Precise Automatic Spectrophotometric Analysis in the Low Parts per Billion Range.

The Radiolysis of Aqueous Nitrate Solutions1

“…27 The principal uncertainty in postulating the reduction of N03by Ois whether the process of electron transfer is exothermic; the energy required to produce a hydrated oxygen atom may be too high. If this is so, an alternative possibility would be the reaction sequence N03-+ 0-+ H20 -> N03 + 20H- (12) and 2N03 -2N02 + 02 (13) However, such a sequence is inconsistent with data from studies with 018-labeled water (Table I) because it would produce 02 from the nitrate ion. Another possibility is the formation of an intermediate compound from N03~and 0~, which could subsequently react to yield oxygen and N02aq.…”

Autoclave digestion procedure for the determination of total iron content of waters

“…Recently, Ishii has developed a micro LC (7,8), which requires a flow rate of only a few microliters per minute and has separation ability almost comparable to the conventional LC.…”

“…A number of accepted colorimetric procedures for soluble or reactive iron are described in the literature, but the use of the chromophore 2,4,6-tri(2-pyridyl)-l,3,5-triazine (TPTZ) is particularly attractive as such systems are highly sensitive and very stable. This reagent was introduced by Diehl and Smith (4), and has been adapted by a number of authors to both manual (5, 6) and automated (7,8) systems. The violet ferrous-TPTZ complex has a molar absorptivity (4) of approximately 2.23 X 104 at 595 nm and thus the interference due to the natural color of samples can usually be eliminated by in-line dilution.…”

Inorganic Microchemistry

“…Two papers dealing with spectrophotometric methods warrant special mention. For trace analysis, at least, automatic methods are rapidly becoming of great interest, and the automatic determination of chloride, nitrate, nitrite, iron, and ammonium in water in the low7 parts per billion range indicates the possibilities that exist for providing sensitive and precise measurements (41). Likewise, the work of Dagnall and West (49) on the use of direct spectrophotometry in nonaqueous media is important.…”