Automatic Titration Research Articles

Does it make a difference to add automatic EPAP titration to the volume-targeted pressure support mode in noninvasive ventilation of hypercapnic ICU patients?

Obese patients are increasing in number in ICUs and more than 90% of them also have sleep apnea syndrome. Variability in upper airway resistance during sleep and awakening periods makes it difficult to set EPAP in these patients. A new mode that automatically titrates EPAP according to upper airway resistance and IPAP according to target tidal volume may be more effective. The aim of this study is to evaluate whether adding automatic EPAP titration to the volume-targeted pressure support mode will provide any therapeutic advantages in hypercapnic ICU patients.

Kinetic buffers.

This paper proposes a new type of molecular device that is able to act as an inverse proton sponge to slowly decrease the pH inside a reaction vessel. This makes the automatic monitoring of the concentration of pH-sensitive systems possible. The device is a composite formed of an alkyl chloride, which kinetically produces acidity, and a buffer that thermodynamically modulates the variation in pH value. Profiles of pH versus time (pH-t plots) have been generated under various experimental conditions by computer simulation, and the device has been tested by carrying out automatic spectrophotometric titrations, without using an autoburette. To underline the wide variety of possible applications, this new system has been used to realize and monitor HCl uptake by a di-copper(II) bistren complex in a single run, in a completely automatic experiment.

Precise determination of hypochlorite in commercial bleaches with established traceability using automatic potentiometric titration

A measurement procedure is proposed for precisely determining hypochlorite in commercial bleaches, with established traceability and a full description of its uncertainty sources. The procedure is based on automatic volumetric titration with potentiometric detection and was evaluated in the analysis of several commercial bleach samples, with Na-hypochlorite mass fractions in the range 0.002–0.027 g g−1, with an average expanded uncertainty (k = 2) of 0.00027 g g−1 and an average relative standard deviation between measurement triplicates of 0.36 %. Compared with a standard procedure based on manual volumetric titration with visual colorimetric detection, the improved procedure produced equivalent results with a lower average expanded uncertainty (0.00029 g g−1 as compared to 0.0015 g g−1 for the standard procedure). This was related to better precision of the volume measurement using an automatic buret and to better precision of the titration endpoint determination using potentiometric detection. Compared with other studies reported in the literature, the improved procedure presented a lower average relative standard deviation between measurement replicates (0.36 % as compared to 1.00–11.53 %).

Optimization of coagulation/flocculation for phosphorus removal from activated sludge effluent discharge using an online charge analyzing system titrator (CAST)

Coagulant dosing is traditionally based upon jar-tests or operator experience, resulting in either overdosing or insufficient dosing. In this study, we assess the feasibility of a new coagulant dose control instrument, the online charge-based automatic titration system, charge analyzing system with titrator (CAST), to determine coagulant dosages from active sludge effluent discharge in municipal wastewater treatment plants. Results show that treated total phosphorous (TP) concentrations were successfully lowered to less than the site's 0.5mg/L limit indicator level. These results suggest that the CAST system to be a very useful automated chemical dosing instrument for the coagulation/flocculation process in wastewater treatment plants (WWTPs).

Surface complexation modeling of arsenate adsorption by akagenéite (β-FeOOH)-dominant granular ferric hydroxide

A surface complexation model has been set up for the first time with akaganéite (β-FeOOH), a major compound of granular ferric hydroxide (GFH) used in groundwater purification units worldwide for arsenic and other toxic pollutant removal. Unlike the situation for the α-FeOOH polymorph goethite, there is yet no published surface complexation model to predict competing oxyanion effects. This is due to a linked bulk-surface reactivity by which excess protons released in an unknown amount from tunnel sites hamper quantification of surface protonation by acid titration. The measured proton uptake thus exceeds what can be expected from OH groups active in surface protonation. However, chloride ions are co-sorbed in 1:1 stoichiometry and co-released with the protons from tunnel sites albeit with slow kinetics. Because of this kinetics, dynamic acid-base titrations using automatic titrators are not feasible for reliable estimation of surface charge vs. pH curves. We propose to precisely monitor the chloride exchange during batch titrations with at least one day batch equilibration times. The thus obtained chloride data were used to correct for the pH-dependent bulk proton exchange and to reconstruct the true surface potential vs. pH curves, and thus to reliably parameterize a CD-MUSIC surface complexation model for arsenate adsorption.

