Carla Teglia - Academia.edu (original) (raw)

Papers by Carla Teglia

This paper proposes a multiway calibration strategy implementing the modeling with MCR-ALS and U-... more This paper proposes a multiway calibration strategy implementing the modeling with MCR-ALS and U-PLS/RBL of second-order chromatographic data for quantitation of six analytes: gliclazide, glibenclamide, glimepiride, aten-olol, enalapril and amlodipine in serum samples, in an analysis time of 3 min. The performance of both algorithms was compared in terms of predictive ability, showing relative error of prediction values below 10% in all cases. LOD values calculated are below 30 ng mL −1 for all the studied drugs, which allow detection in human serum in patients under treatment. U-PLS/RBL has higher sensitivity and better detection and quantification limits for all the studied analytes; however results obtained by MCR-ALS enable its usage as well. Both methods provide comparable results for glibenclamide, glimepiride and gliclazide. With this multiway calibration strategy, the presence of enalapril, amlodipine and atenolol could be quantitated with high accuracy. Run time was reduced by 50% considering previous reports, as well as reduction of solvents, in accordance with green chemistry principles.

A dispersive liquid–liquid micro extraction (DLLME) liquid chromatographic method that allows ext... more A dispersive liquid–liquid micro extraction (DLLME) liquid chromatographic method that allows extraction and separation of gliclazide, glibenclamide and glimepiride from serum was developed and optimized with the use of experimental design. The analyzed factors in optimization were type of extracting solvent, extracting solvent volume , dispersing solvent volume, pH and protein precipitation. The selected conditions for DLLME were dichloro-methane 100 μL (extracting solvent), acetonitrile 1000 μL (dispersing solvent) and no protein precipitation. This procedure is simple, requires no sophisticated procedures and produces excellent analyte recoveries. Quantita-tion of glibenclamide, gliclazide and glimepiride in serum samples was carried out by HPLC. This analytical method has been developed and validated, allowing quantitation of the target analytes in presence of atenolol, enalapril and amlodipine besides other serum sample interferents. The chromatographic method is linear, accurate , precise and specific and has the ability to separate the antihyperglycemic drugs from antihypertensive drugs, which are usually found in serum of diabetic patients (LOQs ca. 0.12 μg L −1 for the three analytes).

An efficient generic static headspace gas chromatography (HSGC) method was developed, optimized a... more An efficient generic static headspace gas chromatography (HSGC) method was developed, optimized and validated for the routine determination of several residual solvents (RS) in drug substance, using a strategy with two sets of calibration. Dimethylsulfoxide (DMSO) was selected as the sample diluent and internal standards were used to minimize signal variations due to the preparative step. A gas chromatograph from Agilent Model 6890 equipped with flame ionization detector (FID) and a DB-624 (30 m Â 0.53 mm i.d., 3.00 mm film thickness) column was used. The inlet split ratio was 5:1. The influencing factors in the chromatographic separation of the analytes were determined through a fractional factorial experimental design. Significant variables: the initial temperature (IT), the final temperature (FT) of the oven and the carrier gas flow rate (F) were optimized using a central composite design. Response transformation and desirability function were applied to find out the optimal combination of the chromatographic variables to achieve an adequate resolution of the analytes and short analysis time. These conditions were 30 °C for IT, 158 °C for FT and 1.90 mL/min for F. The method was proven to be accurate, linear in a wide range and very sensitive for the analyzed solvents through a comprehensive validation according to the ICH guidelines.

