Juan Manuel Padró

• PhD Student at National University of La Plata

The partition coefficients, P IL/w, of several compounds, some of them of biological and pharmacological interest, between water and room-temperature ionic liquids based on the imidazolium, pyridinium, and phosphonium cations, namely 1-octyl-3-methylimidazolium hexafluorophosphate, N-octylpyridinium tetrafluorophosphate, trihexyl(tetradecyl)phospho...

This study explores the copolymerization of acrylic acid and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) in supercritical carbon dioxide (scCO2) as a sustainable alternative to traditional solvent-based methods. Using free-radical polymerization in scCO2, copolymers were synthesized without the need for additional drying. The influence of A...

The synthesis of poly(acrylic acid-co-acrylamide) was investigated to enhance its rheological properties. Syntheses were conducted in both aqueous and supercritical fluid media, with and without the incorporation of a novel star-shaped macromonomer. The macromonomer, synthesized from a Boltorn H30 core with PEGMA⁵⁰⁰ arms and modified to contain a s...

Stimuli‐responsive polymers stand out for their ability to respond to small environmental changes. One of the most representative thermo‐sensitive materials is poly( N ‐isopropyl acrylamide) (PNIPAm), which presents reversible phase transitions close to the human body temperature. However, previous studies observed that the copolymerization of NIPA...

Acrylamide polymers are typically used in industrial and healthcare sectors as thickening agents; however, their thickening capabilities rely mainly in their molecular mass. A versatile and simple strategy to improve their performance is the copolymerization with specific monomers or their chemical modification with structures like dendritic or hyp...

This study focuses on the synthesis of a polymer through the grafting of tannic acid onto poly(acrylamide-co-acrylic acid). The main goal is to generate polymers with lateral branched structures with the versatile bonding abilities associated with tannic acid and then study their ability to modify the viscosity of aqueous solutions for potential ap...

This work demonstrates the potential of two-dimensional liquid chromatography (2D-LC) to increase the resolution capacity of multiple pesticides in a single analysis of samples that contain both chiral and achiral compounds. The setup is based on the combination of a chiral column in the first dimension and an achiral column in the second dimension...

In past decades, the combination of polymers to obtain blends in film shapes has been a very effective strategy to meet the needs of the increasingly demanding market. In this sense, pH- and thermo-sensitive (PHT) polymers have recently drawn the attention of researchers for their countless applications. However, binary mixtures of typical PHTs lik...

Analytical method validation is the first step for quantitative analysis, and both validation and quantitation are usual and fundamental tasks in analytical work; hence it is extremely important to perform them in the most rigorous way to obtain quality results. Then, in this sense, are we able to answer the question: is standard addition calibrati...

In this study, we describe the experimental variables influencing enantioseparation of twelve β-blockers when analyzed under polar-organic, reversed-phase and hydrophilic interaction liquid chromatography conditions on a column with immobilized amylose tris(3-chloro-5-methylphenylcarbamate) as chiral stationary phase. Regarding polar-organic mode,...

In this work, the use of different solvents and temperatures was explored, aiming to evaluate their influence on the enantioseparation of pesticides by HPLC in polar-organic conditions, employing a column containing immobilized amylose tris(3-chloro-5-methylphenyl-carbamate) . The chiral separation of seventeen different pesticides widely used as h...

Polysaccharide-based chiral stationary phases have been recognized as one of the most powerful ones for high performance liquid chromatography (HPLC) separations of chiral compounds in analytical and also in preparative scale. Immobilized polysaccharide-based chiral stationary phases constitute a remarkable achievement due to their stable nature on...

We used a permethyl-β-cyclodextrin chiral stationary phase under reversed-phase conditions for the chiral separation of four aryloxyphenoxy-propionate herbicides (fenoxaprop-p-ethyl, quizalofop-p-ethyl and tefuryl and haloxyfop-p-methyl) with mixtures of methanol, ethanol, 2-propanol, n-propanol, tert-butanol, or acetonitrile and water as mobile ph...

In this work, we studied the combination of chemometric methods with chromatographic separations as a strategy applied to the analysis of enantiomers when complete enantioseparation is difficult or requires long analysis times and, in addition, the target signals have interference from the matrix. We present the determination of ibuprofen enantiome...

Valuable quantitative information could be obtained from strongly overlapped chromatographic profiles of two enantiomers by using proper chemometric methods. Complete separation profiles where the peaks are fully resolved are difficult to achieve in chiral separation methods, and this becomes a particularly severe problem in case that the analyst n...

Chagas disease constitutes a major public health problem in Latin America. Human breast milk is a biological sample of great importance for the analysis of therapeutic drugs, as unwanted exposure through breast milk could result in pharmacological effects in the nursing infant. Thus, the goal of breast milk drug analysis is to inquire to which exte...

s s pK a measurements of dihydrogen phosphate and Tris(hydroxymethyl) aminomethane in acetonitrile/water mixtures from 20 to 60 1C: Potentiometric method Buffer pK a Dihydrogen phosphate Tris(hydroxymethyl)aminomethane Acetonitrile/water mixtures Temperature a b s t r a c t We measured pK a values of Tris(hydroxymethyl)aminomethane and dihydrogen p...

Due to migration, Chagas disease is a significant public health problem in Latin America, and in other nonendemic regions. The 2 drugs currently available for the treatment, nifurtimox and benznidazole (BNZ), are associated with a high risk of toxicity in therapeutic doses. Excretion of drug into human breast milk is a potential source of unwanted...

a b s t r a c t Two different cysteine peptidases obtained from plant latex (papain from Carica papaya and araujiain from Araujia hortorum) demonstrated to be good catalysts for the condensation of coded and non-coded Cbz-amino acids and amines such as amino alcohols and amino acetals in acetonitrile containing 1% (v/v) water. Both kinetically and...

A chiral anion-exchanger stationary phase based on cinchonidine (CD) was developed. Two columns were packed with and without endcapping (EC) treatment (CD-chiral stationary phase[CD-CSP(EC)] and [CD-CSP], respectively) and studied for their ability to separate N-2,4-dinitrophenyl α-amino acids (DNP-amino acids) enantiomers over a temperature range...

A new automated and rapid potentiometric method for determining the effect of organic-solvent composition on pK(a) has been developed. It is based on the measurements of pH values of buffer solutions of variable solvent compositions using a combined glass electrode. Additions of small volumes of one precisely thermostated solution into another, bot...

The natural alkaloid quinine (QN) was immobilized on porous silica particles, and part of the material was subsequently endcapped with n-hexyl hydrocarbon chains. Two synthetic strategies for silanization of the support were first compared. These columns were thoroughly evaluated in order to study the influence of endcapping in the enantiorecogniti...

The partition coefficients, P(IL/w), for different probe molecules as well as for compounds of biological interest between the room-temperature ionic liquids (RTILs) 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF(6)], 1-hexyl-3-methylimidazolium hexafluorophosphate, [HMIM][PF(6)], 1-octyl-3-methylimidazolium tetrafluoroborate, [OMIM][BF...

The vibrational properties of two difluoroaminocarbonyl species were analyzed by recording the FTIR spectra of the vapor for difluoroaminocarbonyl fluoride, F(2)NC(O)F, and difluoroaminocarbonyl isocyanate, F(2)NC(O)NCO. Moreover, the Raman spectrum of liquid F(2)NC(O)NCO was obtained. Vibrational assignments were made on the basis of a normal coor...