Fresenius Journal of Analytical Chemistry, Mar 13, 1998
Electrodes selective to potassium and calcium with improved senstivity were constructed like conv... more Electrodes selective to potassium and calcium with improved senstivity were constructed like conventional electrode (ISEs), but used an operational amplifier to sum the potentials supplied by the four membranes (ESOAs). The results obtained during the evaluation of their working characteristics were compared to those obtained by conventional ISEs and were found to be similar, but with higher precision. The electrodes were used in the potentiometric determination of potassium, calcium and magnesium in wines. The results given by ESOAs were more precise than those from ISEs. The results obtained by potentiometry were in good agreement with those from AES for potassium and AAS for calcium and magnesium.
Abstract Understanding the potential of ionic liquids in biocatalysis is both useful and difficul... more Abstract Understanding the potential of ionic liquids in biocatalysis is both useful and difficult. The unique properties of ionic liquids, such as their tunability, allow for the medium to be adjusted to the reaction, thereby supporting both substrate solubility and enzyme activity. Thus, the effect of 9 different ionic liquids with different structures (in terms of cation, anion, and the attached substituents) on the activity of β-galactosidase, an enzyme widely used in food industry processes, was investigated. According to the findings of this study, three of the nine tested ionic liquids promoted an increase in β-galactosidase activity, while two of them ([bmpyr][Cl] and [bmpyr][BF4]) promoted an inactivation (with EC50 of 20.4 and 10.7 mmol L−1, respectively), most likely due to the presence of the cation [bmpyr]. Some correlations between the structure of ionic liquids and the activity of β-galactosidase were established. To carry out these studies, a microfluidic automatic system was used, allowing for greater control of the reaction conditions as well as a reduction in reagent consumption and waste generation. It demonstrated the system's potential as a simple, versatile, robust, and fast analytical tool for the automation of enzymatic assays in ILs medium.
The results obtained in on-line monitoridg of lipase production by Candida rugosa in a batch ferm... more The results obtained in on-line monitoridg of lipase production by Candida rugosa in a batch fermentation process are presented. For this purpose an automatic lipase concentration analyzer has been developed and tested. Its good reproducibility and its capability to perform the analysis in less time than the classical titrimetric method make it very suitable for on-line determination lipase concentration in fermentation processes.
International Journal of Environmental Analytical Chemistry, 1997
This work describes the construction and the evaluation of a nitrate potentiometric transducer wi... more This work describes the construction and the evaluation of a nitrate potentiometric transducer with improved sensitivity and it application to the determination of low levels of nitrate in natural waters. The results obtained in these determinations were evaluated comparatively with those obtained by the conventional ion-selective electrodes and by the reference methods which include colourimetric measurement.The construction of the developed
Cancer is one of the most alarming diseases due to its high mortality and still increasing incide... more Cancer is one of the most alarming diseases due to its high mortality and still increasing incidence rate. Currently available treatments for this condition present several shortcomings and new options are continuously being developed and evaluated, aiming at increasing the overall treatment efficiency and reducing associated adverse side effects. Gemcitabine has proven activity and is used in chemotherapy. However, its therapeutic efficiency is limited by its low bioavailability as a result of rapid enzymatic inactivation. Additionally, tumor cells often develop drug resistance after initial tumor regression related to transporter deficiency. We have previously developed three gemcitabine conjugates with cell-penetrating hexapeptides (CPP6) to facilitate intracellular delivery of this drug while also preventing enzymatic deamination. The bioactivity of these new prodrugs was evaluated in different cell lines and showed promising results. Here, we assessed the absorption and permeab...
Pharmacokinetics (PK) is a branch of pharmacology present and of vital importance for the researc... more Pharmacokinetics (PK) is a branch of pharmacology present and of vital importance for the research and development (R&D) of new drugs, post-market monitoring, and continued optimizations in clinical contexts. Ultimately, pharmacokinetics can contribute to improving patients’ clinical outcomes, helping enhance the efficacy of treatments, and reducing possible adverse side effects while also contributing to precision medicine. This article discusses the methods used to predict and study human pharmacokinetics and their evolution to the current physiologically based pharmacokinetic (PBPK) modeling and simulation methods. The importance of therapeutic drug monitoring (TDM) and PBPK as valuable tools for Model-Informed Precision Dosing (MIPD) are highlighted, with particular emphasis on antibiotic therapy since dosage adjustment of antibiotics can be vital to ensure successful clinical outcomes and to prevent the spread of resistant bacterial strains.
