Computer techniques for three-dimensional analysis in atomic-absorption flame photometry

Flame methods, specifically in atomic-absorption work, have been augmented and enhanced by computer techniques for data reduction and mathematical analysis. Three-dimensional graphic display of experimental results allows for both a realistic and comprehensive approach to atomic-absorption analysis. The computer procedures and the mathematical techniques are described. Their coordination establishes quick, reliable, easily interpreted and useful results. The various equipment used is also described. The use of the remote scope (basically a cathode-ray tube) for immediate on-line display of three-dimensional data representation is explored. Several typical problems and their resulting solutions are presented in detail. Variations of absorbance are studied as a function of analyte concentration and a second variable: height of selection zone, concentration of interferent components, feed rate, slit width, or pressure of combustion gases. Variations of absorbance values are closely related to variations of percentual sensitivity.     

Slide-rule for atomic-absorption flame photometry

A new slide-rule is described for calculations in the field of atomic-absorption flame photometry. Most of the quantities used in analytical applications and in studies on the analytical behaviour of determinants are included in the operations which may be performed with the slide-rule. It can also be used for the most common operations necessary for calculation of concentrations, dilutions, dilution ratios and analytical factors. The rule described quickens calculation and reduces use of conversion tables.     

Qualitative and quantitative sensitivity in flame photometry

Concepts of sensitivity in flame photometry are discussed. A distinction is made between sensitivity itself, concentration limits and dilution limits applied to qualitative and quantitative analysis by flame photometry. Sensitivity values, as well as the concentration limits, are considered from two different aspects: as a function of the slope of calibration curves-percentual values-and as a function of fluctutions-fluctuational values. The concepts are applied to the two main branches of flame photometry, emission and absorption.     

Mechanism and elimination of interferences in flame photometry

Summary Recently developed methods for analysing the mechanisms of interferences (the separate atomization method and the location dependence method) have been applied to the analysis of the interference of potassium with other alkali metals. Results by the former method indicate the shift of some equilibrium in gaseous phase and/or variation in some atomization conditions, while analysis by the latter method supports the equilibrium-shift mechanism. This conclusion lends support to the existing hypothesis advocating the mechanism of ionization equilibrium shifts. In the location dependence method it has been observed that the interferences do not occur at the bottom part of the flame. This is significant from the view-point of eliminating the interferences.UsingSaha's relation, the location dependences of the slopes of the specifiedC- I curves of all alkali metals were analysed and it has been concluded that the degrees of ionisation of alkali metals are abnormally low at the bottom part of the flame. The temperature distribution measurement indicated that this is not due to the low-temperature effect in that part of the flame but possibly to a slow ionisation rate. Finally, a new method called the external buffer technique has been shown to be effective for eliminating the mutual interferences of akali elements.

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Zusammenfassung Vor kurzem ausgearbeitete Methoden zur Untersuchung der Störungsmechanismen (Verfahren der getrennten Versprühung bzw. Lichtmessung in verschiedenen Flammenregionen) wurden zur Analyse der gegenseitigen Beeinflussung des Kaliums und der anderen Alkalimetalle angewendet. Ergebnisse des erstgenannten Verfahrens deuten auf eine Verschiebung des Gleichgewichtes in der Gasphase und/oder eine Veränderung der Flammentemparatur während die Untersuchung nach dem zweiten Verfahren auf eine Gleichgewichts verschiebung deutet. Dies bestätigt die Annahme eines verschiebbaren Ionisationsgleichgewichtes. Bei Lichtmessung in verschiedenen Flammenregionen wurde beobachtet, daß im Basisanteil der Flamme keine Störungen auftreten, was im Hinblick auf deren Beseitigung bedeutungsvoll ist. Die Regionsabhängigkeit des Verlaufs der Konzentrationsintensitätskurve bei allen Alkalimetallen wurde mit Hilfe der Beziehung vonSaha analysiert und daraus geschlossen, daß das Ausmaß der Ionisation der Alkalimetalle in der Flammenbasis außergewöhnlich gering ist. Die Messung der TemperaturVerteilung ergab, daß dafür nicht niedere Temperaturen in dieser Flammenregion verantwortlich sind, sondern möglicherweise die geringe Ionisationsgeschwindigkeit. Schließlich wurde gezeigt, daß ein neues Verfahren der 'äußeren Pufferung zur Ausschaltung der gegenseitigen Störung der Alkalimetalle geeignet ist.

