Use Of Standard Solutions Research Articles

Automatic determination of chlorine without standard solutions using a biamperometric flow-batch analysis system

This study presents an automatic analysis system that does not require the use of standard solutions. The system uses an electrochemical flow cell for in line generation of the standards, and operates under the standard addition technique. The versatility of this system was demonstrated by the development of a one key touch fully automatic method for the determination of total available chlorine in real samples. The extremely simple, accurate and inexpensive method was based simply on the biamperometric monitoring of the well known redox reaction of chlorine with iodide ions in a flow-batch system, where the produced iodine (triiodide ions) generates an electrical current proportional to the chlorine concentration in the sample. The flow-batch parameters were optimized to maximize the sensitivity without losses on the precision of the analysis. An excellent linear dependence between the biamperometric signal and the chlorine concentration for the standard additions and a good agreement between the proposed approach and a reference method were obtained. The method was successfully applied to determine chlorine in several different bleach and chlorinated water samples (r=0.9995, LOD=8.261 x 10(-7) mol L(-1)) and could be easily extended to other oxidants and samples. Comparison to a reference method and recoveries close to 100% demonstrated the reliability of the proposed method. In addition, low residue disposal and reagent consumption, allied with high accuracy and precision, make it very promising for routine applications.

A European Survey on the Possibilities and Obstacles of Electronic Prescriptions in Cross-Border Healthcare

This study investigated the possibilities and obstacles for cross-border electronic prescriptions within the European internal market. Cross-border electronic prescribing requires interoperability of the systems and use of standardized solutions. We conducted a survey-based case study. A questionnaire on the use of electronic prescriptions was sent by e-mail to the delegates from 14 European Union (EU) member countries and 2 European Economic Area (EEA) countries during spring-summer 2003. A reply was received from 11 delegates in 11 countries contacted. Currently electronic prescriptions are in everyday use in only a few EU member countries, while many others are running or considering pilot projects. We found that electronic prescribing across national borders is impeded by many obstacles, which may relate to other systems or to lack of standardization. Information technology is likely to gradually spread to prescribing in Europe. Before more countries will integrate electronic prescribing into national healthcare, it would be important to ensure interoperability and common standards between national systems. Only then can electronic prescribing offer its full potential, and cross-border electronic prescribing can be realized at the EU level.

Determination of volatile oak compounds in aged wines by multiple headspace solid-phase microextraction and gas chromatography–mass spectrometry (MHS-SPME–GC–MS)

Multiple headspace solid-phase microextraction (MHS-SPME) with gas chromatography-mass spectrometry is proposed for quantification of nine volatile oak compounds in aged wines. These compounds are formed and extracted by wine when it is matured in oak barrels and are responsible for particular organoleptic properties and the high quality of these wines. Some important variables of the extraction process, for example volume of sample and extraction time, were studied. Extraction of 50 microL wine was performed with a divinylbenzene-Carboxen-polydimethylsiloxane fibre at 55 degrees C for 60 min. For calibration the same conditions were used, except that the wine was substituted by 50 microL of a standard solution in synthetic wine. The linearity, detection limits, and repeatability of the method were determined by use of standard solutions in synthetic wine. Detection limits were between 0.01 and 10 microg L(-1) (for eugenol and furfural, respectively) and repeatability, expressed as relative standard deviation, was from 2 to 6%. The method was used to analyse six red wines and the concentrations obtained were statistically compared with those obtained by the standard addition method for the same wines.

Parenteral nutrition with standard solutions in paediatric intensive care patients

Paediatric intensive care patients often require parenteral nutrition (PN). Only very few standard mixtures are available for infants and children. Individual PN solutions need to be compounded manually on the ward, if preparation by the hospital pharmacy is not feasible. Since manual compounding is associated with a greater risk of compounding errors and microbial contamination, the use of standard solutions might be a preferable alternative. We evaluated the use of standard solutions on the paediatric intensive care unit of the von Hauner Children's Hospital at the University of Munich over a period of 8 months. PN solutions were either prescribed individually or as standard solutions. We evaluated the frequency of standard solution prescriptions and their modification, compared nutrient intakes with standard vs. individual PN solutions as well as the occurrence of laboratory anomalies. Standard PN solutions were prescribed in 68% of cases, individual PN solutions in 32%. Modifications of standard PN solutions were performed in 54%. The intake of a number of macronutrients and electrolytes was similar with individual and standard PN, but calcium and phosphate intakes were lower with individual total PN. Electrolyte imbalances occurred slightly more often with individual PN than with standard PN (34% vs. 26%, respectively). Standard PN solutions were used in the majority of patients on a paediatric intensive care unit. We did not detect indications for inadequacy of standard solutions in the majority of patients reviewed.

