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Seven β2-agonist (clenproperol, clenbuterol, salbutamol, bronbuterol, ractopamine, clenpenterol and clencyclohexerol) were determined simultaneously in human and bovine urine by isotope dilution LC-ESI-MS/MS in a triple quadrupole instrument. The method is based on the application of multiple linear regression in combination with compound-specific minimally 13C-labelled analogues. Additionally, the increase of the bandpass of the first quadrupole during the selected reaction monitoring (SRM) measurement procedure allowed the simultaneous quantification of the seven compounds at sub ngg-1 levels in a single chromatogram without resorting to a methodological calibration graph. Recovery values at concentration levels between 5.0 and 0.05ngg-1 ranged from 95 to 110% in fortified bovine urine and from 91 to 108% in human urine, with relative standard deviations lower than 5% except for salbutamol and ractopamine. The proposed methodology was validated by analyzing the certified reference material BCR-503 (lyophilized bovine urine) certified for clenbuterol and salbutamol. The limits of detection (LOD) for a sample volume of 10mL of both human and bovine urine was found to be lower than 0.012ngg-1 for all compounds, except to salbutamol in bovine urine which was of 0.029ngg-1. The use of compound-specific isotopically labelled analogues minimally labelled in 13C minimized the occurrence of isotope effects and corrected for matrix effects during ESI ionization and can be efficiently applied for the quantification of ultra-trace concentrations of β2-agonists in human and bovine urine.

The development of a simple and rapid multielemental speciation method is described with the ultimate goal to simultaneously determine various organometallic compounds of mercury, lead and tin (inorganic mercury, methylmercury, trimethyllead, triethyllead, monobutyl-, dibutyl- and tributyltin) in natural water samples. The analytical method consists on the ethylation with NaBEt 4 , simultaneous headspace-solid phase microextraction (HS-SPME) of the derivatives and final gas chromatographic-mass spectrometric (GC–MS) analysis. After optimization of important process parameters, like SPME fiber coating, extraction time and extraction temperature, the analytical characteristics were evaluated. Detection limits in the low ng l −1 level, linearity over three orders of magnitude and repeatability in the range of 3–20% were achieved for all compounds under study. The accuracy of the method in terms of average percentage recovery of the compounds in spiked river water and seawater samples was better than 90%. Finally, application of the proposed method to real natural aqueous samples enabled the simultaneous determination of all the compounds under study in seawater samples obtained from the marina area of Gijon (Asturias, Spain).

The feasibility of developing a single-step clean-up, enrichment procedure for organochlorine pesticides (OCPs) in fish tissue samples based on solid-phase microextraction (SPME) was investigated. The general analytical methodology developed combines conventional solid-liquid extraction of the OCPs from the sample using an organic solvent with SPME over the organic extract followed by gas chromatography-electron-capture detection (GC-ECD) analysis. Experimental SPME conditions such as extraction time, temperature and matrix effects were optimised. Under optimised conditions, precision, linearity range, detection limits and accuracy were evaluated. Detection limits obtained for fish tissue samples were in the range of 0.1-0.7 ng g(-1). Good recoveries (over 70% in all cases) were achieved from samples spiked at a concentration level of 10 ng g(-1). The accuracy of the developed SPME-GC-ECD procedure in real samples has been verified by analysing, using the standard addition method, a certified reference material (CRM 430, OCPs in pork fat) with satisfactory results.

The coupling of reversed-phase high-performance liquid chromatography (RP-HPLC) with inductively coupled plasma mass spectrometry (ICP-MS) using post-column isotope dilution analysis (ID) was applied to the study of cadmium binding to standard rabbit liver metallothionein isoform 1 (MT-1). The analytical performance of three different ICP mass spectrometers, time of flight (TOF), double focussing (DF) and quadrupole (Q), was compared according to their performance for cadmium detection during chromatographic separation. Chromatographic conditions were optimised on a Vydac C8 VHP 259 RP column using a water–methanol gradient. Seven different sub-isoforms were distinguished by using this column coupled to a UV–Vis spectrophotometer, which greatly improved the resolution power exhibited by conventional anion-exchange chromatography. The ICP-DF-MS instrument was seriously affected by the methanol gradient and, thereafter, showed the worst performance in all cases. In contrast, the ICP-TOF-MS was able to resist up to 50% methanol with no serious changes in sensitivity or plasma stability. This instrument exhibited the lowest detection limits. The ICP-Q-MS provided results in between the other two instruments. In all cases, the use of post-column isotope dilution analysis was able to correct for matrix effects and signal drift, allowing for accurate determination of total MT concentration and the actual distribution of Cd-binding sub-isoforms.

