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DNA is a universal analyte found in almost every organism. It is the code that dictates our genetic make-up and it provides a vast library of information. DNA sequences can indicate genetic modification of foodstuffs, how we may metabolise pharmaceuticals and the likelihood of suffering particular diseases. The basis for many of these genetic tests would benefit greatly from procedures that can accurately quantitate DNA in an absolute manner. This would then provide a sound and universally consistent foundation for regulatory and diagnostic decision making. This work compares two different enzymatic digestion systems as precursor steps to high accuracy isotope dilution mass spectrometry (IDMS) quantitation of a 20mer oligonucleotide. In the first approach, snake venom phosphodiesterase (SVP) digests the oligonucleotide to its constituent deoxynucleotides (dNMPs), followed by liquid chromatography-IDMS (LC-IDMS) quantitation. The second enzyme digestion approach used a combination of snake venom phosphodiesterase and shrimp alkaline phosphatase (SAP) which reduces the oligonucleotide to its constituent deoxynucleosides (dNs). This was then followed by an alternative LC separation and equivalent IDMS measurements. Total phosphorous content of the 20mer oligonucleotide was measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). This provided independent data for comparison with the two enzyme digestion-IDMS based procedures. The most appropriate method of quantitation was found to be the combined SVP and SAP digestion. This approach negates the need to consider and/or account for the lack of a 5' terminal phosphate residue. It also enables the use of positive ion mass spectrometry which simplifies the chromatographic requirements. Based on the exact matched IDMS of the adenine deoxynucleoside, the concentration of the original 20mer oligonucleotide was found to be 110+/-9 microg g(-1). This showed good agreement with the ICP-OES data based on the measurement of phosphorus which gave an equivalent value for the original 20mer oligonucleotide of 108+/-5microg g(-1) (uncertainties at the 95% confidence interval). It is intended that this high accuracy methodology should be used to produce high calibre reference standards. These, in turn, could then be used to underpin the quality and consistency of routine measurements involving a variety of more commonly encountered methodologies. It should be noted that the IDMS procedures are equally applicable to both sequenced and non-sequenced oligonucleotide materials.
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PMID:A comparison of enzymatic digestion for the quantitation of an oligonucleotide by liquid chromatography-isotope dilution mass spectrometry. 1568 82

A technique was developed to measure the total gaseous phosphorus content in biogas. The amount of air needed for a neutral to oxidising flame was mixed with the biogas. The gas mixture was burnt in a closed quartz burner and the combustion gasses were bubbled through a nitric acid solution. The phosphate content in the bubbling liquid was determined with sector field ICP-MS. The technique was validated in the lab with phosphine. Afterwards the set-up was installed on a landfill. The total gaseous phosphorus content in the landfill gas, measured with the combustive technique, ranged from 1.65 to 4.44 microg P/m3. At the same time the phosphine concentration in the landfill gas was determined gas chromatographically (GC). The phosphine (PH3) content measured with GC ranged from 7.6 to 16.7 microg PH3-P/m3. Since the phosphine-P content (GC) was consistently higher than the total gaseous phosphorus content (burner/ICP-MS), the hypothesised presence of highly toxic gaseous phosphorus compounds other than phosphine could not be demonstrated.
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PMID:Combustive approach for measuring total volatile phosphorus content in landfill gas. 1573 79

The determination of the animal feed additive roxarsone (3-nitro-4-hydroxyphenylarsonic acid) and six of its possible transformation products (arsenite, arsenate, monomethylarsonate, dimethylarsinate, 3-amino-4-hydroxyphenylarsonic acid, and 4-hydroxyphenylarsonic acid) in chicken manure was investigated using capillary electrophoresis-inductively coupled plasma-mass spectrometry (CE-ICP-MS). Initial method development was conducted using ultraviolet (UV) detection for ruggedness and time efficiency. Separation of these seven arsenic species was effected using a 20 mM phosphate buffer at pH 5.7. The CE-ICP-MS limits of detection in terms of As for each of the species was in the low microg.L(-1) range, corresponding to absolute detection limits in the range 20-70 fg As (based on a 23 nL injection). Overall, the method developed in this study provides high selectivity and low limits of detection (1-3 microg.L(-1) or low-ppb, based on As), uses small sample volume (low nL), and produces minimal wastes.
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PMID:Roxarsone and transformation products in chicken manure: determination by capillary electrophoresis-inductively coupled plasma-mass spectrometry. 1576 18

