This paper critically reviews the non-thermal plasma techniques for reduction of volatile organic compounds (VOC) in air streams. The currently used technologies fall into two categories: those based on nonthermal plasma generated from various forms of corona discharge and those exploiting high energy electron beams. Relative advantages and disadvantages of non-thermal plasma and conventional techniques are discussed.

A method is reported for improved accuracy for nitrate and nitrite determinations in aqueous solutions, especially plant extracts. The sampling procedure can be adapted for automated determinations: At least 6 aliquots with increasing volume of nitratecontaining solutions are subjected to the reducing agent under stabilized conditions to obtain nitrite, treated with one of 2 different diazotization reagents, and measured colorimetrically. The slope of the curve, absorbance vs sampled volume, is determined by linear regression; this slope is directly dependent on the nitrate (nitrite) content. Original nitrite is determined by omitting the reducing step. Low nitrate levels (<0.1 μg/mL) can be determined directly with the sulfanilamide-N-(l-naphthyl)ethylenediamine dihydrochloride diazotization procedure or indirectly by constant nitrate addition, with the sulfanilic acid-1-naphthylamine hydrochloride diazotization mixture (Griess reagent). The latter procedure can be used to measure concentrations up to20μg/mL.

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