Development of an automatic photometric titration procedure to determine olive oil acidity employing a miniaturized multicommuted flow-batch setup

The present work proposes an automatic procedure for photometric determination of olive oil acidity, employing a miniaturized multicommuted flow-batch analysis setup without the use of calibration curves. Under microcomputer control, the proposed setup was able to mimic the manual procedure suggested by the European Commission Regulation. A homemade LED-based photometer was designed by coupling a radiation source and a photodetector to the titration chamber, creating a compact and downsized unit. The photometric titration of olive oil was carried out using potassium hydroxide solution in an n-propanol medium, which was done without any previous pretreatment, thereby allowing that a true photometric titration procedure in a non-aqueous medium was carried out for the first time. After establishing better operational conditions, the proposed procedure was applied to determine acidity in olive oil samples. The accuracy was assessed by applying the paired t-test to results obtained using a reference method, and there was no significant difference at a 95% confidence level. Other useful features were achieved, including a relative standard deviation of 1.8% (n = 6), a sample consumption of 125 μL per determination, an effluent generation of 1.4 mL per titration, and a sampling throughput ranging from 40 to 50 determinations per hour, whereby indicating that it could be an effective alternative for routine analysis of olive oil.

Совершенствование электрохимического метода определения титруемых кислот в винах, соках и безалкогольных напитках

An apparatus for determining the concentration of acid by an electrochemical method . The installation consists of a DC source , a three-level special cells that allows to analyze three samples simultaneously and potentiometric sensor . The sensor signal is transmitted to the computer . PC detects the change in pH as a function of electrolysis time in the automatic mode. If desired, the assay can be conducted without sample dilution , addition of dry potassium chloride , lithium, sodium , or 20-100 cm 3 directly in solution. Based on the analysis of the titration curves of wines developed quantitative criteria for assessing the quality and authenticity of the wine. Keywords : device for automatic titration, potentiometry, coulometry , the three-tier cell, acid wines, juices. (Russian) DOI: http://dx.doi.org/10.15826/analitika.2014.18.1.006 O . N . Shelud ` ko 1 , N . K . Strizhov 2 , T . V . Guzik 2 1 State Scientific Organization North Caucasian Regional Research Institute of Horticulture and Viticulture of the Russian Academy of Agricultural Sciences , Krasnodar, Russian Federation 2 Kuban State Technological University , Krasnodar, Russian Federation

RETRACTION: Maintained Cocaine Self-Administration Is Determined by Quantal Responses: Implications for the Measurement of Antagonist Potency

The change in frequency of cocaine self-administration as a function of the unit dose is widely assumed to represent a graded pharmacodynamic response. Alternatively, a pharmacological theory states that during maintained self-administration, a quantal response occurs at a minimum maintained cocaine concentration (satiety threshold). Rats self-administered cocaine at unit doses spanning an 8-fold range from 0.75 to 6 µmol/kg. Despite an approximately 7-fold difference in the interinjection intervals, there were no differences in the plasma cocaine concentration at the time of lever press across this range of unit doses, consistent with the satiety threshold representing an equiactive cocaine concentration. Because self-administration always occurs when cocaine concentrations decline back to the satiety threshold, this behavior represents a process of automatic back titration of equiactive agonist concentrations. Therefore, the lower frequency of self-administration at higher unit doses is caused by an increase in the duration of the cocaine-induced satiety response, and the graded dose-frequency relationship is due to cocaine pharmacokinetics. After the interinjection intervals at a particular unit dose were stable, rats were injected with the competitive D₁-like dopamine receptor antagonist R-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine (SCH23390; 15 nmol/kg intravenously) and the session continued. At all cocaine unit doses, SCH23390 accelerated self-administration with a concomitant increase in the calculated satiety threshold, and these equiactive cocaine concentration ratios were independent of the cocaine unit dose. Therefore, the measurement of antagonist potency requires only a single unit dose of cocaine, selected on the basis of convenience, and using multiple cocaine unit doses is redundant.

