Single Quadrupole Mass Spectrometry Research Articles

Advances in the determination of degradation intermediates of personal care products in environmental matrixes: a review

In this review, recent methods developed for the determination of degradation intermediates of personal care products in environmental matrixes focusing on the extraction and determination steps are discussed. The five classes of personal care products evaluated are stimulants, fragrances, sunscreens, antimicrobials, and insect repellents. Methods are critically reviewed in terms of the analytical steps involved in the analysis, sample pretreatment, separation, and detection as well as the different confirmation strategies employed. Preconcentration from aqueous matrixes was performed by solid-phase extraction, liquid-liquid extraction, or solid-phase microextraction, allowing the simultaneous extraction of parent compounds and their degradation intermediates. Following the extraction and cleanup steps, the identification and quantification of degradation intermediates of personal care products at environmental levels (i.e., parts per trillion to parts per billion range) is usually performed by using mass spectrometry techniques such as single quadrupole mass spectrometry and more recently by time-of-flight mass spectrometry or tandem mass spectrometry. The main scope of this review is to critically evaluate the current state of the art of the analytical techniques used and to identify the research needs in the determination of degradation intermediates of personal care products in environmental matrixes.

Synthesis and analytical follow-up of the mineralization of a new fluorosurfactant prototype

Fluorinated surfactants have become essential in numerous technical applications due to their unparalleled effectiveness and efficiency. The environmental persistence of the non-biodegradable perfluorinated alkyl moiety has become a matter of concern. Therefore, it was searched for new molecules with chemically stable fluorinated end groups which can be microbially transformed into labile fluorinated substances.One prototype substance, 10-(trifluoromethoxy)decane-1-sulfonate, has shown biomineralization. Monitoring the formation of metabolites over time elucidated the mechanism of biotransformation. Analysis was performed utilizing liquid chromatography–single quadrupole mass spectrometry (LC–MS) and quadrupole-time of flight tandem mass spectrometry (QqTOF-MS).It was possible to distinguish between two major degradation pathways of the fluorinated alkylsulfonate derivative: (i) a desulfonation and subsequent oxidation and degradation of the alkyl chain being predominant and (ii) an insertion of oxygen with a subsequent cleavage and degradation of the molecule. The utilized trifluoromethoxy-endgroup resulted in instable trifluoromethanol after degradation of the alkyl chain, which led to a high degree of mineralization of the molecule.

Direct-Injection Mass Spectrometric Method for the Rapid Identification of Fentanyl and Norfentanyl in Postmortem Urine of Six Drug-Overdose Cases

A rapid mass spectrometric method was developed for the identification of fentanyl and its major hepatic metabolite norfentanyl in postmortem urine of six drug-overdose victims involving fentanyl use. To reduce matrix effects or ion suppression, sample preparation consisted of centrifugation and solid-phase extraction. Deuterium-labeled internal standards ((2)H(5)-fentanyl and (2)H(5)-norfentanyl) were used to compensate for instrument variation in signal, analyte recovery during sample preparation, and ion suppression. Structural information for fentanyl and norfentanyl were collected using mass spectrometry (MS) with electrospray ionization (ESI) operated in the positive ion mode. Fentanyl (m/z 337) was found in each of the six overdose cases by the appearance of the MS-MS daughter ion on both an ion trap and a triple-quadrupole MS resulting from the fragmentation pathway of fentanyl (m/z 337 --> 188). Norfentanyl was detected in all six cases by the appearance of the MH(+) ion, m/z 233, with a single-quadrupole MS and confirmed in an ion trap MS. Ion suppression, as determined by the comparison of ion intensities from spiked samples in water with postmortem urine from the cases, ranged from 18% to 98% in three ESI sources. The use of stable isotope-labeled internal standards obviates sample preparation because ratios of analyte/internal standard remain constant in the presence of extensive matrix effects. This MS method provided sufficient sensitivity and selectivity for the rapid identification of fentanyl and norfentanyl in urine at levels >/= 10 ng/mL without prior analyte resolution by chromatography and with a total analysis time of less than 1 h.

