Gas chromatographic method for determination of chlorpyrifos and its metabolite 3,5,6-trichloro-2-pyridinol (TCP) in dates.

A method is described for the determination of the insecticide chlorpyrifos and its metabolite TCP in green, unprocessed, and processed dates with the seeds incorporated. After extraction, chloropyrifos is cleaned up using Florisil and analyzed using a gas chromatography (GC) equipped with a nitrogen/phosphorus detector. TCP is derivatized using bis-(trimethylsilyl)-acetamide (BSA) to form the TCP-derivative and analyzed by a gas chromatograph equipped with a Hall electrolytic conductivity detector. Recoveries of chlorpyrifos from all fortified dates (0.05 and 0.1 ppm) ranged from 86 to 110% with an average of 94.5%. Recoveries of TCP from all fortified dates (0.1 and 0.2 ppm) ranged from 79 to 99% with an average of 86%. Limits of detection for chlorpyrifos and TCP in green, unprocessed, and processed dates were 0.02 and 0.05 ppm, respectively.

Chromatographic determination of dicofol and metabolites in egg yolks.

Egg yolk was spiked with p,p'-dicofol (p,p'-DCF) (0.1-2.0 micrograms/gm), p,p'-dichlorobenzophenone (p,p'-DCBP) (0.1-2.0 micrograms/gm), and 1,1-bis(4-chlorophenyl)-2,2-dichloroethylene (p,p'-DDE) (0.05-1.0 micrograms/gm). The fortified egg yolk (2-5 g) was mixed with acetonitrile to extract non-fat organic materials. After removal of acetonitrile, the spiked chemicals were separated with a column chromatograph packed with acid alumina. Recovery efficiencies for p,p'-DCBP and p,p'-DDE were determined by gas chromatography, and for p,p'-dicofol by high performance liquid chromatography. The recovery efficiencies for p,p'-dicofol, p,p'-DCBP and p,p'-DDE were 77.2-93.8%, 84.1-101.1%, and 88.5-96.0%, respectively.

Furazolidone residues in chicken and swine tissues after feeding trials.

Broiler chickens and swine fed furazolidone in their diet were sacrificed, and samples of liver, kidney, skin/fat and muscle were harvested and analyzed for furazolidone residue. Chickens fed 200 g of furazolidone/ton of feed were withdrawn from treatment 21, 14, 7, 5, 3, or 0 days before slaughter. Birds withdrawn from medication more than 5 days prior to slaughter had no residues in any of the tissues sampled. One of the 12 birds in each of the 5 day and 3 day withdrawal groups had detectable residues in the skin/fat. Seven of the 12 birds in the 0 day withdrawal group had residues of less than 2 ppb in skin/fat samples. Chickens fed 400 g furazolidone/ton of feed were withdrawn from treatment 0 days before slaughter. Residues of 0.7 to 3.5 ppb were found in the skin of these birds; residues were not found in other tissues. Swine were fed 300 g furazolidone/ton of feed for 2 weeks or 150 g/ton for 5 weeks. They were withdrawn from treatment 10, 7, 5, 3, or 0 days before slaughter. Tissue samples taken from these swine did not contain detectable furazolidone residues.

Furazolidone in turkey tissues following a 14-day feeding trial.

Feed supplemented with furazolidone was fed to turkeys on a research farm near Modesto, CA. The birds fed furazolidone-medicated feed were housed in isolated pens in a manner to prevent any cross contamination from an adjoining treatment. Furazolidone-medicated feed was supplied to the ration for 14 days prior to withdrawal with two exceptions; the controls were not fed medicated feed, and a 400 g/ton treatment was fed for 24 hr prior to processing. Treatments, representing different withdrawal periods, ranged from 0 to 21 days. Two 400 g/ton treatments with 0-day withdrawal periods were included in the study. One of these treatments involved a 14-day medicated feeding period while the other was for 24 hr. All other treatments were fed medicated feed at the rate of 200 g/ton. Tissue samples from the processed birds included skin, fat, liver, kidney, as well as breast and thigh muscle. No detectable residues were found in any of the liver, kidney, fat, or muscle tissues at any of the withdrawal periods including the 0-day withdrawal groups. Skin tissues contained detectable furazolidone residues only in the 0-day withdrawal treatments, and even these levels were below the 2 ppb level.

Dissipation of parathion and paraoxon on citrus foliage dust and dry soil surfaces in a treated orchard.

