Electron spectroscopy (ESCA).  Use for trace analysis

Hercules, David M.; Cox, L.E.; Onisick, Stephen.; Nichols, Gary D.; Carver, James

doi:10.1021/ac60333a037

Cited by 94 publications

(26 citation statements)

References 8 publications

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“…Proton decoupling can produce a nuclear Overhauser effect (NOE) (11,12) which enhances signal intensities such that peak areas may no longer be proportional to the number of nuclei. Although there are various means of avoiding this possibility (13,14), the measurements here did not use proton decoupling and, thus, the NOE did not exist.…”

Section: Stanley a Sojka" And Roger A Wolfementioning

confidence: 99%

“…The technique has been used in the analysis and study of. among others, thin-layer chromatography plates ( I ) ; semiconductor materials ( 2 ) ; low magnitude optical absorption coefficients (3)(4)(5); thermal diffusivity constants (6); fluorescence in solids (7)(8)(9); radiationless transitions ( 1 0 , I I ) ; qualitative identification of uranium tetrafluoride (12); biological systems (13)(14)(15)(16); and excited states of a solid (17).…”

Section: Harry E Eaton" and James D Stuartmentioning

confidence: 99%

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Analysis of commercial sodium tripolyphosphates by phosphorus-31 Fourier transform nuclear magnetic resonance spectrometry

Sojka¹,

Wolfe²

1978

Anal. Chem.

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of alkylamine-silanized metal oxide electrode. We can draw from this the intimation that a redox reagent bound to the alkylamine-silane may find itself in a spectrum of slightly different chemical environments. The redox reagent may as a consequence exhibit a spectrum of formal electrochemical potentials, which in turn has the effect of broadening the electrochemical surface wave observed fur the reagent. To what extent broadening we have observed in surface waves on alkylamine-silanized electrodes is due to this chemical heterogeneity as opposed to interactive effects within the chemically bound layer (62) or to both, remains tu be resulved.

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Section: Stanley a Sojka" And Roger A Wolfementioning

confidence: 99%

Section: Harry E Eaton" and James D Stuartmentioning

confidence: 99%

Analysis of commercial sodium tripolyphosphates by phosphorus-31 Fourier transform nuclear magnetic resonance spectrometry

Sojka¹,

Wolfe²

1978

Anal. Chem.

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“…Similarly, Hercules et aZ. 59 reported the preparation of immobilised dithiocarbamate material, and Leyden and LuttrelPO described their use as pre-concentration aids for multielement analysis by X-ray fluorescence spectrometry. The capacity of these resins ranged from 0.5 to 1.0 mmol g l .…”

Section: Other Methods For Separationmentioning

confidence: 99%

Determination of metals in foods. A review

Crosby¹

1977

Analyst

125

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In many instances, however, such additions were made in ignorance of their possible harmful effects on the consumer.Details of such malpractices can be found in the works of Accum,l Hassal12 and Bell.3 Examples of the first type of adulteration include the addition of flour, sand, china clay or water to samples of spices, tea, milk, etc. The most frequently encountered mineral adulterants were alum and chalk in bread, copper as (FeS0,.7H20) in beer, Prussian blue in tea, and soapstone (magnesium silicate), French chalk, sulphate of lime, lead chromate, oxides of iron and so on in a wide variety of food commodities. Perusal of the early volumes of The AnaZyst shows that by 1879 some such practices still remained, although on a much reduced scale. In the Annual Report of the Local Government Board for 1878,4 the addition of alum to flour was detected in 7% of the bread samples examined, while the use of noxious ingredients in beer was reported to be almost obsolete.In more recent times, interest in metallic elements in food has broadened from the detection of gross criminal malpractices to, on the one hand, investigations of chronic but possibly harmful effects on health of trace amounts present adventitiously as contaminants, together with, on the other hand, the beneficial and nutritional requirements of those elements now known to be essential to human or animal life. Such investigations require methods of analysis that are capable of measuring low levels of a wide variety of metals and metalloids in different organic substrates (foods, feedingstuffs, animal and plant tissues). Many elements are present in living tissues only at levels that are at, or even below, the limit of detection of the analytical methods formerly available and, hence, became known as trace elements. Nowadays, with the use of advanced instrumental techniques, the limits of detection have been lowered significantly and most elements can be measured with an accuracy and precision that are more than adequate for the study and interpretation of toxicological factors. However, the term "trace element" has survived and now refers to elements that occur at the milligrams per kilogram (parts per million) level or below, and which can exert some influence on plant or animal biochemistry and cell function. In this review, no distinction will be made between such elements and certain "major" elements, such as calcium or iron, which may be present in tissues or foods at much higher levels. Essential and Non-essential ElementsSimilarly, it is not possible to draw a clear distinction between essential and toxic elements, as all metals are probably toxic if ingested in sufficient amounts. In some instances, e.g., selenium or fluorine in man and copper in sheep,5 the margin between toxicity and deficiency is very small. However, it is usual to differentiate between those elements which are known (or thought) to be essential for animal (human) life and those which display severe toxicological effects at extremely low levels and have no known function in li...

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“…Many different chemical and physical preconcentration techniques have been proposed, including surface adsorption on activated carbon [18] electrodeposition [19], precipitation chromatography [20], liquid/liquid extraction [21], immobilized reagents [22], preconcentration on ion exchange treated polyurethane foam [23], plus a variety of other techniques well known to the analytical chemist. However, by far the most popular, and also the most successful, techniques have been those based on the use of ion exchange resin.…”

Section: Preconcentration Techniquesmentioning

confidence: 99%

Specimen Preparation and Presentation

Jenkins¹

1999

X‐Ray Fluorescence Spectrometry

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Electron spectroscopy (ESCA). Use for trace analysis

Cited by 94 publications

References 8 publications

Analysis of commercial sodium tripolyphosphates by phosphorus-31 Fourier transform nuclear magnetic resonance spectrometry

Analysis of commercial sodium tripolyphosphates by phosphorus-31 Fourier transform nuclear magnetic resonance spectrometry

Determination of metals in foods. A review

Specimen Preparation and Presentation

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