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CHANG ET AL.: JOURNAL OF AOAC INTERNATIONAL V OL. 99, NO . 4, 2016 1049
RESIDUES AND TRACE ELEMENTS
High-Throughput Analytical Techniques for Determination of
Residues of 653 Multiclass Pesticides and Chemical Pollutants
in Tea, Part VI: Study of the Degradation of 271 Pesticide
Residues in Aged Oolong Tea by Gas Chromatography-
Tandem Mass Spectrometry and Its Application in Predicting
the Residue Concentrations of Target Pesticides
QIAO-YING CHANG
Yanshan University, College of Environmental and Chemical Engineering, Qinhuangdao, Hebei 066004, People’s Republic of
China
GUO-FANG PANG1
Yanshan University, College of Environmental and Chemical Engineering, Qinhuangdao, Hebei 066004, People’s Republic of
China; Chinese Academy of Inspection and Quarantine, Beijing 100176, People’s Republic of China
CHUN-LIN FAN and HUI CHEN
Chinese Academy of Inspection and Quarantine, Beijing 100176, People’s Republic of China
ZHI -BIN WANG
Yanshan University, College of Environmental and Chemical Engineering, Qinhuangdao, Hebei 066004, People’s Republic of
China
The degradation rate of 271 pesticide residues
in aged Oolong tea at two spray concentrations,
named a and b (a < b ), were monitored for 120 days
using GC–tandem MS (GC-MS/MS). To research
the degradation trends and establish regression
equations, determination days were plotted as
horizontal ordinates and the residue concentrations
of pesticide were plotted as vertical ordinates.
Here, we consider the degradation equations of
271 pesticides over 40 and 120 days, summarize
the degradation rates in six aspects (A–F), and
discuss the degradation trends of the 271 pesticides
in aged Oolong tea in detail. The results indicate
that >70% of the determined pesticides coincide
with the degradation regularity of trends A, B,
and E, i.e., the concentration of pesticide will
decrease within 4 months. Next, 20 representative
pesticides were selected for further study at higher
spray concentrations, named c and d (d > c > b >
a ), in aged Oolong tea over another 90 days. The
determination days were plotted on the x-axis, and
the differences between each determined result and
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plotted on the y -axis. The logarithmic function was
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allowing the degradation value of a target pesticide
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functions at d concentration were applied to
predict the residue concentrations of pesticides at
c concentration. Results revealed that 70% of the 20
pesticides had the lower deviation ratios of predicted
and measured results.
As one of the world’s three major health drinks, tea makes
up the majority of exported traditional commodities
of China. The tea plant is prone to be attacked by
various pests and diseases during its growth because it is
mostly planted in warm temperate zones and subtropical areas.
Different kinds of pesticides have been widely used to control
pests and plant diseases of tea in an effort to increase harvest
productivity. However, pesticide residues in tea may cause
damage to human health (1–4). With the strengthening of food
safety policies in different countries and regions of the world,
the awareness of pesticide residues in tea has generated great
public concern (5–8).
The study of degradation regularity of pesticides, together
with a model to simulate the dynamics in a tea sample, can be
applied to analyze and predict pesticide residues in tea. This
research is signi¿cant for guiding farmers to spray pesticides
on tea plants in a reasonable way and is helpful for predicting
the risk of pesticide residues in the tea trade. The degradation
of pesticides is a complex process affected by many factors,
including temperature, humidity, sunshine, metals, etc. (9,
10). Many studies have been carried out on the degradation
of pesticides in agricultural products using different kinetic
models (11–13). Ozbey and Uygun (14) investigated the
behavior of some organophosphorus pesticide residues in
peppermint tea during the infusion process. Manikandan et al.
(15) studied the leaching of certain pesticides, such as ethion,
endosulfan, dicofol, chlorpyrifos, deltamethrin, hexaconazole,
fenpropathrin, propargite, quinalphos, and Ȝ-cyhalothrin, from
powdered black tea into the brew. Lin et al. (16) studied the
Received March 03, 2016. Accepted by AK March 24, 2016.
1 Corresponding author’s e-mail:
Supplemental information is available on the J. AOAC Int. website,
DOI: 10-5740/jaoacint.16-0063