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Résumé Les méthodes récemment mise au point pour l'analyse des mécanismes des perturbations (la méthode d'atomisation séparée et la méthode de la dépendance de la localisation) ont été appliquées à l'analyse des perturbations apportées par la présence de potassium lors de la détermination d'autres métaux alcalins. Les résultats obtenus avec la première méthode montrent le déplacement de quelques équilibres en phase gazeuse et (ou) des variations de la température de la flamme tandis que l'analyse effectuée avec la seconde méthode confirme le mécanisme de changement d'équilibre. Cette conclusion confirme l'hypothèse concernant le mécanisme d'ionisation de déplacement de l'équilibre. Dans la méthode de la dépendance de la localisation on a observé que les perturbations ne se produisent pas à la partie inférieure de la flamme. Cette observation est significative du point de vue de l'élimination des perturbations.En utilisant la relation deSaha les dépendances de la localisation des pentes des courbes standardiséesC-I de tous les métaux alcalins ont été analysées; il en est résulté la conclusion que les degrés d'ionisation des métaux alcalins à la partie inférieure de la flamme sont anormalement faibles. La mesure de la distribution de la température a montré que cette anomalie n'est pas dûe à l'effet de basse température dans cette partie de la flamme mais probablement à la faible vitesse d'ionisation. Finalement les auteurs ont montré qu'une nouvelle méthode dénommée «technique de tampon externe» était efficace pour l'élimination des perturbations mutuelles des éléments alcalins.

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This work was presented before Twelfth Annual Meeting of the Chemical Society of Japan, at Kyoto University, April, 1959.     

Mechanism of elemental spectral excitation in flame photometry

It is generally believed that emission spectra result from thermal excitation. 1t is proposed that ultraviolet light present in a flame is. also responsible for exciting metal atoms present. Experimentally it las been shown that the intensity of metal emission spectra is a function of the U.V. characteristics of the flame even at constant flame temperature. It was also demonstrated that spectral intensity can be enhanced by external radiation of U.V. liglit of tlie correct wavelength.     

Mechanism and elimination of interferences in flame photometry

Summary The mechanism of the suppressing effects of aluminium, borate, phosphate, sulphate upon calcium radiation has been investigated. A very stable long flame was used with a specially designed Meker Burner. Variations in the interferences were observed when Ca and those interfering substances were separately atomized into one and same flame, and also when the point in the flame from which the light was drawn was changed by the use of a specially designed optical system attached to a Hitachi-EPU-2 A spectrophotometer. It is concluded that the suppression of Ca radiation is caused by hindering of the vaporization process because of the formation of non-volatile compounds of Ca with those interfering substances.A method of eliminating the suppressing effects of borate, phosphate and sulphate on alkaline earth radiations has been suggested.

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Zusammenfassung Die durch Aluminium, Borat, Phosphat und Sulfat hervorgerufene Intensitätsminderung der durch Calcium bedingten Flammenfärbung wurde untersucht. Bin besonders konstruierter Meker-Brenner wurde zur Erzeugung einer sehr konstanten und langen Flamme verwendet. Versprüht man das Calcium und die erwähnten Störstoffe in dieselbe Flamme oder wechselt man die zur Lichtmessung gewählte Flammenregion unter Verwendung eines dafür geeigneten, an einem Hitachi-EPU-2 A-Spektrophotometer angebrachten optischen Systems, so zeigen sich jeweils verschieden starke Störungen. Daraus ergibt sich, daß die Unterdrückung der Calcium-Strahlung durch eine Beeinträchtigung des Verdampfungsvorganges infolge Bildung nichtflüchtiger Verbindungen verursacht wird, die sich aus Calcium und den angeführten Störstoffen bilden.Ein Verfahren zur Beseitigung des durch Borat, Phosphat und Sulfat herbeigeführten Unterdrückungseffektes auf alkalische Erden wurde vorgeschlagen.

