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ANALYTICAL CHEMISTRY, VOL. 63, NO. 19, OCTOBER 1, 1991
are not reported in most of the papers. Figure 1 shows a electrophoretic separation of pd(A)16-ao on a 7.5% T, 3.3% C gel. Plate numbers for this sample amounted to about 200000 for capillaries of about 22-cm effective length. For an even larger DNA fragment sample pd(A)ll,, an approximate plate number of 2 X 106 was observed (electropherogram not shown). No significant loss in performance was observed after 50 injections. However, sometimes bubbles formed at the injection end of the capillary gel column after several injections. The separation power could be restored by cutting 1 or 2 mm (3). At electric field strengths higher than 200 V/cm, bubble formation occurred, similar to other experiences (14).
40
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I
20
ACKNOWLEDGMENT The technical assistance of G . Feenstra is acknowledged.
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18
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26
30
34
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LITERATURE CITED
time (minutes)
Hj6t?en, S. J . Chromatogr. 1989, 270, 1. Cohen, A. S.; Karger, B. L. J . Chrmrogr. 1987, 397, 409. Paulus, A.; Ohms, J. I. J . Chromatogr. 1990. 507, 113. Bente, P. F.; Myerson, J. Eur Pat. EP0272925 A2 (Hewlett-Packard Co.), June 29, 1988. Lux, J. A.; Hausig, U.; Schomburg. G. J . High Resolut. Chromatogr. 1990, 13, 436. HjBrten, S., J . Chromatogr. 1985, 347, 191. Yin, H. F.; Lux, J. A,; Schomburg, G. J . High Resolut. Chromatogr. 1990, 13, 625. ToCk. P. P. H.; Stegeman, 0.; Peerboom, R.; Poppe, H.; Kraak, J. C.; Unger, K. K. Chromatographia 1987, 24, 617. Bruin. G. J. M.; Tock, P. P. H.; Kraak, J. C.; POOW, . . H. J . Chrometm. 1990, 517,557. Lux, J. A.; %usig, U.; Schomburg, G. J . High Resolut. Chromatogr. 1990. 1.3. 373. . Hi&&, S. Arch. Blochem. Bbphys. Suppl. 1962, 1 , 147. Oster, G. K.; Oster, G.; Prati, G. J . Am. Chem. SOC.1957, 79, 595. Davis, B. J. Ann. N . Y . Aced. Sci. 1964, 121, 404. Drossman, H.; Luckey, J. A.; Kostichks, A. J.; D'cunha, J.; Smith, L. M. Anal. Chem. 1990, 62, 900.
Flgure 1. Separation of oligcdeoxyadenylic acids P ~ ( A ) , ~spiked -~, with pd(A),,. Conditions: capillary IhWt = 21.7 cm, L = 30.0 cm, 53 pm 1.d. polyacrylamide gel, 7.5% T, 3.3% C; injection voltage 3020 V; Injection time 5 s; buffer (see text): separation voltage 173 V k m ; UV detection at A = 260 nm. The numbers in the electropherogram refer to the number of bases in the oligonucleotides.
under these conditions, the first visible gel forming occurred after about 10 min of illumination. Success rate of preparation of bubble-free polyacrylamide gelfilled capillaries was about 80% for the 7.5% T, 3.3% C gels discussed here. For other types of gels (not reported here) we likewise found much better success rates with photopolymerization as compared to conventional methods; linear gels (0% C) giving the best and gels with high values for T and C still giving the worst results. It is difficult to compare the success rate percentage for this method with that of other methods, because these percentages
..
~
RECEIVED for review March 11,1991. Accepted July 3,1991.
CORRECTION Composite Multivariate Quality Control Using a System of Univariate, Bivariate, and Multivariate Quality Control Rules S. J. Smith, S. P. Caudill, J. L. Pirkle, and D. L. Ashley (Anal. Chem. 1991,63, 1419-1425). The second equation on p 1420 is incorrect. It should read
+
[log [ E d 2 K ] ] / n
for 0
