Sampler clogging

The constancy of the nebulizer gas flow is of prime importance for the precision achievable in ICP-MS. After stabilizing the nebulizer gas flows, relative standard deviations can be below 1%. They can be improved still further by internal standardization [509]. The tolerable salt concentrations (1-5 g/L) are much lower than in ICP-AES, because of the risks of sampler clogging and depend on the respective salts. The memory effects may become limiting and in the case of a high matrix load rinsing times of 1-2 min are required. 

Cjg, C8, or Cj siloxane stationary phases may be used for reversed-phase separations. Mobile phases of high pH values should be avoided as hydrolysis of the siloxane stationary phase occurs and so the packing material degrades over time. Phosphate or acetate buffers may be used to control the pH of the mobile phase, although the concentration of these salts should be kept to a minimum so that clogging of the torch injector and sampler cone does not occur. 

Cameras or other systems would be needed to ensure that the sampler is not tampered with. Clogging of the filter medium with sand or high dust loading would limit the duty cycle between filter changes. 

Initially, a 50 mM NH4H2PO4 mobile phase was used however, it was found to deteriorate and clog a nickel sampling cone in approximately two hours. This prompted a reduction in phosphate concentration to 15 mM and the use of an aluminum sampler with a 0.7 mm diameter... 

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