The presence of chromium in chromium-tanned leather represents a considerable health problem since it can lead to chronic allergic contact dermatitis. Apart from trivalent chromium (Cr(III)), which is used for tanning, leather often contains hexavalent chromium (Cr(VI)), resulting from the oxidation of Cr(III) during the tanning process. This study deals with the chromium compounds in simulated sweat when brought into contact with Cr(III) or Cr(VI) and with chromium-tanned leathers. A capillary electrophoresis (CE) method was developed, with inductively coupled plasma-sector field-mass spectrometry (ICP-SF-MS) for element-specific detection. Two different electrophoretic runs, applying once the positive and once the negative polarity mode, were necessary for the detection of positively and negatively charged chromium species. Although sometimes described in the literature, a pre-run derivatization of the chromium-species was not performed here to prevent species transformation. 50 mmol.L(-1) sodium phosphate at a pH of 2.5 was used as CE separation buffer and as make-up liquid for the CE-ICP-SF-MS interface. When applied to simulated sweat samples incubated with Cr(VI), this method showed that methionine is responsible for the reduction of Cr(VI) into Cr(III), which, at its turn, forms a complex with lactic acid. In the case of sweat plus Cr(III), the latter step was also seen. Applied to simulated sweat in contact with leather samples, the method developed showed the presence of the former species among a much more complex pattern.
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PMID:Capillary electrophoresis hyphenated to inductively coupled plasma-sector field-mass spectrometry for the detection of chromium species after incubation of chromium in simulated sweat. 1580 Sep 66

The effect of changing the amount of external added Co(His)n and phosphate on the interaction of Cu2Zn2SOD with organic metal compound (Cobalt (II)-Histidine) have been studied by means of ICP, VIS and measurement of enzyme activity. It has found that in aqueous solution, there exists a direct interaction of the metal ions of the active center in the metalloenzyme (Cu2Zn2SOD) with external added Co(His)n. As a result, part of the metal ions in metalloenzyme were replaced and the corresponding metalloenzyme derivatives (Co (II)-substituted derivatives of SOD) were produced and the catalytic activity of enzyme were affected. It has also studied the intensity of interactions in different molar ratios (Cobalt (II)-Histidine) and of the presence of phosphate and got some results under the effect of corresponding factors.
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PMID:[Study on the interaction of copper-zinc superoxide dismutase with cobalt (II)-histidine by spectral analysis--II. Effect of amount of external added Co(His)n, phosphate]. 1582 1

The potential for developing improved procedures for phosphate measurement through combinations of gel electrophoresis and quadrupole-based ICP mass spectrometry utilising (47)PO(+) is investigated. Laser ablation of gels offers a rapid and direct quantitation route, but is subject to high blanks due to P impurities in gels and associated reagents; nevertheless optimisation of laser sampling afforded improved method sensitivity (limit of detection 0.09 microg g(-1)). Implementation of whole gel elution (WGE) with FI-ICP-MS (conventional solution nebulisation) following gel electrophoresis permitted quantitation at the sub microg l(-1) level, and microcolumn processing (activated alumina) was effective at rejecting phosphate contamination. The potential for S-induced molecular ion interference at mass 47 was demonstrated.
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PMID:Combination of gel electrophoresis and ICP-mass spectrometry-novel strategies for phosphoprotein measurement. 1599 73

The combination of ion chromatography (IC) and inductively coupled plasma emission spectroscopy (ICP-ES) was used forthe sensitive and specific detection of hypophosphite (PO2), phosphite (PO3), methylphosphonic acid (MPA), and phosphate (PO4). Application of this technique to a wide range of environmental samples proved that reduced phosphorus was present in some situations including process water from thermal phosphorus plants, drinking water contacting cast iron, and phosphorus corrosion inhibitor used in water treatment and in sewage wastewater. Preliminary testing did not detect high concentrations of reduced phosphorus and phosphine in situations where it was previously reported to be very important, including anaerobic digesters in wastewater treatment plants. The new IC-ICP-ES technique is a promising tool for use in corrosion and soil research where phosphites are likely to be present.
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PMID:Analysis of reduced phosphorus in samples of environmental interest. 1604 69

