Integration of enzyme-linked immunosorbent assay with conventional chromatographic procedures for quantitation of aflatoxin in individual cotton bolls, seeds, and seed sections

Integration of an enzyme-linked immunosorbent assay (ELISA) with conventional chromatographic methods proved the versatility of ELISA as a research tool and allowed for rapid assessment of aflaxtoxin in individual cottonseeds, parts of cottonseed, and composite samples of seeds taken from individual cotton bolls. Aqueous acetone was substituted for methanol in the extraction procedure prescribed by ELISA. The substitution allowed the use of a common extract for all analytical methods. An aliquot of the extract was used to screen samples by ELISA. Negative samples were identified, and toxin levels between 1 and 70 ng/g were quantitated by ELISA. Samples with toxin levels beyond the upper limit of detection by ELISA were then subjected to more time-consuming conventional cleanup prior to quantitation by liquid chromatography (LC) or thin-layer chromatography (TLC). Toxin levels detected by LC or TLC ranged from 100 to 845,000 ng/g sample. The screen by ELISA detected large numbers of toxin-negative cotton bolls or individual seeds in minimum analysis time. The combination of techniques verified the presence of seed with no toxin adjacent to toxin-containing seed in the same lock. Toxin-negative portions of individual seed with high toxin in another portion were identified for the first time. Integration of techniques provided needed information on distribution patterns of aflatoxin in cotton so that preventive measures can be developed.

Relationship of byssinosis to the generation of oxygen radicals by bract tissues of cotton plants

Byssinosis is a hazardous respiratory disorder of workers in natural fiber processing industries and, in the case of cotton, is caused by exposure to respirable dust generated from leafy trash associated with raw fibers. To understand the chemical characteristics of involucral trash components that might contribute to bysinosis, we examined the human airway constricting activity and oxygen radical generating activity of dry, frost-killed cotton bracts. In response to inhalation of aerosolized bract extracts, the expiratory flow rates of human volunteers at 40% of vital capacity during partial forced expiration decreased by 3 to 32%. These values enabled us to identify two potentially byssinogenically active bract specimens, a specimen virtually inactive, and a fourth intermediately so. Using spin trapping techniques of electron spin resonance spectrometry, we found that all specimens catalyzed the generation of hydroxyl (preponderantly) and superoxide radicals from hydrogen peroxide. However, the weakest constrictor was the most potent catalyst, and vice versa. This was consistent with transition metal content of the specimens; the most potent catalyst also contained the largest amounts of those metals, suggesting a Fenton-type reaction mechanisms. Other possibilities for the inverse relationship of airway constricting (byssinogenic) activity with oxygen radical generation are discussed. We also found that neither aflatoxin nor endotoxin, contingent contaminants of bracts, catalyzed oxygen radical production from hydrogen peroxide.

Automated solid-phase extraction and liquid chromatography for assay of cyclosporine in whole blood

In this rapid, precise, accurate, cost-effective, automated liquid-chromatographic procedure for determining cyclosporine in whole blood, the cyclosporine is extracted from 0.5 mL of whole blood together with 300 micrograms of cyclosporin D per liter, added as internal standard, by using an Advanced Automated Sample Processing unit. The on-line solid-phase extraction is performed on an octasilane sorbent cartridge, which is interfaced with a RP-8 guard column and an octyl analytical column, packed with 5-microns packing material. Both columns are eluted with a mobile phase containing acetonitrile/methanol/water (53/20/27 by vol) at a flow rate of 1.5 mL/min and column temperature of 70 degrees C. Absolute recovery of cyclosporine exceeded 85% and the standard curve was linear to 5000 micrograms/L. Within-run and day-to-day CVs were less than 8%. Correlation between automated and manual Bond-Elut extraction methods was excellent (r = 0.987). None of 18 drugs and four steroids tested interfered.

Automated solid-phase extraction and liquid chromatography for assay of cyclosporine in whole blood

In this rapid, precise, accurate, cost-effective, automated liquid-chromatographic procedure for determining cyclosporine in whole blood, the cyclosporine is extracted from 0.5 mL of whole blood together with 300 micrograms of cyclosporin D per liter, added as internal standard, by using an Advanced Automated Sample Processing unit. The on-line solid-phase extraction is performed on an octasilane sorbent cartridge, which is interfaced with a RP-8 guard column and an octyl analytical column, packed with 5-microns packing material. Both columns are eluted with a mobile phase containing acetonitrile/methanol/water (53/20/27 by vol) at a flow rate of 1.5 mL/min and column temperature of 70 degrees C. Absolute recovery of cyclosporine exceeded 85% and the standard curve was linear to 5000 micrograms/L. Within-run and day-to-day CVs were less than 8%. Correlation between automated and manual Bond-Elut extraction methods was excellent (r = 0.987). None of 18 drugs and four steroids tested interfered.

