Collision‐induced dissociation as “mass spectrometric filter” for rapid screening of tetrapyrrole derivatives and their chelated metal species in complex biological and environmental samples

Abstract

Rationale Cyclic tetrapyrroles, such as chlorophylls and their diagenetic derivatives, are structurally diverse and often chelated with certain metal species in the natural environment. A high throughput analytical method enabling quick tetrapyrrole screening in complex samples will promote the study of tetrapyrrole biogeochemistry and probably discoveries of new tetrapyrroles. Methods Total lipid extracts of biological and environmental samples were injected onto a C18 column to separate compounds with a reverse‐phase gradient. Collision‐induced dissociation (CID) was performed at different energy levels, from 40 to 200 eV, on a quadrupole time‐of‐flight mass spectrometry (QTOF‐MS) to identify cyclic tetrapyrroles in complex matrices. Results Under 200 eV CID cyclic tetrapyrroles exhibit a unique fragmentation behavior, the production of fragments larger than 300 Da. Utilizing such feature as a filter to extract product ions in the range of 300–500 Da, various cyclic tetrapyrrole derivatives are readily recognized in all tested biological and environmental samples. The 200 eV CID setup also dissociates chelated to porphyrin metals, including Cu, Fe, Mn, Ni, and V, as single‐charged ions for direct MS detection. Conclusions The 200 eV CID setup provides an efficient approach for the identification of cyclic tetrapyrroles, such as chlorophylls and fossil metalloporphyrins, in complex environmental samples. The direct detection of chelated to porphyrin metal ions with QTOF‐MS shows the potential for compound‐specific metal isotope analysis.

Tocopherols and associated derivatives track the phytoplanktonic response to evolving pelagic redox conditions spanning Oceanic Anoxic Event 2

“…The instrument setup for the analysis of TDs in this study was identical to previously published efforts, which document the development and application of an LC-qTOF-MS method capable of characterizing a broad range of analytes relevant to paleoenvironmental investigations (Connock et al, 2022;Liu, 2023). Briefly, an Agilent 1290 UPLC system was coupled to an Agilent 6530 qTOF mass spectrometer through an Agilent jet stream dual electrospray ionization (AJS-ESI) interface, where the ESI drying gas (N 2 ) temperature was set at 300°C with a flow rate of 8 L min −1 and the nebu- (1.8 μm, 2.1 × 150 mm) in series maintained at 35°C with the LC program set first from 100% A to 90% A and 10% B for 5 min, followed by a gradient to 35% B at 30 min, and to 50% B at 70 min, and finally re-equilibrated with 100% A for 10 min where the flow rate was 0.2 mL min −1 .…”

Streamlined Arsenolipid Identification via Direct Arsenic Detection Using RPLC-ESI-QTOF-MS with Collision-Induced Dissociation

“…This approach enables direct detection of organically bonded arsenic through high-voltage CID and high-resolution mass analysis with QTOF. A similar configuration has already been proven successful in the analysis of metalloporphyrins, and it promises to greatly facilitate the identification of other metal/metalloid-containing organic molecules, as well.…”