The importance of closely observing patients receiving antibiotic therapy, performing therapeutic... more The importance of closely observing patients receiving antibiotic therapy, performing therapeutic drug monitoring (TDM), and regularly adjusting dosing regimens has been extensively demonstrated. Additionally, antibiotic resistance is a contemporary concerningly dangerous issue. Optimizing the use of antibiotics is crucial to ensure treatment efficacy and prevent toxicity caused by overdosing, as well as to combat the prevalence and wide spread of resistant strains. Some antibiotics have been selected and reserved for the treatment of severe infections, including amikacin, gentamicin, tobramycin, and vancomycin. Critically ill patients often require long treatments, hospitalization, and require particular attention regarding TDM and dosing adjustments. As these antibiotics are eliminated by the kidneys, critical deterioration of renal function and toxic effects must be prevented. In this work, clinical data from a Portuguese cohort of 82 inpatients was analyzed and physiologically b...
Background:: Vancomycin has been in clinical use for nearly 50 years and remains the first-line t... more Background:: Vancomycin has been in clinical use for nearly 50 years and remains the first-line treatment option for Gram-positive infections, including methicillin-resistant Staphylococcus aureus (MRSA). There are multiple strategies to monitor therapy and adjust the dose of this antibiotic. AUC24/MIC ratio has been demonstrated to be the best parameter to predict the effectiveness and safety of vancomycin, and a target ratio of ≥400 is recommended. Still, trough and peak serum levels at steady-state conditions have been used in clinical settings as an accurate and practical method to monitor vancomycin. Methods:: In this work, we collected and analyzed clinical information of patients being treated in a hospital center in Porto (Portugal) and studied the pharmacokinetics of vancomycin in silico, developing several physiologically based pharmacokinetic (PBPK) models using simulation software GastroPlus™. Different dosages and treatment regimens were studied, and the influence of pa...
Renal elimination is an important part of drugs' excretion. At the same time, renal function ... more Renal elimination is an important part of drugs' excretion. At the same time, renal function can be impaired as a side effect of medication, particularly during prolonged treatments. Thus, the assessment of patients' renal function is of major consequence, especially in cases where the therapeutic regimen is adjusted taking into consideration renal clearance. Serum creatinine concentration is the most common indicator of renal clearance, since the most accurate indicator, glomerular filtration rate (GFR), is not easily measured. Using equations developed over the last decades, creatinine clearance (CLCr) is readily estimated taking into account patients' biological sex, age, body composition, and sometimes race. In this work, differences in estimated CLCr between different equations were studied and the influence of some patients' characteristics evaluated. Data collected from 82 inpatients receiving antibiotic therapy was analyzed and CLCr was estimated using a tota...
An automated flow-rate meter easy to construct and operate is described. This is controlled by a ... more An automated flow-rate meter easy to construct and operate is described. This is controlled by a microcomputer connected to an analog/digital converter interface and by a control software. It uses two acrylic flow cells, each comprising a bicolor light-emitting diode and a phototransistor placed on opposite sides. The performance of this flow-rate meter was evaluated by applying it to three flow manifolds: one monosegmented flow titration system by binary sampling; one conventional monosegmented flow system, and one single-line FIA system. The FIA system flow rate was assessed by means of a Vanderslice's expression. The time range of measurement of the flow rates was of 3.5-19.5 seconds and relative errors of 0.2-2.6% as well as relative stan-Correspondence to: Mário César U. Araú jo.
A monosegmented flow system involving sample and titrant sequential injections and the establishm... more A monosegmented flow system involving sample and titrant sequential injections and the establishment of a tandem plug between two air bubbles is proposed for automated titrations. The end point is found after successive variations of the sample and titrant volumes, determined by an algorithm based on the one-dimensional optimization method of Fibonacci. The set up includes a multi-port solenoid valve with four inlets and one outlet. The feasibility of the system was demonstrated in the spectrophotometric determination of the total acidity in vinegar with NaOH and phenolphthalein used as the titrant and indicator, respectively. The sample throughput was ca. 30 h −1 and consumption of the sample and titrant was about 0.7 ml. The results were in agreement with the expected values, with relative errors lower than ±0.4%. After 12 successive analyses of typical samples with a 47.1-53.4 total acidity, expressed as g l −1 acetic acid, the relative standard deviations of the results were estimated within the 1.2-2.1% range.