A commercial real-time manufacturing integration platform for the new control system on FTU

In 1994 a working group was set up in Frascati to investigate how to build up a new control system for FTU (Frascati Tokamak Upgrade) considering the evolution in the information technology. Strong emphasis was placed on the use of standard solutions (be they de-facto or de-jure) and commercial platforms where-ever possible. This paper describes our operational experience with the new control system based on the commercial DEC BASEstar family of products. BASEstar is based on client/server computing technologies, providing an environment to collect, process, manage, distribute and integrate real time manufacturing data. UNIX, VMS, PC Win, OS-9 are integrated to handle hosts, PC, VME CPUs. A 4 GL programming language, CIMfast, has been used to handle via automatic procedures the tokamak discharge. X11 standard based mimics are available to display the plants status. A real flexibility of the whole system has been experience and the further use of the this system has been planned for the ITER DTP (Divertor Test Platform).

Inductively coupled plasma-atomic emission spectrometer warning diagnosis procedure using blank solution data

Lines available while running a blank solution were used to monitor the analytical performance of an inductively coupled plasma atomic emission spectrometry (ICP-AES) system in real time. Using H and Ar lines and their signal-to-background ratios (SBRs), simple rules in the form of a prediction table were developed by inspection of the data. These rules could be used for predicting changes in radio-frequency power, carrier gas flow rates, and sample introduction rate. The performance of the prediction table was good but not excellent. Another set of rules in the form of a decision tree was developed in an automated fashion using the C4.5 induction engine. The performance of the decision tree was superior to that of the prediction table. It appears that blank spectral information can be used to predict with over 90% accuracy when an ICP-AES is breaking down. However this is not as definitive at identifying the exact fault as some more exhaustive approaches involving the use of standard solutions.

Laser ablation ICP-MS elemental analysis of individual fluid inclusions: An evaluation study

Details are given of the elemental analysis of single fluid inclusions using a UV laser ablation microprobe interfaced to an inductively coupled plasma mass spectrometer. The UV laser, a frequency quadrupled Nd:YAG operating at 266 run, allows higher spatial resolution (<2 μm) than can be achieved using near-IR or visible wavelengths. Tests have been carried out on 10–100 μm diameter aqueous (liquid + vapour) inclusions in fluorite, quartz, and halite up to 60 μm beneath the surface. A key feature of the system is a novel high temperature ablation cell which substantially improves the efficiency and reproducibility of fluid release. Calibration was carried out using a dual gas flow system that allowed use of standard solutions and NIST glasses for tuning the instrument and for obtaining relative sensitivity factors. As an alternative to synthetic fluid inclusions, a new calibration approach is described involving the encapsulation of microdroplets of standard solutions in hydrophobic epoxy resins fluid inclusion analogues. To illustrate the scope and performance of the instrument, data are reported for Ba, Ca, Cs, Cu, K, Mg, Mn, Na, Pb, Rb, Sr, and Zn in saline aqueous inclusions associated with evaporite and low temperature base metal deposits. Element detection limits vary according to the mass of material released for analysis and are thus related to the volume and composition of each inclusion. Precision is estimated to be better than 30%.

Quantitative X-ray analysis of biological fluids: the microdroplet technique.

X-ray microanalysis can be used to quantitatively determine the elemental composition of microvolumes of biological fluids. This article describes the various steps in preparation of microdroplets for analysis: The manufacturing of micropipettes, the preparation of the specimen support, the deposition of droplets on the support, shock-freezing, and lyophilization. Examples of common artifacts (incomplete rehydration prior to freezing or partial rehydration after lyophilization) are demonstrated. Analysis can be carried out either by wavelength-dispersive analysis, which is the most sensitive method, or by energy-dispersive analysis, which is more commonly available. The minimum detectable concentration is 0.05 mmol.liter-1 for 0.1-nl samples analyzed by wavelength-dispersive spectrometry and 0.5-1 mmol.liter-1 for samples analyzed by energy-dispersive spectrometry. A major problem, especially in wavelength-dispersive analysis, where high beam currents are used, is radiation damage to the specimen; in particular chloride (but also other elements) can be lost. Quantitative analysis requires the use of standard solutions with elemental concentration in the same range as those present in the specimen.

