Figure 1.Injection peaks showing typical response generated from nanomolar [Fe2+] in this work. A. 100 nM Fe2+; B. 100 nM Fe2+ with 1 mg C L-1 fulvic acid (FA); C. 10 nM Fe2+; D. 10 nM Fe2+ with 1 mg C L-1 FA. Inset: Typical Gaussian response curve generated from …2.?Experimental2.1. Reagents and SamplesAll chemicals (except H2SO4) were reagent grade. Oxalic acid dihydrate and ferrous ammonium sulfate hexahydrate were purchased from J.T. Baker Chemical Co. (Phillipsburg, NJ, USA). L-Ascorbic acid, glycine, and hydroxylamine hydrochloride were supplied by Fisher Scientific (Fair Lawn, NJ, USA). Hydrazine dihydrochloride and L-cysteine were purchased from Sigma-Aldrich (St. Louis, MO, USA). Sulfuric acid, veritas, redistilled was acquired from GFS Chemicals (Columbus, OH, USA).
Suwannee River humic and fulvic acid standards were purchased from the International Humic Substance Society (IHSS. St. Paul, MN, USA).Natural water samples collected from a mountain stream (Middle Crow Creek) and an unnamed alpine lake, both in SE Wyoming, USA, were acidified to pH 3, stored in the dark at room temperature, and analyzed within three weeks of collection. Middle Crow Creek is an undeveloped watershed at about 2,400 m elevation that originates near Pole Mountain in the Laramie Range in SE Wyoming, USA. This area is impacted by livestock grazing, nearby motorized traffic and human recreation (fishing and hiking). There is significant input of organic matter from overhanging trees and streamside bushes. Our research group has studied the site for several years.
The small alpine lake is located in the Snowy Range of SE Wyoming at ~ 3,300 m above sea level. At this elevation there is little organic input from trees and shrubs, but there are grasses and other vegetation along the lakeshore. Human impact on this lake is limited to nearby camping and hiking; there are no anglers, and cattle are excluded from the area.All solutions were prepared with 18.2 M�� Millipore reverse-osmosis, de-ionized (RO) water and H2SO4. All samples were acidified to pH 3 [50], which slows the oxidation of ferrous iron [32,51,52]. Iron standards, including those used in experiments wi
In recent years, research and development of biosensors has received a great deal of attention since their extensive application potential is highly recognized in areas such as medical diagnostics and the food industry [1-4].
Biosensors are normally composed of two main components – the sensing device and the sensing molecule, i.e. chemical Anacetrapib or biological recognition elements. As a functional hybrid system, the biggest challenge is to optimize this system to benefit from coupling of the unique features of the bio-recognition event with the sensitive signal recognition and amplification potential of a sensing device [5].