Simultaneous Determination of Caffeine, Ergotamine, and Metamizol in Solid Pharmaceutical Formulation by HPTLC-UV-FLD with Mass Confirmation by Online HPTLC-ESI-MS

A new high-throughput method is developed to quantify caffeine, ergotamine, and metamizol in a solid pharmaceutical formulation. After dissolution, the compounds are separated on silica gel 60 F(254) high-performance thin-layer chromatography (HPTLC) plates with ethyl acetate-methanol-ammonia 90:15:1 (v/v/v) as the mobile phase. Detection is performed by UV absorption at 274 nm for caffeine and metamizol, and by fluorescence at 313 /> 340 nm for ergotamine. Calibrations are linear or polynomial with determination coefficients (R(2)) >or= 0.9986. Recoveries of the three compounds are between 95% and 102% at three different concentration levels. Repeatability [relative standard deviation (RSD)] of all substances in the matrix is between +/- 0.9% and +/- 1.7%. Intermediate precision (RSD) of the three compounds range from +/- 2.0% to +/- 3.1%. Mass confirmation is performed by a single quadrupole mass spectrometry in positive electrospray ionization full scan mode for caffeine and ergotamine and in negative mode for metamizol. The results proved that this method is a simple and reliable alternative for routine analysis.

Application of pressure assisted electrokinetic injection technique in the measurements of DNA oligonucleotides and their adducts using capillary electrophoresis–mass spectrometry

The identification and measurement of negatively charged DNA oligonucleotides and their benzo[a]pyrene-7,8,9,10-tetrahydro-7,8-dihydrodiol-9,10-epoxide (BPDE) adducts by capillary zone electrophoresis (CZE) hyphenated mass spectrometry (MS) system using an on-line enrichment technique, the constant pressure assisted electrokinetic injection (PAEKI), is described here. With optimized PAEKI conditions, an on-line sample concentration power of 300–800 times could be reached for both single-stranded (ss) and double-stranded (ds) oligonucleotides during a 90-s PAEKI injection. The detection limits using single quadrupole MS in the scan mode were 0.01–0.03 μM for ss and 0.04–0.08 μM for ds oligonucleotides, respectively. The relative standard deviations at 1 μM of oligonucleotides were from 7.6 to 15.8%. A dynamic linear calibration range of about two orders of magnitude were observed. Good mass spectra of oligonucleotides and BPDE–oligonucleotide adducts at low micromolar levels could be obtained using single quadrupole MS which could be a helpful tool in DNA adducts studies.

Analysis of carbamate and phenylurea pesticide residues in fruit juices by solid-phase microextraction and liquid chromatography–mass spectrometry

A new analysis method to detect carbamates and phenylurea pesticide residues in fruit juices was developed using solid-phase microextraction (SPME) coupled with liquid chromatography–single quadrupole mass spectrometry (LC/MS) and liquid chromatography–quadrupole ion trap mass spectrometry (LC/QIT-MS). The pesticide residues present in watery matrices as fruit juices were extracted using three types of fibers: 50-μm Carbowax/templated resin (CW/TPR), 60-μm poly(dimethylsiloxane)/divinylbenzene (PDMS/DVB) and 85-μm polyacrylate. The different extraction conditions were evaluated choosing as the best parameters 90 min (time), 20 °C (temperature) and 1 ml (volume). After extraction, the desorption (in a static mode) was performed in the specific interface chamber SPME/HPLC, previously filled with 70% methanol and 30% water. The best recoveries, evaluated at two fortification levels (0.2 and 0.5 mg kg −1) in fruit juices, were obtained using PDMS/DVB and CW/TPR fibers, and ranged from 25 to 82% (monolinuron, diuron and diethofencarb), with relative standard deviations (RSDs) from 1 to 17%. All the limits of quantification (LOQs) were in the range of 0.005–0.05 μg ml −1 and, in any case, equal to, or lower than, maximum residue limits (MRLs) established by Italian and Spanish legislations. The mass spectrometry analyses were carried out using an electrospray ionization (ESI) source operating in the positive mode both for single quadrupole and for QIT mass analysers, operating in selected ion monitoring (SIM) and in multiple reaction monitoring (MRM) modes, respectively. The proposed new method can be applied to the determination of selected pesticides in real samples of fruit juices.

