NEW RAPID ANALYSIS OF TWO CLASSES OF PESTICIDES IN FOOD WASTEWATER BY QuEChERS-LIQUID CHROMATOGRAPHY/MASS SPECTROMETRY

Abstract

The rapid analytical method was developed in response to increasing concern over the environmental impact of azoles (sterol biosynthesis inhibitors) and neonicotinoids (nicotinic acetylcholine receptor site). These chemicals are commonly used to protect fruit and vegetables crops against fungi and pests. Seven insecticides and twenty one fungicides commonly occurring in food industrial wastewater have been determined. For this purpose, active substances from two new pesticide classes were extracted and isolated by QuEChERS by addition of acetonitrile, buffering salts and chitin as a clean-up sorbent. The novelty of this procedure was one step sample preparation including extraction and removing of co-extracts in short time. Instrumental analysis was conducted by liquid chromatography coupled with mass spectrometry using multiple reaction monitoring. The limits of detection ranged from 0.05 to 0.2 µg/L with satisfactory sensitivity (limits of detection below 30 ng/L), accuracy and precision. The recoveries for the pesticides ranged from 81-103%, with high repeatability (n = 3, RSD ≤ 9%) and low LOQs (0.6-0.9 ng/L). Matrix effects calculated were less than 12% for all analyses. The method was applied to routine analysis of food industrial wastewater. Concerning the results, total pesticide levels in most cases were below 1 μg/L. The most significant pesticides in terms of concentration and frequency of detection were acetamiprid (0.07 μg L-1); tebuconazole (1.2 μg L-1) and thiacloprid (0.04 μg L-1).

Keywords

• wastewater
• LC-MS/MS
• QuEChERS
• azole
• neonicotinoids