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Résumé Recherche sur le mécanisme des effets de suppression de l'aluminium, des borates, des phosphates, des sulfates sur la radiation du calcium. A cette fin, l'auteur a employé une flamme longue, trés stable d'un brûleur Meker spécialement prévu. Des variations de ces effets ont pu être constatées lorsque le calcium et les substances gênantes étaient atomisés séparément dans un flamme unique et lorsqu'on faisait varier le point de la flamme émetteur de la lumière observée; ces mesures ont été rendues possibles par l'emploi d'un système optique spécialement conçu fixé à un spectrophotomètre Hitachi-EPU-2 A. La conclusion de ce travail est que la suppression de la radiation du calcium est dûe à un processus d'empêchement de la vaporisation inhérent, à la formation de composés non volatils du calcium avec les substances gênantes.L'auteur suggère une méthode permettant l'élimination des effets de suppression des borates, des phosphates et des sulfates sur les radiations des alcalino-terreux.

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This work was precented before The Eleventh Annual Meeting of The Chemical Society of Japan, in Tokyo, April, 1958.     

食品中有机磷酸酯阻燃剂检测技术的研究进展

有机磷酸酯(OPEs)是阻燃剂和塑化剂的主要原料,通常以添加形式存在于各种材料中,在生产和使用过程中伴随磨损和挥发易释放到环境中,现已成为新兴污染物。因为该类化合物的神经毒性、致癌性、破坏内分泌系统以及生殖系统等毒性,食品样品中OPEs的检测成为近年来关注的热点。该文重点围绕食品基质中OPEs检测存在的含量低、本底干扰严重、缺乏灵敏可靠分析方法等问题,对OPEs类化合物的性质、样品前处理、检测技术、质量控制等进行了全面评述。首先总结了30余种常见OPEs类化合物的类型、官能团、极性、沸点等理化性质,对可能的前处理和检测技术进行了理论分析;其次梳理了加速溶剂萃取(ASE)、基质固相分散萃取(MSPD)、微波辅助萃取(MAE)、超声辅助萃取(UAE)、QuEChERS、固相萃取(SPE)、凝胶渗透色谱(GPC)、分散固相萃取(d-SPE)等前处理方法在食品中OPEs化合物分析中的特点,其中UAE和QuEChERS结合多步净化能够有效降低高脂类食品的基质效应,具有良好应用前景;此外比较了气相色谱和液相色谱在分离和检测方面的优缺点,比较已有文献的检出限、回收率等数据;概括了标准品和内标物来源、过程污染与基质效应的产生原因和预防措施;最后对高分辨质谱筛查和鉴别OPEs未知代谢物,以及相关分析方法趋势进行了展望。     

Interferences of three elements in flame photometry Cr-Co-Mn system

The correction methods proposed by two of the authors (F.B-M and J.R-M ), for interferential systems of two or three elements in flame photometry, have been applied to the interferential effects that occur in solutions containing chromium, cobalt and manganese, all three elements being present or combinations of two of them.A comparison has been made of the different systems in aqueous and sulphuric acid solutions, with concentrations which varied between 50 and 500 p.p.m. of cobalt or manganese and between 200 and 2000 p.p.m. of chromium.The correction methods that may be applied to experimental values obtained by flame photometry with these systems have been indicated. A series of examples have also been included in order to show the results obtained with prepared solutions of known concentration and with samples previously analysed by chemical methods.Finally, the possibility of increasing the accuracy of the methods by means of a double correction has been considered.     

Applications of sensitivity diagrams to atomic-absorption flame photometry

Sensitivity diagrams have been applied to atomic-absorption work, in the form of plane and space diagrams. These diagrams facilitate the representation and comparison of the analytical behaviour of different elements in terms of percentual and fluctuational sensitivity. They also aid in the study of single elements under diverse experimental conditions or with different instruments. Space diagrams permit the representation and study of variations of sensitivity in the presence of one or more masking agents under the same or differing experimental conditions. Limiting interference ratios can easily be calculated with the help of diagrams of this type.     

An auxiliary table for concentration calculations in atomic-absorption flame photometry

A table has been prepared for atomic-absorption work which gives concentrations in ppm and percent of analyte in original sample for a given series of standards as a function of the dilution ratio used during the steps of sample preparation. The use of original concentrations simplifies the calculation of concentration in manual graphical interpolation and allows the operator the use of simple interpolation computer programs, if desired, without the need of introducing constant or variable conversion factors. The table covers the most frequent concentration ranges of minor and micro components and dilution ratios from 1:10 to 1:10000.     