Preharvest aflatoxin contamination: effect of moisture and substrate variation in developing cottonseed and corn kernels

Variations in moisture and substrate in preharvest corn kernels and cottonseed were linked with the ability of Aspergillus parasiticus to infect the seed and produce aflatoxin. Osmotic pressures and moisture content (MC) levels of developing starch-rich corn kernels and lipid-rich cottonseed were determined. For in vivo studies, corn kernels and cottonseed were inoculated with A. parasiticus conidia and retained on plants through maturation. For in vitro studies, samples of corn kernels and cottonseed were collected at various stages, sterilized, inoculated, incubated for 2 weeks, and assayed for toxin. Aflatoxin levels were highest in corn kernels inoculated at 28 days postflowering (52% MC) in both the in vivo and in vitro tests. Toxin concentrations in cottonseed were greatest with inoculation at 35 days postflowering (70% MC) in seed retained on the plant, but toxin accumulation continued to increase with the maturity of the seed inoculated in cottonseed used in the in vitro trials. Moisture and substrate conditions in the midrange of seed development provided optimum conditions for fungal development and toxin production in seed retained on the plant.

Liquid chromatographic determination of cyclosporine in whole blood with the advanced automated sample processing unit

We describe a rapid, precise, cost-effective, and accurate isocratic liquid chromatographic (LC) procedure for determining cyclosporine in whole blood. The cyclosporine is extracted from 0.5 ml of whole blood together with 200 micrograms of cyclosporin D, added per liter as internal standard, by using an Advanced Automated Sample Processing (AASP) unit. The on-line solid-phase extraction is performed on an octasilane sorbent cartridge which is interfaced with a Perkin-Elmer 83 X 4.6 mm I.D. cartridge column, packed with 3-micron octadecyl packing. The column is eluted with a mobile phase containing acetonitrile-water (13:7) at a flow-rate of 1.0 ml/min at a column temperature of 70 degrees C. The column effluent is monitored at 210 nm. The absolute recovery of cyclosporine exceeded 87% and the linearity extended up to 2000 micrograms/l. Within-run and day-to-day coefficients of variation were less than 8%. The correlation between AASP-LC and manual Bond-Elut extraction-LC method was excellent (r = 0.97).

Airway constrictor response to cotton bract extracts in the absence of endotoxin

Crude and purified aqueous extracts of cotton bracts shown to cause airway constriction in naive subjects were assayed for endotoxin content. Pulmonary function measured by flow changes on partial expiratory flow volume curves was used to assess airway responses to the bract extracts after their inhalation by a panel of volunteers. These responses are similar to the acute responses experienced by cotton textile workers. Crude aqueous extracts from various bracts harvested before and after senescence of the cotton plant displayed endotoxin concentrations ranging widely from 0.086 to 50 micrograms/ml. No correlation was found between these differences in endotoxin content and the severity of the airway constrictor response. Purifying the bract extract by a series of procedures that included precipitation of polymeric material by addition of methanol and chromatography on an anion exchange column of DEAE-Sephacel resulted in the elimination of almost all the endotoxin. The partially purified extract contained less than 1 ng/ml of endotoxin. The panel of volunteers responded to this purified bract extract, however, with a decrease in pulmonary function which was more than 60% of that seen with the crude extract of bracts. It is concluded that aqueous extracts of cotton bract contain an agent(s) other than endotoxin that causes acute airway constriction in people.

Biologic activity of purified cotton bract extracts in man and guinea pig

Purified aqueous extracts of cotton bract induce acute airway constriction in healthy volunteers never before exposed to cotton bract. The response is similar to that of textile workers who inhale cotton dust. Approximately 60% of volunteers respond to bract extract with significant decreases in lung function, and these volunteers show an increased number of lymphocytes present in their lungs. Following inhalation of bract, the percent of polymorphonuclear leukocytes increases. Macrophages obtained by bronchoalveolar lavage from volunteers pre-challenged with bract extract release increased amounts of chemotactic factor and superoxide anion. Efforts to detect release of histamine and leukotrienes in volunteers following challenge with bract show no increase in urinary histamine and no significant release of leukotrienes in lung lavage fluid. Purified extracts exhibit chemotactic activity in vitro. They also contract guinea pig ileal longitudinal muscle in vitro. This preparation contains mast cells but no basophils, and the H-1 blocker, mepyramine blocks the contraction. Purified bract extracts contain no histamine or endotoxin but other contractors of smooth muscle may be present. The purified extract exhibits spectral, fluorescent, and radioimmune assay properties similar to a leukotriene B-like component. Cotton bract appears to have direct as well as cell-mediated activities.