Single quadrupole mass spectrometry for pre-clinical pharmacokinetic analysis: Quantitation of carvedilol in dog plasma

The pharmaceutical industry standard for bioanalysis is LC/MS/MS. There are, however, many instances where a single quadrupole detector could successfully be used to provide adequate sensitivity and selectivity for quantitation of drug substances in biological matrices. This paper presents one example of how a single quadrupole detector can be employed in a sensitive and selective analytical method for quantitation of carvedilol. A Synergi Hydro-RP (50 mm × 2 mm i.d.; 4 μm) column was used with acetonitile:water:formic acid mobile phase (32:68:0.01, v/v) at a flow rate of 200 μL/min into a single quadrupole mass spectrometer with an electrospray interface in the positive SIM mode. Using a 300 μL plasma aliquot and a liquid–liquid extraction procedure the limit of quantitation for the assay was 1 ng/mL. The assay utility was demonstrated in the analysis of carvedilol pharmacokinetic profiles in beagle dogs following oral carvedilol administration.

Qualitative and quantitative analysis of iridoid glycosides in the flower buds of Lonicera species by capillary high performance liquid chromatography coupled with mass spectrometric detector

A highly sensitive and specific method, based on capillary high performances liquid chromatography coupled with single quadrupole mass spectrometry using electrospray ionization (capillary HPLC–ESI/MS), is proposed for the identification and quantification of iridoid glycosides in the flower buds of five Lonicera species. A Zorbax SB-C18 (0.3 mm × 150 mm, 5 μm) capillary column and a gradient elution with methanol–acetonitrile–aqueous acetate acid were utilized. The most intensive electrospray ionisation signals were found in the negative ion spectra owing to CH 3COO − adducts. Eight iridoid glycosides derived from the flower buds of Lonicera species were analyzed by mass spectrometry: sweroside (IG1), 7- O-ethyl sweroside (IG2), 7-epi vogeloside (IG3), secoxyloganin (IG4), secoxyloganin 7-butyl ester (IG5), dimethyl-secologanoside (IG6), centauroside (IG7), and loganin (IG8) using combined information on retention time, the molecular ion mass and fragment ion masses. Detection limits were lower than 1.9 ng/mL in selected ion monitoring (SIM) mode and all calibration curves showed good linear regression ( r 2 > 0.9938) within test ranges. The validated method was successfully applied to analyze eight iridoid glycosides in the flower buds of five Lonicera species and provided a new basis of assessment on quality of Flos Lonicerae.

Strategies to avoid the mis-identification of anatoxin-a using mass spectrometry in the forensic investigation of acute neurotoxic poisoning

Anatoxin-a (AN) is a potent neurotoxin, produced by a number of cyanobacterial species, and consumption of freshwater contaminated with this toxin has led to animal deaths. Forensic investigations of suspected AN poisonings are frequently hampered by difficulties in detecting this toxin in biological matrices due to its rapid decay. In addition, detection of AN using single quadrupole mass spectrometry (MS) is suspect due to the presence of the amino acid, phenylalanine (Phe), since these compounds are isobaric and elute similarly in reversed phase liquid chromatography (LC). Approaches to prevent the misidentification of AN that have been explored in these studies included: (a) fluorimetric LC following derivatisation using 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F); (b) methylation using diazomethane prior to LC–MS determination; (c) multiple tandem MS using a quadrupole ion-trap (LC–MS 3); and (d) hybrid quadrupole time-of-flight (QqTOF). Interference from Phe was not observed in any of procedures, (a)–(c), and the high mass accuracy obtained in method (d), readily distinguished between AN (165.11536) and Phe (165.07898). LC–MS n was also employed to study the fragmentation pathway of Phe and multi-stage MS spectra provided characteristic fragmentation information that clearly distinguished between AN and Phe. The difficulties associated with the over reliance on low resolution MS without MS/MS data in forensic toxicology are discussed.

A method for screening for various sedative-hypnotics in serum by liquid chromatography/single quadrupole mass spectrometry

A screening method for the detection of sedative-hypnotics in serum is described. The target drugs, which include practically all the sedative-hypnotics distributed in Japan, consisted of 5 barbiturates, 30 benzodiazepine-related drugs and 11 other sedative-hypnotics (i.e., apronalide, bromisovalum, chloral hydrate, triclofos, chlorpromazine, promethazine, diphenhydramine, hydroxyzine, zopiclone, zolpidem and tandospirone). Thirty-nine analytes, selected in terms of the pharmacokinetics of the target drugs, in human serum were screened using a combination of mixed-mode solid-phase extraction and liquid chromatography/electrospray-ionization single-quadrupole mass spectrometry. The detection limits (non-basic analytes, 1–50 ng/ml; basic analytes, 0.1–5 ng/ml) were sufficient to permit the screening of a single therapeutic administration of a target drug.

