Detection of pesticides in popular medicinal herbs: a modified QuEChERS and gas chromatography–mass spectrometry based approach

Abstract

Although a lot of work has been conducted in the pesticide residues analysis in food matrices but the quality determination (with respect to major contaminants such as pesticide residues) in medicinal plant matrices has a long way to go. Hence a study was conducted to determine pesticide residues in four medicinal herbs, which are highly traded commodities in international market. Samples were extracted and cleaned up by modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) approach and analyzed by gas chromatograph-mass spectrometer (GC-MS). The method was subjected to thorough validation procedure in-terms of accuracy, precision, limits of quantification (LOQ), matrix effect, linearity and uncertainty analysis. The mean recoveries for most of the pesticides were in the range of 70-120% with RSD \20% and measurement uncertainties were less than 20% for all the compounds at spiking level of 0.5 mg kg -1 in all the matrices. The limits of quantification (LOQ) ranged from 0.01 to 0.069 mg kg -1 . The proposed method was successfully applied to determine pesticide residues in 52 commercial market samples obtained from different locations in India.

The pesticide residue analysis in commodities with high content of chlorophyll based on the quick, easy, cheap, effective, rugged, and safe method: A review

“…The necessity of using PSA as a cleanup sorbent was confirmed by Tripathy et al, who tested 11 active substances in medicinal herbs. The cleanup variant with MgSO 4 /PSA (with recoveries 64.3−119.7% and ME ± 40%) turned out to be better than other options, which included no cleanup (53.4−96.4%) and mixture MgSO 4 /C 18 (36.5−86.6%) [51]. It is not only the presence or absence of PSA that affects pesticide recovery, but also the amount of it.…”

“…Lowering the level of coextractives was an additional benefit of a smaller sample size [46]. The sample mass equal to 2 g is quite commonly used in herbs [43,51,52] and tobacco [40,53]. According to Lehotay, 15 g is the maximum sample size that can be used in 50 mL test tube [29].…”

“…The choice of extraction solvent plays an important role in QuEChERS sample preparation, since acting as a transferring agent it can lower the coextractives level and thereby it influences recoveries and ME [56]. The most frequently used solvent for QuEChERS extraction is acetonitrile due to the fact that it is effective for both polar and nonpolar pesticides as well as providing high recoveries in different matrices [38,47,51,57]. As indicated by Anastassiades et al acetonitrile has several advantages over acetone and ethyl acetate.…”

“…Therefore, to avoid negative consequences of such an exothermic reaction, different cooling approaches are used. A typical technique is to freeze the tube before adding the partition salts in temperatures −18 to −20 • C for 10−15 min [40,43,53] or longer for 30 min [51,59]. Also, employing ice bath for a while was reported to be used [57].…”

“…On the other hand, it should be noticed that in the presence of C 18 , a decrease of recoveries of some pesticides was also observed. Tripathy et al reported such cases with alpha-HCH, gamma-HCH, chlorpyrifos, pendimethalin, profenofos, and trifloxystrobin in the study of 11 pesticides in medicinal herbs [51]. Similarly, Rutkowska et al also observed that phenomenon for nonpolar pesticides as alpha HCH, beta-HCH, lindane, p,p'-DDE, p,p'-DDD, o,p'-DDT, and, p,p'-DDT in the article, where 235 active substances were tested for herbal samples [43].…”