Phosphine Residues Research Articles

Balancing phosphine in manure fermentation

The evolution of phosphine gas during the anaerobic batch fermentation of fresh swine manure was detected and correlated to the production of methane and hydrogen sulphide. A close temporal relationship between phosphine liberation and methane formation was found. However, the gaseous phosphine released from manure during fermentation only represents a tiny fraction of the overall phosphine balance. The majority of phosphine is captured in solid manure constituents. This matrix‐bound phosphine is eliminated by more than 50% during anaerobic batch‐fermentation. Seasonally determined phosphine concentrations in biogas and manure from two large‐scale manure treatment plants also revealed net losses of phosphine in fermentation. Consequently, manure has to be considered more as a sink of phosphine rather than a phosphine‐generating medium. Furthermore, a close relationship between phosphine in the feed of swine and manure of these swine was observed, implying that phosphine residues in the feed (possibly as a result of grain fumigation) represent an important source of phosphine in manure technologies that is relevant before the faecals of swine enter manure treatment plants.

Effect of Physical Attributes of Robusta Coffee on Phosphine Residue

Lower grade Robusta coffee (bulk 63) with broken and holed beans having dark rough surfaced husks, have a higher phosphine (PH3) residue (0.1820 mg/kg) compared to higher grade beans (bulks 41, 48 and 54). The computed phosphine residue in pre-aired (0.1541 mg/kg) and 1 d aired (O.0675 mg/kg) samples of bulk 63 was less than the corresponding determinable free PH3 residues (0.1820 and 0.1530 mg/kg respectively), while the computed PH3 residue in pre-aired beans of bulks 41 (0.1571 mg/kg), 48 (0.1561 mg/kg) and 54 (0.1635 mg/kg) was more than the corresponding determinable free PH3 residue (0.0718, 0.0992 and 0.0774 mg/kg respectively). Both pre-aired and 1 d aired samples of bulk 63 attained zero-residue level at 24 d compared to 27 to 33 d by those of bulks 41, 48 and 54, indicating that low grade Robusta coffee beans did not only adsorb large amounts of PH3 during fumigation but also desorbed faster during storage. Physical attributes had affected the level of free PH3 residue only. Slightly more inorganic phosphorus residue was found in the beans of bulk 63 compared to that in the other three bulks.

Spectrophotometric method for phosphine residue determination in coriander

Spectrophotometric method for the determination of phosphine (PH3) residues in coriander has been developed based on the reaction of phosphine with silver nitrate in 2% aqueous isopropanol. The yellow chromophore formed has an absorption maximum at 430 nm and the linear relation between the absorbances at 430 nm and the concentration of PH3 is obeyed in the range of 0.02 to 0.17 μg. The method is sensitive with a detection limit of 0.008 μg and can be applied for determination of 0.02 μg/g residue in coriander. Recovery of added PH3 from a closed system ranges from 96 to 101%.

Three Methods of Aluminum Phosphide Application for the In-Transit Fumigation of Grain Aboard Deep-Draft Bulk Cargo Ships

Three methods of applying aluminum phosphide were tested aboard a deep draft vessel to determine the suitability of each method for fumigating grain in transit. Results showed that all three methods were highly effective with only low levels of phosphine residues resulting in the wheat. However, the recirculation method provided faster and more even distribution of phosphine throughout the grain mass than did the two passive methods. After a fumigation exposure of 26 d, all insects exposed at positions where concentration × time (C × T) values were > 1.0 were killed. As tested in this study, all three methods posed no hazards to the ship’s crew or to dock workers unloading the cargo at destination.

Spectrophotometric Method for Determination of Phosphine Residues in Cashew Kernels

A spectrophotometric method reported for determination of phosphine (PH3) residues in wheat has been extended for determination of these residues in cashew kernels. Unlike the spectrum for wheat, the spectrum of PH3 residue-AgNO3 chromophore from cashew kernels does not show an absorption maximum at 400 nm; nevertheless, reading the absorbance at 400 nm afforded good recoveries of 90-98%. No interference occurred from crop materials, and crop controls showed low absorbance; the method can be applied for determinations as low as 0.01 ppm PH3 residue in cashew kernels.

