Arsenic signaling

Start the vapour generator cycle so that the absorption cell is flushed with argon gas and the pre-set volume of NaBH4 (1 mL) is pumped into the sample vessel. After the pre-selected reaction time (0.5 minute), AsH3 vapour is flushed into the absorption tube. Record the value of each arsenic signal as a peak height measurement. Read off the arsenic concentration of the sample, which is displayed on the instrument video screen. 

Conventional ICP-MS has great sensitivity but suffers from serious interferences. Chlorine interference leads to the formation of " °Ar Cl, which has the same mass/charge ratio as the mono-isotopic As (w/z = 75). Hence, HCl and HCIO4 should not be used for preservation or dissolution if ICP-MS is to be used. There may also be significant interference in samples with naturally high Cl/As ratios. A chlorine concentration of 1,000 mg gives an arsenic signal equivalent to —3-10 p,g L. ... 

Start the recorder and record the baseline. Raise the zinc dosing tube to a vertical position and quantitatively transfer the zinc dust to the solution. Record the arsenic signal until the recorder returns to the baseline. Either peak height or peak area may be used to indicate arsenic response. 

The decomposition step is carried out in a mixture of 0.5 M sulfuric acid and 100 volume hydrogen peroxide. The copper(II) sulfate, potassium/sodium dichromate and arsenic pentoxide in CCA preservatives undergo fixation to form potassium/sodium sulfate by-products. Any potential interference in the chromium and arsenic signals from these compounds in the leachate is overcome by an excess of sodium... 

Resolution of Che Mo 3p peaks showed molybdenum Co be present as Mo" for the calcined catalysts, and a mixture of Mo" " and Mo" for sulfided catalysts. The Mo 3p peaks were used since both arsenic and sulfur peaks interfere with the Mo 3d doublet. Although some authors have been able to resolve a peak attributed to Mo" "5 on sulfided catalysts (8-9), we were able to resolve our peaks using only two component peaks. Curve resolving consistently showed that about 70% of the molybdenum signal in the sulfided catalysts was due to Mo". ... 

Platinum complexes are cytotoxic agents yet the paradigm in cancer chemotherapy has moved to a more targeted approach, with special emphasis on signaling pathways. In this respect a remarkable story is that of arsenic trioxide, As203 (Trisenox, Cell Therapeutics Inc, Seattle, USA) which was approved by the FDA in September 2000 for treatment of acute promomyelo-cytic leukemia (APL) in patients who have relapsed or are refractory to retinoid and anthracycline chemotherapy. An estimated 1,500 new cases of APL are diagnosed yearly in the US, of which an... 

M. Ozsoz, A. Erdem, P. Kara, K. Kerman, and D. Ozkan, Electrochemical biosensor for the detection of interaction between arsenic trioxide and DNA based on guanine signal. Electroanal. 15, 613-619... 

Yu, H.-S. et al., Arsenic Induces Tumor Necrosis Factor a Release and Tumor Necrosis Factor Receptor 1 Signaling in T Helper Cell Apoptosis, J. Invest. Dermatol., 119, 812, 2002. 

Barchowsky, A. et al., Low levels of arsenic trioxide stimulate proliferative signals in primary vascular cells without activating stress effector pathways, Toxicol. Appl. Pharmacol., 159, 65, 1999. 

Tanaka-Kagawa, T. et al., Arsenite and arsenate activate extracellular signal-regulated kinases 1/2 by an epidermal growth factor receptor-mediated pathway in normal human keratinocytes, Br. J. Dermatol., 149, 1116, 2003. 

Survey of Sensitivity Characteristics of Typical Delay Ignitor Flash and Signal-Type Pyrotechnic Compounds Joseph Kristal and Seymour M. Kaye Picatinny Arsenal, Dover New Jersey 439383 111... 

Green smoke Paraffin Black powder. Potassium nitrate. Red arsenic. Sulfur, Green smoke produced, Screening/signaling smoke ... 

Arsenic Inorganic arsenic salts Gastrointestinal, respiratory (all mucosal surfaces), skin Predominantly soft tissues (highest in liver, kidney). Avidly bound in skin, hair, nails Cardiovascular shock, arrhythmias. CNS encephalopathy, peripheral neuropathy. Gastroenteritis pancytopenia cancer (many sites) Inhibits enzymes interferes with oxidative phosphorylation alters cell signaling, gene expression Methylation. Renal (major) sweat and feces (minor)... 

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