Phosphorus in Wine: Comparison of Atomic Absorption Spectrometry Methods

Phosphorus in wine may be determined directly or indirectly by atomic absorption spectrometry. The direct method uses the carbon rod atomizer as the excitation source and a phosphorus hollow cathode lamp. In the indirect determination, one measures the amount of molybdenum that will complex with phosphorus in the wine. Both nitrous oxide-acetylene and air-acetylene flames are suitable as atomization sources in this indirect method. The resultant data have been compared with those from the AOAC colorimetric method (11.032-11.034). A 2-sample comparison test showed the results to be insignificantly different at the 95% confidence limits.

Determination of Cu, Mn, Fe, and Ca in six regions of normal human brain, by atomic absorption spectroscopy.

A method is reported for measuring copper, manganese, iron, and calcium in brain tissue. We solubilized 100-mg samples of brain tissue with Soluene-350 and diluted the mixtures with methyl isobutyl ketone. Copper and manganese concentrations were measured by using a carbon rod atomizer, iron and calcium concentrations by using an air/acetylene and nitrous oxide/acetylene flame, respectively. The basal ganglia (caudate, putamen, globus pallidus, and substantia nigra) contained high concentrations of iron (10 to 19 mumol/g dry wt) as compared to concentrations found in the cortex (4 mumol/g) or the hippocampus (2.8 mumol/g). Copper exhibited a similar distribution pattern among the regions studied; 526 to 1140 mumol/g (dry wt) in the basal ganglia vs 496 mumol/g in the cortex and 426 mumol/g in the hippocampus. Manganese and calcium were uniformly distributed in the regions examined.

Design and Performance of a Time Multiplex Multiple Slit Multielement Flameless Atomic Absorption Spectrometer

The design and performance characteristics of a new multielement flameless atomic absorption spectrometer are presented. Radiation from four hollow cathode lamps is combined by beam splitters and directed through a Varian model 63 carbon rod atomizer and then into a special monochromator with a separate exit slit for each element. The light exiting from all slits is directed to a single photomultiplier tube. Absorbance signals from different elements are distinguished with a time multiplex approach. Data acquisition and presentation is accomplished with a PDP-11 computer system. The absolute light levels are lower than those normally encountered with single element atomic absorption resulting in signal shot noise limited measurements. Detection limits (in ppb) of 0.2 (Cd), 2 (Mn), and 8 (Pb) were determined under multielement conditions. The measurement precision of moderate absorbance multielement solutions was determined to be 7% with manual injection of 5 μl samples.

Flameless Atomic Absorption Spectroscopic Determination of Heavy Metals in Whole-Fish Samples

Flameless atomic absorption spectroscopy with a carbon rod atomizer was used to determine lead, cadmium, and chromium in wholefish samples. Samples were dry-ashed, and the metals were separated by solvent extraction with ammonium pyrrolidine dithiocarbamate in methyl isobutyl ketone, and then back-partitioned into an aqueous acid solution for analysis. The back-partitioning step allows a direct comparison of sample solutions with aqueous solutions of the standard. Recoveries of the metals from fortified samples averaged 91% (±9.6) for lead and 100% (±5.6) for chromium at the 0.1–1 ppm level, and 100% (±13.3) for cadmium at the 0.01–0.1 ppm level.

Atomic Absorption Determination of Nickel in Heavy Crudes via Carbon Rod Atomizer

A method is described for the determination of nickel in heavy crude oil by carbon rod atomic absorption spectroscopy in the parts per million range. A 5-g sample is completely dissolved to 25 ml of tetrahydrofuran (THF) stabilized with 0.1% hydroquinone and further diluted with THF. Nickel can be measured at a concentration of 0.1 ppm with a relative standard deviation of about 10% after a 100-fold dilution of the crude. The analysis by standard curve method as well as standard additions methods gave reproducible results. These results also agreed well with values obtained by conventional activation analysis. The method is relatively rapid after sample dilution.