Analytical validation using a gas mixing system for the determination of gaseous formaldehyde.

Formaldehyde levels in the atmosphere are a concern in the indoor and outdoor air and many methods for determining this compound have been developed. The use of 2,4-dinitrophenylhydrazine (DNPH) for reaction with formaldehyde, catalyzed by acid, forming a hydrazone derivative in cartridges is considered the standard method for analyzing formaldehyde compounds in the air. However, formaldehyde is quantified using an analytical curve, created by diluting liquid standards of the formaldehyde-DNPH product.

Inorganic content of rock dust waste from northwest of Rio de Janeiro, Brazil: do environmental risks incur from its use as natural fertilizer?

The ornamental rock exploration and coating industry has led to significant environmental impacts due to the inadequate manner in which these residues are released into the environment. This impact may be reduced by using these residues for soil enrichment, as they contain high levels of inorganic nutrients. However, some elements may be potential contaminants, thus requiring a thorough previous research before employing these substances in agriculture.