Screening test to detect meat adulteration through the determination of hemoglobin by cation exchange chromatography with diode array detection.

A simple sample preparation procedure, consisting of an extraction step with Milli-Q water as extraction solvent for hemoglobins from meat samples, followed by a filtration step with a cellulose acetate filter, is applied. After cation exchange chromatographic separation and diode array detection, different peak patterns for extracted hemoglobins of cow, lamb or pork meat are obtained. Other heme-group containing proteins like myoglobin or cytochrome C, which could be also detected with diode array detection at 416 nm, are chromatographically separated from the hemoglobins. By the use of these characteristic peak patterns, the species of the meat can be specified permitting the qualitative assessment of meat adulteration with the proposed screening method.

Universal screening method for the determination of US Environmental Protection Agency phenols at the lower ng l(-1) level in water samples by on-line solid-phase extraction-high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry within a single run.

The applicability of a previously optimized method for the analysis of the US Environmental Protection Agency (EPA) regulations phenols, based on on-line solid-phase extraction coupled to liquid chromatography with mass spectrometric (MS) detection in different matrix loaded water samples is demonstrated. The comprehensive optimization of the mobile phase conditions and their influence on the ionization process in atmospheric pressure ionization is described in detail. In particular, MS detection of the weakly acidic phenols such as phenol, monochlorinated phenols and methylated phenols requires the absence of acidic mobile phase modifiers and buffers. Thus lower retention times and slight peak broadening of the more acidic dinitrophenols are obtained if the entire range of EPA phenols is analyzed within a single chromatographic run. The figures of merit for the method were determined and the applicability to real water samples was investigated. Limits of detection for phenols ranging from 40 to 280 ng l(-1) and relative standard deviations below 8% in SCAN mode are obtained for all phenols if only 10-ml river water samples with low dissolved organic carbon (DOC 5 mg C l(-1) concentrations are preconcentrated. The method was used to detect 2-nitrophenol and 4-nitrophenol in river water samples in the lower ng l(-1) range. The analysis of highly matrix-loaded samples (DOC 210 mg C l(-1)) requires a reduced enrichment volume resulting in decreased sensitivity. Still the method is capable of reaching excellent detection limits which demonstrates its excellent suitability for screening analysis.

Hydrolysis of the tumor-inhibiting ruthenium(III) complexes HIm trans-[RuCl4(im)2] and HInd trans-[RuCl4(ind)2] investigated by means of HPCE and HPLC-MS.

High performance capillary electrophoresis (HPCE) as well as high performance liquid chromatography-mass spectrometry (HPLC-MS) have been applied to the separation, identification and quantification of the tumor-inhibiting ruthenium compounds HIm trans-[RuCl4(im)2] (im = imidazole) and HInd trans-[RuCl4(ind)2] (ind = indazole) and their hydrolysis products. The half-lives for the hydrolytic decomposition of the Ru(III) compounds were determined by monitoring the relative decrease of the original complex anion under different conditions by means of capillary electrophoresis. The decomposition follows pseudo-first-order kinetics. The rate constants in water at 25 degrees C are 1.102 +/- 0.091 x 10(-5) s-1 for HIm trans-[RuCl4(im)2] and 0.395 +/- 0.014 x 10(-5) s-1 for HInd trans-[RuCl4(ind)2]. About 8% of HIm trans-[RuCl4(im)2] but only about 2% of HInd trans-[RuCl4(ind)2] were hydrolyzed after 1 h at room temperature. Whereas the hydrolysis rate of the imidazole complex is independent of the pH value, the indazole complex hydrolyzes much faster at higher pH. The half-life of HInd trans-[RuCl4(ind)2] in phosphate buffer at pH 6.0 and 37 degrees C is 5.4 h, whereas it is less than 0.5 h at pH 7.4. In contrast to the imidazole complex, where no dependence on the buffer system was observed, hydrolysis of the indazole complex is even faster if a buffer containing hydrogen carbonate is used. The formation of [RuCl2(H2O)2(im)2]+ could be demonstrated by HPLC-MS measurements. In the case of the indazole complex, a release of the indazole ligands results in the formation of [RuCl4(H2O)2]-.

Phenyl-modified reversed-phase liquid chromatography coupled to atmospheric pressure chemical ionization mass spectrometry: a universal method for the analysis of partially oxidized aromatic hydrocarbons.

A new liquid chromatographic method for the efficient separation of aromatic compounds having a wide range of sizes, molecular structures, and polarities has been developed. Based on a phenyl-modified silica reversed stationary phase and a methanol-water solvent gradient, it allows the separation of mono- and polycyclic aromatic hydrocarbons (PAHs) having up to five condensed aromatic rings and partially oxidized derivatives within a single chromatographic run of 40-min duration. The applicability of the method is demonstrated using 81 reference substances (PAHs, phenols, quinones, acids, lactones, esters, etc.) and real samples of environmental, medical, and technical relevance (ozonized PAHs, lake water, human urine, diesel exhaust condensates). The retention times of the investigated aromatics exhibit a regular increase with molecular mass and a systematic decrease with increasing number and polarity of functional groups. In case of intramolecular hydrogen bonding, a positive shift of retention time provides additional structural information. The combination of chromatographic retention time with the molecular mass and structural information from mass spectrometric detection allows the tentative identification of unknown aromatic analytes at trace levels, even without specific reference substances. With atmospheric pressure chemical ionization (APCI), low detection limits and highly informative fragmentation patterns can be obtained by in-source collision-induced fragmentation in a single-quadrupole LC-APCI-MS system as applied in this study, and multidimensional MS experiments are expected to further enhance the potential of the presented method.

