Pesticides in essential oils: Occurrence and concentration in organic and conventional orange essential oils from eleven geographical origins.

In this paper is described for the first time the application of both gas chromatography-tandem mass spectrometry (GC-MS/MS) and ultra performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-QTOF-MS) to the determination of 75 priority pesticides in orange essential oils (EOs). The sample preparation consisted in a 10-fold dilution of orange EO followed by a direct injection for GC-MS/MS technique and a freeze-out step in the case of UPLC-QTOF-MS analysis. The analytical methods were validated using the SANCO criteria and gave reporting limits (RLs) of 10 µg L-1, 25 µg L-1, 50 µg L-1 and 100 µg L-1 for 57, 13, 4 and 1 pesticides, respectively. The analysis of four others EOs in the context of a proficiency test demonstrated very good performance and versatility of the methods with a detection rate of 100%, 97.8% of correct quantifications and no false negative. Then 49 orange EOs of known origin and quality were analysed using the standard addition procedure. It enabled to highlight significant matrix effects leading to differences in response factor up to 9.0 in GC-MS/MS and 53.1 in UPLC-QTOF-MS, between an orange EO sample to another. It was found that a conventional EO contained on average 17 pesticides for a total concentration of 5.1 mg L-1. Up to 29 different pesticides, 39 in the case of a concentrated EO, were detected in one sample and the sum of the concentration reached 51.1 mg L-1. Regarding the organic samples, none were free of pesticides but the contamination was found to be clearly lower than in conventional EOs. It was found that an organic orange EO contained on average 4 pesticides for a total concentration of 0.087 mg L-1.

A workflow for multiclass determination of 256 pesticides in essential oils by liquid chromatography tandem mass spectrometry using evaporation and dilution approaches: Application to lavandin, lemon and cypress essential oils.

This paper describes the determination of 256 multiclass pesticides in cypress and lemon essential oils (EOs) by the way of liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI/MS/MS) analysis using the scheduled selected reaction monitoring mode (sSRM) available on a hybrid quadrupole linear ion trap (QLIT) mass spectrometer. The performance of a sample preparation of lemon and cypress EOs based on dilution or evaporation under nitrogen assisted by a controlled heating were assessed. The best limits of quantification (LOQs) were achieved with the evaporation under nitrogen method giving LOQs≤10µgL(-1) for 91% of the pesticides. In addition the very satisfactory results obtained for recovery, repeatability and linearity showed that for EOs of relatively low evaporation temperature, a sample preparation based on evaporation under nitrogen is well adapted and preferable to dilution. By compiling these results with those previously published by some of us on lavandin EO, we proposed a workflow dedicated to multiresidue determination of pesticides in various EOs by LC-ESI/sSRM. Among the steps involved in this workflow, the protocol related to mass spectrometry proposes an alternative confirmation method to the classical SRM ratio criteria based on a sSRM survey scan followed by an information-dependent acquisition using the sensitive enhanced product ion (EPI) scan to generate MS/MS spectra then compared to a reference. The submitted workflow was applied to the case of lemon EOs samples highlighting for the first time the simultaneous detection of 20 multiclass pesticides in one EO. Some pesticides showed very high concentration levels with amounts greatly exceeding the mgL(-1).

Behavior of Multiclass Pesticide Residue Concentrations during the Transformation from Rose Petals to Rose Absolute.

This study investigates the concentrations of 54 multiclass pesticides during the transformation processes from rose petal to concrete and absolute using roses spiked with pesticides as a model. The concentrations of the pesticides were followed during the process of transforming the spiked rose flowers from an organic field into concrete and then into absolute. The rose flowers, the concrete, and the absolute, as well as their transformation intermediates, were analyzed for pesticide content using gas chromatography/tandem mass spectrometry. We observed that all the pesticides were extracted and concentrated in the absolute, with the exception of three molecules: fenthion, fenamiphos, and phorate. Typical pesticides were found to be concentrated by a factor of 100-300 from the rose flowers to the rose absolute. The observed effect of pesticide enrichment was also studied in roses and their extracts from four classically phytosanitary treated fields. Seventeen pesticides were detected in at least one of the extracts. Like the case for the spiked samples in our model, the pesticides present in the rose flowers from Turkey were concentrated in the absolute. Two pesticides, methidathion and chlorpyrifos, were quantified in the rose flowers at approximately 0.01 and 0.01-0.05 mg kg(-1), respectively, depending on the treated field. The concentrations determined for the corresponding rose absolutes were 4.7 mg kg(-1) for methidathion and 0.65-27.25 mg kg(-1) for chlorpyrifos.

New biomarkers of coffee consumption identified by the non-targeted metabolomic profiling of cohort study subjects.

