Inorganic gases, sampling

This technique is one of the cornerstones of chromatographic analysis, being suitable for the separation of very complex organic and inorganic gas samples. The mobile phase is a carrier gas chosen to maximize separation efficiency as per the van Deemter equation, while concurrently maximizing the sensitivity of the detector. The stationary phase is either a solid or a viscous organic liquid coated on a solid support (hundreds available) or an open tubular capillary column (for very high efficiency separations). 

Dukhanin, A.S., 1990. Distribution of heavy metals in gas samples from mineral deposits. Abstracts of the Second All-union Conference for Inorganic Gas Analysis. Leningrad State Univ. pp. 255-256 (in Russian). 

Since gas samples can thus be introduced through nozzles, the furnace part at the bottom of the cryostat (Fig. 5, e) was replaced by an optical window for simultaneous irradiation with light. For vaporizing non-volatile inorganic compounds, the small electric furnace was attached to the setup (Figs. 5 and 6). 

The tubing containing the coupon samples were placed inside a Vycor glass tube (2.2 cm. I. D. and 85 cm.long) that was positioned horizontally in an electrical furnace controlled at either 700 or 900°C. For inorganic gas treatments Incoloy 800 and polished Incoloy 800 coupons were positioned side by side 4. 5 cm. upstream of the reactor midpoint polished and unpolished aluminized Incoloy 800 coupons were likewise positioned side by side except 2.0 cm. upstream... 

Principles and Characteristics Combustion analysis is used primarily to determine C, H, N, O, S, P, and halogens in a variety of organic and inorganic materials (gas, liquid or solid) at trace to per cent level, e.g. for the determination of organic-bound halogens in epoxy moulding resins, halogenated hydrocarbons, brominated resins, phosphorous in flame-retardant materials, etc. Sample quantities are dependent upon the concentration level of the analyte. A precise assay can usually be obtained with a few mg of material. Combustions are performed under controlled conditions, usually in the presence of catalysts. Oxidative combustions are most common. The element of interest is converted into a reaction product, which is then determined by techniques such as GC, IC, ion-selective electrode, titrime-try, or colorimetric measurement. Various combustion techniques are commonly used. 

Over the past two decades, capillary electrophoresis (CE) and related techniques have rapidly developed for the separation of a wide range of analytes, ranging from large protein molecules to small inorganic ions. Gas chromatography has been considered as a powerful tool due to its sensitivity and selectivity, especially when coupled with mass spectrometry. Nevertheless, liquid chromatography is the most used method to separate and analyze phenolic compounds in plant and tissue samples. 

In this method the sample is acidified and the inorganic carbon is removed with nitrogen. An aliquot is resampled for analyses. Buffered persulfate is added and the sample is irradiated in the ultraviolet destructor for about 9 min. The hydroxylamine is added and the sample stream passes into the dialysis system. The carbon dioxide generated diffuses through the gas-permeable silicon membrane. A weakly buffered phenolphthalein indicator solution is used as the recipent stream, and the colour intensity of this solution decreases proportionately to the change in pH caused by the absorbed carbon dioxide... 

---