Validation of an ultra-high-performance liquid chromatography-tandem mass spectrometry method to quantify illicit drug and pharmaceutical residues in wastewater using accuracy profile approach.

The analysis of biomarkers in wastewater has become a common approach to assess community behavior. This method is an interesting way to estimate illicit drug consumption in a given population: by using a back calculation method, it is therefore possible to quantify the amount of a specific drug used in a community and to assess the consumption variation at different times and locations. Such a method needs reliable analytical data since the determination of a concentration in the ngL-1 range in a complex matrix is difficult and not easily reproducible. The best analytical method is liquid chromatography - mass spectrometry coupling after solid-phase extraction or on-line pre-concentration. Quality criteria are not specially defined for this kind of determination. In this context, it was decided to develop an UHPLC-MS/MS method to analyze 10 illicit drugs and pharmaceuticals in wastewater treatment plant influent or effluent using a pre-concentration on-line system. A validation process was then carried out using the accuracy profile concept as an innovative tool to estimate the probability of getting prospective results within specified acceptance limits. Influent and effluent samples were spiked with known amounts of the 10 compounds and analyzed three times a day for three days in order to estimate intra-day and inter-day variations. The matrix effect was estimated for each compound. The developed method can provide at least 80% of results within ±25% limits except for compounds that are degraded in influent.

Development and validation of an isotope dilution ultra-high performance liquid chromatography tandem mass spectrometry method for the reliable quantification of 1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) and 14 other explosives and their degradation products in environmental water samples.

A comprehensive method for the determination and characterization of 15 common explosive compounds in water samples by ultra-high pressure liquid chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (APCI-MS/MS) is presented. The method allows the determination of 10 nitroaromatics, two nitroamines and three nitrate ester compounds. Among these, 1,3,5-Triamino-2,4,6-trinitrobenzene (TATB) was quantified and detected for the first time in our knowledge at trace levels (0.2 µg/L). Furthermore, the collision induced dissociation (CID) mass spectrum of TATB is discussed and a fragmentation mechanism is proposed. The signal for each explosive was normalized by isotopically-enriched congeners used as internal standards. The limits of detection (LOD) reached 20 ng/L, depending on the type of energetic molecule, which are adequate for water samples and the linearity was verified from 1.4 to 2 orders of magnitude. The sensitivity of the UHPLC-APCI-MS/MS approach allows direct injection of aqueous samples without preceding extraction for concentration. Besides, the method displays a good reliability with low signal suppression in various matrices such as spring water, mineral water, acidified water or ground water. The effectiveness of the method is demonstrated by the analysis of underground water samples containing traces of explosives from test fields in France.

ESI formation of a Meisenheimer complex from tetryl and its unusual dissociation.

The reactivity of the explosive tetryl (N-methyl-N,2,4,6-tetranitroaniline; Mw = 287 u) was studied using electrospray ionization in negative mode. The main species detected in the spectrum corresponds to the ion observed at m/z 318 (previously assumed to be the odd-electron ion [tetryl + HNO](-•), C7H6O9N6). In this study, we show using D-labeling combined with high-resolution mass spectrometry that this species corresponds to an even-electron anion (i.e. C8H8O9N5), resulting from the formation of a Meisenheimer complex between tetryl and the methanol used as the solvent. Fragmentation of this complex under CID conditions revealed an unexpected fragment: the formation of a 2,4,6-trinitrophenoxide anion at m/z 228. (18)O-labeling combined with quantum chemical calculations helped us better understand the reaction pathways and mechanisms involved in the formation of this product ion. This occurs via a transition state leading to a SN2-type reaction, consequently evolving toward an ion-dipole complex. The latter finally dissociates into deprotonated picric acid.