Solid-phase extraction and liquid chromatography for improved assay of cyclosporine in whole blood or plasma

In this simple, precise, accurate, and specific isocratic liquid chromatographic procedure for determining cyclosporine, the cyclosporine is extracted from 1 mL of whole blood or from plasma, with 500 micrograms of cyclosporin D added per liter as internal standard, by elution from a Bond-ElutTM C18 extraction column with 300 microL of a mixture of ethanol and tetrahydrofuran. A 100-microL aliquot of the eluate, injected onto a cyano-phase analytical column, is eluted with a mixture of acetonitrile and pH 7.0 phosphate buffer at a flow rate of 1.0 mL/min and at 50 degrees C. Detection is at 210 nm. The chromatography is complete in less than 14.0 min. The method can measure less than 10.0 micrograms/L. Analytical recovery of cyclosporine added to whole blood ranged from 99 to 109% for concentrations up to 2000 micrograms/L. Between-run CVs ranged from 6.4 to 6.6%. None of numerous drugs and steroids tested interfered. Results by radioimmunoassay exceeded by 20 to 350% those measured by the present method.

Solid-phase extraction and liquid chromatography for improved assay of cyclosporine in whole blood or plasma

In this simple, precise, accurate, and specific isocratic liquid chromatographic procedure for determining cyclosporine, the cyclosporine is extracted from 1 mL of whole blood or from plasma, with 500 micrograms of cyclosporin D added per liter as internal standard, by elution from a Bond-ElutTM C18 extraction column with 300 microL of a mixture of ethanol and tetrahydrofuran. A 100-microL aliquot of the eluate, injected onto a cyano-phase analytical column, is eluted with a mixture of acetonitrile and pH 7.0 phosphate buffer at a flow rate of 1.0 mL/min and at 50 degrees C. Detection is at 210 nm. The chromatography is complete in less than 14.0 min. The method can measure less than 10.0 micrograms/L. Analytical recovery of cyclosporine added to whole blood ranged from 99 to 109% for concentrations up to 2000 micrograms/L. Between-run CVs ranged from 6.4 to 6.6%. None of numerous drugs and steroids tested interfered. Results by radioimmunoassay exceeded by 20 to 350% those measured by the present method.

Liquid-chromatographic determination of tobramycin in serum with spectrophotometric detection

We describe a simple, precise, accurate, and specific liquid-chromatographic procedure for determination of tobramycin in 50 microL of serum. Tobramycin and the internal standard (sisomicin) are quantitatively converted into their trinitrophenyl derivatives by reaction with a water-soluble derivatizing agent (2,4,6-trinitrobenzenesulfonic acid) at 70 degrees C for 30 min. The derivatives are extracted from the crude reaction mixture by using a reversed-phase Bond-Elut C18 column, and separated on a reversed-phase octyl column with a mobile phase consisting of an acetonitrile/phosphate buffer (70/30 by vol) at a flow rate of 3.0 mL/min. The eluted compounds are detected at 340 nm, and quantified from their peak areas. Chromatography is complete in less than 4.5 min at the optimum column temperature of 50 degrees C. The lower limit of detection for tobramycin is less than 0.2 mg/L. Analytical recoveries for tobramycin varied from 94 to 99%, linearity extended to 25 mg/L, and day-to-day precision (CV) was between 4.6 and 5.1%. Numerous drugs and antibiotics tested do not interfere. Results correlate well (r greater than 0.95) with those by radioimmunoassay and EMIT.

Liquid-chromatographic determination of tobramycin in serum with spectrophotometric detection

We describe a simple, precise, accurate, and specific liquid-chromatographic procedure for determination of tobramycin in 50 microL of serum. Tobramycin and the internal standard (sisomicin) are quantitatively converted into their trinitrophenyl derivatives by reaction with a water-soluble derivatizing agent (2,4,6-trinitrobenzenesulfonic acid) at 70 degrees C for 30 min. The derivatives are extracted from the crude reaction mixture by using a reversed-phase Bond-Elut C18 column, and separated on a reversed-phase octyl column with a mobile phase consisting of an acetonitrile/phosphate buffer (70/30 by vol) at a flow rate of 3.0 mL/min. The eluted compounds are detected at 340 nm, and quantified from their peak areas. Chromatography is complete in less than 4.5 min at the optimum column temperature of 50 degrees C. The lower limit of detection for tobramycin is less than 0.2 mg/L. Analytical recoveries for tobramycin varied from 94 to 99%, linearity extended to 25 mg/L, and day-to-day precision (CV) was between 4.6 and 5.1%. Numerous drugs and antibiotics tested do not interfere. Results correlate well (r greater than 0.95) with those by radioimmunoassay and EMIT.

