Notes on analytical procedures : Determination of carbon dioxide

For the determination of carbon dioxide, methods suitable for general applications are described. a. Macro-titration method. The CO2 is absorbed in sodium hydroxide in a bubble column filled with glass beads. The excess of NaOH is titrated after the addition of BaCI2. b. Scmi-micro-titration method. The CO2 is absorbed in barium hydroxide, the excess of which is determined by titration with 0.1 n hydrochloric acid on cresolphthalein as the indicator. The absorption and titration are performed in a special vessel in which the liquid is kept in circulation by the injected stream of air. c. Gravimetrical method.Method b. is specially recommended.     

Notes on analytical procedures: Colorimetric determination of magnesium in water

A simple procedure is described for a visual colorimetric determination of Mg+2 in Water, based on the well-known reaction with titan yellow.Ein cinfaches Verfahren zur visuellen kolonmetrischen Bestimmung von Mg+3 in Wasser, das auf der bekannten Reaktion mit Titangelb beruht, wird beschrcben..     

Notes on analytical procedures : Influence of the acid concentration on the oxidimetric determination of antimony

In the oxidimetric determination of antimony, the quantity of the acid has to be adjusted. Low acidity causes the separation of a basic antimony salt, at high concentrations HCl is oxidised to chlorine.     

Novel analytical procedures for screening of drug residues in water, waste water, sediment and sludge

Traces of pharmaceuticals are continuously introduced into the aquatic environment mainly by sewage treatment plant effluents. Final data about their impact on the ecosystem are still partly missing. Progress in instrumental analytical chemistry has resulted in the availability of methods that allow a monitoring of these pollutants at ng L⁻¹ levels. In this review the state-of-the-art of residue analysis of pharmaceuticals by chromatographic and electrophoretic techniques is summarized. Improvements in detection limits over the past years have mainly been due to sophisticated mass spectrometric detection techniques. Furthermore, robust sample preparation and preconcentration protocols based on solid-phase extraction and related procedures have contributed significantly to the achievements observed so far. This review also covers several immunochemical approaches which may serve as an inexpensive alternative for quick screening of samples.     

全自动间断化学分析法测定锅炉水中磷酸根离子

建立全自动间断化学分析法测定锅炉水中磷酸根离子含量的方法.样品加入量为90μL,钼酸铵和酒石酸锑钾酸性混合溶液(R1)加入量为160μL,抗坏血酸溶液(R2)加入量为470μL,加入R1反应时间为50 s,加入R2反应时间为300 s,检测波长为880 nm,采用稀释模式检测.磷酸根离子的质量浓度在5～50 mg/L范...     

Radiometric control of analytical separation procedures

Summary Different analytical separation procedures were investigated by radioactive tracer techniques.By liquid-liquid extraction with isoamylacetate it was found possible to eliminate traces of chromium from a great excess of iron. The iron thus purified was tested for residual Cr by thermal neutron irradiation. A corresponding extraction technique, using cuproïne in isoamylalcohol as extractant, was used for the separation of traces of copper from irradiated zinc.The quantitative extraction of zinc with methyldioctylamine in xylol and the quantitative character of the Zn[Hg(SCN)₄] precipitation were furthermore proved.The separation of nickel and cobalt by dimethylglyoxime precipitation was investigated with⁶⁵Ni and⁶⁰Co tracers. About 0.6% cobalt was coprecipitated.Coprecipitation of sodium with potassium dipicrylaminate and with potassium tetraphenylborate was found to be about 0.5%. As this decontamination was sufficient to permit selective-counting of⁴²K in presence of²⁴Na, no double precipitation purification step was attempted.

