tion with samples stacked over a 10-cm distance within the rabbit and five standards interspaced through the unknowns. The values range from 1 to 12% with an average of about 5%. The variations include all the sources of error that can occur during neutron activation analysis of a sample. We routinely employ this method for the analysis of sea salt aerosols and water samples for major components and biological fluids for both major and minor elements. In the irradiation of sea salt aerosols and water samples, we have had no sample or standards break open during irradiation. This has involved the irradiation of several hundred discs, some for up to 4 hours. The authors have removed filter discs from the sealed plastic for Na, C1, and Br analysis. The blank values for single Whatman 41 filter paper discs are 1.05 f 0.10 pg, 1.29 f 0.01 pg, and 0.005 f 0.002 pg for Na, C1, and Br, respectively. There is a severe deterioration of the filter paper with 50-11 aliquots of any 2N acid solutions, during a 7-hour irradiation, such that removal of the filter disc from the plastic is not possible. The filter paper can still be handled when neutral or basic solutions are used or if the irradiation time is reduced to 4 hours and care is used in handling. Loss of sample to the plastic occurs when aliquots larger than 50 p1 are used and the filters are removed. Loss of halogens (probably as gaseous HCl and HBr) occurs when acid solutions are irradiated for even short periods.
Blood samples have been irradiated for as long as 35 hours and breakage has occurred only when aliquots of between 0.1 to 1.0 ml have been used. In these cases, failures of sealed discs have occurred between 5 to 10% of the time.
ACKNOWLEDGMENT The authors thank A. C. Bachelder and the University of Rhode Island Engineering Instrument Shop for the construction of the apparatus, the staff of the Rhode Island Nuclear Science Center for space and facilities for analysis, and the University of Rhode Island Computer Laboratory for data processing and reduction. RECEIVEDfor review June 23, 1975. Accepted July 25, 1975. This research was supported by the Office for the International Decade of Ocean Exploration, National Science Foundation under NSF-IDOE Grant GX-33777 and by the United States Department of Health, Education, and Welfare, Public Health Service, National Institutes of Health Grant No. 1 R 0 1 HD 06675-02. LITERATURE CITED Jr., Ed., "Guide to Activation Analysis", D. Van Nostrand Co., Inc., N e w York. 1964, pp 14-20. (2) G. H. Friedlander, J. W. Kennedy, and J. M. Miller, "Nuclear and Radio(1) W. S. Lyon,
chemistry", 2nd ed., John Wiley 8 Sons, Inc., New York, 1964, pp 411413.
CORRECTION Errors Caused by Fiowrate Variation In High Performance Size Exclusion Chromatography (GPC)
In this articleby D. D. Bly, H. J. Stoklosa, J. J. Kirkland, and W. W. Yau, Anal. Chem., 47, 1810 (1975), the tabular portions of Figures 1-4 were inadvertently eliminated. These data are essential for following the discussion and
-
% RANDOM VARIATION IN FLOW RATE
Mn MEAN 112,900
0.0
Rw
2aFOR IO RUNS
2uFOR IO RUNS
MEAN
0
278,100
0
0.5
112,900
700
278,100
1,100
I .o
113,000
1,300
278,200
1,900
3.0
I 12,800
4,000
278, I O 0
6,400
5.0
112,600
7,000
277,400
11,200
10.0
I 11,800
Figure 1. Random variation zero to end of GPC curve
12,700
276,500
19,000
in flowrate about a fixed level from time
n
INCREASING FLOW RATE
_..-..
DEVIATION IN
M,
RELATIVE PERCENT ERROR
00
112,900
0.5
113,800
1.0
l14,W
-
INCREASING FLOW RATE dCviiiioN IN FLOW RATE
-
8,
RELATIVE PERCENT ERROR
0.0
112,900
0.0
0.5
114,800
1.7
1.0
123,400
9.3
3.0
146,700
299
RELATIVE PERCENT ERROR
RELATIVE PERCENT ERROR
00
278,100
0.0
112,900
0.8
278,900
0.3
112,100
-0.7
277,300
-0.3
I 5
279,700
06
111.200
-1.5
276,600
-0.5
0.0
278,100
258,400
-71
-23.8
222,600
-20.0 -31.3
-36.8
191,100
43,500
-61.5
128, 7tl)
change in flowrate from time zero to end of
RELATIVE PERCENT ERROR
0.0
PERCENT DEVIATION ,dNRAn
RELATIVE PERCENT ERROR
iin
ii,
-53.7
GPC
DECREASED FLOW RATE RELATIVE PERCENT ERROR
M,
RELATIVE PERCENT ERROR
M,
RELATIVE PERCENT ERROR
0.0
112,900
00
278,100
0.0
112,900
00
278,100
00
0.5
125,030
10.7
305,000
9.1
101,900
-9.7
253,400
-89
1.0
13a.mo
22.4
334,
too
20 J
91,900
-18.6
230, 700
-170
30
2 0 4 , ~
81.0
477.000
715
60,100
-468
157,000
-43 5
672,003
141.6
38,590
-65 9
105, I00
-62 2
II,M)O
-89.7
35,703
-872
107,800
-4.5
273,400
-1.7
104,400
-7.5
270.3W
-2.8
5.0
297,603
1636
-5.7
10.0
716,200
5344
2328
-8.6
86,000 71,300
1.7
262,300
103,203
42.9
2.9
-15 I
-36
100.8
282,900
95,800
0.0
268,100
397,500
286,100
57
278,100
-4.3
558,xx)
7.6
flowrate across the GPC curve
7.6 24.2
0.0
108,000
53.9
4.6
294.W
299,100
345,300
112,900
130.7
118,100
15.2
1.6
#,
173,800
121,500
130, 100
00
RELATIVE PERCENT ERROR
ERROR
260,KK)
3.0
10.0
278,100
282,500
RELATIVE PERCENT
5.0
5.0
Figure 2. Uniform change in
a,,
iNCREASED FLOW RATE
3,
aw
RELATIVE PERCENT ERROR
nw
10.0
DECREASiNG FLOW RATE
Rn
DECREASING FLOW RATE
PFRCFNT
Figure 3. Uniform
PSWFNT ,
FLOW RATE
conclusions on pp 1811-1812. The sketches in the figures illustrate the type of flowrate variation employed while the tabular portion of each curve shows the results obtained. Figures 1-4 are here reproduced in their entirety.
Figure 4. Fixed
ANALYTICAL CHEMISTRY, VOL. 47, NO. 13, NOVEMBER 1975
1,500.xIo 4396
flowrate deviation from specified value
