Spray chambers jacketed

Fosinopril sodium Pd 0.1 pg/g Plasma Quad PQ 11 Turbo plus ICP-MS Jacketed Scott Type Spray Chamber [95]... 

Spray chambers can be cooled via a water jacket or Peltier cooling to reduce the amount of solvent vapor introduced into the ICP [31, 32). A further reduction in the amount of solvent introduced can be realized via a desolvation system. Traditionally, such a desolvation system consisted of a sequence of a heated and a cooled tube. In the heated tube, the solvent is vaporized, after which it condenses on the inner wall of the cooled tube and is thus removed. Nowadays, desolvation systems equipped with a membrane desolvator are often used [33, 34). These basically consist of a tube manufactured from a semipermeable porous material, around which heated Ar gas is flowing in the opposite direction to the sample aerosol flow. The solvent is vaporized, and the gaseous solvent molecules leave the central tube via the pores and are carried off by the heated Ar flow. Desolvation of the sample aerosol can lead to an 10-fold increase in signal intensity. For rather volatile analyte elements, (partial) analyte loss needs to be taken into account [35]. 

Water-jacketed spray chambers have been shown to be helpfid in reducing oxide signals [668], as well as the 1// noise component on the signals [669]. Sanz-Medel and coworkers [670] found that the isotope ratio precisions and accuracies of TOF-ICP-MS surpassed those of quadmpole-based systems. This was impressively demonstrated in the case of Pb by Carrion et al. [671], who reported RSDs of 0.08% for... 

Longerich H. P. and Diegoe W. (2001) Evaluation of a water-jacketed spray chamber using time-of-flight inductively coupled plasma mass spectrometry (TOF-ICP-MS), J. Anal. At. Spectrom. 16 1196-1201. 

Figure 4(a) shows details of the test chamber. The teflon jacket-copper block assembly was mounted on a stainless steel plate. The sprayed liquid was drained back to the reservoir installed below the test section. Thermocouples to measure the liquid temperature were installed both upstream of the flow meters and downslream of Ihe orifiee plate. Another thermocouple was used to measure the ambient temperature. The HAGO nozzle and the orifiee plate (for microjets) were attached to the end of a pipe whieh eould be moved up and down. Thus the distance between the sprays or jets and the heated surfaee eould be varied. The liquid pressure was measured using a pressure transducer (0 - 2.07 MPa, 0.25% aeeuraey) just before the sprays or jets were formed. All the data were recorded using two lOTech 16-bit data aequisition boards. 

FIGURE 45.18 Continuous scraper-type freeze dryer (1) vacuum chamber (2) spray nozzles (3) scraper (4) radiators (5) cooling jacket (6) freezant (7) motor and (8) vacuum lock. (From Shumski, K.P., Vacuum Apparatus and Equipment in Chemical Industry, Mashinostroyenie, Moscow, Russia, 1974 (in Russian).)... 

A liquid product of low concentration of the solid phase (up to 40%) is sprayed by nozzles placed on the rotating central pipe and then freezes on the chamber walls. The dryer chamber is a cylinder equipped with a cooling jacket. The heat of sublimation is supplied by radiators also placed on the central pipe. Dry product is scraped from the chamber walls by adjustable brushes or scrapers. 

Solvent condensation the gas inside a spray drying process equipment is partially saturated with solvent and, therefore, is prone to condense if exposed to cooler surfaces. If the surface is allowed to cool down below the dew point of the gas stream, then condensation will occur and the powder will accumulate on those wet surfaces (Fig. 8.3a illustrates an example where condensation occurred in the filter bag). To prevent this, the spray dryer is typically insulated or heat jacketed and the heating of the chamber prior to start of the atomization process is done in a gradual manner and over an extended period of time (typically between 20 and 60 min). 

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