Automatic administration of propofol and remifentanil guided by the bispectral index during rigid bronchoscopic procedures: a randomized trial

Anesthesia for rigid bronchoscopic procedures is a demanding procedure. Automatic titration of propofol and remifentanil to maintain the bispectral index (BIS) within the recommended range (40-60) has been reported during routine surgical procedures. The aim of the present study was to evaluate its use during rigid bronchoscopy. Patients were enrolled in a randomized study comparing manual target-controlled infusion of propofol and remifentanil (manual TCI group) with automatic titration guided by the BIS (dual-loop group). Categorical variables were compared by the Fisher's exact test, and continuous variables (median [interquartile range 25-75]) were compared by the Mann-Whitney test. Thirty-four patients were included in the manual TCI group and 33 were included in the dual-loop group. Baseline characteristics were well balanced between the groups. Intervention by the anesthesiologist in charge to modify propofol and/or remifentanil targets in the dual-loop group was not necessary. Percentage of time spent in the BIS interval (40-60) was similar in the manual TCI and dual-loop groups (69% [48-79] vs 70% [58-80], respectively). Durations of induction and of maintenance and propofol and remifentanil doses were also similar between groups, except for the amount of propofol needed for induction (P = 0.002). Time to tracheal extubation was also similar. No case of intraoperational awareness was detected. The present study could not establish the superiority of automatic system over manual adjustment for bronchoscopy. Further studies with a different design and a larger number of patients are required to establish the place of automatic delivery of anesthetic agents. This study was registered at ClinicalTrials.gov number, NCT00571181.

Home Unattended Portable Monitoring and Automatic CPAP Titration in Patients with High Risk for Moderate to Severe Obstructive Sleep Apnea

Obstructive sleep apnea is a disorder characterized by recurrent obstruction of the upper airways during sleep. The high prevalence of this disease led to proposed new strategies based on the home evaluation and management of patients. To compare home unattended portable monitoring and automatic CPAP titration with attended in-laboratory analysis, in a sample of patients with high risk for moderate to severe obstructive sleep apnea. We enrolled 131 subjects, who were randomly divided into 2 groups: the home group (n = 66) was diagnosed and titrated at home; the laboratory group (n = 65) was analyzed in the sleep laboratory of our hospital. Diagnostic evaluations were carried out with portable monitoring at home, and with polysomnography in the sleep laboratory. Titration of CPAP was performed with the same automatic CPAP device in both groups. At the end of the study, 13 (19%) subjects had dropped out of the home group, and 9 (14%) of the laboratory group (P = .50). There were no significant differences among groups in both baseline and with-CPAP values of apnea-hypopnea index, oxygen desaturation index, and total sleep time with SpO2 below 90%. In the home group, the therapeutic pressure values reached at the end of each unattended home titration night were similar. A home diagnosis and titration approach should be considered in a subset of patients with obstructive sleep apnea. A single unattended titration night is sufficient to determine the therapeutic pressure.

Comparison of manual versus automatic continuous positive airway pressure titration and the development of a predictive equation for therapeutic continuous positive airway pressure in Chinese patients with obstructive sleep apnoea

Whether the therapeutic nasal continuous positive airway pressure (CPAP) derived from manual titration is the same as derived from automatic titration is controversial. The purpose of this study was to compare the therapeutic pressure derived from manual titration with automatic titration. Fifty-one patients with obstructive sleep apnoea (OSA) (mean apnoea/hypopnoea index (AHI) = 50.6 ± 18.6 events/h) who were newly diagnosed after an overnight full polysomnography and who were willing to accept CPAP as a long-term treatment were recruited for the study. Manual titration during full polysomnography monitoring and unattended automatic titration with an automatic CPAP device (REMstar Auto) were performed. A separate cohort study of one hundred patients with OSA (AHI = 54.3 ± 18.9 events/h) was also performed by observing the efficacy of CPAP derived from manual titration. The treatment pressure derived from automatic titration (9.8 ± 2.2 cmH(2)O) was significantly higher than that derived from manual titration (7.3 ± 1.5 cmH(2)O; P < 0.001) in 51 patients. The cohort study of 100 patients showed that AHI was satisfactorily decreased after CPAP treatment using a pressure derived from manual titration (54.3 ± 18.9 events/h before treatment and 3.3 ± 1.7 events/h after treatment; P < 0.001). The results suggest that automatic titration pressure derived from REMstar Auto is usually higher than the pressure derived from manual titration.