---

Zusammenfassung Verschiedene analytische Trennungsverfahren wurden mit Hilfe radiometrischer Indikatormethoden überprüft.Durch Flüssig-flüssig-Extraktion mit Isoamylacetat lassen sich Chromspuren aus großen Eisenüberschüssen entfernen. Das so gereinigte Eisen wurde durch Bestrahlung mit thermischen Neutronen auf Chromreste geprüft. Ein analoges Extraktionsverfahren mit isoamylalkoholischer Cuproinlösung wurde zur Abtrennung von Kupferspuren aus bestrahltem Zink verwendet. Weiters wurden die quantitative Extraktion von Zink mit Methyldioctylamin in Xylol und die Vollständigkeit der Fällung von Zink-Thiocyanatomercuriat überprüft. Die Trennung von Nickel und Kobalt mittels Dimethylglyoxim wurde mit Spuren⁶⁵Ni und⁶⁰Co untersucht. Ungefähr 0,6% Kobalt wurden mitgefällt. Die mit Kaliumdipikrylaminat und Kaliumtetraphenylborat mitgefällte Natriummenge beträgt etwa 0,5%. Da diese Reinigung zur selektiven Messung der-Aktivität des⁴²K in Gegenwart von²⁴Na ausreicht, wurde keine weitere Reinigung durch wiederholte Fällung versucht.

---

Résumé Plusieurs méthodes de séparations analytiques furent contrôlées à l'aide de traceurs radioactifs. Il s'avéra possible d'éliminer des traces de chrome d'un excès de fer en employant une technique d'extraction liquide-liquide à base d'acétate d'isoamyle. Le degré de purification du fer fut contrôlé par irradiation dans un flux de neutrons thermiques.Le 2-2 dichinolyle fut employé pour l'extraction sélective de traces de cuivre d'un échantillon de zinc irradié. Il fut ensuite prouvé que le zinc peut être isolé quantitativement par extraction au méthyle-dioctylamine ou en le précipitant sous la forme de Zn[Hg(SCN)₄].La séparation nickel-kobalt à l'aide du diméthyleglyoxime fut contrôlée à l'aide de⁶⁵Ni et de⁶⁰Co. Environ 0,5% du cobalt présent fut coprécipité dans les conditions expérimentales données. Enfin, la coprécipitation du sodium avec le dipicrylaminate ou le tetraphénylborate de potasse fut déterminée; en moyenne elle fut de l'ordre de 0,5%.

---

---

Dedicated to Prof. Dr. Ing.Fritz Feigl on occasion of his 70th birthday.

---

Research Fellow I. I. K. W. (Belgium).     

Determination of sodium hydroxide in boiler water by a linear titration plot method

A simplified linear titration plot has been developed specifically for determining the sodium hydroxide content of boiler water. A known quantity of strong acid is added, in excess, to the alkaline sample which is then titrated with standard alkali. Functions are constructed from the titration data (pH, volume added) and known constants. These functions are linearly related, so that plotting one against the other gives a straight line of slope V_Y and intercept V_X, where V_X and V_Y are the volumes of titrant required to neutralize the “strong” (including for this purpose acetic and other carboxylic acids) and “weak” (ammonium ion and silicic acid) components. These are sufficient to enable the original sodium hydroxide concentration to be calculated. The constants required for the functions are the autoprotolysis constant of water and the association constant of ammonium ion. The functions can be calculated very easily with a programmable calculator.     

Estimating uncertainty in analytical procedures based on chromatographic techniques

Chromatographic techniques are very frequently used in analytical procedures for the separation, determination and identification of a wide spectrum of analytes present in samples with complex and sometimes variable matrices. However, the estimation of uncertainty of the final results does not include the uncertainties associated with the actual chromatographic process. In effect, such results cannot always be treated as a reliable source of analytical information. In this paper we present the basic terms, sources of uncertainty, and methods of calculating the combined uncertainty that any presentation of final determinations should include.     

