Rodney J. Bushway

Determination of atrazine residues in water and soil by enzyme immunoassay.

Atrazine, a triazine herbicide, is the second most widely used pesticlde in the United States with approximately 79 million pounds of active ingredient being applled each year (Anonymous 1987) as a preor post-emergent weed-control agent in the U.S. for corn, sorghum, sugarcane and pineapple. Because of its extensive use, possible seasonal stability and inadequate toxicological data (Wilson et al. 1987), there is a need for monitoring atrazine in water and soil. Municipal and private water sources should be monitored periodlcally in areas of frequent atrazine use. In soil, atrazine carry over may be injurious to certain rotational crops and thus the soil should be analyzed before planting (Ferris and Haigh 1987).

Separation of carotenoids in fruits and vegetables by high performance liquid chromatography

Abstract Several isocratic high performance liquid chromatographic (HPLC) methods, including both normal and reversed-phase, have been developed to separate provitamin A compounds and other carotenoids - α-carotene, β-carotene, stereoisomers of β-carotene, γ-carotene, β-cryptoxanthin, canthaxanthin and lycopene- in fruits and vegetables. The normal phase systems used either an amino or alumina column with 99.5% isooctane and 0.5% tetrahydrofuran. Procedures employing reversed-phase used C18 columns- Vydac 201TP54, Vydac 218TP54, Zorbax ODS and NovaPak C18- with nonaqueous solvent systems comprised of various mixtures of acetonitrile, methanol, tetrahydrofuran and chloroform. All compounds were monitored at 470 nm or 450 nm. Each method has certain advantages and disadvantages for the analysis of carotenoids in fruits and vegetables.

High-performance liquid chromatographic separation of potato glycoalkaloids

Separations of three glycoalkaloids (a-chaconine, β-chaconine, and a-solanine) have been achieved by using three different columns: μBondapak C18, μBondapak NH2, and a carbohydrate analysis column. These methods have been employed to examine the purity of the potato glycoalkaloids isolated by thin-layer and column chromatographic separations. Also, samples of tubers, peels, blossoms, and sprouts have been analyzed to determine their content of a-chaconine, β-chaconine, and a-solanine by using the carbohydrate and μBondapak NH2 columns.

High-performance liquid chromatographic determination of carbaryl and 1-naphthol at residue levels in various water sources by direct injection and trace enrichment

Abstract A high-performance liquid chromatographic method is described for determining carbaryl and its hydrolysis product, 1-naphthol, in water at residue levels by direct injection and trace enrichment. Water from three sources, public water supply, stream and the ocean, was analyzed for carbaryl and 1-naphthol at concentrations as low as 3.78 and 10 ppb, respectively, without a clean-up, concentration or derivatization step. Carbaryl was detected at 0.1 ppb and 1-naphthol at 0.5 ppb by employing a concentration step involving a C 18 Sep-Pak cartridge. The coefficients of variation for all determinations ranged from 2.5 to 10.7%. Fourteen other widely used pesticides—carbofuran, methomyl, thiram, azinphos-methyl, benomyl, monuron, diuron, propham, chlorpropham, pentachlorophenol, the oxygen analogue of azinphosmethyl, pentachloronitrobenzene, simazine and atrazine— were chromatographed using this system. Pentachloronitrobenzene, diuron and thiram interfered with the determination of 1-naphthol, while atrazine co-chromatographed with carbaryl.

Determination of capsinoids by HPLC-DAD in Capsicum species.

Capsicum fruits contain a newly discovered phytochemical called capsinoids. Because little is known about the quantities of these compounds in both sweet and pungent pepper fruits, a high-performance liquid chromatography (HPLC) method was developed to identify and quantify the capsinoids (naturally present E-capsiate and dihydrocapsiate) utilizing fruit obtained from a variety of Capsicum spp. in the U.S. Department of Agricultures Capsicum germplasm collection. Capsinoids were extracted with acetonitrile, filtered, and analyzed using an HPLC system equipped with a C(18) monolithic column, gradient pump, and diode array detector. The elution solvents were acetonitrile and water (60:40) with an isocratic flow rate of 1.0 mL/min. Forty-nine samples representing distinct morphotypes of four cultivated species ( C. annuum var. annuum, C. annuum var. glabriusculum, C. baccatum , C. chinense , and C. frutescens ) contained detectable levels (11-369 microg/g) of E-capsiate quantified at a wavelength of 280 nm. Nine of the E-capsiate-containing samples also had dihydrocapsiate (18-86 micro/g). Gas chromatography with a mass spectrometry detector (GC-MS) confirmed the presence of these compounds in the Capsicum spp.