When determining endogenous compounds in biological samples, the lack of blank or analyte-free ma... more When determining endogenous compounds in biological samples, the lack of blank or analyte-free matrix samples involves the use of alternative strategies for calibration and quantitation. This article deals with the development, optimization and validation of a high performance liquid chromatography method for the determination of retinoic acid in plasma, obtaining at the same time information about its isomers, taking into account the basal concentration of these endobiotica. An experimental design was used for the optimization of three variables: mobile phase composition, flow rate and column temperature through a central composite design. Four responses were selected for optimization purposes (area under the peaks, quantity of peaks, analysis time and resolution between the first principal peak and the following one). The optimum conditions resulted in a mobile phase consisting of methanol 83.4% (v/v), acetonitrile 0.6% (v/v) and acid aqueous solution 16.0% (v/v); flow rate of 0.68 mL min −1 and an column temperature of 37.10 • C. Detection was performed at 350 nm by a diode array detector. The method was validated following a holistic approach that included not only the classical parameters related to method performance but also the robustness and the expected proportion of acceptable results lying inside predefined acceptability intervals, i.e., the uncertainty of measurements. The method validation results indicated a high selectivity and good precision characteristics that were studied at four concentration levels, with RSD less than 5.0% for retinoic acid (less than 7.5% for the LOQ concentration level), in intra and inter-assay precision studies. Linearity was proved for a range from 0.00489 to 15.109 ng mL −1 of retinoic acid and the recovery, which was studied at four different fortification levels in phuman plasma samples, varied from 99.5% to 106.5% for retinoic acid. The applicability of the method was demonstrated by determining retinoic acid and obtaining information about its isomers in human and frog plasma samples from different origins.

This paper reports the development of a method based on high-performance liquid chromatography (H... more This paper reports the development of a method
based on high-performance liquid chromatography (HPLC)
coupled to second-order data modeling with multivariate
curve resolution-alternating least-squares (MCR–ALS) for
quantification of retinoic acid and its main isomers in plasma
in only 5.5 min. The compounds retinoic acid (RA), 13-cisretinoic acid, 9-cis-retinoic acid, and 9,13-di-cis-retinoic acid
were partially separated by use of a Poroshell 120 EC–C18
(3.0 mm×30 mm, 2.7 μm particle size) column. Overlapping
not only among the target analytes but also with the plasma
interferents was resolved by exploiting the second-order advantage of the multi-way calibration. A validation study led to
the following results: trueness with recoveries of 98.5–
105.9 % for RA, 95.7–110.1 % for 13-cis-RA, 97.1–
110.8 % for 9-cis-RA, and 99.5–110.9 % for 9,13-di-cis-RA;
repeatability with RSD of 3.5–3.1 % for RA, 3.5–1.5 % for
13-cis-RA, 4.6–2.7 % for 9-cis-RA, and 5.2–2.7 % for 9,13-
di-cis-RA (low and high levels); and intermediate precision
(inter-day precision) with RSD of 3.8–3.0 % for RA, 2.9–
2.4 % for 13-cis-RA, 3.6–3.2 % for 9,13-di-cis-RA, and 3.2–
2.9 % for 9-cis-RA (low and high levels). In addition, a
robustness study revealed the method was suitable for monitoring patients with dermatological diseases treated with pharmaceutical products containing RA and 13-cis-RA

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2013

A simple and fast on line spectrophotometric method combined with a hybrid hard-soft modeling mul... more A simple and fast on line spectrophotometric method combined with a hybrid hard-soft modeling multivariate curve resolution (HS-MCR) was proposed for the monitoring of photodegradation reaction of ciprofloxacin under UV radiation. The studied conditions attempt to emulate the effect of sunlight on these antibiotics that could be eventually present in the environment. The continuous flow system made it possible to study the ciprofloxacin degradation at different pH values almost at real time, avoiding errors that could arise from typical batch monitoring of the reaction. On the base of a concentration profiles obtained by previous pure soft-modeling approach, reaction pathways have been proposed for the parent compound and its photoproducts at different pH values. These kinetic models were used as a constraint in the HS-MCR analysis. The kinetic profiles and the corresponding pure response profile (UV-Vis spectra) of ciprofloxacin and its main degradation products were recovered after the application of HS-MCR analysis to the spectra recorded throughout the reaction. The observed behavior showed a good agreement with the photodegradation studies reported in the bibliography. Accordingly, the photodegradation reaction was studied by high performance liquid chromatography coupled with UV-Vis diode array detector (HPLC-DAD). The spectra recorded during the chromatographic analysis present a good correlation with the ones recovered by UV-Vis/HS-MCR method.