Use of external calibration for the determination of trace metals in biological materials by inductively coupled plasma mass spectrometry

Inductively coupled plasma mass spectrometry (ICP-MS) was used for the analysis of two marine biological materials (cod liver tissue and shellfish tissue). A rapid dissolution of the materials was achieved by digestion in pressurised vessels in a microwave oven. Twelve elements (Cr, Fe, Mn, Ni, Cu, Zn, As, Ag, Cd, Sn, Hg and Pb) were then determined. It was possible to obtain accurate results by external calibration (i.e., the use of standard solutions), even at sub-µg g–1 levels. Internal standardisation using 40Ar40Ar was carried out when required to correct for instrumental drift. The isotope dilution technique generally gave more accurate and precise results, especially at the lower concentration levels.

Determination of traces of lead and cadmium in high-purity tin by polarized zeeman atomic-absorption spectrometry with direct atomization of solid sample in a graphite-cup cuvette

Lead at the μg g level and cadmium at ng g - μg g levels in high-purity tin have been determined by polarized Zeeman atomic-absorption spectrometry with direct atomization of the solid sample. Pieces of high-purity tin weighing up to 5 mg for lead and 20 mg for cadmium were analysed. Calibration graphs were constructed by use of standard solutions of lead and cadmium in the presence of pure tin having lead and cadmium contents below the detection limit. The tin matrix remained in the graphite-cup cuvette after atomization and did not adhere to the wall of the cuvette, so it could be easily removed and the same cuvette repeatedly used.

Zinc in plasma, neutrophils, lymphocytes, and erythrocytes as determined by flameless atomic absorption spectrophotometry.

Zinc is determined in neutrophils and lymphocytes (isolated from whole blood on discontinuous gradients of Ficoll-Hypaque) and in microliter quantities of plasma and erythrocytes by flameless atomic absorption spectrophotometry with greater sensitivity than with conventional flame atomic absorption spectrophotometry. Before analysis, neutrophils and lymphocytes are digested with nitric acid and diluted with de-ionized water. Plasma and erythrocytes required no digestion, only dilution. Overall CVs were 4.0, 3.0, 5.0, and 4.6% for neutrophils, lymphocytes, erythrocytes, and plasma, respectively. Matrix effects were fully compensated for by use of standard solutions that simulated the sample matrix. Results for plasma and erythrocytes agreed with those obtained by the conventional technique.

Chemistry

THIS book provides a suitable course in volumetric analysis for the higher school certificate examinations. Thus an account is given of the preparation and use of standard solutions of acids, alkalis, potassium permanganate and dichromate, iodine, thiosulphate, and silver nitrate in neutral and acid solution. A concise and clear explanation is also given of the theory of indicators, including adsorption indicators. A useful feature of the book, especially from the point of view of scholarship candidates, is the list of practical problems at the ends of the chapters. Atomic weights, tables of logarithms and an index are given at the end of the book.

The Organic matter in heavy alkaline soils

1. Sudan soils are very low in organic matter, the total organic carbon being usually less than 1 per cent. In the Gezira, the humus carbon is about 40 per cent, of that of the total.2. Humus preparations purified as far as possible could not be obtained ash-free. Specimens of humus from widely different sources contain nearly the same proportion of carbon.3. Humus solutions (in very dilute alkali) keep fairly well in the dark. They also keep in bright sunlight if air is excluded. The use of standard solutions for colorimetric purposes is justified if not kept too long.4. Field studies show that the humus content of good soil is greater than that of poor, and that there is a marked inverse connection between salt and humus content.5. The above conclusion does not apply to the depth distribution of these constituents. In the Gezira, the maximum humus content is found at the fourth foot and the maximum salt content is found at about the same depth.6. The total nitrogen content of the soils studied is low, usually about 0·03 per cent. About one-fifth of this is humus nitrogen, and the carbon-nitrogen ratio is about twelve to one.

COLORIMETRIC DETERMINATION OF REACTION OF BACTERIOLOGIC MEDIUMS AND OTHER FLUIDS

The colorimetric methods in common use for determining and adjusting the reaction of bacteriologic mediums and other fluids involve the use of standard solutions of known hydrogen ion concentration. A variety of such solutions has been described, and they are readily prepared by any one having a moderate chemical equipment and ability. Just now, however, many men with comparatively little chemical training are confronted with problems of this nature, and the method here described has therefore been devised to accomplish a fairly accurate determination of hydrogen ion concentration without the necessity of preparing standard solutions or of depending on those prepared by others. We are here concerned only with reactions lying between 7.0 and 8.0, and only phenolsulphone-phthalein has been used as an indicator. Other indicators and other ranges of acidity will be investigated later. In this method use is made of the principle of superimposing the two extreme colors