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ANALYTICAL CHEMISTRY, VOL. 59, NO. 14, JULY 15, 1987
essary for the analytical decomposition of the various hydrides. It is this step that imparts predictable initial sensitivity between cells. The cell is operated by applying ac voltage across the Nichrome heating element with a variac. As expected, the interior cell temperature is a linear function with respect to applied voltage. The slope is 23 "C per root mean square V ac. The resistance of the wire is 11 R. At 850 "C the current is 3.6 A, yielding 145 W. Expansion of the heating element (150%) is accommodated by the double jacket design, minimizing shearing stresses on the thin and fragile wire during operation.
d
Figure 1. Electrically heated quartz atomization cell: (a) atomization chamber: (b) inlet tube: (c) heating element: (d) outer jacket (requires 2); (e) quartz tape.
The insulation is secured by a twist of Nichrome wire. DISCUSSION As this design has an integral heating element, rinsing with HF after assembly is not practical. This requires the presensitization of the atomization chamber, which involves sandblasting, removal of surface impurities by acids, and annealing the quartz. Sandblasting provides a large, fresh surface, which increases the reproducibility between cells and yields a longer cell life by increasing the active surface area. Soaking in a nitric and hydrofluoric acid bath removes both trace impurities and higher temperature phases of quartz, which act as devitrification "seeds" ( I ) and significantly reduce the longevity of the cell. Annealing the chamber at 1100 "C provides the uniform vitreous quartz surface, which is nec-
ACKNOWLEDGMENT I thank Steve Sweat and Pat Smythe of Precision Glass of Colorado, Denver, CO, for their invaluable aid in developing this cell. Registry No. Quartz, 14808-60-7. LITERATURE C I T E D Verlinden, M. Anal. Chim. Acta 1982, 740, 229-235. Welz, B.; Melcher, M. Analyst (London) 1983, 708, 213-224. Lee, D.S. Anal. Chem. 1982, 1682-1686. Open-file Rep. U .S . Geol. Surv. 1985, No. 85-495, 541. Thompson, A. J.; Thoresby, P. A. Analyst. (London) 1977, 702,9-16. Agemain, C.; Bedrek, E. Anal. Chim. Acta 1980, 779, 323-330. Wood, G. R.; Vijan. P. N. Taianta 1976, 23, 89-94. Briggs, P. H.; Crock, J. G. Open-File Rep. U . S . Geoi. Surv. 1986, No. 86-40. (9) Crock, J. G.: Lichte, F. E. Anal. Chim. Acta, 1982, 223-233. (10) Designing Heating Elements, Driver-Harris: Harrison, NJ, 1985. (1) (2) (3) (4) (5) (6) (7) (8)
RECEIVED for review October 2, 1986. Resubmitted March 16,1987. Accepted March 26,1987. Use of brand names does not constitute endorsement by the U.S.G.S.
CORRECTION S q u a r e Wave Voltammetry at t h e Mercury Film Electrode: Theoretical T r e a t m e n t S q u a r e Wave Anodic S t r i p p i n g Voltammetry at t h e M e r c u r y Film Electrode: Theoretical T r e a t m e n t
S. P. Kounaves, J. J. O'Dea, P. Chandrasekhar, and Janet Osteryoung (Anal. Chem. 1986,58,3199-3202; Anal. Chem. 1987, 59, 386-389). On the title page of each paper, the last name of the third author, Chandrasekhar, is spelled incorrectly as Chandresekhar.
