REPORT FOR ANALYSTS NOo
Ν()·2
+
>P-X
\ ο
CH2
CH2
colorless
X - NaOH
>P
ο
ΝΟί
+ XaX + HoO (Ή
The 25-pound nerve gas detec tor developed b y the Army Chemical Corps and RCA is now being miniaturized t o one fifth the present weight. It has a sensitivity of 0.1 microgram per liter. It also detects o r g a n o : phosphorus type insecticides
Courtesy Esso Research & Engineering Co.
THE IDEAL PRESS FOR MAKING KBR PELLETS FOR INFRARED SPECTROSCOPIC ANALYSIS
>P — Ο
blue Xmax 025 ταμ The above method has been success fully used in the analysis of alkylating agents, but is not widely used for organophosphorus compounds because of lack of sensitivity. Understandably, the U. S. Army Chemical Corps has been interested in discovering new reactions useful in the detection and analysis of toxic phos phorus compounds. I t was observed in its laboratories that compounds such as Tabun and Sarin reacted rapidly with hydroxylamine. Moreover, these com pounds were observed by one of the authors in 1950 to react very rapidly with keto-oximes to liberate acidic de composition products. In the case of nitrosoacetone, one of the decomposi tion products was found to be hydrogen cyanide. Subsequently, a sensitive and rapid method for the determination of Sarin and Tabun was evolved, based on the electrometric or colorimetric deter mination of the liberated cyanide. Further studies along these lines in volved the use of the sodium salt of diisonitrosoacetone, which gave a ma genta color directly with phosphorylating agents as well as other reactive acylating agents. The reaction is also obtained with cyanogen halides. A number of analytical procedures were de vised by U. S. Army Chemical Corps personnel based on this reagent. In order to increase the sensitivity of diisonitrosoacetone toward the toxic phosphorus compounds and acylating agents, a number of enhancing sub stances such as o-dianisidine, o-tolidine, p-aminodiphenylamine, and aminop3_rimidines were added to the test solu-
tions. A t t e m p t s t o elucidate t h e n a t u r e of t h e reaction between t h e phosphorylating a n d acylating agents a n d diiso nitrosoacetone, alone or in t h e presence of t h e enhancing substances, h a v e been unsuccessful t o d a t e . As t h e mode of biological action of these organophosphorus compounds is generally a t t r i b u t e d t o a n irreversible combination with t h e enzyme acetyl cholinesterase, n u m e r o u s procedures were evolved based on t h e m e a s u r e m e n t of t h e stoichiometric inhibition of en zymatic activity. T h u s , Hestrin, in 1949, developed a method for t h e deter mination of acetylcholine, involving its reaction with hydroxylamine t o form acethydroxamic acid which complcxcd with ferric ion t o produce a highly in tense color. This reaction was em ployed in conjunction with acetylcholin esterase t o measure t h e degree of in hibition of t h e enzyme b y t h e anticholin esterase, acetylcholine being used as t h e substrate. At present t h e generally used en zymatic m e t h o d for t h e determination of organophosphorus insecticides is t h a t of Giang a n d Hall (#) or some modi fication thereof. Samples are incubated with s t a n d a r d cholinesterase a n d buffer to effect partial inhibition of t h e enzyme. S t a n d a r d acetylcholine is t h e n added and again incubated to determine t h e a m o u n t of reactive enzyme remaining. T h e p H change produced b y t h e gener ated acetic acid is measured in t e r m s of per cent inhibition a n d related t o micrograms of inhibitor in question. T h e acid so generated h a s been deter mined by conductometric, electrometric, a n d colorimetric procedures,, t h e l a t t e r involving t h e use of p H indicators—• e.g., b r o m o t h y m o l blue.
Also for forming pellets for x-ray and other types of spectroscopic analysis * 2 0 Ton Press
Capacity
* Accurate eration
alignment
Hydraulic in
op
* Guided m o v i n g platen * Sturdy 3 column construction •
Even pressure distribution for uniformly dense pellets
*
Self-contained
•
Bench mounted
•
H a n d operated
•
9 " χ 9 " platen area
•
2 2 " max. adjustable
vertical
opening,
A multi-purpose unit w i t h quickly adjusted vertical o p e n i n g , by h a n d w h e e l , per m i t s m a n y different s e t - u p s in m i n i m u m time. U s e d around the w o r l d for RESEARCH, C O N T R O L & TESTING. Available accessories include: Heat ing and Cooling Platens; Temp. Con trols, Auxiliary low pressure gauges; Fast air closing; Extruding units; Testing units, etc. Available in 30 and 50 ton sizes.
Write for Bulletin.
LOOMIS E N G I N E E R I N G & MANUFACTURING CO. Dept. A , Route 4 6 , C a l d w e l l , N . J. Circle No. 23 A on Readers' Service Card, page 83 A VOL.
2 9 , N O . 1 2 , DECEMBER 1 9 5 7
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23
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