4
Diflubenzofuron
10.0%
Biphenyl-d10
7.5%
Biphenly
9.5%
o-Phenylphenol
8.2%
Fenobucarb
6.0%
Diphenylamin
5.7%
Terbutylazin
4.4%
Propyzamid
3.1%
Terbazil
5.8%
Fipronil-desulfinyl
6.9%
Alachlor
6.7%
Prometryn
8.3%
Ethofumesat
7.4%
Bromacil
8.3%
Chlorpyrifos
6.9%
Tetraconazol
6.2%
Triadimefon
11.7%
Dicapton
10.7%
Butralin
6.6%
Fipronil
5.5%
Penconazol
7.5%
Allethrin
8.4%
Pyrifenox
5.5%
Procymidon
5.7%
Triadimenol
11.5%
Picoxystrobin
7.0%
Flutriafol
6.3%
Hexaconazol
9.2%
Isoprothiolan
9.7%
Uniconazol
7.0%
Kresoxim-methyl
9.9%
Myclobutanil
9.2%
Flusilazol
4.4%
Cinerin 1
8.1%
Buprofezin
7.4%
Diclobutrazol
2.6%
Cyproconazol
2.6%
Chlorbenzilat
3.3%
Etoconazol
4.4%
Iprodion
11.1%
Diniconazol
2.9%
Aclonifen
9.0%
Trifloxystrobin
6.0%
Propiconazol
3.1%
Propargit
6.0%
Tebuconazol
4.3%
Nitralin
9.2%
Piperonyl butoxid
8.3%
Brompropylat
5.8%
Fenoxycarb
9.1%
Etoxazol
8.8%
Fenazaquin
3.3%
Metconazol
5.3%
Pyriproxyfen
8.5%
Fenamirol
8.5%
Fluquinconazol
4.9%
Pyridaben
5.2%
Etofenprox
10.2%
Silafluofen
10.2%
Indoxacarb
8.5%
Results from Real Life Samples
The above method was used for the analysis of a wide
variety of herbs, teas and dried fruit known as one of the
most challenging analytical task for controlling the
pesticide maximum residue levels due to the heavy matrix
impact. Table 3 gives a representative overview of positive
results from different samples with the indication of the
pesticide compound and concentration found. All
compounds were detected by using at least two SRM
traces and were subsequently confirmed by checking the
calibrated ion ratios. The concentration ranges covered
were from close to the MRL level of 10 mg/kg to high
levels of up to 50 times above the regulated maximum.
Figure 5 provides an example of confirmed residue
detection in a thyme sample.
Table 2. Coefficients of variation for lemon peel matrix spiked QC samples for a set of 60 pesticides under investigation (avg. 7.4%, 24 injections)
Sample Matrix
Pesticide
Residues Found
Concentration
(mg/kg)
Dried Herbs
o-Phenylphenol
0.017
Dried Herbs
Tebuconazol
0.023
Dried Fruit
Diflubenzuron
0.049
Dried Fruit
Myclobutanil
0.023
Dried Fruit
Propargit
0.479
Dried Fruit
Tebuconazol
0.081
Dried Fruit
Difenconazol
0.013
Dried Herbs
Picoxystrobin
0.228
Dried Herbs
Picoxystrobin
0.233
Dried Herbs
o-Phenylphenol
0.011
Herbal Tea
o-Phenylphenol
0.014
Herbal Tea
o-Phenylphenol
0.011
Herbal Tea
Terbutylazin
0.016
Table 3. Positive results above MRL level found in samples of
various matrices
Analytical Precision
Within a routine series of 50 commercial samples, the
quality control samples were measured with replicate
injections. The results for a range of compounds is given
in Table 2. The relative effects on known problematic
pesticide compounds can be seen, while coefficients of
variation (CV%) for unaffected compounds all stay well
below 10% even within this long series of matrix injections.