Comparison of different sorbent materials for on-line solid-phase extraction with liquid chromatography-atmospheric pressure chemical ionization mass spectrometry of phenols.

On-line solid-phase extraction (SPE) was interfaced to liquid chromatography with atmospheric pressure chemical ionization mass spectrometry (HPLC-APCI-MS) for the determination of US Environmental Protection Agency (EPA) phenols. The system, allowing fully automated operation, was used to evaluate different SPE cartridge materials and dimensions. Six different SPE materials (C18 HD, Polymer Labs PLRP-s, Hamilton PRP-1, Hysphere GP, Hysphere SH and Waters Oasis) were tested. Criteria for their comparison were first the recovery for the different phenols and its reproducibility, but also chromatographically relevant items like peakshape in the on-line elution mode. High recoveries and good relative standard deviations were obtained particularly for the newer, strongly retaining SPE materials that have become commercially available recently (the Hysphere materials and Waters Oasis) compared to the well known silica-based and weaker polymeric adsorbents like PLRP-s and PRP-1. These advantages are, however, traded in for good chromatographic peakshape, since the stronger adsorbents give rise to notable peak broadening in on-line elution. This is particularly true when using APCI-MS detection which on the one hand offers excellent selectivity and sensitivity, but imposes additional restrictions on the mobile phase composition in order not to suppress the response significantly. The influence of these parameters on the on-line-SPE-HPLC-MS determination of EPA phenols is discussed and present limitations are pointed out.

Metabolism of camptothecin, a potent topoisomerase I inhibitor, in the isolated perfused rat liver.

PURPOSE: Camptothecin (CPT) is a potent topoisomerase I inhibitor that has recently been undergoing phase I clinical trials. Though CPT shows high activity against various tumor cells, its biotransformation is still unknown. To investigate the metabolism and biliary excretion of CPT, an isolated perfused rat liver system was used. METHODS: CPT was added to the perfusion medium at a concentration of 20 microM, and bile and perfusate samples were collected for 90 min. CPT (lacton and carboxylate) and three novel metabolites were identified by mass spectroscopy and quantified by reversed-phase high-performance liquid chromatography (HPLC). Kinetic parameters of CPT and its biotransformation products were then estimated in bile and effluent perfusate. RESULTS: Biliary secretion of CPT and its three metabolites reached a peak secretion of 37.6 +/- 16.3, 0.94 +/- 0.29, 0.19 +/- 0.023 and 0.302 +/- 0.076 nmol/g liver/min, respectively, after 20 min. The total amount of CPT and M1-M3 excreted into bile during 90 min of perfusion was 63.5 +/- 15.4%, 1.8 +/- 0.37%, 0.43 +/- 0.06%, and 0.72 +/- 0.15% of CPT cleared from the perfusate during 90 min, respectively. In the perfusate, only one metabolite (M3) could be detected (cumulative release into the perfusion medium: 0.37 +/- 0.026 micromol/liver). Analysis of the biliary metabolites by mass spectroscopy supported the existence of dihydroxy-CPT derivatives (M1 and M2), whereas M3 appears to be a monohydroxy-analog. CONCLUSION: CPT is biotransformed to three novel metabolites, mainly excreted into bile. The possible pharmacological effects of these new metabolites need to be considered.

Separation and identification of polar degradation products of benzo[a]pyrene with ozone by atmospheric pressure chemical ionization-mass spectrometry after optimized column chromatographic clean-up.

The environmental relevance of oxidized degradation products of polycyclic aromatic hydrocarbons (PAHs) increases due to enhanced combustion of organic matter and fossil fuels. For PAHs consisting of more than three condensed aromatic rings, soot aerosols are the main carrier, on the surface of which they can react with trace gases like ozone. In this study the clean-up procedure and analysis of ozonized benzo[a]pyrene (B[a]P) was optimized. B[a]P and its degradation products were preseparated into three fractions. Different reversed-phase materials were evaluated for high-performance liquid chromatographic separation. Among these, a phenyl-modified silica material proved best-suited and the chromatographic separation was optimized on this material. For the detection of separated degradation products, liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) was used. With this method, 29 components could be characterized. Besides the three known main degradation products (B[a]P-1,6-dione, B[a]P-3,6-dione, B[a]P-6,12-dione, B[a]P-4,5-dione and 4-oxa-benzo[d,e,f]chrysene-5-one (B[def]C-lactone), were identified for the first time with the help of reference substances. B[def]C-lactone is known as a substance with a mutagenic potential similar to B[a]P. Several other compounds could be tentatively identified.

High-performance liquid chromatography-atmospheric-pressure chemical ionization mass spectrometry as a new tool for the determination of the mycotoxin zearalenone in food and feed.

A new method for the determination of the mycotoxin zearalenone (ZON) in food and feed, based on HPLC-MS with an atmospheric-pressure chemical ionization (APCI) interface after extraction from cereals and clean-up by either conventional solid-phase or immunoaffinity cartridge is presented. The APCI interface parameters are optimized to provide detection of ZON with maximum sensitivity after RP separation of ZON on a C18 column with acetonitrile-water (40:60, v/v) at 1 ml/min column flow without split. Using APCI-MS detection, the sensitivity of the method was improved by a factor of ca. 50 in comparison to HPLC with fluorescence detection, allowing determination of ZON down to 0.12 microgram/kg maize which is well below present threshold values. Due to the selectivity of MS detection, it also was possible to quantitatively determine ZON both in raw extracts without clean-up using a normal-size (100 mm) chromatographic column or using only a short (20 mm) chromatographic column, when a clean-up was done to minimize possible interferences.