3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
Table II
Schedule of the treatment against storage diseases
Code
Pesticide preparation [kg ha –1 ]
Application date
active ingredient – safety period
S1 – –
S2
Delan 700 WG (0.7)
dithianon – 21 days
September 19, 2007
S3
Thiram Granuflo (3.0)
thiram – 14 days
September 26, 2007
S4
Zato 50 WG (0.15)
trifloxystrobin – 14 days
September 26, 2007
A n a l y t i c a l M e t h o d s
Most of pesticides were liquid chromatography (LC)
amenable, so for isolation of 14 from 17 examined analytes
the QuEChERS method 3 was applied. Crude extract (without
cleanup step realized with primary-secondary amine (PSA))
was examined by LC coupled with tandem mass spectrometry
(MS/MS). Limits of quantitation (LOQ) for these
pesticides were 0.002 mg kg –1 , only for dodine LOQ was
0.005 mg kg –1 . Ethylenbisdithiocarbamates (EBDC), in this
study represented by mancozeb, metiram and thiram, were
determined as a sum by solid phase micro-extraction (SPME)
of their degradation product (carbon disulfide), identification/
quantitation was performed by gas chromatography coupled
with mass spectrometry (GC-MS), LOQ was 0.001 mg kg –1 .
s808
Results
At the time of harvest, residues of some pesticides (acetamiprid,
cyprodinil, flufenoxuron, fluquinconazole, fenoxycarb,
tetraconazole and thiacloprid) used for treatment
(Table I) were not detected. Other pesticides exceeding the
method LOQ could be grouped into three categories based
on their concentration levels: (i) compounds with residues
below 0.01 mg kg –1 at the time of harvest (i.e. difenoconazole,
dithianon, methoxyfenozide, EBDC), (ii) compounds with
residues exceeding the “baby food” limit at the harvest time,
but declining below the limit at the end of the storage period
(i.e. bitertanol, etofenprox) and (iii) compounds with residues
not significantly declining and exceeding the 0.01 mg kg –1 all
the time (i.e. dodine, pyrimethanil). no generalization on the
relationship between residues dynamics and apple variety
could be drawn. The highest amount of bitertanol residues
occurred in variety Golden Delicious (Fig. 1. A) and etofenprox
residues was the highest in variety Idared (Fig. 1. B) in
all experiments. Worth to notice that the changes of pesticides
classified as concentration category (iii) were not dependent
on apple variety.
Treatment for post-harvest disease protection was carried
out before the harvest in compliance with required safety
period. For this purpose three fungicide preparations with
different active ingredients (dithianon, thiram and trifloxystrobin)
were tested (Table II). Thiram, although applied only
14 days before the harvest, did not exceed “baby food” limit,
Fig. 1. The dynamics of selected pesticides during cold storage (1–3 ºC); A: bitertanol, B: etofenprox, C: trifloxystrobin,
D: dithianon