Automatic potentiometric determination of uranium in the presence of organic solvents

Redox potentiometric titration of small amounts of uranium in mixed systems aqueous H3PO4 solutionorganic solvent using an automatic titrator was studied. The accuracy of the U determination strongly depends on the kind and concentration of the solvent. In determination of 0.1–0.2 mg of U in mixed phosphoric acid-organic solvent systems using ammonium vanadate as titrant, the determination accuracy decreases in the order acetone ≫ acetonitrile > nitromethane > ethanol. In the presence of acetone, 0.1 mg of U can be determined with high accuracy, which was impossible when using aqueous H3PO4 solutions. With all the organic components tested, the metrological characteristics are improved with an increase in the organic solvent content from 10 to 37 vol %.

THE DETERMINATION OF CARBONATE CONTENT IN MARINE SEDIMENTS BY AUTOMATIC POTENTIOMETRIC TITRATOR

Based on the volumetric method,the determination of carbonate content in marine sediment was carried out by automatic potentiometric titrator with related software-tiamo,which can export the results automatically.This method is simple and rapid for batch measurement.The results were consistent with standards defined by the National Standard Reference of Deep-Sea Sediment.Seven independent determinations were measured for the same sample,and the standard deviation of the results was less than 0.9 %.Several samples of sediment core MD06-3050 were used to measure carbonate content by automatic potentiometric titrator and ICP-OES.The results of two methods were consistent.

Automatic Biamperometric Titration of Copper(II) by Iodide in Some Non-Aqueous Media

Automatic Biamperometric Titration of Copper(II) by Iodide in Some Non-Aqueous Media

Evaluation study of an ion selective field effect transistor electrode for measuring quality parameters of fuel ethanol

An ion selective field effect transistor (ISFET) electrode was evaluated for measuring pH and acid number (AN) of fuel ethanol and compared to two glass electrodes with different reference filling solutions: KCl aqueous solution (glass-KCl electrode) and LiCl ethanolic solution (glass-LiCl electrode). pH was determined at different measurement times and AN was determined using automatic potentiometric titration. For pH, the glass-KCl electrode showed the best precision and stability, with an average repeatability about four times better when compared to the ISFET electrode for the measurement time of 30 s (as indicated in the ASTM D6423 standard). For AN, the glass-KCl and glass-LiCl electrodes showed similar repeatabilities, which were about three times better than that of the ISFET electrode. In addition, the results from a recovery study demonstrated better accuracy of the glass-LiCl electrode, with a recovery value of 100.1%.

Proton release by tea plant (Camellia sinensis L.) roots as affected by nutrient solution concentration and pH

Solution culture experiments were conducted and the protons released were measured with an automatic titration system to determine the main factors affecting proton release by tea roots. Results indicated that the higher were the cation concentrations, the more protons were released from the roots, suggesting that tea roots took up a large amount of cations during growth, and then released protons to maintain charge balance of the plant body. The amount of protons released from tea roots at controlled pH was much higher than that in the treatments with uncontrolled pH. Stepwise multiple linear regression analysis showed that both NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;&amp;nbsp;and Al(III) played distinct roles in proton release by tea plant roots. The uptake of Al(III) and NH&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;+&lt;/sup&gt;&amp;nbsp;and subsequent release of protons may be an important mechanism for soil acidification in tea gardens.

Control of OSA During Automatic Positive Airway Pressure Titration in a Clinical Case Series: Predictors and Accuracy of Device Download Data

To investigate the factors associated with physiologic control of obstructive sleep apnea (OSA) during automatic positive airway pressure (APAP) titration in a clinical series. To also assess the usefulness of apnea-hypopnea index (AHI) data downloaded from the APAP device (Dev AHI). Retrospective review of a consecutive series of patients with OSA who underwent APAP titration (Autoset Spirit, ResMed, Bella Vista, New South Wales, Australia ) with simultaneous polysomnographic (PSG) monitoring in the sleep laboratory. Tertiary sleep clinic. There were 190 consecutive patients with OSA referred for APAP titration. There were 58% of patients who achieved optimal or good control of OSA (titration PSG AHI < 10, or at least 50% reduction in AHI if diagnostic AHI < 15/hr) during APAP titration. The independent predictors of titration PSG AHI were a history of cardiac disease and elevated central apnea and arousal indices during the diagnostic study. Although the median and interquartile range (IQR) AHI from the device (7.0, 3.9-11.6 events/hr) was only slightly less than the PSG AHI (7.8, 3.9-14.4 events/hr, P = 0.04) during titration, case-by-case agreement between the two measures was poor (chi-square < 0.001). In a clinical sample control of OSA during APAP titration is often poor, and close clinical follow-up is particularly needed in patients with a history of cardiac disease or with high arousal or central apnea indices on the diagnostic study. Device AHI does not reliably assess control during APAP titration, and PSG assessment may be required if clinical response to treatment is poor. The findings relate to the ResMed AutoSet device and may not apply to other devices.

