Report for Analytical Chemists
3
Chromosorb "Century Series' polymer supports are now available in 5 grades for more versatility than ever.
W = W + cY»
(8)
Combining Equations 7 and 8 gives s' = W ' - Y i = (W + cY^Yi
(9)
which can be soh'ed for c to give s' — s If, as described above, it is desired that s' = —s, then —2s
Chromosorb 101 Fast, efficient separation of free fatty acids, glycols, alkanols, alkanes, esters, ketones, aldehydes and ethers.
and the new weight vector W is cal culated from the equation W =
Chromosorb 102 For light and permanent gas and low molecular weight compounds. No tailing of water and alcohols.
Chromosorb 103 Efficient, quick separation of amines, amides, alcohols, aldehydes and ketones.
Chromosorb 104 Highest polarity. Efficient separation of nitriles, nitro-paraffins, xylenols, and oxides of nitrogen and ammonia.
Chromosorb 105 Intermediate polarity. Separates aqueous mixtures containing formaldehyde and acetylene from lower hydrocarbons, water from organic compounds.
For more specific information on "Century Series" and other Chromosorb grades, write: Johns-Manville, Box 1960, Trenton, New Jersey. Also available in Canada and overseas. Cable: Johnmanvil.
Johns-Manville
9/31
CHROMOSORB IS A JOHNS-MANVILLE REGISTERED TRADEMARK FOR ITS BRAND OF PROD UCTS FOR USE AS SUPPORT MATERIAL OR ADSORBENTS FOR GAS CHROMOTOGRAPHY, CIRCLE 9 2 O N READER SERVICE CARD
26 A ·
ANALYTICAL CHEMISTRY, VOL. 43, NO. 10, AUGUST 1971
W -
( Ϋ ^ ) Υ .
(12)
Of course, other methods can easily be derived which could also be properly termed negative error-cor rection feedback. Generalization. T h e application of an error-correction feedback process to a set, of data which is not known a priori to be linear-sep arable has some interesting aspects. First, successful convergence dem onstrates t h a t such a linear classifi cation is possible, even though it might not have been predicted by theory. On the other hand, lack of convergence in less t h a n an infinite number of feedbacks proves noth ing. Programs have been written, however, t h a t can accomplish a large number of investigations for a fairly low expenditure in computer time. I t has been the experience of the authors, while using an errorforcing computational algorithm, that convergence often occurs within a number of feedbacks t h a t is about twice the number of p a t terns in the training set. Hence, while inseparability is never proved, it m a y be reasonably suspected without an inordinate expenditure of computer time. The use of such empirically de veloped decision-makers can be a p plied to the routine classification of data. Furthermore, it m a y be pos sible to learn something about the chemistry involved in the experi mentation process. Once a rela tionship is proved to exist, there is encouragement to t r y to determine