Determination of calcium in the presence of interfering anions by flame photometry using an oxygen-enriched air-acetylene flame and a displacement method

Summary The interferences due to phosphate, oxalate, sulphate, arsenate, borate, nitrate and perchlorate in the flame photometric determination of calcium can be eliminated by the use of an oxygen-enriched airacetylene flame and the addition of excess sulphate to the sample. A method for the determination of calcium in the presence of these interferences is described and some results (1.0 and 0.5 mmole of Ca/l) are given.

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Flammenphotometrische Calciumbestimmung in Gegenwart störender Anionen mit Hilfe einer Sauerstoff-angereicherten Luft-Acetylen-Flamme und eines Verdrängungsverfahrens

Zusammenfassung Die Störungen durch Phosphat, Oxalat, Sulfat, Arsenat, Borat, Nitrat und Perchlorat konnten durch Verwendung einer Sauerstoff-angereicherten Luft-Acetylen-Flamme und durch Zusatz von überschüssigem Sulfat zur Probe verhindert werden. Eine entsprechende Methode wird beschrieben und einige Ergebnisse (1,0 und 0,5 mMol Ca/l) mitgeteilt.

     

Advances in thermoanalytical techniques

Journal of Thermal Analysis and Calorimetry - Thermogravimetry coupled with chemometrics has proved to be a rapid and cost-effective diagnostic tool for β-thalassemia screening. This model,...     

The mechanisms of interference effects and their elimination in the determination of alkaline earth metals by flame photometry

The depressing effect of aluminum on the signal of alkali earth metals in an acetylene-air flame with a spray chamber and the various possibilities of eliminating this interference were investigated. The importance of processes taking part in the crystalline aerosol particles before volatilization, as revealed by flame profiles is emphasized, and appropriate mechanisms for the depressing effect and its elimination are suggested.     

蛋白质组学定量的技术与方法研究进展

蛋白质组学是一门在整体水平上研究细胞内蛋白质组成及其活动规律的新兴学科。定量蛋白质组学是指通过某种方法或技术，对生物样品(细胞、组织或体液等)在某些过程中蛋白质的含量进行比较分析。近几年来，定量蛋白质组的技术发展很快，稳定同位素标记技术的提出，为准确定量在细胞或组织体系中发挥重要功能的低丰度蛋白质提供了一个理想的方法。本文综述了蛋白质组定量分析技术及其最新的研究进展。     

Advances in arsenic speciation techniques

The present review describes the speciation techniques of arsenic. The principal advanced techniques discussed are gas chromatography, reversed-phase liquid chromatography, ion chromatography, capillary electrophoresis. Some other techniques are also mentioned. The extraction procedures of arsenic species from unknown samples are also discussed. Arsenic speciation is summarized in tabular form and optimizing parameters are also discussed.     

Mechanical feed burner with total consumption for flame photometry and atomic absorption spectroscopy

A mechanical feed burner has been developed for use in flame photometry and atomic absorption spectroscopy. The optimum flame conditions for cinisaion and absorption are very different. These conditions are also modified when organic instead of aqueous solvents are used. When different organic solvents are used, the interference is eliminated with atomic absorption but not emission. Flame profiles of a.tomic absorption and emission signals indicate that the processes are independent; the best signal for each is obtained at different parts of the flame. With emission, it appears that line spectra and background emission originate from the same process e.g. chemiluminescence     

A computer controlled photon counting flame emission spectrometer

An automated emission spectrometer has been developed around a simple commercial instrument. The manner in which a computer is used for control and the way data are acquired and assimilated are discussed. The interfacing to the computer is described, sample programs are illustrated and methods of analyses are given. Sensing is achieved through photon counting. The linearity of the system has been examined and it was found that, for lithium, quantitative results can be obtained with an accuracy of 1 per cent for a concentration range of four orders of magnitude. The time required for analysis is discussed and, although the spectrometer is serial in nature, the increased information rate obtained through photon counting results in high speed data acquisition.