Determination of the surfactant density on SWCNTs by analytical ultracentrifugation

We report on the extensive characterization of single-walled carbon nanotubes (SWCNTs) dispersed in a variety of surfactants, such as sodium dodecyl benzene sulfonate (SDBS), sodium cholate (SC), and three synthesized perylene-based surfactants, by using differential sedimentation in H(2)O and D(2)O. Multidimensional evaluation of the absorption profiles over radius, wavelength, and time allows the determination of the anhydrous specific volumes of the SWCNT-surfactant complexes as well as the concentration of the surfactant reservoir in free micelles with very slow sedimentation coefficients (<1 Svedberg). Among the perylene bisimide surfactants, the smallest derivative is densely adsorbed on the nanotube backbone with an anhydrous specific volume significantly above that of SC or SDBS. Bulky Newkome dendritic groups on one or both ends of the perylene moiety gradually reduce the adsorption density, in accord with the absolute adsorption between 0.66 and 1.7 mmol surfactant per gram SWCNTs. Furthermore, hydrodynamic analysis reveals that SDBS favors the "tails-on" configuration. The distribution of sedimentation coefficients of SWCNTs prepared by high-pressure carbon monoxide decomposition (HiPco) is broader and shifted to faster sedimentation than those prepared by using cobalt-molybdenum catalysis (CoMoCAT), which reflects the polydispersity in diameter and length.     

Determination of trace amounts of morpholine and its thermal degradation products in boiler water by HPLC

Summary Morpholine and its amine-type thermal degradation products present in boiler feed water and steam condensate were derivatised with N-succinimidyl-p-nitrophenylacetate. These pre-column derivatives were determined by high-performance liquid chromatography with UV detection at 280 nm. The analytical column was Supelco-sil-ODS with an isocratic mobile phase. Morpholine and its breakdown products were monitored in the range 0.01–10 g ml^–1 with a relative standard deviation of 0.4–3.0%. Chromatographic analysis of boiler feed water and steam condensate samples collected from a boiler servicing a petroleum refinery is described.     

Effect of water hardness on the interaction of cationic dye with anionic surfactants

ABSTRACT

The effect of water hardness causing ions on the critical micelle concentration (cmc) of surfactants was studied using conductivity measurement. Spectrophotometric and conductometric studies of dye and surfactant interaction under the influence of water hardness causing ions were also investigated. It was found that with increasing hardness in water, cmc of the surfactants tends to decrease. The change in the colour of the solution was observed as the degree of hardness increases. Hardness of water can consider as a major contributor of fading or change in colour during washing and cleaning of dyed material. Dye in a surfactant solution containing varying amount of hardness causing ions undergoes a blue shift in the visible region and red shift in ultraviolet region. The comparison between sodium dodecylsulphate (SDS) and saponin natural surfactant showed that turbidity was observed only in the aqueous solution of SDS in the presence of very hard water.     

Determination of low degrees of hardness in water using a soap solution according to clark. I

1. The determination of low degrees of hardness in water according to the usual methods does not yield satisfactory results. Therefore an investigation was carried out with a soap solution of sodium, oleate according to clarke, and also nephelometric measurements were made. 2. Measurements were cairied out at degrees of hardness from 0.5 to 39.0 p.p.m. (i.e. 0°.005–3°.09 FH; or 0°.003–2°.18 DH), made out of pure calcium chloride solutions, at different pH values; also with calcium chloride solations, containing NaCI and alcohol. Magnesium, chloride solutions were investigated in the same way. 3. The calcium oleate, that precipitates when the hardness is determined, has a composition of 5 CaOl₂-2NaOl. The magnesium oleate has a corresponding composition. Dependent on the circumstances also 5 CaOl₂-3NaOl and calcium oleates. containing yet more sodium oleate may be formed. This phenomenon occurs especially at very low degrees of hardness. 4. No turbidity of calcium oleate arises when precipitation takes place at degrees of liardness lower tlian 1.2 p.p.m. CaCO₃(0°.07 DH), Magnesium olcate does not precipitate at degrees of hardness lower than 3.2 p.p.m. (0°.18 DH). 5. As a result of the phenomenon referred to in. point 3 the determination according to clarke for degrees of hardness below 5 p.p.m. CaCO₃(0°.3 DH) are only reliable if very important errors (up to 30%) are tolerated. In order to determine these degrees of hardness it is therefore advisable to add so much concentrated CaCl₂ solution as to reach a handy hardness of the water sample.     