Development and validation of a liquid chromatographic/electrospray ionization mass spectrometric method for the quantitation of prazepam and its main metabolites in human plasma

A method was developed and fully validated for the quantitation of prazepam and its major metabolites, oxazepam and nordiazepam, in human plasma. Sample pretreatment was achieved by solid-phase extraction using Oasis HLB cartridges. The extracts were analysed by high-performance liquid chromatography (HPLC) coupled with single-quadrupole mass spectrometry (MS) with an electrospray ionization interface. The MS system was operated in the selected ion monitoring mode. HPLC was performed isocratically on a reversed-phase XTerra MS C18 analytical column (150 x 3.0 mm i.d., particle size 5 microm). Diazepam was used as the internal standard for quantitation. The assay was linear over a concentration range of 5.0-1000 ng ml(-1) for all compounds analyzed. The limit of quantitation was 5 ng ml(-1) for all compounds. Quality control samples (5, 10, 300 and 1000 ng ml(-1)) in five replicates from three different runs of analysis demonstrated an intra-assay precision (CV) of < or = 9.1%, an inter-assay precision of < or = 6.0% and an overall accuracy (relative error) of < 4.6%. The method can be used to quantify prazepam and its metabolites in human plasma covering a variety of pharmacokinetic or bioequivalence studies.

Development of a Solid-Phase Extraction-HPLC/Single Quadrupole MS Method for Quantification of Perfluorochemicals in Whole Blood

A method for the determination of perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA) simultaneously with 10 closely related perfluorochemicals (PFCs) in human whole blood was developed and validated. PFOS and PFOA are used in various applications, for example, as surfactants and plastic additives, and are subject to environmental and health research due to their persistence. The main part of the data on PFCs in human blood is from serum samples, analyzed mainly by ion pair extraction followed by high-performance liquid chromatography (HPLC) and negative electrospray (ESI) tandem mass spectrometry (MS/MS). The analytical method developed here is suitable for human whole blood and involves solid-phase extraction (SPE) and HPLC negative electrospray single quadrupole mass spectrometry (HPLC/ES-MS). A whole blood aliquot was treated with formic acid and extracted on a octadecyl (C18) SPE column. The PFCs were isolated with methanol, and quantification was performed using single quadrupole mass spectrometry and perfluoroheptanoic acid as internal standard. Validation was performed in the range 0.3-194 ng/mL with recovery between 64 and 112% and limit of detection in the 0.1-0.5 ng/mL range for 11 of the 12 PFCs studied. We applied this method to 20 whole blood samples collected in 1997-2000 from the Swedish population in the ages 24-72. Eleven of the 12 PFCs were detected, and they were quantitatively and qualitatively confirmed using triple quadrupole LC/MS/MS analysis. PFOS, perfluorooctanesulfonamide, perfluorohexanesulfonate, PFOA and perfluorononanoic acid were quantified in all samples. In addition, perfluorohexanoic acid, perfluorodecanoic acid, perfluorodecanesulfonate, perfluoroundecanoic acid, perfluorododecanoic acid, and perfluorotetradecanoic acid were detected in some samples. This study shows that SPE and single quadrupole MS can be applied for extraction and quantification of PFCs in human whole blood, resulting in selectivity and low detection limits.

