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A method has been developed for the sensitive and rapid analysis of polycyclic aromatic hydrocarbons (PAHs) in environmental samples using liquid chromatography time-of-flight mass spectrometry as well as the selective atmospheric pressure laser ionization (APLI) process (LC-APLI-MS). Upon analyzing 34 PAHs, the limits of detection of this method were found to range from 0.008 to 1.824 pg (0.024 pg for benzo[ a]pyrene). The method therefore provides 30-fold to 5,400-fold increased sensitivity compared with the established GC-MS technique. This LC-APLI-MS method was optimized for higher molecular weight PAHs (C-C PAHs with 6-8 rings), which are difficult to detect or cannot be detected by GC-MS. Using the LC-APLI-MS method, various 6- to 8-ring PAHs were detected in environmental samples for the first time. After developing the method, it was successfully validated in ruggedness tests. The concentrations determined by the LC-APLI-MS method were in good accord with the certified concentrations in three certified reference materials (contaminated soils and sediments). Upon applying the method to environmental samples, it was found that (1) the presence of dibenzo[ a, i]pyrene and dibenzo[ a, h]pyrene in urban soil samples could only be detected using LC-APLI-MS (i.e., not GC-MS) due to its high sensitivity, (2) a bituminous coal sample yielded 211 tentative peaks from aromatic compounds in the C-C range, and (3) eleven of those compounds occurred in different environmental samples in similar patterns. Hence, 6- to 8-ring PAHs occur in solid environmental samples in which other 6-ring PAHs such as indeno[1,2,3- cd]pyrene or benzo[ ghi]perylene may also be present. Some of these numerous higher molecular weight PAH compounds could have very high carcinogenic potential, which will need to be elucidated to ensure the reliability of PAH risk assessments. [ABSTRACT FROM AUTHOR]

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Atmospheric pressure laser ionization (APLI) (Constapel et al. in Rapid Commun Mass Spectrom 19:326-336, ; Schiewek et al. in Anal Chem 79:4135-4140, ; Schmitz and Benter (2007) J Chromatography Library 72:89-114) is an ultra-sensitive and selective ionization method for the determination of polycyclic aromatic compounds. The selectivity is an advantage but also a disadvantage. To overcome the limitation of APLI to aromatic compounds, we have already reported some derivatization strategies for common organic functional groups (Schiewek et al. in Angew Chem Int Ed 47:9989-9992, ). Here, we describe the synthesis of new APLI ionization labels and their use in new derivatization strategies. These new labels widen the range of APLI-(TOF)MS analysis to non-aromatic compounds with the most common functional groups such as amines, alcohols and carboxylic acids to gas chromatography (GC) and lower the limits of detection (LOD) down to concentrations as small as pmol/L and attomole on column. [ABSTRACT FROM AUTHOR]

The application of polycyclic aromatic hydrocarbon (PAH) analysis by gas chromatography coupled with atmospheric pressure laser ionization and mass spectrometry (GC-APLI-MS) to environmental samples was investigated in the study. The limit of detection for 40 PAH in a standard mixture was 5-100 fg, demonstrating GC-APLI-MS to be a highly sensitive technique and more sensitive by a factor of 100-3,500 compared to GC-MS. Acenaphthylene and cyclopenta[ cd]pyrene were not detectable <2,500 fg per injection. To make use of this very high PAH sensitivity, the technique was applied to samples of environmental interest with limited available sample amounts such as particulate matter (PM), soot and a sample from a bioaccumulation test with Lumbriculus variegatus. First, special sample preparation was necessary and ultrasonic extraction proved to be suitable, if a thorough clean-up was performed and plastic materials avoided. By GC-APLI-MS and GC-MS, 224 and 28 single PAH compounds were detected in PM, about 1,000 and 15 in birch soot, and 9 and 2 in worm tissue, respectively, revealing the enormous potential of the method. The selectivity of GC-APLI-MS was shown for a crude oil where >2,200 PAH were detected without any sample preparation. [ABSTRACT FROM AUTHOR]

Over the past decade, multimode ion sources operating at atmospheric pressure (i.e., more than one ionization method is operative in the ion source enclosure) have received considerable interest. Simultaneous operation of different ionization methods targeting different compound classes within one analysis run has several advantages, including enhanced sample throughput and thus significant laboratory cost reductions. Potential drawbacks are enhanced ion suppression and other undesirable effects of the simultaneous operation of ionization methods. In this contribution we present an alternative approach-the development and characterization of a widely applicable, multipurpose ion source operating at atmospheric pressure. The optimized source geometry allows rapid changing from LC-API methods (ESI, APCI, APLI) to GC-API methods (APCI, APLI, DA-APLI) along with the appropriate coupling of chromatographic equipment required. In addition, true multimode operation of the source is demonstrated for LC-ESI/APLI and LC-APCI/APLI. [ABSTRACT FROM AUTHOR]

Recently we have established atmospheric-pressure laser ionisation (APLI) as a method for coupling time-of-flight mass spectrometric detectors (TOF MS) with chromatographic systems (HPLC and GC) to allow two-photon ionisation of non-polar aromatic compounds. Here we demonstrate that APLI can be combined with chip-electrospray ionisation (cESI) coupled to Fourier-transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) for ultrahigh-resolution analysis of complex samples. With the laser turned off, the analytes are ionised only by ESI, whereas when the laser is switched on non-polar aromatic substances also are ionised. In combination with the extremely high mass resolution of an FT-ICR MS, simultaneous qualitative analysis of polar and non-polar analytes is possible in both positive and negative modes, as is exemplified with a crude oil sample. Nevertheless, ion suppression was observed (up to ca. 70% for D10-pyrene) and thus sample preparation with chromatographic or electrophoretic pre-separation is necessary for quantitative analysis of targets. In addition, for the first time, the dopant-assisted APLI method in combination with cESI (DA-cESILI) was used for determination of 1-nitrocoronene. [ABSTRACT FROM AUTHOR]