Computer-assisted furnace atomic absorption spectrometric analysis

Abstract

The anomalous behavior of manganese and nickel is interesting. In the case of manganese, filtration of the insoluble hydrated oxides removes most manganese (sample 2), but the purification treatment leaves over 90% of the manganese in solution (sample 3). We suspect that in the former case, insoluble manganese dioxide is formed via oxidation by dissolved oxygen and is filtered off. In the latter case, the reduction step keeps manganese in the +2 oxidation state, which apparently remains in solution as an hydroxo complex.

Cadmium bioaccumulation assays. Their relationship to various ionic equilibriums in Lake Superior water

“…Of several heavy metal pollutants in the aquatic environment, cadmium concentrations in some anthropogenic deposits have shown one of the largest relative increases, compared to natural conditions (7). In addition, reported cadmium concentrations in natural waters can show more than two orders of magnitude variation (2,3).…”

Determination of lead and cadmium in fish and clam tissue by atomic absorption spectrometry with a molybdenum and lanthanum treated pyrolytic graphite atomizer

“…The range was adjusted so that 1 absorbance unit corresponded to 1 V at its output (pins 9 and 14 of P/J4, schematic r 290-0218-E). The output from the UDR-2 was input to the inverting input of an amplifier-summing circuit (18) which was set to unity gain. The base-line voltage from the 1-V spectrophotometer output was input through a 10-kfi resistor to the inverting input of the summing amplifier.…”

“…Remote A/D sampling was initiated at the proper time after atomization by closure of a relay actuated by a NE555 timer (Signetics). The timer was triggered during the charring cycle with a relay installed in the furnace power supply; before each atomization cycle, zero absorbance on the spectrophotometer was automatically set with a similarly installed relay (18). Acquired data were reduced using a computer-assisted procedure similar to that previously described for a different computer system (J8).…”

“…Molybdenum and lanthanum treated pyrolytic graphite tubes were also characterized by determining the degree of chemical interference from a few relatively simple and common inorganic salts. The percent recovery of standard amounts of lead (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) Mg/L) added to solutions containing MgCl2 or Ca(C104)2 was determined, relative to identical standards without these salts present. The determined mean recovery values were: 92% (0.1% w/v MgCl2), 98% (0.2% w/v Ca(C104)2), and 90% (1% w/v Ca(C104)2).…”