Robert O. Harrison

Evaluation of an enzyme‐linked immunosorbent assay (ELISA) for the direct analysis of molinate (Ordram®) in rice field water

A direct ELISA for the thiocarbamate herbicide molinate was used to study distribution and dissipation of the compound in a treated rice field. No sample preparation other than buffering and dilution was required for the analysis of field water samples. Analyses were performed in 96‐well microplates and required less than 0–5 man‐hour per sample (three dilutions per sample, four replicate wells per dilution). Spiked samples and selected field samples were split for analysis by ELISA and gas chromatography. Two control samples of 92 and 93 ppb (after dilution) had between run coefficients of variation of 13.8 and 13.9% for 37 ELISA runs. A nested ANOVA analysis revealed that the largest source of error for the ELISA was due to within replicate variability, partly attributable to interwell variability of the 96‐well plates. Practical aspects of reducing assay error and handling ELISA data are discussed. Quality control data showed that reliability of the direct ELISA is comparable to the gas chromatography ...

Determination of atrazine and simazine in water and soil using polyclonal and monoclonal antibodies in enzyme‐linked immunosorbent assays

An enzyme‐linked immunosorbent assay (ELISA) was developed as a rapid, reproducible and cost‐effective method for routine analysis of atrazine and simazine in environmental samples. Atrazine recoveries from C18 solid phase extractions (SPE) of water spiked from 0.1 ppb to 100 ppb showed good correlations with gas chromatography (GC), [14C] atrazine radioassay and ELISA methods. The C18 cartridges demonstrated very good recovery for extracting and concentrating the herbicide by all three analytical methods. Comparison between ELISA and GC for analysis of 75 well water samples showed no false negatives and a low (5%) occurrence of false positives. Soil extracts from a controlled simazine spill were also analyzed by GC and ELISA, with excellent correlation between the two methods. Characterization of the s‐triazine assay for tolerance to organic solvents and salts demonstrated the method to be resistant to such modifiers. Additionally, comparison of two monoclonal and two polyclonal antibodies raised against...

Statistical design of ELISA protocols

This paper shows how to obtain accuracy and efficiency in an ELISA analysis by allocating the wells on a 96-well microplate between calibration and determination of unknowns, and by choosing the known concentrations for calibration. The method also can determine how much is lost in precision by using a convenient but non-optimal protocol.