Determination of uncertainty for hardness measurement: proposal of the standard,available software

After the next revision of the ISO-standards for hardness testing (ISO 6506–6508) an estimation of the uncertainty (ISO/IEC 17025, ISO 5725) is mandatory. The two proposed approaches of part one (ISO 6506–6508) of the ISO Standards for hardness are exemplified. The calculation approach implemented in an Excel-based file, which is available via , is announced.Presented at the Metro Trade Workshop on Traceability and Measurement Uncertainty in Testing, 30–31 January 2003, Berlin, Germany     

Development of analytical procedures for trace-level determination of polybrominated diphenyl ethers and tetrabromobisphenol A in river water and sediment

The aim of this work was to develop procedures for the simultaneous determination of selected brominated flame retardants (BFRs) in river water and in river bed sediment. The target analytes were polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol A (TBBPA). To determine dissolved BFRs, a novel mixed-mode solid-phase extraction procedure was developed by combining a hydrophobic sorbent (C₁₈) with a silica-based anion exchange sorbent, so as to overcome the negative artefact induced by dissolved organic carbon. Extraction recoveries exceeded 73% for most analytes, except for BDE-183 and BDE-209 (57%). As regards suspended sediment and river bed sediment, extraction was carried out by means of ultrasonication (recoveries: 73–94%). These procedures, combined to gas chromatography coupled to negative chemical ionisation mass spectrometry (GC-NCI-MS), enabled the determination of BFRs at trace level: 3-160 pg L⁻¹ in river water, 5–145 pg g⁻¹ in bed sediment. These methods were applied to the determination of PBDEs and TBBPA in a suburban river (near Paris, France). PBDEs were systematically detected in the water column (ΣBDEs, 2,300–4,300 pg L⁻¹); they partitioned between the dissolved and particulate phases and BDE-209 was the dominant congener, followed by BDE-99 and BDE-47. TBBPA was detected in the dissolved phase only (<35–68 pg L⁻¹). All selected BFRs were ubiquitous in bed sediments and levels ranged from 3,100 to 15,100 pg g⁻¹ and from 70 to 280 pg g⁻¹ (dry weight), for ΣBDEs and TBBPA, respectively.     

An approach to detection capabilities estimation of analytical procedures based on measurement uncertainty

Detection capabilities are important performance characteristics of analytical procedures. There are several conceptual approaches on the subject, but in most of them a level of ambiguity is presented. It is not clear which conditions of measurements should be used, and there is a relative lack of definition concerning blanks. Moreover, there are no systematic experimental studies concerning the influence of uncertainty associated with bias evaluation. A new approach based on measurement uncertainty is presented for estimating quantities that characterize capabilities of detection. It can be applied to different conditions of measurement and it is not necessary to perform an additional experiment with blanks. Starting from a modelling process of the combined uncertainty of concentration, it is possible to include in the estimated quantities the effects due to random errors and the uncertainty associated to evaluation of bias. The detection capabilities are then compared with the results obtained using some other relevant approaches. Slightly higher values were obtained with the measurement uncertainty approach due to inclusion of uncertainty associated with bias.     

Sequential injection technique for automation of complex analytical procedures: fluorometric assay of factor thirteen

A non-segmented flow method is used to automate an analysis which involves five different reagents. The fluorometric assay for factor thirteen (FXIII) is performed by the sequential injection analysis (SIA) technique. Two reactions take place in a single fine SIA system to produce the final fluorescing product. Because of its mechanical simplicity and versatility, the sequential injection (SI) technique is shown to be an attractive tool for automation of a complex analytical procedure. In addition to collecting quantitative and kinetic information, the SI system is illustratively used for optimization of the analysis and for obtaining validation information.