Determination of C2–C5 hydrocarbons in the atmosphere at low parts per 109 to high parts per 1012 levels

Low Parts per Billion Determination of Sulfide by Coulometric Argentometry

Present methods for the determination of sulfide in wastewater are hindered by poor detection limits and extensive sample pretreatment. A less problematic method has been developed with a method detection limit of 2.5 μg L-1. With this technique, sparged hydrogen sulfide is precipitated in an acetate-supporting electrolyte by electrogenerated silver ions. Analysis of basepreserved samples was p...

Commodity Parts per

■ 2. Section 180. 628 is amended as follows: ■ i. Add alphabetically tolerances for beet, sugar, molasses; berry large shrub/ tree, subgroup 13–07C; berry, low growing, subgroup at 13–07G; onion, bulb, subgroup 3–07A; tea, dried; Ti, leaves; Ti, root; vegetable, leaves of root and tuber, group 2; vegetable, root and tuber, group 1; to the table in paragraph (a); ■ ii. Revise the tolerances for ...

Determination of perchlorate at parts-per-billion levels in plants by ion chromatography.

A method for the analysis of perchlorate in plants was developed, based on dry weight, and applied to the analysis of plant organs, foodstuffs, and plant products. The method reduced greatly the ionic interferences in water extracts of plant materials. The high background conductivity, due to the plant matrix, was reduced sufficiently to allow quantitation of perchlorate with little or no matri...

ZnO functionalization of multiwalled carbon nanotubes for methane sensing at single parts per million concentration levels

Parts-per-million level loading organocatalysed enantioselective silylation of alcohols.

The field of organocatalysis has blossomed over the past few decades, becoming an alternative to transition-metal catalysis or even replacing the realm of transition-metal catalysis. However, a truly powerful organocatalyst with a high turnover number (TON) and turnover frequency (TOF) while retaining high enantioselectivity is yet to be discovered. Similar to metal catalysis, extremely low cat...