NSWC/WOL/TR 75-3 5 



4. Trained analysts must be at the site to perform or 

 supervise the analyses. 



In view of the above limitations, it is recommended all the 

 analyses for the explosive test program to be performed in the 

 laboratory with the exception of some parameters, (e.g. temperature, 

 turbidity, and dissolved oxygen), which require in-situ measurements. 



4.2.3 Concentration and Separation 



Many current methods of water analysis do not permit the direct 

 determination of elements at low concentrations because of limits 

 of detectability by certain analytical instruments and because of 

 interferences from other constituents in the sample. This is 

 particularly true for seawater analysis, which, as previously 

 discussed, presents many difficulties in the direct determination. 



Before the determination can be made, it is usually necessary 

 to concentrate the trace element from a large volume of water. After 

 concentration, the element is separated, where necessary, from other 

 elements which may also be removed by the concentration procedure, 

 and determined by a specific and sensitive physico-chemical method. 



Concentration and separation techniques have been discussed in 

 the literature. H* ^ , 13 A SUIT imary of these techniques is presented 

 in Table 4 . 



Although these various separation and concentration techniques 

 are useful and frequently required, they do introduce another step 

 into the analytical process. The procedures involved often are time- 

 consuming and there always exists a possibility of contamination 

 introduced by the reagents and the manipulation used in the procedures, 

 Thus, wherever possible, interferences should be removed by masking 



Spencer, D. W. and Brewer, P. G., "Analytical Methods in Oceano- 

 graphy, I. Inorganic Methods", Crit. Rev. Solid State Sci., 1, 

 409 (1970) . 



1 9 



Andelman, J. B. and Caruso, S. C. , Handbook of Water and Water 

 Pollution, L. L. Ciaccio, Ed., Vol. 1, Chapter 13, p. 213, Marcel 

 Dekker, New York, 1965. 



13 



Berg, E. W., Physical and Chemical Methods of Separation, McGraw- 

 Hill, New York 1963. 



37 



