The sorption of methyl bromide by wheat

Abstract

with water (cn. 15 nil.) and the excess sodium nrsetiite titrnted with ntandnrd (0.02 N) iodine solution to stnrch indicntor. Blnuk deterniiuntiotis (5 ml. solvent rcplnciiig tlie solution of unenponifinl~le matter) werc cnrried out simultaneously. From tlie titre of periodic acid consumed, the prcentege glyceryl ether, 11s selncliyl nlcohol, was crrlculntetl. DETEHAIJ~'~TIOS OF THE FORJIALDEIIYU?: &xEHATED IS T I E REACTIOSTo tlie osidntion iiiixturc, nftcr stniidiirg for four hours its iibove, wntm (30 ml.) IWS ndtlcd, followeil by N hydrochloric acid (9 nil., to give cb norninlity of HCI of 0-1-0-2 N) nnd N swliuin arsrnito solution (3 xnI.).1* The solution wns swirled thoroughly. %\'lien the colour geiienrted hnd ctisuppearcd, 60 ml. of it buffer solution (iiindc by mixing 1 volunic of 1.7 N iiydrochloric acid with 2 volnnies of 1.7 N sodiuni Iicetriter2) wcrc uddcd, and the whole filtered tliroiigli n pnd of filter-nit1 with gentle suction. The flnsk rriitl ptitl were washed with n furtlicr 20 nil. of buffer solutiou, nnd then with :iliont 10 ml. of wnter from ti wash-bottle. To the clcnr filtrate (pH .I *f;) 5% :tlcoholic dinledone solution (2 nil.) \ u s addetl, : l i d thc sollit ion thoroughly sliaken, uiicl nllowed to stnnd for 18 hours. The prccipihte v;ns then filtered off, in a tared sintcred gltrss crucible, and washed with distilled water. Drying wis cnrriccl out a t 85' for 20 minutes, and the crucible then cooled in rr c\esicc:rtor and weighed. A blriiik was usunlly curried out on the rcngeiits, hut was never found positive. Thc method is not regnrded us giving results to genter ;recurucy than about 1.5%.~\'ole.--\\'here the K-glyCCryl ether content of tin 11tisnp01ii~i:rb~e fraction was low, it wns alwnys ndvnutrigeous to use 6-ml nliquots containing more thnn 50 nig. of unsnponifinble nintter. In these cirses ethyl rrcetate wns tlic more useful solrelit, owing to the grc:itcr solubility of unscrlmouifinble ninttcr in this solvent than in ethyl nlcohol. The use of diquots yrcntcr thnn 5 nil. neccssitnted iidjustments in d l oper;itioiis subsequent to the oxidation, nud iii the cnsc of ethyl neetnte in particulnr, cnuscd unneccssnry diffic~~ltic~s.The nuthors nckno\vledgc fiiinuciol clssistnncc froni tlie h'ntionnl Hesenrch Couiicil and B o d , nud from the following industrial concerns : llessrs. Coiiccntrn (Pty.) Ltd., Messrs. I n i n und Jolinso~i (S.A.) Ltd.Tho totol sorption, and rut-of sorption of tnothyl hromiclu by rholu and milled wheat, by wheat glutonin.md hy wheat starch, havo tmn

Effects of methyl bromide on phosphorus metabolism in the adult housefly, Musca domestica L.

“…Methyl bromide readily and irreversibly methylates certain free and protein amino acids, especially the SH groups of cysteine and reduced glutathione, the S -CH, group of methionine, and the imidazole group of histidine (Blackburn, Consden & Phillips, 1944;Winteringham & Harrison, 1946;Lewis & Eccleston, 1946;Lewis, 1948;Winteringham, Harrison, Bridges & Bridges, 1955b;. The rapid blocking of the free SH groups of the tissues of Calliphora erythrocephala larvae in vivo by high concentrations of methyl bromide vapour has been demonstrated (Loveday & Winteringham, 1951).…”

Modelling the kinetics of ethyl formate sorption by wheat using batch experiments

“…Equilibrium isotherms have been estimated for methyl bromide, but, as this fumigant significantly reacts with grain, this resulted in expressions for specific sorption periods (e.g. 24 h) 25–28…”

A kinetic model of fumigant sorption by grain using batch experimental data

“…These fumigants were chosen because data are available that describe their adsorption properties using the widest range of values of key experimental factors, enabling the components of the prospective mass transfer models to be evaluated. Methyl bromide exhibits comparatively rapid adsorption characteristics,7–9 which requires fan‐forced distribution systems to overcome adsorption losses in practice. Phosphine exhibits slow adsorption characteristics,6 yet even with well‐sealed stores, adsorption can cause zones of low fumigant concentration in large stores where passive distribution is used 10…”

“…Results of finite volume experiments are often presented as graphs of fumigant concentration against exposure period. For methyl bromide, and phosphine on some grain types, adsorption has been observed to continue until all the fumigant is removed from the air 6, 9, 10. Methyl bromide adsorption exhibits two ‘phases’, which can be identified by a distinct change in the concentration versus time slope:6, 9, 10 an initial rapid fumigant loss period followed by a slower loss period.…”

“…Sorption on whole grain kernels has been demonstrated to be partially reversible with both methyl bromide7–9, 15, 18, 20 and phosphine 5, 6, 19, 21, 22. Desorption is initially rapid, then reduces to zero with transfer ultimately ceasing 6, 9, 19, 21.…”