Detectability and system linearity identify the H-P Model 402 High-Efficiency Gas Chromatograph A high-efficiency gas chromatograph is a complex instrument with a long list of specs t h a t tend to obscure its real function, which is analytical per formance. Reduced t o this fundamental, t h e highefficiency gc can be positively identified by two characteristics : Detectability. Does it detect small quantities of hard-to-chromatograph substances ? In other words, if you inject a nanogram, say, of an easily degradable material such as a steroid, will it analyze it without decomposition to produce a usable chrom a t o g r a m ? If it does, it has detectability, a system characteristic which is substantially more mean ingful t h a n t h e usual " d e t e c t o r sensitivity" found in a typical list of specs. System Linearity. Does it respond proportionately to different amounts of hard-to-chromatograph substances? In other words, if you inject exactly twice t h e a m o u n t of t h a t same material, will it produce a recorder peak size t h a t ' s exactly twice as large? If it does, it has system linearity, a char
acteristic t h a t is incalculably more important t h a n t h e usual " d e t e c t o r linearity" spec. I n t h e two series of chromatograms reproduced here, we offer convincing evidence t h a t t h e H - P Model 402 High-Efficiency GC possesses system detectability and linearity t o a n almost perfect degree. I n t h e first place, b o t h trifluoperazine and testosterone chloroacetate are hard-to-chromato graph substances . . . and t h e 402 detected both in t h e nanogram range. Moreover, a quick glance a t the linearity plot will show t h a t the 402's response closely approaches t h e theoretical ideal. You can get full information by writing for Bul letin 4020 ( . . . it contains a "long list of specs") or by calling the nearest H - P sales office. Prices s t a r t a t $4,000.00. Hewlett-Packard, R o u t e 4 1 , Avondale, P a . 19311. I n E u r o p e : 54 R o u t e des Acacias, Geneva, Switzerland. Elsewhere: 1501 Page Mill Road, Palo Alto, California 94304.
HEWLETT
PACKARD
ANALYTICAL
INSTRUMENTS
Superimposed on these two system linearity plots are the actual recorded peaks, accurately reproduced from the original chromatograms in the same scale.
100 ω ι/ι
% 80
Testosterone Chloroacetate (electron capture detector)
80
Trifluoperazine (flame detector)
ο ο. ω CC
a.
ΐ 60
CD
"Ξ 40 Ο
§ 40
ce
20
Cd
20 5.78 v
7.5
Nanograms
15
20
25
Nanograms
43711
Circle No. 1 on Readers' Service Card VOL. 4 0 , N O . 1 0 , AUGUST 1 9 6 8
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25
A
