222 P. SOUPART 
50-cm columns! , which is more rapid and less laborious than the techniques em- 
ployed heretofore. 
Data presented in this report have been obtained by use of the 1954 technique, 
referred to here as the “manual” procedure, as,well as by use of the 1958 “automatic” 
procedure. With regard to blood and urine amino acid analysis, the advantages of 
the 1954 procedure have been discussed at length elsewhere!. The overall precision 
of these two ion-exchange methods is + 5°%, except when the amounts of some of 
the amino acids contained in the sample are very small, in which cases the relative 
precision becomes less satisfactory. 
However, there are three amino acids for which recovery is low. First, methionine 
yield is consistently 90% of theoretical, and has to be corrected for this loss. Secondly, 
tryptophane is destroyed toa variable but large extent (40-60%, ) during the chromatog- 
raphic process. As it seems to be present as traces only in the free state in biological 
fluids and owing to the loss during chromatographic analysis, no value for trypto- 
phane concentrations will be reported here. Thirdly, part of the free glutamic acid 
escapes determination because of partial cyclization into pyrrolidone carboxylic 
acid which does not react with ninhydrin. Values given below for free glutamic 
acid are thus to be taken as minimal. 
On the other hand, values reported for glutamine are somewhat too high; the 
glutamine peak, in the case of blood plasma for instance, also contains asparagine 
in the proportion of about one tenth of the glutamine present!?. When urine is ex- 
amined this peak might also contain sarcosine if Dowex 50-X4 is used but is com- 
pletely free from it if chromatographed on Dowex-50-X5 (manual procedure). When 
the automatic procedure is used, sarcosine, if present, is also completely separated 
from the mixture of glutamine and asparagine. 
Manual procedure (MOORE AND STEIN’s 1954 technique). Most of the data submitted 
here have been obtained by use of the MooRE AND STEIN 1954 procedure, ion- 
exchange chromatography on Dowex-50-X4 columns®,® associated with an automatic 
siphon device for automatic collection instead of the original drop-counting pro- 
cedure’. The main drawback of the manual procedure lies in the fact that it is 
rather time- and labour-consuming, a complete analysis requiring about rooo indi- 
vidual colorimetric determinations at a rate not exceeding 200 analyses per day. 
Automatic procedure. This completely automatic procedure, described by SPACKMAN, 
STEIN AND Moore in 1958", is by far the most convenient method and, in our opinion, 
should definitely become the standard method for any amino acid investigation. 
Notwithstanding the heavy initial investment involved and the fact that its 
operation still requires much technical skill, the economy of labour it allows for 
and the precision of the results it furnishes are well worth the investment. We have 
had the opportunity to verify at length the assessment ofits authors, that the greatest 
value of the automatic recording equipment resides in the fact that it acts like an 
objective and constant observer of the full course of a chromatographic experiment. 
From such observation valuable and unexpected information has often been gained. 
Some minor technical modifications have been introduced in the original procedure 
which allow for greater ease in continued operation and maintenance’. Such a 
machine has been continuously operated in the department since June 1959 and 
a good deal of the data submitted here have been obtained by its use. 
References p. 261/262 