Pesticides applied to an orchard may be transported via dust from the orchard floor to the foliage. The dust containing the pesticide facilitates oxygen analog formation. This study involves the evaluation of existing methods and new procedures for measuring pesticide fate (parathion and paraoxon) on soil surfaces in a field environment; the results were correlated with dislodgeable foliar residues. Residues in soil dust removed from the ground floor via vacuum varied considerably and did not correlate with dislodgeable foliar residues. Although residues found on masonite plates coated with a thin layer of soil were different from dislodgeable foliar residues, the ratios of paraoxon to parathion was very similar for the first 14 to 21 days. The thin-layer soil on the plates had serious deficiencies including difficulty of preparation in the field, handling of the coated plates, and physical movement of the soil from the plate due to environmental forces including rain. Soil tags prepared from fine mesh window screen saturated with soil resulted in approximately the same residue as the soil plates and at the same time avoided most of the deficiencies experienced with the plates. They were very resistant to physical forces, easy to prepare in the field, and not affected by environmental forces except appreciable quantities of rain. The results should encourage the use of soil screen tags, not in lieu of but along with other methods when conducting field studies with pesticides involving worker safety.

Ultra trace determination of furazolidone in turkey tissues by liquid partitioning and high performance liquid chromatography.

A simple and sensitive procedure is presented for the determination of furazolidone in turkey tissues, using liquid partitioning followed by high performance liquid chromatography (HPLC). Fat, liver, kidney, skin, and muscle tissues are ground with methylene chloride in a Polytron homogenizer, followed by solvent removal, partitioning in hexane-0.01M acetic acid, and back-partitioning the 0.01M acetic acid with methylene chloride. The determination by HPLC used a reverse phase Ultrasphere-ODS 5 micrometer column. The method is sensitive to 0.5 ppb, with a standard deviation of 6.39% at the 2 ppb fortification level. Recovery from fortified tissues averaged 84% from samples fortified with 0.5-10 ppb furazolidone. An alternative cleanup procedure using a Sep-Pak C18 cartridge is also presented.

Gas-liquid chromatographic determination of S-[(5-methoxy-2-oxo-1,3,4-thiadiazol-3(2H)-yl)-methyl]O,O-dimethyl phosphorodithioate (Supracide) and its monoxone metabolite in safflower seed, meal, and oil.

A gas-liquid chromatographic (GLC) method for determining residues of the inseticide-acaricide Supracide (S-[5-methoxy-2-oxo-1,3,4-thiadiazol-3(2H)-yl)-methyl]O,O-dimethyl phosphorodithioate) and its monoxone metabolite in safflower seed, meal, and oil is presented. Supracide and its monoxone metabolite are separated by partitioning with acetonitrile-sodium sulfate and petroleum ether. The petroleum ether fraction containing the Supracide is extracted with acetonitrile and further cleaned up on Florisil column before determination by GLC, flame photometric detection (FPD). The monoxone metabolite is partitioned from the acetonitrile-sodium sulfate fraction with chloroform and cleaned up on a Florisil column before GLC/FPD. Average Supracide recoveries were 86, 82.5, and 92%, and average Supracide monoxone recoveries were 85.7, 81.5, and 89%, in seed, meal, and oil, respectively. The limit of detection was 0.005 ppm for both compounds on all tissues analyzed.

Airborne and surface residues of parathion and its conversion products in a treated plum orchard environment.

Airborne pesticide residues were collected both within and downwind from a parathion-treated plum orchard by high volume sampling through XAD-4 macroreticular resin. Levels of paraoxon in excess of 100 ng/m3 were found in orchard air, along with parathion, during the early days of two 21-day sampling studies. Paraoxon:parathion ratios in the orchard air were relatively constant, averaging ca. 0.5 for days 1 to 21 following treatment. Likely sources of airborne paraoxon include vaporization and dislodgement from soil and leaf surfaces, and chemical conversion of parathion in the air. Support for the latter came from observation of an increased paraoxon:parathion ration in air samples collected downwind from the orchard. Atmospheric conversion of parathion to paraoxon, accelerated by sunlight, was indicated by both field and laboratory studies. Overall dissipation of parathion from the orchard air, soil, and leaf tissue proceeded to a considerable extent through breakdown to paraozon under the dry climatic conditions of these studies. Eventual conversion to the relatively stable breakdown product, p-nitrophenol, was indicated from analysis of air in the orchard vicinity.

Degradation of parathion applied to peach leaves.

Parathion was applied to peach trees in three different formulations 70 days before harvest. Leaf samples were taken periodically through the 70-day period and gas-liquid chromatographic analyses were conducted for dislodgable and penetrated residues. Analyses were also conducted for paraoxon and the s-ethyl isomer of parathion. Punched samples were compared to whole-leaf samples; generally residue levels for both types corresponded closely. A new experimental formulation, encapsulated parathion, produced highest levels of total parathion throughout the 70-day study, but even this formulation resulted in low total residue levels around 1 ppm at time of harvest. Degradation of the s-ethyl isomer of parathion was generally very rapid in all formulations studied. Dislodgable residues of paraoxon may be significant in some formulations and should be included in parathion degradation studies. Much of the parathion found on peach leaves throughout the growing season was dislodgable residue, but this depended considerably on the formulation used.