Use of Perforated Tubing to Distribute Phosphine During the In-transit Fumigation of Wheat1

Wheat aboard a bulk dry-cargo/oil vessel was treated in transit with aluminum phosphide on the surface and distributed in slotted tubing (10.16 cm o.d.) to carry phosphine gas to the bottom and middle of the cargo. Dosage applied averaged 1.07 g (AI)/m3. Approximately 22% of the aluminum phosphide pellets were applied by pouring them mixed with grain down the tubes; the remaining 78% was applied to the surface of the wheat. Gas distribution was rapid in the 26.8 m-deep holds; after 5 days, all depths had concentrations of ≥40 ppm. After 9 days, all depths had phosphine in concentrations of ≥150 ppm. Thirty-two days after application, just before the holds were opened for discharge in Bangladesh, mean concentrations at various depths in the holds ranged from 208 to 365 ppm. All insects exposed at various depths in the wheat were killed by the treatment. No phosphine was detected in any living or working areas of the ship during the voyage from Seattle, Wash., to Bangladesh. Residues of phosphine on wheat discharged were highest at the surface where application of the aluminum phosphide was made. Rapid, uniform distribution of phosphine throughout the wheat mass is attributed to the method of application, which utilized slotted tubing.

Feasibility of Fumigating Unmodified River Barges with Phosphine While in Transit1

Six unmodified barges containing corn were fumigated in transit on the Mississippi River between St. Louis, Mo., and New Orleans, La., with aluminum phosphide pellets at the rate of 1.7 g/m3. Insufficient concentrations of phosphine in most areas of the cargo precluded control of either natural pest infestation or caged insects. Also, extensive leaking of phosphine through hatches and lids of barges could lead to hazardous conditions aboard the barge tow or towboat or both. Largest phosphine residue on the grain following fumigation was 0.046 ppm, below established tolerance of 0.1 ppm. Results indicate that fumigation of river barges as presently practiced is ineffective, potentially hazardous, and could lead to development of significant levels of resistance.

Determination of phosphine residues in fumigated cereals and other foodstuffs

AbstractAn improved method for the determination of phosphine residues in a range of stored foodstuffs with a limit of detection better than 0.1, μg kg−1 is described. The method has been used to obtain data on the amount of phosphine which remains in these commodities after treatment at typical dosage levels and on its persistence during storage. Results show that in cereal grains and nuts residues fall quickly to below internationally recommended levels although trace amounts of phosphine could be detected several months after treatment in all commodities examined.

Intramolecular phosphine-directed hydroformylation. Application to the total synthesis of (+)-phyllanthocin

The temporary incorporation of a coordinating phosphine residue [m-(Ph2P)C6H4CO] into the tetracyclic phyllanthocin precursor1a directed the [(COD)RhOAc]2-catalyzed hydroformylation of1d largely to the desired C(3) position. This “intramolecular hydroformylation” strategy substantially improves a key transformation in the total synthesis of (+)-phyllanthocin.

Phosphine residue and its desorption from cereals

Extent and pattern of desorption of PH3 residue in wheat, raw polished rice, raw unpolished rice, and parboiled rice were followed at laboratory level for 60 days. The PH3 residue on each day of storage was computed by knowing the total amount of PH3 desorbed over 60 days. PH3 desorption patterns from four types of cereals are discussed under 3 stages: up to 19 days, 20-49 days, and 50-60 days of storage. The relationship between the logarithm of such residues vs. storage in days is linear over the first 19 days, except in the case of residue from raw polished rice, which is only up to the first 9 days. During the period of linearity the desorption follows first-order kinetics. Between days 20 and 49 there is a waxing and waning in the amount of PH3 desorbed. Between days 50 and 60 there is a regular fall in PH3 residues due to uniform decreased desorption, except in raw unpolished rice in which desorption is a bit sluggish up to 56 days.

Spectrophotometric Determination of Phosphine Residues in Rice

Phosphine residues were determined in 2 types of rice samples, raw polished and parboiled. The yellow chromophore due to phosphine from raw polished rice had 2 absorption maxima, a strong one at 370-380 nm and a weaker one at 400-410 nm. The chromophore from parboiled rice also had 2, one at 390-400 nm and the other at 410-420 nm. A closed system containing rice and a phosphine tablet or powder yielded 93-99% recovery of fortified phosphine. At any given dose of phosphine, parboiled rice retained a higher amount of residue after aeration than did raw polished rice.