Comparison of enzyme-linked immunosorbent assay and high-performance liquid chromatography for the analysis of atrazine in water from Czechoslovakia

Twenty-two water samples from Bohemian Paradise in Czechoslovakia were analyzed for atrazine (2-chloro-4-ethylamino-6-isopropylamino-l,3,5-triazine) by enzyme immunoassay (EIA) and high-performance liquid chromatography (HPLC). Three samples were drinking water, the others were creek water. The amount of atrazine found by EIA ranged from 0.2 to 12,700 ng/ml and 0.10 to 10,300 ng/ml by HPLC. Agreement between the methods was good. Nine samples containing the highest concentrations of atrazine were used to check the day-to-day reproducibility of both methods at high atrazine levels. The percent coefficients of variation (% CVs) ranged from 5.9 to 26.2 for the EIA and 1.5 to 33.2 for the HPLC. Day to day% CV values for each calibrator concentration ranged from 5.7 to 10.9 for EIA and 9.9 to 13.9 for HPLC. Sensitivity of the EIA was 0.2 ng/ml while it was 0.1 ng/ml for solid phase extraction HPLC and slightly less than 60 ng/ml for direct injection HPLC.

Pesticide testing by enzyme immunoassay at trace levels in environmental and agricultural samples

Pesticide testing is currently dominated by such chromatographic methods as high performance liquid chromatography (HPLC) and gas chromatography (GC). A generation of analytical chemists have experience with such methods and a vast amount of historical and reliable data has been accumulated with these methods and associated instrumentation. However, in the last 3–5 years there has been an increasing number of reports on the use of enzyme immunoassay (EIA) techniques for detecting pesticides. EIA technology is a well-known, accurate and reliable technique, widely utilized and in itself historically proven in both human and veterinary diagnostics. It is therefore logical and in fact inevitable that they would find application in the ‘environmental diagnostic’ marketplace. EIAs are antibody-based techniques combining the analyte-binding properties of the antibody with the signal amplication advantages of an enzyme. Although many varieties of EIAs (or ‘ELISA’: Enzyme Linked Immunosorbent Assays) exist, the format described herein utilizes antibody-coated plastic tubes or microwells. The antibodies, to various pesticides, were raised in rabbits and immobilized onto the solid phases by a proprietary process that provides long term stability and reactivity. The sample analyte (pesticide) plus peroxidase ‘tagged’ pesticide reagent (‘conjugate’) are simultaneously added to the tube or well and ‘compete’ for the antibody. Following a wash step and substrate addition, color is generated and the results interpreted: the lower the color, the greater the pesticide concentration. The concentration of analyte can be determined by comparison of the sample color to a standard curve prepared in parallel. EIAs have a number of advantages when compared to HPLC and GC methods. They are simple (suitable for ‘field’ use), sensitive (with detection limits of) ∼ 10–20 parts per trillion), specific (to classes or even individual compounds), rapid (results as quickly as 6–7 min) and inexpensive (typically US

Herbicide and plant growth regulator analysis by capillary electrophoresis

5–

Determination of hexazinone and its metabolites in groundwater by capillary electrophoresis

15). However, they are not always the most suitable method and care must be taken to avoid ‘false-positives’ by including appropriate controls. Immunoassays for the very low detection of atrazine (water and milk), procymidone and benomyl (wine) and paraquat (water) will be described together with correlative chromatography data.

Inhibition of acetyl cholinesterase by solanaceous glycoalkaloids and alkaloids

Capillary electrophoresis (CE) is a relatively new analytical technique that is just beginning to be employed in the area of pesticide residue analysis. With the development of more sensitive detectors and in conjunction with CE separation powers, it should be a well accepted technique for pesticide residue analysis in the future. This review describes CE methods that have been developed to analyze herbicides and grow regulators in water, soil and food.