Measurement of steroid synthesis in zona glomerulosa cells by liquid chromatography–electrospray ionization–mass spectrometry: inhibition by nitric oxide

A liquid chromatography–electrospray ionization–mass spectrometry method was developed to simultaneously determine the concentrations of aldosterone, corticosterone, cortisol, deoxycorticosterone, pregnenolone, and progesterone in bovine adrenal zona glomerulosa (ZG) cells. Steroids were extracted by liquid–liquid extraction, separated on a reverse-phase C 18 column, ionized by electrospray, and detected by single-quadrupole mass spectrometry in a positive ion mode. All steroids formed sodium adducts at high abundance. Factors affecting the formation and signal of sodium adducts were investigated. The limits of detection ( S/ N = 3) using selected ion monitoring are 2 pg for these steroids and 10 pg for pregnenolone. DETA NONOate, a nitric oxide donor, inhibited the basal, angiotensin-II-stimulated, and 25-hydroxycholesterol-stimulated syntheses of these steroids in ZG cells in a concentration-dependent manner. The technique demonstrates the ability to determine the individual steroid in each enzymatic step of aldosterone synthesis and the activity of steroidogenic enzymes in adrenal ZG cells.

Identification of dimethylarsinic acid as the major arsenic compound in fish sauce by liquid chromatography/electrospray ionization-mass spectrometry

: Arsenobetaine, the major arsenic compound in marine animals, is substantially non-toxic. It is, however, possible that arsenobetaine undergoes bacterial transformation during manufacturing of fermented fishery products. In the present study, therefore, three types of fish sauce were examined for arsenic concentrations and species compared with those in the raw materials (sardine, Japanese sandfish and Japanese common squid). Arsenic concentrations of the three types of fish sauce were almost equivalent to those in their raw materials, suggesting no accumulation of arsenic during fermentation. Arsenic speciation was performed by a combination of cation-exchange liquid chromatography (LC) and electrospray ionization (ESI)-single quadrupole mass spectrometry (MS). Optimal conditions of LC/ESI-MS were established to analyze seven arsenic compounds (arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, trimethylarsine oxide, arsenocholine and tetramethylarsonium ion) found in biological samples. When analyzed by LC/ESI-MS, the major arsenic compound in the raw materials was arsenobetaine as expected, while not arsenobetaine but dimethylarsinic acid was identified as the major arsenic compound in the three types of fish sauce. These results suggest that arsenobetaine in the raw materials is converted to dimethylarsinic acid but not to arsenate with high toxicity by bacterial actions during manufacturing of fish sauce.

Synthesis and identification of two potential oxidation degradants of oxymetazoline.

Two potential oxidation degradants of oxymetazoline have been isolated by liquid chromatography and monitored by electrospray single quadrupole mass spectrometry. The structures of the products are shown to be oxymetazoline N-oxide and hydroxyamine by multiple-stage fragmentation ion trap mass spectrometry. The product ion spectra were installed in a library database and the library was used to examine an aged commercial product; one of the degradants was detected, but at a level of less than 0.1% of the parent.

On-line micellar electrokinetic chromatography–mass spectrometry: feasibility of direct introduction of non-volatile buffer and surfactant into the electrospray interface

An on-line method for the coupling of micellar electrokinetic chromatography (MEKC) and mass spectrometry (MS) is presented which allows conventional MEKC conditions to be employed without further modification. The MEKC system is coupled directly to electrospray ionization (ESI) MS using a triaxial interface. A systematic study of the influence of the surfactant concentration, the nature and concentration of buffer salts and presence of organic modifier on the interface performance indicated the feasibility of the MEKC–MS approach. Effective interfacing of MEKC was achieved with both single quadrupole and ion-trap MS instruments. Using a background electrolyte containing 20 m M sodium dodecyl sulfate (SDS) and 10 m M sodium phosphate buffer, it is demonstrated that full MEKC runs of test mixtures of mebeverine and related compounds can be monitored by ESI-MS with satisfactory sensitivity. Sub-μg/ml levels of the analytes can still be detected in full scan mode, while detection limits are in the 10–50 ng/ml range when selected ion monitoring is applied. It is shown that such sensitivity would allow full-scan MS detection of 0.1% (w/w) levels of potential impurities in mebeverine. With the ion-trap instrument successful MEKC–MS/MS experiments were carried out providing information-rich MS spectra of the related compounds. Repeated MEKC–MS analyses proved that in the course of 1 day the migration time of mebeverine remained fairly constant while the MS-signal intensity only gradually decreased to approximately 65% of its original value. Once-a-day cleaning of the first part of the ion source, which takes only 5 min, suffices to preserve an optimal interface performance for a prolonged period of time.