Fluorometric liquid-chromatographic determination of serum cortisol

We describe a sensitive and specific liquid-chromatographic assay for serum cortisol, exploiting acid-induced fluorescence. Each analysis requires only 50 microL of serum, and chromatography is complete in 7 min. Analytical recovery of cortisol added to serum ranged from 90 to 105% and between-run precision (CV) from 6 to 8%. The lower limit of detection for cortisol is 10 micrograms/L, and linearity extends to 1600 micrograms/L. Numerous steroids and drugs tested did not interfere.

Fluorometric liquid-chromatographic determination of serum cortisol

We describe a sensitive and specific liquid-chromatographic assay for serum cortisol, exploiting acid-induced fluorescence. Each analysis requires only 50 microL of serum, and chromatography is complete in 7 min. Analytical recovery of cortisol added to serum ranged from 90 to 105% and between-run precision (CV) from 6 to 8%. The lower limit of detection for cortisol is 10 micrograms/L, and linearity extends to 1600 micrograms/L. Numerous steroids and drugs tested did not interfere.

Simultaneous liquid-chromatographic determination of zinc protoporphyrin IX, protoporphyrin IX, and coproporphyrin in whole blood

We describe a method for simultaneously measuring concentrations of coproporphyrin, zinc protoporphyrin IX, and protoporphyrin IX in whole blood by liquid chromatography, with use of reversed-phase ion-pair system, fluorometric detection, and internal standardization. Each analysis requires 10 microL of whole blood and 15 min total analysis time. Analytical recovery ranged from 84 to 92%, day-to-day precision (CV) from 5 to 12%. Uroporphyrin, though not studied in detail, can also be detected by this method.

Simultaneous liquid-chromatographic determination of zinc protoporphyrin IX, protoporphyrin IX, and coproporphyrin in whole blood

We describe a method for simultaneously measuring concentrations of coproporphyrin, zinc protoporphyrin IX, and protoporphyrin IX in whole blood by liquid chromatography, with use of reversed-phase ion-pair system, fluorometric detection, and internal standardization. Each analysis requires 10 microL of whole blood and 15 min total analysis time. Analytical recovery ranged from 84 to 92%, day-to-day precision (CV) from 5 to 12%. Uroporphyrin, though not studied in detail, can also be detected by this method.

Simultaneous liquid-chromatographic determination of zinc protoporphyrin IX, protoporphyrin IX, and coproporphyrin in whole blood

We describe a method for simultaneously measuring concentrations of coproporphyrin, zinc protoporphyrin IX, and protoporphyrin IX in whole blood by liquid chromatography, with use of reversed-phase ion-pair system, fluorometric detection, and internal standardization. Each analysis requires 10 microL of whole blood and 15 min total analysis time. Analytical recovery ranged from 84 to 92%, day-to-day precision (CV) from 5 to 12%. Uroporphyrin, though not studied in detail, can also be detected by this method.

Improved liquid chromatographic determination of placental estriol in urine

Placental estriol in urine can be determined, after enzymatic hydrolysis, by liquid chromatography. A single-step extraction technique results in rapid processing with minimal sample manipulation. Analytical recovery of estriol added to urine was 96 to 106%. Day-to-day precision (CV), established by 10 replicate analyses at a mean concentration of 15.9 mg of estriol per liter, was 3.7%.

Improved liquid chromatographic determination of placental estriol in urine

Placental estriol in urine can be determined, after enzymatic hydrolysis, by liquid chromatography. A single-step extraction technique results in rapid processing with minimal sample manipulation. Analytical recovery of estriol added to urine was 96 to 106%. Day-to-day precision (CV), established by 10 replicate analyses at a mean concentration of 15.9 mg of estriol per liter, was 3.7%.

Levels and chemical composition of cotton gin dust

Dust levels were determined in the three principal work areas of five high-capacity, saw-type cotton gins processing spindle-picked cotton. Dust levels measured by the vertical elutriator, OSHA personal and stationary personal samplers averaged 0.66, 0.96 and 0.87 mg/m3, respectively. Gross chemical analyses of dust samples collected indicated that the composit0n of the dust was highly variable and different for the principal work areas within each gin -- 15 to 53% ash, 2 to 5% moisture, 8 to 18% protein, 19 to 55% cellulose and 8 to 16% water-extractable constituents. Major elements were silicon, potassium, aluminum, calcium and magnesium.