Ja. Itak et al., DETERMINATION OF CAPTAN IN WATER, PEACHES, AND APPLE JUICE BY A MAGNETIC PARTICLE-BASED IMMUNOASSAY, Journal of AOAC International, 77(1), 1994, pp. 86-91
A magnetic particle-based enzyme-linked immunosorbent assay (ELISA) wa
s used to determine captan residues in water, peaches, and apple juice
. Precision studies of captan-spiked water samples showed coefficients
of variation (CVs) of 24% at 0.1 ppm and 15% at 2.0 ppm. Average reco
veries from water were 110-118%, with an estimated sensitivity of 0.01
ppm for captan. tow cross-reactivity was seen with the related phthal
imide fungicides captafol and folpet. A least-detectable dose (LDD) of
1 ppm was estimated for captafol in the immunoassay; an LDD of 8.6 pp
m was estimated for folpet. Apple juice samples were analyzed by a 3-s
tep procedure: the sample was concentrated on a Cls bonded silica soli
d-phase column, the eluate was diluted in buffer, and the sample was a
ssayed by ELISA. The detection limit in apple juice was estimated to b
e 0.1 ppm on the basis of the detection limit observed in water and th
e required calculation factors; the average recovery was 115%. Acetone
extraction, C rs bonded silica solid-phase extraction column, and the
immunoassay were used consecutively to analyze peach samples. The det
ection limit in peaches was estimated to be 0.15 ppm on the basis of t
he detection limit observed in water and the required calculation fact
ors. Captan residues were found in all but one of the peach samples an
d ranged from 0.15 to 1.12 ppm (mu g/g). Recovery of added captan from
peaches averaged 98% for both spike levels tested. Results of analysi
s of captan in peaches by immunoassay and gas chromatography with elec
tron capture detection (GC/ECD)were compared. GC/ECD gave an average r
ecovery of 75%; immunoassay gave an average recovery of 112%.