Quantitative analysis of cytokinins in plants by liquid chromatography–single-quadrupole mass spectrometry

A sensitive method for the quantitative analysis of all natural isoprenoid cytokinins in plant material by electrospray single-quadrupole mass spectrometry is presented. A baseline chromatographic separation of 20 non-derivatised naturally occurring cytokinins has been developed. Precise analyses of O-glucoside and ribonucleotide fractions were also performed by the high-performance liquid chromatography–mass spectrometry (HPLC–MS) but run separately from the basic cytokinin metabolites. Using post-column splitting, the flux from narrow-bore (2.1 mm i.d.) reversed-phase liquid chromatography column was simultaneously introduced into the diode array and mass detector. Optimal conditions, including final flow rate, desolvation temperature, desolvation gas flow, capillary and cone voltage for effective ionisation in the electrospray ion source were found. When low cone voltage (20 V) was applied, all studied cytokinins were determined in aqueous methanol as dominant quasi-molecular ions of [ M+H] + with limits of detection ranging between 10 and 50 fmol. For routine analysis a linearity range between 25 (75) fmol and 100 pmol was obtained. Developed liquid chromatography–mass spectrometry (LC–MS) method in selective ion monitoring mode was employed to quantify cytokinin species in tobacco BY-2 suspension culture and poplar leaves ( Populus× canadensis Moench, cv Robusta). Purified plant cell (BY-2) and plant tissue (poplar leaves) extracts were obtained by using two different ion-exchange chromatography steps, in combination with immunoaffinity purification using a broad-spectrum monoclonal anti-cytokinin antibody. The antibody strongly recognises the presence of N 6-substituent on purine skeleton and thus does not bind adenine and related compounds. The presence of authentic cytokinins in the extracts quantified by LC–MS was further verified by enzyme-linked immunosorbent assays (ELISAs) with prior LC preparation. The combination of liquid chromatography–single-quadrupole mass spectrometry with immunoaffinity chromatography offers an efficient and elegant method for detection and quantification of cytokinin metabolites.

Rapid characterization of anthocyanins in red raspberry fruit by high-performance liquid chromatography coupled to single quadrupole mass spectrometry

Anthocyanins from red raspberries were extracted from the fruit by homogenizing in acidified methanol. The methanolic extract was centrifuged and the supernatant analyzed by reversed-phase HPLC. The eluent was monitored at 371 and 520 nm before being introduced into a single quadrupole mass spectrometer through an atmospheric pressure chemical ionization probe operating in positive ion mode. This method allowed the identification of eight anthocyanins. In the absence of readily available reference compounds, approaches that can be taken to analyse anthocyanins by HPLC with absorbance and mass spectrometric detection are discussed.

High-throughput SNP genotyping with the Masscode system.

QIAGEN Genomics, Inc, has developed the Masscode tagging system for DNA labeling and detection. In this application, the Masscode system is described as applied to high-throughput single-nucleotide polymorphism (SNP) genotyping. The labeling system is based on a small-molecular-weight tag that is covalently attached through a photocleavable linker to a DNA oligonucleotide. The tagged oligonucleotide is used as a primer in an allele-specific PCR SNP discrimination assay. The allele-specific amplicons are differentiated through their Masscode tag assignments. After a photolysis step to cleave the tags from the amplicon, the samples are introduced into a single quadrupole mass spectrometry detection system for analysis. Genotyping determinations are based on the relative proportions of the paired allele tags. The system has a lower limit of detection in the femtomolar range (10(-15) M). At present, 30 different Masscode tags may be used simultaneously in a multiplex fashion to routinely provide more than 40,000 SNP genotyping measurements daily. Further developments will allow for the simultaneous detection of several hundred tags.

Liquid chromatography with post-column electrochemical treatment and mass spectrometric detection of non-polar compounds.

The first hyphenation of high performance liquid chromatography (HPLC), electrochemical online oxidation and mass spectrometry (MS) is described. Ferrocenecarboxylic acid esters of various alcohols and phenols have been synthesized, separated by reversed-phase HPLC and oxidized (ionized) coulometrically prior to single quadrupole MS analysis using electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) interfaces. The dependence of the ionization on the electrochemical pretreatment is demonstrated. Limits of detection for selected derivatives range from 4 x 10(-9) to 4 x 10(-7) mol dm-3 depending on the individual compound and the selected interface.