Coffee contains various bioactives implicated with human health and disease risk. To accurately assess the effects of overall consumption upon health and disease, individual intake must be measured in large epidemiological studies. Metabolomics has emerged as a powerful approach to discover biomarkers of intake for a large range of foods. Here we report the profiling of the urinary metabolome of cohort study subjects to search for new biomarkers of coffee intake. Using repeated 24-hour dietary records and a food frequency questionnaire, 20 high coffee consumers (183-540 mL/d) and 19 low consumers were selected from the French SU.VI.MAX2 cohort. Morning spot urine samples from each subject were profiled by high-resolution mass spectrometry. Partial least-square discriminant analysis of multidimensional liquid chromatography-mass spectrometry data clearly distinguished high consumers from low via 132 significant (p-value<0.05) discriminating features. Ion clusters whose intensities were most elevated in the high consumers were annotated using online and in-house databases and their identities checked using commercial standards and MS-MS fragmentation. The best discriminants, and thus potential markers of coffee consumption, were the glucuronide of the diterpenoid atractyligenin, the diketopiperazine cyclo(isoleucyl-prolyl), and the alkaloid trigonelline. Some caffeine metabolites, such as 1-methylxanthine, were also among the discriminants, however caffeine may be consumed from other sources and its metabolism is subject to inter-individual variation. Receiver operating characteristics curve analysis showed that the biomarkers identified could be used effectively in combination for increased sensitivity and specificity. Once validated in other cohorts or intervention studies, these specific single or combined biomarkers will become a valuable alternative to assessment of coffee intake by dietary survey and finally lead to a better understanding of the health implications of coffee consumption.

Multiresidue determination of 256 pesticides in lavandin essential oil by LC/ESI/sSRM: advantages and drawbacks of a sampling method involving evaporation under nitrogen.

The determination of 256 multiclass pesticides in lavandin essential oil has been performed by liquid chromatography-electrospray ionization tandem mass spectrometry using the scheduled selected reaction monitoring mode available on a quadrupole-linear ion trap mass spectrometer. With the aim of improving the limits of quantification (LOQs) of the target molecules, a sampling step based on evaporation of the essential oil under a nitrogen flow assisted by controlled heating was tested. The LOQs determined in this case were compared with the values obtained with the classic dilution preparation method. With sampling by dilution, 247 pesticides were detected and quantified at low concentration, with 74 % of the pesticides having LOQs of 10 µg L(-1) or less. With the evaporation method, a global improvement of the LOQs was observed, with lower LOQs for 92 active substances and LOQs of 10 µg L(-1) or less for 82.8 % of the pesticides. Almost twice as many active substances had an LOQ of 1 µg L(-1) or less when the evaporation method was used. Some pesticides exhibited poor recovery or high variance caused by volatilization or degradation during the evaporation step. This behavior was evidenced by the case of thiophanate-methyl, which is degraded to carbendazim.

Multiresidue analysis of multiclass pesticides in lavandin essential oil by LC/MS/MS using the scheduled selected reaction monitoring mode.

In this paper we describe the development of the first multiclass pesticide residue method applied to essential oils. A total of 70 pesticides covering a wide range of polarity and currently used on essential oil crops have been included in the method. The procedure consists of a 10-fold dilution of lavandin essential oil followed by a direct injection analysis by liquid chromatography/tandem mass spectrometry. The system used is an API 4000 QTrap equipped with an electrospray ionization interface and operating in scheduled selected reaction monitoring acquisition mode. Matrix effects were evaluated by comparing the slopes of matrix-matched and solvent-based calibration curves. Weak signal suppression or enhancement (<20%) was observed for most of the compounds. Method sensitivity was determined statistically by the injection of five matrix-matched calibration curves with the distribution's normality and the variance's homogeneity checked before establishment of a suitable regression model. Limits of detection (LODs) and quantification (LOQs) were then determined using the blank standard's deviation and the slope of the mean curve. The analytical method has been validated for 67 of the 70 pesticides and meets the following LOQs: ≤1 µg/L for 9 pesticides, ≤5 µg/L for 44, ≤10 µg/L for 9, and ≤20 µg/L for 5.

Advantages of the scheduled selected reaction monitoring algorithm in liquid chromatography/electrospray ionization tandem mass spectrometry multi-residue analysis of 242 pesticides: a comparative approach with classical selected reaction monitoring mode.

This paper illustrates the advantages of using the scheduled selected reaction monitoring (sSRM) algorithm available in Analyst Software 1.5 to build SRM acquisition methods in the application field of pesticide multi-residue analysis. The principle is to monitor the SRM transitions only when necessary. Based on the analytes' retention times, the scheduled SRM algorithm decreases the number of concurrent SRM transitions monitored at any point in time, allowing both cycle time and dwell time to remain optimal at higher levels of SRM multiplexing. To compare the scheduled SRM and the classical SRM modes, a mixture containing 242 multi-class pesticides has been analyzed ten times by three acquisition methods, using liquid chromatography/tandem mass spectrometry (LC/MS/MS) with an API 4000 QTrap mass spectrometer. The scheduled SRM mode demonstrates better results in all fields: more data points per peak, better reproducibility (coefficients of variation (CVs) <5%) and higher signal-to-noise ratio (S/N), even when the number of SRM transitions is doubled. The use of scheduled SRM mode instead of the classical one gives an enhancement of the limits of quantification by a factor two or even higher (up to six), depending on the analyte transitions.