Hydrogen-Oxygen Combustion Apparatus
Hydrogen-Oxygen Combustion Apparatus V 5 According to the Wickbold-method
Offers high working safety at cotinuous operation due to
• electncal control
• electronic surveillance
• and clear design for disintegration of organic samples for CI, Br, F, B, S, Hg, J, P, Pb, Se, As, V, Cd, Zn analysis
The Proven Wickbold Method
The Wickbold method has been a proven success for about 30 years. It was formerly developed for the disintegration or organic samples in petrochemistry, to determine halogens and sulphur.
This method is very suitable for sulphur contents of 1 to 50,ODD ppm and chlonne contents of 0.5 to 10 ppm. Certainly, substances with higher contents can also be disintegrated.
In the course of time, however, this method has also proved suitable for the disintegration of organic samples, whose content of mercury, arsenic and selenium is to be determined. Lately, the Wickbold method has also been used for the determination of EOX and the detection of sulphur in spruce.'' and pine
In comparsion with other disintegration methods, oxidizing combustion in a hydrogen-oxygen flame (above 2000°C} has the advantage that after disintegration, the elements to be determined are on hand as ions in a hydrous solution. Very often, the analytical determination can directly be performed in this solution, because it is free from excess disintegration auxiliaries.
Therefore, this method is used increasingly in the analyses of trace metallic elements in organic mathces. In the case of very low trace element concentrations, the continuous flame combustion permits consumption of a larger quantity of substance, thereby ensuring a concentration above the level of detection. Through simple concentration of the aqueous solution, it is possible to achieve the necessary concentration levels for the use of, for example, AAS. Furthermore, by the addition of complex formers the metallic trace elements can be enriched, in particular, the mettiod is suitable for the precipitate exchange reaction on a thin sulphide layer to enrich heavy metals for the trace determination by the AAS and X-ray fluorescent methods. Using pre-enriching techniques, limits of detection in aqueous solutions in the ng/l range are achievable.
Operating convenience - high reliability
For still better operating convience and additionally higher reliability the combustion apparatus type 5 is available. It was designed according to ergonomic principles. High reliability and operational convience characterise the new development of this apparatus. All display and control elements are - easily visible - coordinated on a console.
The control of the inert and combustion gas is carried out by convenient handoperated valves on the front side of the console.
On the front panel of the console there are two valves on the left side, these are for controlling the wor1<ing
pressure, as well as a mixing valve which allows the convenient distribution of the gases when used with the soiid burners. By using a throttle and by-pass valve, it is possible to maintain constant pressure under varying operation conditions. The manometer is easily readable on the lateral front of the console. Situated underneath it are all the swfltches and buttons for the electncal control of the apparatus.
The blocking of all gas flows is achieved with magnetic valves so that the handoperated needle valves are used exclusively to control the gas flow. Electronic safety circuits control the apparatus in operation. Extinguishing of the main flame or failure of the cooling water system automatically switches off the gass supplies.
Electrical control, eletronic monitoring
Multi switches control the gas supply to the individual quartz gfass burners. LED (light emitting diodes) above the appertaining control valves and flowmeters, indicate the working position of the magnetic valves. A further light-emitting-diode indicates the operation of the cooling water. A fixture for supporting the quartz glass burner dunng intervals between combustion processes is equipped with an electhcal ignition system. Burner ignition is simply achieved by push button. Change-over to main flame takes place automatically on removal of the burner. If it is not indroduced immediately in the combustion chamber, the flame will extinguish after a short time.
Combustion chamber/Absorption vessel/ Rinsing device
The combustion apparatus type 5 contains an absorption vessel with a rising device according to Dr. Bruning and Roth, which permits the continuous operation with series analyses. The rinsing device on the top end of the absorption vessel allows the addition of absorption solutions as well as quantitative rinsing of the inner waL. The burner remains operational throughout.
The long combustion chamber of the apparatus allows a rapid combustion of large quantities of substances. After intensive cooling, the gas flow reaches the absorption vessel disthbuted into fine bubbles by a fnt. This allows the combustion products to be washed out quanti-tatively by the absorption vessel. Due to the bubbling effect, a large gas/ liquid interface is produced in the absorption vessel, resulting in a maximum of product exchange. The geo-metrical surface of the absorption vessel is very small and the absorption of trace elements on the glass is minimal.
The outlet for the analysis solution is placed immediately above the frit plate of the absorption vessel. Draining of the liquid into a measuring flask is achieved by means of a multi-way lap. This controls, by means of mutual locking, the gas extraction, the ventilation of the measuring flask and the outflow of the liquid, thus excluding the possibility of operational faults. In order to achieve shorter flow paths for the liquids, the taps on the rinsing device and ab-sorption vessel are not buiJt into the console as individual control elements.
Precombustlon Unit VE for solids, pasty samples and contaminated liquids.
The electhcally heated precombustlon unit VE optimizes the precombustlon by providing a targetable and controllable preincineration temperature in a semimonocoque tubular oven.
The burner allows a careful pyrolysis process that is individually selectable for each type of sample.
The avoidance of buildup of condensates in the burner and its capillaries guarantees trans-mission of all organic sample components into the H^/ O2 flame.
Possible residues in the burner capillaries can be removed with a H2/ 0; flame.
As the result of modifications in the gas supply feeds, the hydrogen/ oxygen flame has been improved in performance.
Quick and simple mounting and dismounting allows easy exchange of burners.