Halides, phosphorus, and

Combustion methods have been used to determine total sulphur and total organic carbon and total halides in soil, total and particulate organic carbon, total halide, phosphorus and nitrogen, total and particulate organic carbon in saline sediments and total nitrogen in sludges. 

Sulphur compounds, halides, phosphorus and arsenic are permanent poisons to ammonia catalysts (22). However, in most plants the upstream low-temperature shift catalyst and the Ni-based methanation catalyst both serve as efficient guards by irreversibly adsorbing traces of such compounds. Thus, permanent poisons are normally not a severe problem. 

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