Effect of gamma irradiation of phosphine-fumigated dates on the development of Ephestia cautella (Walker) (Lepidoptera: Pyralidae)

Possible toxicological effects from interactions between gamma radiation (1 KGy at 46 rad/s) and phosphine residues in fumigated dates were studied when the dates were fed to Ephestia cautella. The results showed comparable development, fecundity and fertility of this insect when reared on a complete diet of fumigated, irradiated, fumigated irradiated or untreated dates.

Phosphine fumigation of thick-film polyethylene food bags and laminated film food packets.

Small, heat-sealed polyethylene bags containing airtight food packets were fumigated with phosphine according to recommended procedures. Some internal packets contamed simulated insect penetrations. Toxic levels of phosphine were found in the 254-μ polyethylene film bags within 24 h, but high levels (92 ppm) were still present after 72 h of aeration. Phosphine did not permeate intact internal packets. There was no survival of Tribolium castaneum (Herbst) in packets with simulated penetrations. Some insects survived for 19 to 20 days in one type of intact, fumigated, or nonfumigated packet. None survived in the other intact, nonfurnigated packets. Phosphine residues exceeding 0.01 ppm were found in foods from slit or penetrated packets after 23 days of aeration.

Efficacy of Perforated Tubing in Assisting Phosphine Distribution for In-Transit Fumigation of Export Corn

Corn aboard a tanker vessel was fumigated in transit with Detia aluminum phosphide tablets and pellets at the rate of 1.06 g (AI)/m3 and with Detia Gas EX-B Bag Blankets at the rate of 1.04 g (AI)/m3. Different lengths and configurations of perforated, polyethylene Advanced Drainage Systems, drainage tubing containing one-third of the dosage and positioned in some of the tanks effected rapid distribution of the phosphine gas throughout the grain mass. Phosphine concentrations achieved within the grain showed that the fumigations in tubing-rigged tanks were far superior to those in either a deep-probed (5 m) or a surface-treated tank not equipped with tubing. Survivors of caged insects and those insects found by incubation of post fumigation grain samples showed that the fumigation in the surface-treated tank was not as efficacious as any of the other treatments. Phosphine residues on the samples of corn taken at off-loading were well below the established tolerance of 0.1 ppm, regardless of the application method used.

Simple Spectrophotometric Method for Determination of Phosphine Residues in Wheat1

A method has been developed for determination of phosphine residues in wheat, based on the reaction of phosphine with silver nitrate in aqueous solution to form an egg-yellow chromophore with an absorption maximum at 400 nm. At this wavelength, there is a linear relationship between absorbance and concentration of phosphine in the range 10-100 ng/mL. Phosphine-fumigated wheat is soaked in a known volume of AgNO3 solution, and the absorbance of the filtrate is read against a blank at 400 nm. The method is sensitive, with lower detection and estimation limits of 0.008 and 0.01 micrograms PH3, respectively. Recovery of added phosphine from a closed system was 85-100%. Accuracy for this method has been compared with that for the gas chromatographic method.

In-Transit Shipboard Fumigation of Wheat on a Tanker1

Wheat in seven tanks of an oil tanker was fumigated by applying aluminum phosphide round tablets at the rate of 1.06 g/m3. Tablets applied by probing into the wheat gave better gas distribution and a more efficacious fumigation than those applied on the surface. Phosphine gas moved slowly downward through the wheat mass beyond the 9-m depth in the center tanks and remained at low concentrations even after 24 days at the 17-m depth. Only one center tank, where the fumigant was probed to a depth of 4.3 m, contained no live insects. Pressure-vacuum readings recorded on tanks over a 10-h daytime period ranged from + 12.5 to −15 mm of Hg. For each 1°C rise in overhead temperature, there was a corresponding rise of 1 mm of Hg in pressure. No phosphine was detected in working areas or living quarters of the tanker. Forced ventilation of the fumigated holds for 1 h before unloading was sufficient to remove phosphine from the head space above the grain mass; however, 24 h was required for natural ventilation. Phosphine was not detected in the overhead space of tanks while the pneumatic conveying system was in operation. Phosphine residues were detected on all postfumigation samples of wheat. Residues ranged from 0.001 to 0.2 ppm on samples taken from the discharge spout of the pneumatic conveying system. Only two samples out of 35 exceeded the 0.1-ppm tolerance.

