VARIAN associates

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ANALYST'S C O L U M N

reliable as first supposed. The production man has learned that when his product goes over the control points he should not argue about the analysis or demand reanalysis, but immediately start looking for troubles in his own department. Statistics is permitting the saving of many man-hours of analytical checks by accepting one analysis with its probable errors. For many purposes this one analysis is sufficient, especially if many checks are run on a process over a period of time. Sampling is probably one of the least appreciated sources of error, and in most cases the analyst does not take the sample, so has no control over taking of a representative sample. Statistical treatment of data has shown that sampling is often at fault and what means can be taken to eliminate this troublesome source of error. Interlaboratory tests are being carried on constantly in academic and applied fields to check methods and assay. There is always more consistency of results within a laboratory than without. Because analysis is partly an art and the technique involved is personal, or the instrument used has its peculiar variations, this condition will be always with us and affect results. Designed experiments statistically set up and results studied by statistical methods are supplying, and will continue to supply, the answers as to the cause and expected magnitude of such variations. Sometimes laboratories whose results fall short of the mark are found to be more correct than laboratories in which a consistent error apparently brings their answers closer to the correct result. This acceptance of statistics as a real aid in their work with one another is a maj or step forward by scientists. Wisely, as they become more familiar with statistical methods, they realize its limitations and so do not blindly follow its conclusions. There is much more work to be done with this tool, to sharpen it for the use of analysts who have too few results to evaluate them properly by present statistical methods. The subject of quality control, in which statistics plays such a major role, should become a regular topic at all our scientific meetings concerning analysis. At present the problems discussed in this field are the results of the organization of special symposia, and then the subject is neglected, to the loss of all those whose day-to-day problems would benefit by greater and more effective use of statistics. V O L U M E 2 7, NO. 4, A P R I L

1955

N-M-R Solves Chemical Puzzles . . . No instrument offers greater advantages for advanced study of chemical systems than Varian's V-4300B High Resolution n-m-r (nuclear magnetic resonance) Spectrometer. This "nuclear detective" is now being used by scientists in many well known universities and research centers for determining molecular structures, analyzing functional groups and monitoring chemical reactions. In all these applications it provides non-destructive observation of undisturbed chemical systems, requires a minimum of sample preparation time. Here are some advanced features of the V-4300B High Resolution n-m-r • • •

Spectrometer:

Exclusive Varian sample spinner permits fine separation of closely spaced resonances. Complete Varian magnet system available to provide unsurpassed field stability and homogeneity. New console mounting puts all controls within easy reach of operator.

THIS IS N-M-R AT W O R K TTPHÔVPHAT

M.XTURE

ANALYSIS OF A PHOSPHA ïfc lYllAiw^- ^ INTERPRETATION DATA

Sample: Mixture otNa 3 P04, P

Na4P,07. and Na6P4013

Volume: 2.0 ce. ^ Signals observed:Ρ

Frequency: 12-3 mc. Field: 7140 gauss Sweep rate: 60 mi«igauss/sec. Zero of reference: H3PO4

pnosphate ions ' " « " " " ί ^ ^ , ΐ ν β numbers of phoss^ectrum shown.below The re l a t r ^ be ohorus nuclei present , n B < " " ' d e r the peaks. In tnis determined from the areas under m ν Λ rase the analysis shows 50% ortno procedure C 20% hexameta-phosphate The a n a l y t i c Ρ requires no sample P/ e P a ' a ™ï e a concentrated soluhe phosphates in water to ™ K e * c 0 n t h e s p e c t r u m tion The time required t 0 J w " E „ ' v t i c a | accuracy can

FOR C O M P L E T E I N F O R M A T I O N . . . ^ .L \f w , w D υ- L η ι .c L 1 O n the Varian V-43008 High Resolution n-m-r Spectrometer and associated Magnet System, write the Special Products Division for: THE MARK OF LEADERSHIP

V A R I A N P A L O

A L T O

* Technical Bulletins . r, * ςίι T , .

associates 4,

C A L I F O R N I A

. M I C R O W A V E TUBES —SPECl AL P R O D U C T S For further information, circle number 15 A on Readers' Service Card, page 47 A

15 A For further information, circle number 16 A on Readers' Service Card, page 47 A ·