Gemcitabine is an anticancer drug used to treat a wide range of solid tumors and is a first line ... more Gemcitabine is an anticancer drug used to treat a wide range of solid tumors and is a first line treatment for pancreatic cancer. Our group has previously developed novel conjugates of gemcitabine with cell-penetrating peptides (CPP), and here we report some preliminary data regarding the pharmacokinetics of gemcitabine, two gemcitabine-CPP conjugates and respective CPP gathered from GastroPlus™, and analyze these results considering our previous evaluation of gemcitabine release and conjugates’ bioactivity. Additionally, seeking to shed some light on the relation between the penetration ability of CPP and their physicochemical properties, chemical descriptors for the 20 natural amino acids were calculated, a new principal property scale (z-scale) was created and CPP prediction models were developed, establishing quantitative structure-activity relationships (QSAR). The z-scores of the peptides conjugated with gemcitabine are presented and analyzed with the aforementioned data.
Pharmacokinetic (PK) studies improve the design of dosing regimens in preclinical and clinical se... more Pharmacokinetic (PK) studies improve the design of dosing regimens in preclinical and clinical settings. In complex diseases like cancer, single-agent approaches are often insufficient for an effective treatment, and drug combination therapies can be implemented. In this work, in silico PK models were developed based on in vitro assays results, with the goal of predicting the in vivo performance of drug combinations in the context of cancer therapy. Combinations of reference drugs for cancer treatment, gemcitabine and 5-fluorouracil (5-FU), and repurposed drugs itraconazole, verapamil or tacrine, were evaluated in vitro. Then, two-compartment PK models were developed based on the previous in vitro studies and on the PK profile reported in the literature for human patients. Considering the quantification parameter area under the dose-response-time curve (AUCeffect) for the combinations effect, itraconazole was the most effective in combination with either reference anticancer drugs. ...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
An automated flow-rate meter easy to construct and operate is descríbed. This is contralled by a ... more An automated flow-rate meter easy to construct and operate is descríbed. This is contralled by a micracomputer connected to an analog/digitai converter interface and by a contrai software. It uses two acrylíc flow cells, each comprising a bicolor líght-emittíng díode anda phototransistor piaced on opposíte sides. The performance of this flow-rate meter was evaiuated by appiying ít to three flow mani-foids: one monosegmented flow titratíon system by binary samplíng; one conventíonai monosegmented flow system, and one singie-iine FIA system. The FIA system flow rate was assessed by means of a Van-derslíce's expression. The time range of measurement of the flow rates was of 3.5-19.5 seconds and relative errars of 0.2-2.6% as well as relative stan-Correspondence to: Mário César U. Araújo. dard deviations fram 0.4 to 3.1 % were attained. The flow-rate meter allows one to optimize precísion and velocíty of measurements just by changing one of its parameters. Moreover, the flow-rate meter can be used with flow systems, therefore ailowing one to perform on-line measurements, which facílítates a quick and effectíve contrai of the channeis flow rate.
An automatic flow titrator based on a multicommutated unsegmented flow system was used to perform... more An automatic flow titrator based on a multicommutated unsegmented flow system was used to perform precipitation titrations with potentiometric detection. The titration approach is based on sequential introduction of increasing titrant and decreasing titrand volumes into a mixing chamber. The system allows the attainment of complete curves, the titration end point being determined by the Gran method, as is usually employed in batch potentiometric titrations. The theoretical model for the analytical process is presented and discussed and the determination of titrand concentration is performed without any prior calibration. The automatic flow titrator developed was applied to chloride determination in bottled natural waters and the results obtained were reproducible (RSD 3.2 and 3.8% for repeatability and reproducibility, respectively) and in good agreement with those given by the reference procedure (relative deviation within the range from 24.6 to 4.8%).
In this work a simple, fast, sensitive and selective flow-based procedure for the chemiluminometr... more In this work a simple, fast, sensitive and selective flow-based procedure for the chemiluminometric determination of carvedilol, a recent noncardioselective -blocker with noteworthy antioxidant activity, is proposed. The developed methodology takes advantage of the antioxidant capacity of carvedilol to inhibit the chemiluminescence response resulting from the oxidation of luminol by hypochlorite, by acting as a hypochlorite scavenger. The analytical process was implemented in a multi-pumping flow system that employs multiple solenoid actuated micro-pumps as the only active components. These acted as solution insertion, propelling and commuting units assuring an easily controlled, low cost, compact and reliable analytical system.