ELECTROPHORESIS, 2016

A dispersive liquid-liquid microextraction procedure was developed to extract nine fluoroquinolon... more A dispersive liquid-liquid microextraction procedure was developed to extract nine fluoroquinolones in porcine blood, six of which were quantified using a univariate calibration method. Extraction parameters including type and volume of extraction and dispersive solvent and pH, were optimized using a full factorial and a central composite designs. The optimum extraction parameters were a mixture of 250 μL dichloromethane (extract solvent) and 1250 μL ACN (dispersive solvent) in 500 μL of porcine blood reached to pH 6.80. After shaking and centrifugation, the upper phase was transferred in a glass tube and evaporated under N2 steam. The residue was resuspended into 50 μL of water-ACN (70:30, v/v) and determined by CE method with DAD, under optimum separation conditions. Consequently, a tenfold enrichment factor can potentially be reached with the pretreatment, taking into account the relationship between initial sample volume and final extract volume. Optimum separation conditions were as follows: BGE solution containing equal amounts of sodium borate (Na2 B4 O7 ) and di-sodium hydrogen phosphate (Na2 HPO4 ) with a final concentration of 23 mmol/L containing 0.2% of poly (diallyldimethylammonium chloride) and adjusted to pH 7.80. Separation was performed applying a negative potential of 25 kV, the cartridge was maintained at 25.0°C and the electropherograms were recorded at 275 nm during 4 min. The hydrodynamic injection was performed in the cathode by applying a pressure of 50 mbar for 10 s.

Chemometrics and Intelligent Laboratory Systems, 2015

Analytical and Bioanalytical Chemistry, 2014

This paper reports the development of a method based on high-performance liquid chromatography (H... more This paper reports the development of a method based on high-performance liquid chromatography (HPLC) coupled to second-order data modeling with multivariate curve resolution-alternating least-squares (MCR-ALS) for quantification of retinoic acid and its main isomers in plasma in only 5.5 min. The compounds retinoic acid (RA), 13-cis-retinoic acid, 9-cis-retinoic acid, and 9,13-di-cis-retinoic acid were partially separated by use of a Poroshell 120 EC-C18 (3.0 mm × 30 mm, 2.7 μm particle size) column. Overlapping not only among the target analytes but also with the plasma interferents was resolved by exploiting the second-order advantage of the multi-way calibration. A validation study led to the following results: trueness with recoveries of 98.5-105.9 % for RA, 95.7-110.1 % for 13-cis-RA, 97.1-110.8 % for 9-cis-RA, and 99.5-110.9 % for 9,13-di-cis-RA; repeatability with RSD of 3.5-3.1 % for RA, 3.5-1.5 % for 13-cis-RA, 4.6-2.7 % for 9-cis-RA, and 5.2-2.7 % for 9,13-di-cis-RA (low and high levels); and intermediate precision (inter-day precision) with RSD of 3.8-3.0 % for RA, 2.9-2.4 % for 13-cis-RA, 3.6-3.2 % for 9,13-di-cis-RA, and 3.2-2.9 % for 9-cis-RA (low and high levels). In addition, a robustness study revealed the method was suitable for monitoring patients with dermatological diseases treated with pharmaceutical products containing RA and 13-cis-RA.