In-Transit Shipboard Fumigation of Corn on a Tanker Vessel1

Corn aboard a tanker vessel was fumigated in transit with aluminum phosphide tablets at the rate of 1.06 g/m3 and with Detia gas bag blankets at the rate of 1.17 g/m3 Gas concentrations were always highest on the surface of the grain; however, some gas was detected at all sample points during the first half of the 44-day fumigation. The ship’s stripper pump was used to facilitate rapid penetration of phosphine in one fumigated tank, but the gas channeled downward directly to the rose box and was not uniformly distributed. To assess safety to the crew, phosphine was monitored in transit three times daily at 26 selected locations throughout the living and working areas of the ship. After fumigation, one tank was found to have a cracked bulkhead, and phosphine levels exceeding the threshold limit value were observed in an adjacent forward locker room. These concentrations dissipated quickly and completely after the locker room door was opened. Although live insects were on-loaded in the com, none were found during unloading. Phosphine residues were lowest on corn fumigated with bag blankets; residues exceeding the tolerance of 100 ppb were found on samples taken from the surface of the com in tanks treated with tablets.

Fumigation of Dates with Phosphine1

Dates in wooden crates were fumigated with phosphine under a 6-mil polyethylene tarpaulin. Insects exposed in various positions within crates of dates were killed except for some eggs of Ephestia cautella (Walker) from which three adults emerged after fumigation. Gas concentrations during the 5-day fumigation, measured with an IR analyzer and phosphine detection tubes. were in close agreement. Concentrations increased to 649 ppm during the first 40 h of the fumigation, then decreased to ca. 50 ppm after 120 h. Residues of phosphine on dates after fumigation ranged from <0.0007 to 0.0013 ppm as measured by two different methods. The phosphine fumigation of dates under a polyethylene tarpaulin appears practical.

Polymer‐supported phosphines: Reactivity of pendant and crosslink groups

AbstractTwo groups of phosphine‐containing resins were prepared by bead copolymerization. In one the phosphine residues were introduced as pendant groups with p‐styryldiphenylphosphine, whereas in the other the phosphine residues were located specifically at crosslinked points with bis(p‐styryl)phenylphosphine. Both groups of resins were used to convert alcohols to alkyl chlorides in the presence of carbon tetrachloride and benzaldyhyde to benzal chloride and β,β‐dichlorostyrene. In the first reaction an increase in the crosslink ratio of the support reduced the reactivity of the resins, although both octanol and octadecanol substrates behaved similarly. No clear difference emerged between resins with pendant phosphine groups and those located on crosslinks and the absence of a strong substrate size effect or substrate selectivity with both series of resins was apparent. The production of benzal chloride and β,β‐dichlorostyrene requires interaction of two phosphine residues to generate the reactive intermediate, and inhibition of phosphine–phosphine interactions in these highly crosslinked networks does indeed inhibit this reaction. Again both series of resins behaved similarly. Among the possible routes by which PPh3/CCl4 converts alcohols to chlorides one involving phosphine‐phosphine interactions must also be inhibited in these supported systems.

In-transit shipboard fumigation of wheat.

Wheat in 3 holds of a bulk dry-cargo vessel was fumigated by applying aluminum phosphide tablets at the rate of 1.77 tablets/m3 of hold capacity. Tablets applied in layers during loading of 2 holds gave better gas distribution and a more efficacious fumigation than stepping the tablets into the surface of the grain in the other hold. Delays in loading of holds fumigated by the layering method sometimes resulted in concentrations of phosphine in the space above the wheat that exceeded the threshold limit value. However, these concentrations were rapidly reduced by ventilation when the main hatch covers were opened. Likewise, in preparation for unloading the wheat at destination, the overhead space of the holds was ventilated rapidly by opening the main hatch covers. Residues of phosphine on wheat samples after fumigation were well below the established tolerance except at one location in each test hold.