Fresenius Journal of Analytical Chemistry, Mar 13, 1998
Electrodes selective to potassium and calcium with improved senstivity were constructed like conv... more Electrodes selective to potassium and calcium with improved senstivity were constructed like conventional electrode (ISEs), but used an operational amplifier to sum the potentials supplied by the four membranes (ESOAs). The results obtained during the evaluation of their working characteristics were compared to those obtained by conventional ISEs and were found to be similar, but with higher precision. The electrodes were used in the potentiometric determination of potassium, calcium and magnesium in wines. The results given by ESOAs were more precise than those from ISEs. The results obtained by potentiometry were in good agreement with those from AES for potassium and AAS for calcium and magnesium.
Abstract Understanding the potential of ionic liquids in biocatalysis is both useful and difficul... more Abstract Understanding the potential of ionic liquids in biocatalysis is both useful and difficult. The unique properties of ionic liquids, such as their tunability, allow for the medium to be adjusted to the reaction, thereby supporting both substrate solubility and enzyme activity. Thus, the effect of 9 different ionic liquids with different structures (in terms of cation, anion, and the attached substituents) on the activity of β-galactosidase, an enzyme widely used in food industry processes, was investigated. According to the findings of this study, three of the nine tested ionic liquids promoted an increase in β-galactosidase activity, while two of them ([bmpyr][Cl] and [bmpyr][BF4]) promoted an inactivation (with EC50 of 20.4 and 10.7 mmol L−1, respectively), most likely due to the presence of the cation [bmpyr]. Some correlations between the structure of ionic liquids and the activity of β-galactosidase were established. To carry out these studies, a microfluidic automatic system was used, allowing for greater control of the reaction conditions as well as a reduction in reagent consumption and waste generation. It demonstrated the system's potential as a simple, versatile, robust, and fast analytical tool for the automation of enzymatic assays in ILs medium.
The results obtained in on-line monitoridg of lipase production by Candida rugosa in a batch ferm... more The results obtained in on-line monitoridg of lipase production by Candida rugosa in a batch fermentation process are presented. For this purpose an automatic lipase concentration analyzer has been developed and tested. Its good reproducibility and its capability to perform the analysis in less time than the classical titrimetric method make it very suitable for on-line determination lipase concentration in fermentation processes.
International Journal of Environmental Analytical Chemistry, 1997
This work describes the construction and the evaluation of a nitrate potentiometric transducer wi... more This work describes the construction and the evaluation of a nitrate potentiometric transducer with improved sensitivity and it application to the determination of low levels of nitrate in natural waters. The results obtained in these determinations were evaluated comparatively with those obtained by the conventional ion-selective electrodes and by the reference methods which include colourimetric measurement.The construction of the developed
Cancer is one of the most alarming diseases due to its high mortality and still increasing incide... more Cancer is one of the most alarming diseases due to its high mortality and still increasing incidence rate. Currently available treatments for this condition present several shortcomings and new options are continuously being developed and evaluated, aiming at increasing the overall treatment efficiency and reducing associated adverse side effects. Gemcitabine has proven activity and is used in chemotherapy. However, its therapeutic efficiency is limited by its low bioavailability as a result of rapid enzymatic inactivation. Additionally, tumor cells often develop drug resistance after initial tumor regression related to transporter deficiency. We have previously developed three gemcitabine conjugates with cell-penetrating hexapeptides (CPP6) to facilitate intracellular delivery of this drug while also preventing enzymatic deamination. The bioactivity of these new prodrugs was evaluated in different cell lines and showed promising results. Here, we assessed the absorption and permeab...
Pharmacokinetics (PK) is a branch of pharmacology present and of vital importance for the researc... more Pharmacokinetics (PK) is a branch of pharmacology present and of vital importance for the research and development (R&D) of new drugs, post-market monitoring, and continued optimizations in clinical contexts. Ultimately, pharmacokinetics can contribute to improving patients’ clinical outcomes, helping enhance the efficacy of treatments, and reducing possible adverse side effects while also contributing to precision medicine. This article discusses the methods used to predict and study human pharmacokinetics and their evolution to the current physiologically based pharmacokinetic (PBPK) modeling and simulation methods. The importance of therapeutic drug monitoring (TDM) and PBPK as valuable tools for Model-Informed Precision Dosing (MIPD) are highlighted, with particular emphasis on antibiotic therapy since dosage adjustment of antibiotics can be vital to ensure successful clinical outcomes and to prevent the spread of resistant bacterial strains.
