Novel method for chlorine determination in biofuel lipid feedstock by coupling a total sample introduction system (hTISIS) to an inductively coupled plasma tandem mass spectrometry (ICP-MS/MS).

BACKGROUND: Chlorine concentrations above 1 mg kg-1 in lipid feedstocks for biofuel production can generate corrosion issues in the different refining units as well as catalyst deactivation by clogging or fouling. To reach accurate analyses by inductively coupled plasma (ICP) techniques at low concentration levels, dilution in organic solvents rises as a simpler and more straightforward sample preparation methodology than conventional sample decomposition procedures (e.g., microwave-assisted acid digestion). However, matrix effects and the impact of the Cl chemical form on the signal must be overcome to obtain accurate results. RESULTS: In this work, the high temperature torch integrated sample introduction system (hTISIS) operated at 350 °C is coupled to an inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) for the determination of Cl in lipid biofuel feedstock samples diluted in xylene and these results are compared with those reported by a conventional sample introduction system. Under optimal conditions of the hTISIS-ICP-MS/MS configuration, matrix effects are efficiently overcome (recovery values ranged from 101 to 104%) as well as the effect of the Cl chemical form on the signal for 6 organochloride compounds. Thus, an external calibration approach can be set to carry out the quantification of this element in real samples. The method is successfully validated, obtaining a good agreement in the Cl concentration reported in a standard reference material (SRM NIST 1634c) and also by comparing the concentration results obtained by external calibration and standard addition approaches in two biofuel feedstock samples. SIGNIFICANCE AND NOVELTY: The hTISIS coupled to an ICP-MS/MS system is used for the first time to overcome not only matrix effects but also the impact of the Cl chemical form in biofuel feedstock samples. This novel method, with a limit of quantification (LOQ) of 7.1 µg kg-1, give access to an accurate Cl determination in all kind of lipid feedstocks for clean fuel production.

Delivery of amitriptyline by intravenous and intraperitoneal administration compared in the same animal by whole-body mass spectrometry imaging of a stable isotope labelled drug substance in mice.

BACKGROUND: The distribution and metabolism of a drug in the organism are dependent on the administration route as well as on the drug formulation. It is important to be able to assess which impact the administration route or formulation of a drug has for its distribution and metabolism. METHODS: The antidepressant drug amitriptyline was intravenously (IV) dosed to a mouse and immediately after, a similar amount of a deuterium-labeled version of the drug was intraperitoneally (IP) dosed to the same animal. Whole-body cryo-sections were made at t = 5, 15, 30, and 60 min post-dosing, and the two drug substances and metabolites were imaged by DESI-MS/MS. RESULTS: After 5 min, the IV dosed drug was detected throughout the animal, while the IP dosed drug was primarily found in the abdominal cavity. At later times, the differences between the two administration routes became less pronounced. Two administration routes provided highly similar metabolite distributions, also at early time points. CONCLUSION: The method provides a unique way to compare delivery and metabolism of a drug by different administration routes or formulations in the very same animal, eliminating uncertainties caused by animal-to-animal variation and avoiding the use of radioactive labeling.