To sensitively and selectively monitor jet fuel for trace levels of copper, two spirobenzopyran
dyes, quinolinospiropyranindoline (QSP) and nitrospiropyranindoline (NQSP), have been investigated for their application in a spectrophotometric method that is amenable to rapid, on-site
detection of μg/L levels of copper in jet fuel. Both NQSP and QSP respond sensitively to various
metal ions in jet fuel, including copper, nickel, and zinc, with NQSP demonstrating the best
performance in terms of selectivity of spectral response and sensitivity. Principal component
analysis (PCA) was applied to the spectral data, and the individual contributions to the absorption
spectra by copper, nickel, and zinc in JP-5 fuel can be readily separated using this technique.
The effect of metal deactivating additives (MDA) in jet fuel on the sensitivity of NQSP for copper
was investigated. Silica-bound diethylenetriamine was investigated as an effective solid-phase
extraction agent for defining the baseline absorbance of NQSP in jet fuel samples being analyzed
by standard addition methodologies.
To meet the need for a portable field test kit for the accurate determination of trace levels of
dissolved copper in jet fuel, a spectrophotometric-based approach has been developed. A
combination of a metal complexation ligand (bathocuproine), reducing agent (ascorbic acid), and
solubilizing agent (ethanol) is introduced directly to jet fuel samples emanating from a number
of different sources and handling histories, and the total copper content is accurately determined.
The detection limits, based on a signal/noise ratio of 3:1, were 6.2 μg/L with a benchtop dual
beam spectrophotometer and 7.5 μg/L with a portable, fiber optic spectrometer. Since bathocuproine, itself, has some reducing capability, the concentration of Cu(I) in these jet fuels could
not be differentiated from the concentration of Cu(II).
Southern Branch Post Office Baton Rouge, Louisiana 70813. ABSTRACT Differential Pulse Voltammetric (DPV) methods for the determination of iron (Fe), titanium (Ti), vanadium (V) and chromium (Cr) in a synthetic milling solution of titanium alloy are presented. N-2-hydroxyethyl-ethylene diamine triacetic acid (EDTriA) or ethylene diamine tetraacetic acid (EDTA) was used to replace fluoride in cornplexing with all the metal ions. EDTriA was found to be a better ligand than EDTA in the determination of Fe, Ti and V. However, the reverse was true for Cr. Ti and 255 1
WE1 AND QIANCr, which would interfere in the determination of V, was precipitated from the synthetic solution by adding EDTriA at very high pH. In the Cr determination, Ti and V were the major interfering species. The difficulty caused by Ti was alleviated by precipitating the Ti with EDTA at very high pH. The other difficulty, which was caused by V, was solved by using peak subtraction because of the perfect overlapping of the V and Cr peaks.
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