Evaluation and prevention of the negative matrix effect of terpenoids on pesticides in apples quantification by gas chromatography–tandem mass spectrometry

Abstract

The sample matrix can enhance the gas chromatography signal of pesticide residues relative to that obtained with the same concentration of pesticide in solvent. This paper is related to negative matrix effects observed in coupled gas chromatography-mass spectrometry ion trap (GC/MS) quantification of pesticides in concentrated extracts of apple peel prepared by the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) method. It is focused on the pesticides most frequently used on the apple varieties studied, throughout the crop cycle, right up to harvest, to combat pests and diseases and to improve fruit storage properties. Extracts from the fleshy receptacle (flesh), the epiderm (peel) and fruit of three apple varieties were studied by high-performance thin-layer chromatography hyphenated with UV-vis light detection (HPTLC/UV visible). The peel extracts had high concentrations of triterpenic acids (oleanolic and ursolic acids), reaching 25mgkg, whereas these compounds were not detected in the flesh extracts (<0.05mgkg). A significant relationship has been found between the levels of these molecules and negative matrix effects in GC/MS. The differences in the behavior of pesticides with respect to matrix effects can be accounted for by the physicochemical characteristics of the molecules (lone pairs, labile hydrogen, conjugation). The HPTLC/UV visible method developed here for the characterization of QuEChERS extracts acts as a complementary clean-up method, aimed to decrease the negative matrix effects of such extracts.

Rapid and High-Throughput Determination of Sixteen β-agonists in Livestock Meat Using One-Step Solid-Phase Extraction Coupled with UHPLC-MS/MS

“…where ka is the slope of the matrix-matched standard curve; kb is the slope of the reagent standard curve. When ME > 1, it indicates a matrix enhancement effect; when ME < 1, it indicates a matrix inhibition effect, and when ME = 1, then there is no matrix interference [22]. The Matrix Effect (ME), which has an impact on the accuracy of the quantitative results, is the interference of other components in the sample with the analytical process of the target compound [21].…”

“…where k a is the slope of the matrix-matched standard curve; k b is the slope of the reagent standard curve. When ME > 1, it indicates a matrix enhancement effect; when ME < 1, it indicates a matrix inhibition effect, and when ME = 1, then there is no matrix interference [22].…”

The apple-matrix effect on GC/MS response of cyprodinil, pyrimethanil and trifloxystrobin standards

“…Apple fruits possess a cuticle with the mixture of C16-C18 chained compounds mainly composed of saturated and unsaturated dihydroxy hexadecenoic, trihydroxy and epoxy hydroxy octadecanoic acids and a triterpenoid-rich cuticular wax mixture [12]. In one study, a significant relationship between triterpenic acids (oleanolic and ursolic acids) was recognized, found in much higher concentrations in the apple peel than in the flesh, and a negative matrix effect in GC/ MS 2 [13]. The most abundant components of the peel wax of Granny Smith variety are compounds such as pentacosane, nonacosane and unsaturated fatty acids like C20:3n6, C18:2n6, C18:3n3, C22:2, C14:1, C16:1 [14].…”

Screening for Astragalus hamosus Triterpenoid Saponins Using HPTLC Methods: Prior Identification of Azukisaponin Isomers

“…The samples were applied to silica plates with the ATS3 CAMAG autosampler (Muttenz, Switzerland). Two different development systems were chosen: (i) System S1 (30 mL of chloroform, 15 mL of hexane, and 5 mL of methanol) [ 56 ], and (ii) System S2 (SS1, SS2, and SS3) [ 57 ]: SS1: Dichloromethane and MeOH (92: 8) up to 26 mm for methylxanthines; SS2: EtOAc, toluene, formic acid, and H 2 O (8.7: 1.3: 1.7: 0.4) up to 70 mm for phenolic compounds; SS3: EtOAc, toluene, formic acid, and H 2 O (9: 1: 2.5: 1) up to 70 mm for saponins. …”