The First 110 Years of Laboratory Automation: Technologies, Applications, and the Creative Scientist

Prior to the widespread availability of electronic components after the Second World War, laboratory automation was constructed by end users and designed for specific tasks, mostly filtration, percolation, and washing operations. The earliest mention of automation in the chemical literature of the United States was in 1875, announcing a device to wash filtrates unattended. In the years that followed, a small number of commercial automated devices were sold, including large grinders for the preparation of coal samples. Around 1900, power stations began adopting automated carbon dioxide analysis. The development of electrical equipment for conductivity measurements enabled the first commercial, automated gas detection instruments for laboratory and field use around the time of the First World War. The growth of industrial production in the 1920s led to a desire for automated testing equipment, and the growing rubber industry was among the more successful early adapters. Photoelectric cells were first used in the early 1930s to create automatic titrators, and by the 1950s, automatic titration encompassed coulometric, potentiometric, and photometric devices. Combinations of chart recorders, photocells, and timers created other types of automated equipment such as stills and fraction collectors. The first true stand-alone automation for the laboratory included clinical chemistry analyzers, introduced during the 1950s.

Automated Oxygen Flow Titration to Maintain Constant Oxygenation

One century after the introduction of the oxygen flow meter into clinical practice, we have developed a device, FreeO(2), that automatically titrates the oxygen flow delivered to spontaneously breathing patients, with the aim of maintaining a stable S(pO(2)). We evaluated this system in healthy subjects during induced hypoxemia. Hypoxemia was induced in 10 healthy subjects while breathing a gas mixture of variable F(IO(2)) (air + nitrogen). Each subject performed 3 hypoxemic challenges with the addition, in a random order, of either: air with constant flow (1.5 L/min); oxygen with constant flow (1.5 L/min); or automatic oxygen flow titration. Subjects were blinded to the intervention. Oxygen flow, S(pO(2)), end-tidal CO(2), respiratory rate, and heart rate were recorded every second. The primary outcome was the time with S(pO(2)) between 92% and 96%. The S(pO(2)) target (92-96%) was achieved a median of 26.0%, 36.8%, and 66.5% (P < .001) of the time with air, constant oxygen, and automated oxygen titration, respectively. Severe oxygen desaturations (S(pO(2)) < 88%) were respectively observed at a median of 33.7%, 12.7%, and 0.4% of the time (P < .001). Hyperoxia was present a median of 4.1%, 39.1%, and 14.5% of the time (P < .001). Tachycardia was present with air and with constant oxygen flow, but not while using automated oxygen titration. These results were obtained with a mean and maximal oxygen flow of 1.3 L/min and 7.6 L/min with the automated titration. In this model of induced hypoxemia, the FreeO(2) system that automatically titrates the oxygen flow was more efficient at maintaining the S(pO(2)) target, while ensuring a statistically significant reduction in the rates of severe hypoxemia and hyperoxia, in comparison with air or constant oxygen flow. These beneficial results were obtained with less oxygen, in comparison to a constant oxygen flow.

Quality Assessment of Honey Using Modern Analytical Tools

The quality of eighteen honey samples collected from the Western district of Saudi Arabia was assessed according to the International Honey regulatory standards using modern analytical methods. A number of quality criteria were measured to determine the botanical and geographical origin of honey. Hydroxymethylfurfural (HMF) as an adulteration marker was analyzed and detected quantitatively via high performance liquid chromatography (HPLC). The moisture content was assessed by Karl Fisher coulometric method using an automatic potentiometric titrator. While, mineral content and toxic heavy metal ions were determined using an inductively coupled plasma-atomic emission spectrometry (ICP-AES) technique after microwave digestion. All the investigated honey samples were of good quality. The elements with the highest frequency were K, Se, and Cd. High content of Cd and Se were found in samples (7 and 9). The maximum residues limit of the most dangerous metal for the human health lead was below European Standards.