The extensive use of chemistry makes the experimental program more complicated 
and more costly. The development of simpler and more rapid analytical procedures 
would be highly beneficial in research. There is also a need for simple, rapid methods 
that can be used in trade channels--methods that do not require expensive, elaborate 
equipment, and that can be handled with little or no laboratory facilities and by people 
who are not necessarily trained chemists. In some cases even purely qualitative rather 
than quantitative results would be of great assistance toa grain buyer, an elevator 
operator, a miller, a feed manufacturer, or a livestock feeder, Such tests would at least 
tell whether residues were present in sufficient amount to require further and more 
detailed checking. They might also indicate whether it would be possible to apply a 
fumigant or protectant without exceeding an established residue tolerance, whether it 
would be safe to use acommodity for some specific purpose, or whether some unapproved 
treatment had been applied in ignorance, in error, or even by intent. 
FUMIGATION 
Tremendous advances have been made in the fumigationof stored products during the 
last few years. A step that can almost be considered as a break-through is the use of 
gas concentration rather than applied dosage asabasis for conducting not only fumigation 
research but also applied fumigations. The analysis of fumigant gas concentrations in air 
is nothing new but until fairly recently was a complicated, time-consuming operation 
requiring a well-equipped chemical laboratory. The application of the thermal-conductivity 
principle to the analysis of some of the common fumigants and the development of 
portable equipment that can be used in the field either for research or practical fumiga- 
tions has been the key to this progress. The development of relativelv inexpensive gas 
chromatography equipment has also aided in fumigation research, 
The evaluation of fumigation results in relation to applied dosage can give at best only 
empirical results. Factors such as sorption and leakage affect the actual gas concentra- 
tion, which governs the results obtained. By being able to determine gas concentrations 
we can also study distribution of a fumigant, channeling of gases, and other conditions 
that may affect the results of a fumigation. Furthermore, by keeping track of gas concen- 
trations during a commercial fumigation, itis often possible to take immediate corrective 
steps to insure a satisfactory job, rather than wait until the operation is completed to 
discover a failure and then have to repeat the whole job. 
The aeration of grain to maintain satisfactory physical condition has gained wide 
acceptance in the lastfew years. A fortunate coincidence showed that the same engineering 
principles of volume and rate of airflow as well as the arrangement of fans and ducts 
could be used to force a fumigant gas through bins of bulk grain. Experiments showed 
that adequate and uniform distribution of gas could be obtained, even in large masses of 
grain in flat storage or silo-type elevators where it had been necessary previously to 
turn the grain to fumigate it. A portable aeration system has even been developed to 
fumigate bulk grain in railroad cars. 
Light-weight, gas-tight plastic films and coated fabrics are now available and have 
permitted several innovations in fumigation procedures. Tarpaulins made of such 
materials can be placed over stacks of commodities to provide a fumigation enclosure 
under many circumstances where a fumigation would otherwise be impossible. A portion 
of the contents of a warehouse can be fumigated without treating the entire structure or 
,other contents. The tarpaulins are sometimes leftin piace to provide an extended fumiga- 
tion period, plus a physical barrier against reinfestation after the gas has all dissipated. 
In the khapra beetle eradication program entire structures have been wrapped in tarpaulins 
and fumigated. One such operation undoubtedly will be remembered a long time in fumi- 
gation history. A large establishment was covered and fumigated as a single unit, the job 
requiring 9-1/2 acres of tarpaulins and 12 tons of fumigant. 
When the time came to establish tolerances for fumigants under the Miller Amend- 
ment, it was surprising to discover how little residue data were available, Industry and 
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