An interface between nanoHPLC and ICP-MS was developed. It allowed the stable introduction into an ICP of mobile phases containing up to 90% of acetonitrile at flow rates of less than 500 nL min⁻¹. The on-line post-column addition of an isotopically enriched spike at flow rates of less than 4 μL min⁻¹ enabled isotope dilution quantification of heteroatom containing analytes while the consumption of the labelled isotope was low. The coupled system was applied to the accurate, sensitive and specific determination of selenopeptides in nanolitre volumes (11 nL) of a tryptic digest of selenomethionyl calmodulin (17002 Da). The peptides were separated by reversed phase nanoLC (340 nL min⁻¹ flow rate) whereas ICP collision cell MS was used for the simultaneous detection of ⁸⁰Se (analyte) and ⁷⁶Se (spike). The absolute detection limit was 40 fg (⁸⁰Se), a factor of 2 less than ever reported for a capillary HPLC-ICP-MS coupling. The sensitivity was constant during the chromatogram, regardless of the percentage of acetonitrile in the mobile phase. The selenium recovery was 103 ± 4%. For selenopeptide analysis the sum of Se determined in each of the peaks equalled the total Se injected on the column. Since the tryptic peptides, miscleaved and/or oxidized peptides, incompletely digested protein and undigested protein could be determined in one run, the method allowed the precise evaluation of the efficiency and quality of tryptic digestion using several nanolitres of sample only.

A sensitive analytical procedure based on nano-volume flow injection (FI) and inductively coupled plasma double-focusing sector field mass spectrometry (ICP-SFMS) was developed for the ultratrace determination of uranium and plutonium. A 54-nl sample was injected by means of a nanovolume injector into a continuous flow of carrier liquid at 7 μl min⁻¹ prior to ICP-SFMS. The absolute detection limits were 9.1 × 10⁻¹⁷ g (3.8 × 10⁻¹⁹ mol, ∼230000 ²³⁸U atoms) and 1.5 × 10⁻¹⁷ g (6 × 10⁻²⁰ mol, ∼38000 ²⁴²Pu atoms) for uranium and plutonium, respectively. The method was validated for the determination of the uranium isotope ratios by the analysis of a certified isotope reference material (NIST U350). The analysis of a contaminated urine sample showed the enriched uranium to be the origin of contamination. Another application concerned the determination of plutonium at the subfemtomolar level in water with a detection limit down to the ag ml⁻¹ range (6 × 10⁻¹⁸ g ml⁻¹).

Asphaltenes, as the heaviest and most polar fraction of petroleum, have been characterized by various analytical techniques. A variety of fractionation methods have been carried out to separate asphaltenes into multiple subfractions for further investigation, and some of them have important reference significance. The goal of the current review article is to offer insight into the multitudinous analytical techniques and fractionation methods of asphaltene analysis, following an introduction with regard to the morphologies of metals and heteroatoms in asphaltenes, as well their functions on asphaltene aggregation. Learned lessons and suggestions on possible future work conclude the present review article.