High‐performance liquid chromatography/inductively coupled plasma mass spectrometry and tandem mass spectrometry for the detection of carbon‐containing compounds

Abstract

High-performance liquid chromatography (HPLC) combined with inductively coupled plasma mass spectrometry (ICPMS) has been studied as a means for the detection of carbon to provide a 'universal' method for detecting organic compounds in chromatographic eluents. Carbon is particularly difficult to ionise and the amount of carbon present in normal chromatographic systems leads to high backgrounds, making detection a challenge. Novel separation approaches were therefore employed, using either entirely aqueous eluents (at temperatures of 60 and 160 degrees C, dependent on the column used) to eliminate the organic modifier completely, or isotopically enriched solvents. For the aqueous eluents, detection limits for sulphanilamide were found to be 2.26 microg, corresponding to 1.13 micromol (0.47 micromol of carbon), injected on a conventional 4.6 mm i.d. column. The use of a narrow bore column with highly isotopically enriched 12C-methanol (99.95 atom%) as organic modifier for the mobile phase enabled the detection of 86 micromol for 13C-triple-labelled caffeine and 79 micromol for 13C-double-labelled phenacetin. The sensitive detection of 12C-compounds with 13C-enriched methanol as organic modifier proved impractical due to a lower level of isotopic enrichment (99 atom%) of this solvent, with the residual 12C-methanol resulting in significant interference.

A Quantitative Universal Detection System for Organic Compounds in Gas Chromatography with Isotopically Enriched 13CO2

“…Postcolumn isotope dilution analysis has mostly been applied to ICP-detectable elements (trace-metal speciation). [7] However, there are only two reports so far of the use of ICPMS and the postcolumn (HPLC) addition of 13 C-labeled species (benzoic acid [8] and methanol [9] ) for the quantification of organic compounds. Clearly, the extremely low ionization yield of carbon in the plasma and the high carbon background under normal ICP operating conditions (atmospheric pressure) seriously hamper the use of this ionization source for the detection of carbon-isotope ratios.…”

Field flow fractionation online with ICP-MS as novel approach for the quantification of fine particulate carbon in stream water samples and soil extracts

“…† UV signals from both FFFsystems are suffering from detector overow (Fig. 4), but are matching well with the ICP-MS signal for 12 C regarding retention time and peak shape. The carbon signal from OCD is detected signicantly later at about 11 minutes.…”

“…S2 of the ESI. † The peak obtained for 12 C is noisier due to 40-fold lower signal intensity but still well above the LOD in spite of the low injection volume. In addition the larger particle size in soil extracts compared to water samples may contribute to increased signal noise, which is typically observed for metallic nanoparticles with increasing size.…”

“…In spite of the promising results from these initial studies, organic carbon monitoring by ICP-MS has been rarely applied. Recently, ICPtandem mass spectrometry was employed for carbon determination in plant digests, amino acids and peptides monitoring 12 14 Quantitative determination of particulate carbon in natural or engineered nanoparticles and colloids by FFF-ICP-MS has not been reported.…”

“…Carbon measurements were performed in medium resolution mode as previously optimised for monitoring of phosphorus using double focussing sector-eld ICP-MS (Element 2, Thermo Fisher Scientic, Bremen, Germany) equipped with concentric nebuliser and double-pass spray chamber. 12 C and 13 C were monitored as well as 9 Be as the internal standard. Initially, carbon background levels were monitored in deionised water using either glass or polystyrene vials with various treatments: (a) non treated, (b) acidied with 0.5% HCl, (c) acidied with 0.5% HCl and sonicated for 15 min, (d) acidied with 0.5% HCl and heated at 55 AE 5 C for 1 h, (e) acidied with 0.5% HCl and purged with Argon for 2 minutes.…”