The use of an inductively coupled plasma mass spectrometer (ICP-MS) with a time-of-flight (TOF) analyser is illustrated for the simultaneous determination of seven elements forming hydrides (As, Bi, Ge, Hg, Sb, Se and Sn) using flow injection (FI) as the sample introduction system. The chemical conditions for an adequate simultaneous volatile species generation as well as the plasma parameters for simultaneous determination were evaluated. The compromise hydride generation conditions were: 1% NaBH4 and 0.7 M HNO3 final concentration, while an Ar carrier gas flow rate of 1.1 l min−1 provided optimum results for the transport of the volatile species to the ICP-MS. Analytical figures of merit were evaluated under these compromise conditions and compared with those obtained by continuous nebulisation of the same elements in the ICP-MS(TOF). Detection limits in the low pg ml−1 region, linearity over more than five orders of magnitude and repeatability of 2–5% were achieved with the proposed methodology. Application of such a strategy was demonstrated by the simultaneous multi-elemental determination of As, Bi, Ge, Hg, Sb, Se and Sn in spiked urine samples with recoveries better than 80%. For Se, accurate results were only obtained by avoiding volatile species generation, demonstrating the presence of selenium species other than Se(IV) in human urine. The accuracy of the method was also checked by analysing a certified urine sample (NIST SRM 2670) by FI-ICP-MS(TOF) with satisfactory results.

The analytical potential of a radiofrequency glow discharge (rf-GD) for the analysis of gaseous samples is evaluated investigating the detection by optical emission spectrometry (OES) of nonmetals in organic vapors using helium as plasma gas. Discrete amounts of low boiling point organic liquids are introduced into the rf-GD through a thermoelectrically heated gas exponential dilutor, and their OES characteristics are measured. The design of the discharge chamber and the effect of operating parameters on the emission signals of typical nonmetallic elements are discussed. Analytical performance is evaluated under the optimum conditions for Cl, C, Br, and S using emission lines in the ultraviolet−visible region. Detection limits in the low picogram-per-second range, good precision (RSD < 5%), and linear ranges of 4−5 decades were observed for the four elements. A comparison of this source is carried out with other, more conventional plasmas for the determination of low levels of nonmetals in organic compoun...

A novel and fast routine method for the simultaneous determination and confirmation of clenbuterol in bovine and human urine samples by gas chromatography electron ionization mass spectrometry (GC-EI-MS) has been developed. The method employs isotope dilution mass spectrometry (IDMS) and is based on a combination of minimal labeling (a single (13)C label in the molecule) and isotope pattern deconvolution (IPD). This new methodology does not require the construction of a methodological calibration graph, and was compared with the classical IDMS procedure employed in clenbuterol analysis based on the use of a deuterated compound as internal standard (d(9)-clenbuterol) and a calibration curve. The sample preparation consists of simple extraction with dichloromethane, which was dried and derivatized with chloro(chloromethyl)dimethylsilane, generating a cyclic dimethylsilamorpholine (DMS) derivative suitable for GC(EI)MS detection and identification. This compound produces five intense ions in the electron ionization source, which allow the presence of clenbuterol to be confirmed in just one analysis, as demanded by European Union directives. The accuracy of the method was studied by performing recovery experiments at different concentration levels (from 0.3 to 5 ng g(-1)) in 5 mL bovine urine samples using two labeled compounds: an in-house-synthesized (13)C(1)-clenbuterol and a commercially available d(9)-clenbuterol. The detection limit of the method in human urine was 0.050 ng g(-1) with a sample volume of 10 mL, and is thus suitable for antidoping control purposes. Finally, the (13)C(1)-clenbuterol standard was employed for the determination of clenbuterol in two reference materials, BCR-503 and BCR-504 (lyophilized bovine urine). The concentrations obtained were in agreement with the certified values, with a reproducibility of below 1% RSD.

A standard GC-MS instrument with electron impact ionisation has been used to develop a fast, simple and reliable method for the simultaneous determination of monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT) in water samples. Isotope dilution analysis (IDA) is used for the determination of species, taking advantage of a commercially available spike solution containing a mixture of MBT, DBT and TBT enriched in 119Sn. Method detection limits for 100-mL samples were between 0.18 and 0.25 ng L(-1) for the three butyltin compounds with typical RSD between 2 and 4% at levels between 100 and 10 ng L(-1), respectively. Recovery of tin species in spiked samples (natural water, wastewater and seawater) was quantitative. The stability of butyltin compounds in collected seawater samples was also studied. The addition of a 1% (v/v) glacial acetic acid preserved tin species in the samples for at least 5 days at room temperature. The IDA method was finally implemented in a routine testing laboratory and it was subsequently accredited by the Spanish National Accreditation Body according to the requirements of UNE-EN ISO/IEC 17025.