Talanta, 2011

The development, optimization and validation of an ion-pairing high performance liquid chromatogr... more The development, optimization and validation of an ion-pairing high performance liquid chromatography method for the simultaneous determination of both nicarbazin (NIC) components: 4,4&amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;-dinitrocarbanilide (DNC) and 2-hydroxy-4,6-dimethylpyrimidine (HDP) in bulk materials and feed additives are described. An experimental design was used for the optimization of the chromatographic system. Four variables, including mobile phase composition and oven temperature, were analyzed through a central composite design exploring their contribution to analyte separation. Five responses: peak resolutions, HDP capacity factor, HDP tailing and analysis time, were modelled by using the response surface methodology and were optimized simultaneously by implementing the desirability function. The optimum conditions resulted in a mobile phase consisting of 10.0 mmol L(-1) of 1-heptanesulfonate, 20.0 mmol L(-1) of sodium acetate, pH=3.30 buffer and acetonitrile in a gradient system at a flow rate of 1.00 mL min(-1). Column was an INERSTIL ODS-3 (4.6 mm×150 mm, 5 μm particle size) at 40.0°C. Detection was performed at 300 nm by a diode array detector. The validation results of the method indicated a high selectivity and good precision characteristics, with RSD less than 1.0% for both components, both in intra and inter-assay precision studies. Linearity was proved for a range of 32.0-50.0 μg mL(-1) of NIC in sample solution. The recovery, studied at three different fortification levels, varied from 98.0 to 101.4 for HDP and from 99.1 to 100.2 for DNC. The applicability of the method was demonstrated by determining DNC and HDP content in raw materials and commercial formulations used for coccidiosis prevention. Assays results on real samples showed that considerable differences in molecular ratio DNC:HDP exist among them.

Chemosphere, Jan 13, 2015

Retinoids are known to regulate important processes such as differentiation, development, and emb... more Retinoids are known to regulate important processes such as differentiation, development, and embryogenesis of vertebrates: Alteration in endogenous retinoids concentration is linked with teratogenic effects. Retinol (ROH), retinoid acid (RA), and isoform 13-Cis-retinoic acid (13-Cis-RA), in plasma of a native adults frog, Leptodactylus chaquensis from a rice field (RF) and a forest (reference site; RS) were measured. ROH did not vary between treatment sites. RA and 13-Cis-RA activities were higher (93.7±8.6μgmL(-1) and 131.7±11.4μgmL(-1), respectively) in individuals collected from RF than in those from RS (65.5±8.6μgmL(-1) and 92.2±10.2μgmL(-1), respectively). The ratios retinoic acid-retinol (RA/ROH) and 13-Cis-RA/ROH revealed significantly higher values in RF than in RS. RA and 13-Cis-RA concentrations in plasma on wild amphibian's species such as L. chaquensis would be suitable biomarkers of pesticide exposure in field monitoring. Finally, the mechanism of alteration in ret...

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2013

ELECTROPHORESIS, 2016

Chemometrics and Intelligent Laboratory Systems, 2015

Analytical and Bioanalytical Chemistry, 2014

This paper reports the development of a method based on high-performance liquid chromatography (H... more This paper reports the development of a method based on high-performance liquid chromatography (HPLC) coupled to second-order data modeling with multivariate curve resolution-alternating least-squares (MCR-ALS) for quantification of retinoic acid and its main isomers in plasma in only 5.5 min. The compounds retinoic acid (RA), 13-cis-retinoic acid, 9-cis-retinoic acid, and 9,13-di-cis-retinoic acid were partially separated by use of a Poroshell 120 EC-C18 (3.0 mm × 30 mm, 2.7 μm particle size) column. Overlapping not only among the target analytes but also with the plasma interferents was resolved by exploiting the second-order advantage of the multi-way calibration. A validation study led to the following results: trueness with recoveries of 98.5-105.9 % for RA, 95.7-110.1 % for 13-cis-RA, 97.1-110.8 % for 9-cis-RA, and 99.5-110.9 % for 9,13-di-cis-RA; repeatability with RSD of 3.5-3.1 % for RA, 3.5-1.5 % for 13-cis-RA, 4.6-2.7 % for 9-cis-RA, and 5.2-2.7 % for 9,13-di-cis-RA (low and high levels); and intermediate precision (inter-day precision) with RSD of 3.8-3.0 % for RA, 2.9-2.4 % for 13-cis-RA, 3.6-3.2 % for 9,13-di-cis-RA, and 3.2-2.9 % for 9-cis-RA (low and high levels). In addition, a robustness study revealed the method was suitable for monitoring patients with dermatological diseases treated with pharmaceutical products containing RA and 13-cis-RA.

Talanta, 2011

Chemosphere, Jan 13, 2015