Since years, ion exclusion chromatography (ICE) has been the standard method to separate strong acid analyte anions from concentrated weak acid matrices such as hydrofluoric acid (HF). In this work, the commercially available IonPac ICE-AS 1 column was used to separate trace levels of chloride, nitrate, sulfate and phosphate from HF solutions at 20% (w/w). The efficiency of the separation was studied in more detail using techniques such as ion chromatography (IC), inductively coupled plasma optical emission spectrometry (ICP-OES) and ICP-mass spectrometry (ICP-MS). For 20% (w/w) HF solutions and at a water carrier flow-rate of 0.50 ml/min, the cut window was set from 8.5 to 14.5 min. Under these conditions, analyte recoveries of better than 90% were obtained for chloride, nitrate and sulfate, but only about 75% for phosphate. The HF rejection efficiency was better than 99.9%. It was found that the ICP techniques, measuring total element levels and not species, yielded significantly higher recoveries for phosphorus and sulfur compared to IC. Evidence will be given that part of the added phosphorus (approximately 15% for an addition of 10 mg PO4/kg) is present as mono-fluorophosphoric acid (H2FPO3). In the case of sulfate, the difference between IC and ICP-MS could be attributed to an important matrix effect from the residual HF concentration.
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PMID:Trace anion determination in concentrated hydrofluoric acid solutions by two-dimensional ion chromatography I. Matrix elimination by ion-exclusion chromatography. 1610 49

Quantitative determination of trace glyphosate and phosphate in waters was achieved by coupling ion chromatography (IC) separation with inductively coupled plasma mass spectrometry (ICP-MS) detection. The separation of glyphosate and phosphate on a polymer anion-exchange column (Dionex IonPac AS16, 4.0 mm x 250 mm) was obtained by eluting them with 20 mM citric acid at 0.50 mL min(-1), and the analytes were detected directly and selectively by ICP-MS at m/z = 31. Parameters affecting their chromatographic behaviors and ICP-MS characteristics were systematically examined. Based on a 500-microL sample injection volume, the detection limits were 0.7 microgL(-1) for both glyphosate and phosphate, and the calibrations were linear up to 400 microgL(-1). Polyphosphates, aminomethylphosphonic acid (the major metabolite of glyphosate), non-polar and other polar phosphorus-containing pesticides showed different chromatographic behaviors from the analytes of interest and therefore did not interference. The determination was also interference free from the matrix anions (nitrate, nitrite, sulphate, chloride, etc.) and metallic ions. The analysis of certified reference material, drinking water, reservoir water and Newater yielded satisfactory results with spiked recoveries of 97.1-107.0% and relative standard deviations of < or = 7.4% (n = 3). Compared to other reported methods for glyphosate and phosphate, the developed IC-ICP-MS method is sensitive and simple, and does not require any chemical derivatization, sample preconcentration and mobile phase conductivity suppression.
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PMID:Determination of glyphosate and phosphate in water by ion chromatography--inductively coupled plasma mass spectrometry detection. 1618 3

Since the species that trigger chromium allergy are not yet known, it is important to gain more of an insight into the mechanism of chromium transport through the skin and into the relationship between chromium allergy and chromium species. In vitro permeation studies with porcine and human skin were performed using a Franz static diffusion cell. Investigations attempted to elucidate (i) which Cr compounds are able to permeate through skin, (ii) the influence the Cr concentration in the donor solution has on the Cr permeation, and (iii) the effect that the time of exposure to the donor solution has on Cr permeation. Capillary electrophoresis hyphenated to inductively coupled plasma-sector field mass spectrometry (CE-ICP-SFMS) was used to separate and quantify the Cr species in the receptor fluid. 50 mmol L(-1) phosphate buffer (pH 2.5) was used for CE separation, and two different electrophoretic runs were carried out (in the positive and negative modes). Pneumatic nebulization (PN)-ICP-SFMS was used in order to quantify the total amount of Cr absorbed by the skin after microwave-assisted acid digestion of the tissue. Cr(VI) was found to pass most easily through the skin. Nevertheless, Cr(VI) was also shown to be absorbed more efficiently by the skin than Cr(III), an observation attributed to a more pronounced rejection of the positively charged Cr(III) ions by the skin barrier. These results were in good agreement with in vitro permeation studies previously reported in the literature in which other analytical techniques were used. Differences observed in the permeation of Cr following the application of aqueous Cr donor solutions and Cr-containing simulated sweat donor solutions are also described.
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PMID:In vitro permeation of chromium species through porcine and human skin as determined by capillary electrophoresis-inductively coupled plasma-sector field mass spectrometry. 1634 96


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