions. A statistical significant difference was observed between the fraction 1 and the remainder fractions and the load solution. The remaining fractions showed an isotopic ratio around the natural abundance (6Li/7Li: 7.59%/92.41% = 0.082). The isotopic ratio of this sample indicated enrichment of 7Li of 0.92% in the fraction number 30. Conclusions: The method of ion exchange with Dowex 50W-x16 resin was efficient on 7Li separation and through ICP-MS method was able to measure the δ 84%₀ enrichment of the 7Li. The isotopic separation procedure via ion exchange is still being studied, however the results are promising.
Sodium interference in lithium isotope ratio analysis by Inductively Coupled Plasma Mass Spectrometry
2022 - ANDRADE, MARIANA N. de; OTOMO, JULIANA I.; GIMENEZ, MAISE P.; NASCIMENTO, LETICIA da S.; NASCIMENTO, HENRIQUE B. do; LEAO, PAULO H.B.; CECILIO, PRISCILA de S.; FERREIRA, JOAO C.; BERGAMASCHI, VANDERLEI S.; BUSTILLOS, OSCAR V.
Introduction: Naturally occurring lithium consists of two stable isotopes, 6Li (7.591%) and 7Li (92.409%) and have applications in nuclear technology, pharmaceutical, automotive and geological research. Enriched 7Li isotope in LiOH form has been used as a pH regulator for Pressurized Water Reactor (PWR) reducing corrosion in the primary water circuit [1-3]. The determination of lithium isotopic composition was analyzed by Inductively Coupled Plasma Mass Spectrometry after ion exchange processes, which has been considered a promising technique for the separation of Li isotopes. One of the concerns in ICP-MS analysis is sodium interference. The presence of sodium in the lithium-containing sample has potential implications for the accuracy of isotopic ratio measurements. For this reason, a method is described for the study of sodium interference in 7Li 295,88%₀ and 303,30%₀ enriched solutions. Methods: For this study, the reference standard L-SVEC was used, it has an isotopic abundance of 92.409% for 7Li and 7.591% for 6Li (6Li/7Li ratio = 0.08251) and solutions enriched at 295,88%₀ (6Li/7Li ratio = 0.06661) and 303,30%₀ (6Li/7Li ratio = 0.06810) of 7Li. Concentrations of 50 μg L-1 of lithium were maintained for the solutions used and it was evaluated with the addition of 50, 100, 300, 450 and 1000 μg L-1 of sodium on the enriched samples suffered significant changes in their isotopic ratio. The ICP-MS used for the sample analysis was a PerkinElmer SCIEX Elan 6000. For the isotopic ratio measurement the parameters used was nebulizer gas flow of approximately 0.94 L min-1 , Radio Frequency (RF) 600 W, gas flow rate 1.2 L min-1 , Peak Hopping mode, dwell time 80 and 480 ms for 6Li and 7Li respectively, 50 sweeps per reading, 1 read per replicate and 10 replicates. Results: For this study, 24 samples were analyzed being divided into four sets of samples with 6 samples each set. The sets were composed of samples without addition of sodium and samples with addition of 50, 100, 300, 450 and 1000 μg L-1 of sodium. The first set of samples, composed of the 295,88%₀ enriched sample, had a standard deviation of 3.59✕10-4. The second set of samples, composed of the 303,30%₀ enriched sample, had a standard deviation of 2.63✕10-4. The third and fourth set of samples, composed of aliquots of the L-SVEC standard, obtained a standard deviation of 2.22✕10-4 e 2.54✕10-4, respectively. Showing that the addition of sodium did not significantly interfere in the ratio of lithium isotopes 6 and 7 according to standard deviation. Conclusions: Through the results obtained from the experiment, it was observed that the variation in the ratio between isotopes 6 and 7 of lithium was not significant for the results of analysis in ICP-MS. However, it should be noted that for the purposes of lithium isotope separation processes using ion exchange resins, the interference of sodium in the chromatographic separation needs to be evaluated.
Multiresidue screening analysis of pesticides in phytotherapics by HPLC - MS/MS and GC/MS
2016 - GIMENEZ, MAISE; MARQUES, JOYCE; OTOMO, JULIANA; LEBRE, DANIEL; VEGA, OSCAR; MARTINS, ELAINE
The active principle of the phytotherapics medicines are derived exclusively from herbal drugs. The use of phytotherapics has increased in the worldwide medicine, rendering important security issues in its development to final product. The pesticide residue is a factor that affects the quality of these medicines, due the absorption of pesticides and its metabolites in plants 1. The ANVISA (Agency of National Health Surveillance) regulates the quality medicine in Brazil. Recently this agency released the resolution - RDC n° 105 due to January 1st, 2018, where the pesticide residue analysis should be monitored in plant species used to phytotherapics 2. The two brands of commercial phytotherapic available in drug stores were evaluated in this project, both have passion flower as the active principle. These medicines are most commonly used as anxiolytic. Therefore, this work aims to perform a multiresidues screening analysis of pesticides (acids, phynylureas, organophophoric, triazines and carbamates) in phytotherapics. Samples will be prepared using QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) technique and analyzed by HPLC - MS/MS and GC/MS 3.
Quantitative analysis of neonicotinoid insecticide residues in surface water by HPLC-MS / MS
2016 - AMARAL, PRISCILA O.; GIMENEZ, MAISE P.; LEBRE, DANIEL T.; MARQUES, JOYCE R.; BUSTILLOS, OSCAR V.
The sudden disappearance of bees in colonies of several countries have attracted the attention of scientists, the public and the world press [1]. This phenomenon was called Colony Collapse Disorder (CCD) and is characterized by a rapid loss of adult bee population. In these colonies, the queen is still alive and accompanied by few adult bees although there are still pups and food in the hive [2]. There are several hypotheses about the causes of this phenomenon; one of them relates a bees exposure for a class of pesticides named neonicotinoids. These are a class of insecticides which began to be produced in 1985 and are based on the nicotine molecule [3]. These insecticides are used to control sucking and chewing insects because of its low toxicity to mammals, fishes and birds, and high toxicity to arthropods, especially insects and crustaceans [4]. The neonicotinoids used in this study are Clothianidin, Imidacloprid and Thiamethoxam. There is no legislation in Brazil to determine the residual limit in water to any of these pesticides, however, the EPA (United States Environmental Protection Agency) has a legislation with limits for each compound. The residual limit for chronic exposures in surface water is 2.1 μg L-1 for Clothianidin [5], 15.8 μg L-1 for Imidacloprid [6] and 0.6 μg L-1 for Thiamethoxam [7]. This study intends to develop and validate a methodology for neonicotinoids in surface water by high performance liquid chromatography with tandem mass spectrometry (HPLC-MS / MS). The samples for this study are surface water collected from a lake in the Bauru country in São Paulo state. The choice of this lake is because its proximity to sugar cane, orange, coffee and watermelon crops. These samples were filtered through a vacuum filtration system and passed through a sample preparation process using the solid phase extraction (SPE). Strata X cartridge was conditioned with methanol - dichloromethane (1:1) and ultrapure water. The water sample was eluted from the cartridge with an alkaline pH range between 9.90 to 10.10, and the analytes of interest were eluted with methanol - dichloromethane (1: 1). The analysis of HPLC-MS / MS used a High Performance Liquid Chromatograph 1100 series by Agilent with an API 2000 mass spectrometer from Sciex. The analysis performed on Multiple Reaction Monitoring (MRM) mode selecting a quantization and confirmation ion for each compound. The quantitation limits are between 1 - 2.5 μg L-1, and the linearity are between 0.991 – 0.997 in this method.