The importance of closely observing patients receiving antibiotic therapy, performing therapeutic... more The importance of closely observing patients receiving antibiotic therapy, performing therapeutic drug monitoring (TDM), and regularly adjusting dosing regimens has been extensively demonstrated. Additionally, antibiotic resistance is a contemporary concerningly dangerous issue. Optimizing the use of antibiotics is crucial to ensure treatment efficacy and prevent toxicity caused by overdosing, as well as to combat the prevalence and wide spread of resistant strains. Some antibiotics have been selected and reserved for the treatment of severe infections, including amikacin, gentamicin, tobramycin, and vancomycin. Critically ill patients often require long treatments, hospitalization, and require particular attention regarding TDM and dosing adjustments. As these antibiotics are eliminated by the kidneys, critical deterioration of renal function and toxic effects must be prevented. In this work, clinical data from a Portuguese cohort of 82 inpatients was analyzed and physiologically b...
Background:: Vancomycin has been in clinical use for nearly 50 years and remains the first-line t... more Background:: Vancomycin has been in clinical use for nearly 50 years and remains the first-line treatment option for Gram-positive infections, including methicillin-resistant Staphylococcus aureus (MRSA). There are multiple strategies to monitor therapy and adjust the dose of this antibiotic. AUC24/MIC ratio has been demonstrated to be the best parameter to predict the effectiveness and safety of vancomycin, and a target ratio of ≥400 is recommended. Still, trough and peak serum levels at steady-state conditions have been used in clinical settings as an accurate and practical method to monitor vancomycin. Methods:: In this work, we collected and analyzed clinical information of patients being treated in a hospital center in Porto (Portugal) and studied the pharmacokinetics of vancomycin in silico, developing several physiologically based pharmacokinetic (PBPK) models using simulation software GastroPlus™. Different dosages and treatment regimens were studied, and the influence of pa...
Renal elimination is an important part of drugs' excretion. At the same time, renal function ... more Renal elimination is an important part of drugs' excretion. At the same time, renal function can be impaired as a side effect of medication, particularly during prolonged treatments. Thus, the assessment of patients' renal function is of major consequence, especially in cases where the therapeutic regimen is adjusted taking into consideration renal clearance. Serum creatinine concentration is the most common indicator of renal clearance, since the most accurate indicator, glomerular filtration rate (GFR), is not easily measured. Using equations developed over the last decades, creatinine clearance (CLCr) is readily estimated taking into account patients' biological sex, age, body composition, and sometimes race. In this work, differences in estimated CLCr between different equations were studied and the influence of some patients' characteristics evaluated. Data collected from 82 inpatients receiving antibiotic therapy was analyzed and CLCr was estimated using a tota...
An automated flow-rate meter easy to construct and operate is described. This is controlled by a ... more An automated flow-rate meter easy to construct and operate is described. This is controlled by a microcomputer connected to an analog/digital converter interface and by a control software. It uses two acrylic flow cells, each comprising a bicolor light-emitting diode and a phototransistor placed on opposite sides. The performance of this flow-rate meter was evaluated by applying it to three flow manifolds: one monosegmented flow titration system by binary sampling; one conventional monosegmented flow system, and one single-line FIA system. The FIA system flow rate was assessed by means of a Vanderslice's expression. The time range of measurement of the flow rates was of 3.5-19.5 seconds and relative errors of 0.2-2.6% as well as relative stan-Correspondence to: Mário César U. Araú jo.
A monosegmented flow system involving sample and titrant sequential injections and the establishm... more A monosegmented flow system involving sample and titrant sequential injections and the establishment of a tandem plug between two air bubbles is proposed for automated titrations. The end point is found after successive variations of the sample and titrant volumes, determined by an algorithm based on the one-dimensional optimization method of Fibonacci. The set up includes a multi-port solenoid valve with four inlets and one outlet. The feasibility of the system was demonstrated in the spectrophotometric determination of the total acidity in vinegar with NaOH and phenolphthalein used as the titrant and indicator, respectively. The sample throughput was ca. 30 h −1 and consumption of the sample and titrant was about 0.7 ml. The results were in agreement with the expected values, with relative errors lower than ±0.4%. After 12 successive analyses of typical samples with a 47.1-53.4 total acidity, expressed as g l −1 acetic acid, the relative standard deviations of the results were estimated within the 1.2-2.1% range.
