4
Sample Analysis
Approximately 200 pesticide compounds were included
in a routine screening method with an approximately
28 min total run time. The method setup as described
above was applied for analyzing samples bought from
the regional market.The results from analysis of market
samples are presented in Figure 4.
FIGURE 4. Traces of Chlorpyrifos ethyl and Kresoxim methyl were detected at 2.3 and 2.7 μg/kg respectively in regional market samples.
Conclusion
A rapid and sensitive quantitative method for a large
number of compounds is always a major goal for
analytical laboratories involved in pesticide analysis.
Within 28 minutes, 200 pesticides were screened
and quantitatively determined using the described
pesticide analysis method. The QuEChERS sample
preparation method provided high recoveries and
good reproducibility. The generic TRACE TR-5MS
column coupled with TRACEGuard provided good
chromatographic resolution of the pesticides studied.
The triple quadrupole mass analyzer TSQ 8000 GC-MS/MS
system with TraceFinder™ software was used for data
processing to reduce the processing time, thereby resulting
in a high throughput method space missing. Linearity,
specificity, recovery, and repeatability of the method
were established with minimal sample preparation time.
The TSQ 8000 system provided very high selectivity for
the sensitive detection and reliable quantitation of the
pesticides even from these samples with a high matrix
load from the short QuEChERS sample preparation.
This method can be utilized for detection and
confirmation of trace amounts of pesticides in difficult
matrices such as herbal churnas. The method has
potential to detect trace level compounds at concentration
as low as 2.5 ng/g. As per the available guidelines, the
concentration of the detected pesticides (0.0023 and
0.0027 mg/kg) were below the required limits of the
Unani Guidelines [3].
References
[1] Narayanaswamy, V., Origin and Development of
Ayurveda (A Brief History), Anc. Sci. Life, Jul-Sep
1(1) (1981) 1–7.
[2] The Pesticides Compound Database, Thermo Fisher
Scientific, Austin, TX, USA, 2013.
[3] Lohar, D.R., Protocol for testing guideline for
Ayurvedic, Siddha and Unani medicines Chapter
2.5.1, Government of India, Department of AYUSH,
Ministry of Health & FamilyWelfare, Pharmacopoeial
Laboratory for Indian Medicines, Ghaziabad, see
Table 2. MRM parameter for the pesticide compounds analyzed.
Nr.
Compound Name
RT
[min]
Quantitation
m/z
CE
[V]
Confirmation
m/z
CE
[V]
R
2
1.
Diflubenzuron (degr. i-cyanat
5.24
153.02 > 90.01
20
153.02 > 125.01
20
0.9969
2.
Diflubenzuron (degr. aniline)
5.75
127.01 > 65.01
30
127.01 > 100.01
30
0.9949
3.
Methamidophos
5.87
141.00 > 95.00
10
141.00 > 126.00
5
0.9930
4.
Dichlorphos (DDVP)
5.94
184.95 > 92.98
17
219.95 > 184.95
10
0.9960
5.
Dichlobenil
6.82
135.97 > 99.98
10
170.96 > 135.97
15
0.9960
6.
Mevinphos
7.39
127.03 > 109.02
10
192.04 > 127.03
12
0.9964
7.
Acephate
7.50
136.01 > 42.00
10
136.01 > 94.01
15
0.9904
8.
Dichloraniline, 3,5-
7.61
160.98 > 89.99
25
160.98 > 98.99
25
0.9989
9.
Molinate (Ordram)
8.58
126.07 > 55.03
10
187.10 > 126.07
10
0.9941
10.
TEPP
8.60
263.06 > 179.04
15
263.06 > 235.06
5
0.9946
11.
Omethoate
9.00
110.01 > 79.01
15
156.02 > 110.01
10
0.9969
12.
Fenobucarb
9.11
121.07 > 77.05
15
150.09 > 121.07
10
0.9977