Gemcitabine is an anticancer drug used to treat a wide range of solid tumors and is a first line ... more Gemcitabine is an anticancer drug used to treat a wide range of solid tumors and is a first line treatment for pancreatic cancer. Our group has previously developed novel conjugates of gemcitabine with cell-penetrating peptides (CPP), and here we report some preliminary data regarding the pharmacokinetics of gemcitabine, two gemcitabine-CPP conjugates and respective CPP gathered from GastroPlus™, and analyze these results considering our previous evaluation of gemcitabine release and conjugates’ bioactivity. Additionally, seeking to shed some light on the relation between the penetration ability of CPP and their physicochemical properties, chemical descriptors for the 20 natural amino acids were calculated, a new principal property scale (z-scale) was created and CPP prediction models were developed, establishing quantitative structure-activity relationships (QSAR). The z-scores of the peptides conjugated with gemcitabine are presented and analyzed with the aforementioned data.
Pharmacokinetic (PK) studies improve the design of dosing regimens in preclinical and clinical se... more Pharmacokinetic (PK) studies improve the design of dosing regimens in preclinical and clinical settings. In complex diseases like cancer, single-agent approaches are often insufficient for an effective treatment, and drug combination therapies can be implemented. In this work, in silico PK models were developed based on in vitro assays results, with the goal of predicting the in vivo performance of drug combinations in the context of cancer therapy. Combinations of reference drugs for cancer treatment, gemcitabine and 5-fluorouracil (5-FU), and repurposed drugs itraconazole, verapamil or tacrine, were evaluated in vitro. Then, two-compartment PK models were developed based on the previous in vitro studies and on the PK profile reported in the literature for human patients. Considering the quantification parameter area under the dose-response-time curve (AUCeffect) for the combinations effect, itraconazole was the most effective in combination with either reference anticancer drugs. ...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
An automated flow-rate meter easy to construct and operate is descríbed. This is contralled by a ... more An automated flow-rate meter easy to construct and operate is descríbed. This is contralled by a micracomputer connected to an analog/digitai converter interface and by a contrai software. It uses two acrylíc flow cells, each comprising a bicolor líght-emittíng díode anda phototransistor piaced on opposíte sides. The performance of this flow-rate meter was evaiuated by appiying ít to three flow mani-foids: one monosegmented flow titratíon system by binary samplíng; one conventíonai monosegmented flow system, and one singie-iine FIA system. The FIA system flow rate was assessed by means of a Van-derslíce's expression. The time range of measurement of the flow rates was of 3.5-19.5 seconds and relative errars of 0.2-2.6% as well as relative stan-Correspondence to: Mário César U. Araújo. dard deviations fram 0.4 to 3.1 % were attained. The flow-rate meter allows one to optimize precísion and velocíty of measurements just by changing one of its parameters. Moreover, the flow-rate meter can be used with flow systems, therefore ailowing one to perform on-line measurements, which facílítates a quick and effectíve contrai of the channeis flow rate.
An automatic flow titrator based on a multicommutated unsegmented flow system was used to perform... more An automatic flow titrator based on a multicommutated unsegmented flow system was used to perform precipitation titrations with potentiometric detection. The titration approach is based on sequential introduction of increasing titrant and decreasing titrand volumes into a mixing chamber. The system allows the attainment of complete curves, the titration end point being determined by the Gran method, as is usually employed in batch potentiometric titrations. The theoretical model for the analytical process is presented and discussed and the determination of titrand concentration is performed without any prior calibration. The automatic flow titrator developed was applied to chloride determination in bottled natural waters and the results obtained were reproducible (RSD 3.2 and 3.8% for repeatability and reproducibility, respectively) and in good agreement with those given by the reference procedure (relative deviation within the range from 24.6 to 4.8%).
In this work a simple, fast, sensitive and selective flow-based procedure for the chemiluminometr... more In this work a simple, fast, sensitive and selective flow-based procedure for the chemiluminometric determination of carvedilol, a recent noncardioselective -blocker with noteworthy antioxidant activity, is proposed. The developed methodology takes advantage of the antioxidant capacity of carvedilol to inhibit the chemiluminescence response resulting from the oxidation of luminol by hypochlorite, by acting as a hypochlorite scavenger. The analytical process was implemented in a multi-pumping flow system that employs multiple solenoid actuated micro-pumps as the only active components. These acted as solution insertion, propelling and commuting units assuring an easily controlled, low cost, compact and reliable analytical system.
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