Positive-ion Electron Ionization Research Articles

Detection and mass spectral characterization of carbofuran and its degradation product

Carbofuran is an N-methyl carbamate pesticide that is extensively used to control insects and nematodes on a range of farming crops because of its wide-ranging biological activity & relatively low persistence when compared to other pesticides. It is highly toxic to birds, mammals, fish and wildlife due to its anticholinesterase activity. In humans, Carbofuran is associated with endocrine disrupting activity, reproductive disorders, cytotoxic and genotoxic abnormalities. In biological and environmental conditions Carbofuran tend to undergo degradation. The screening, identification and characterization of the Carbofuran and its degradation product in biological samples are an important task in the area of forensic toxicology. In a case study Carbofuran and its degradation product Carbofuran phenol were detected and identified by Gas Chromatography Mass Spectrometry. The present study deals with the successful detection & characterization of the Carbofuran and its degradation product under positive ion Electron Ionization (EI) mass spectrometry. The EI mass spectra of the Carbofuran and its degradation product showed the stable molecular ion [M+•] peaks in addition to the other diagnostic fragment ions that enable unambiguous identification of Carbofuran and its Carbofuran phenol. The general fragmentation patterns of these two compounds are discussed in detail. Carbofuran showed an ion at m/z 164 as the base peak corresponds to loss of Methylisocyanato group (CH3NCO) from the [M+•] ion, which was formed by the Mclafferty rearrangement. Carbofuran phenol showed a more stable Molecular ion [M+•] peak compared to Carbofuran and showed a major peak at m/z 149 corresponds to the loss of methyl group from the [M+•] ion. The detection and identification of these compounds will be an invaluable support during investigation and in conviction of criminal cases in courts of law in Carbofuran poisoning cases.

Differentiation of isomeric 2‐aryldimethyltetrahydro‐5‐quinolinones by electron ionization and electrospray ionization mass spectrometry

A series of isomeric 2-aryl-6,6-dimethyltetrahydro-5-quinolinones (set I) and 2-aryl-7,7-dimethyltetrahydro-5-quinolinones (set II) were studied under positive ion electron ionization (EI) and electrospray ionization (ESI) techniques. Under EI conditions, the molecular ions were found to be less stable in set I isomers, and they resulted in abundant fragment ions, i.e., [M-CH(3)](+), [M-CO](+.), [M-HCO](+), [M-(CH(3),CO)](+), and [M-(CH(3),CH(2)O)](+), when compared with set II isomers. In addition, the set I isomers showed specific fragment ions corresponding to [M-OH](+) and [M-OCH(3)](+). The retro-Diels-Alder (RDA) product ion was always higher in set II isomers. The ESI mass spectra produced [M + H](+) ions, and their decomposition showed favorable loss of CH(3) radical, CH(4) and C(2)H(6) molecules in set I isomers. The set II isomers, however, showed predominant RDA product ions, and specific loss of H(2)O. The selectivity in EI and ESI was attributed to the instability of set I isomers by the presence of a gem-dimethyl group at the α-position, and it was supported by the data from model compounds without a gem-dimethyl group. Density functional theory (DFT) calculations successfully corroborated the fragmentation pathways for diagnostic ions. This study revealed the effect of a gem-dimethyl group located at the α-position to the carbonyl having aromatic/unsaturated carbon on the other side of the carbonyl group.

Mass spectrometry of polycyclic tetracarboxylic ('ARN') acids and tetramethyl esters

Polycyclic C(80) tetracarboxylic (so-called 'ARN') acids are found as calcium salts in deposits which form in certain oilfield pipelines and equipment. Characterisation of these acids is important for improving the prediction and hence avoidance or minimisation of oilfield deposition problems. Although several of the acids have been isolated and characterised (as regioisomeric mixtures) by nuclear magnetic resonance spectroscopy, mass spectrometric methods are likely to be much more useful for the routine analysis of oils and deposits containing the acids. A publication summarising the mass spectra of the purified acids and major derivatives might thus be a very useful source of reference for scientists and technologists studying these unusual compounds. We now report the characterisation of several of the purified acids and of the tetramethyl esters by electrospray ionisation mass spectrometry (ESI-MS) in both positive ion and negative ion modes, by multistage ESI-MS with a suggested rationalisation of the ions produced, by positive ion atmospheric solids analysis probe (ASAP) atmospheric pressure chemical ionisation (APCI), and by positive ion electron ionisation (EI)-MS. Tentative identifications of C(80) acyclic, mono-, bi- and tricylic tetraacids and the δ(13)C isotope values of a mixture of the semi-pure acids determined by MS are also reported for the first time.

ChemInform Abstract: Mass Spectrometry of Prenylated Flavonoids

The fragmentation patterns originating from the degradation of prenyl group(s) in positive ion electron ionization (EI), fast-atom bombardment (FAB) and chemical ionization (CI) mass spectrometry (MS) of prenylated flavonoids were reviewed. The EI spectra showed the characteristic fragmentation patterns reflecting the location of prenyl group in the flavonoid compounds, whereas the FAB and CI spectra showed relatively monotonous patterns. It was described how the EI and FAB fragmentation patterns are useful for the identification of prenylated flavonoids

In vivo biotransformation of metoprolol in the horse and on-column esterification of the aminocarboxylic acid metabolite by alcohols during solid phase extraction using mixed mode columns

The in vivo biotransformation of metoprolol tartrate in the thoroughbred racehorse was studied after administration of a single oral dose. Metoprolol and its basic and bifunctional phase I metabolites were isolated from urine and plasma using mixed mode solid phase extraction (SPE) cartridges. The isolates were derivatised as trimethylsilyl ethers and analysed by capillary column gas chromatography—positive ion electron ionisation and ammonia chemical ionisation mass spectrometry. Metabolism was primarily confined to the oxidative transformations of the p-(2-methoxy)ethyl substituent. Metoprolol and five phase I metabolites were detected in horse urine. In common with man, rat and dog, the zwitterionic compound (±)-4-(2-hydroxy-3-isopropylaminopropoxy)-phenylacetic acid (H117/04), was the principle metabolite in the horse. This compound was readily isolated from both plasma and urine samples by SPE and, in addition, an unusual on-column esterification of the carboxylic acid moiety by alcohols was observed. Metoprolol and the major aliphatic acid metabolite were detected for about 10 and 40 h, respectively in unhydrolysed urine. After enzymatic hydrolysis, the detection period increased to 15 and 60 h, respectively indicating some phase II metabolism of metoprolol and its metabolites in the horse.

N-Deethylation and N-oxidation of etamiphylline: identification of etamiphylline- N-oxide in greyhound urine by high performance liquid chromatography–mass spectrometry

Millophyline-V ®, (etamiphylline camsylate) was administered intramuscularly to two racing greyhounds at a dose of 10 mg kg −1. Unhydrolysed pre- and post-administration urine samples were extracted using mixed mode solid phase extraction (SPE) cartridges, the basic isolates derivatised as trimethylsilyl ethers and analysed by positive ion electron ionisation gas chromatography–mass spectrometry (GC/EI+/MS). The parent drug and one metabolite, N-desethyletamiphylline, were detected in urine for up to 72 h. For semi-quantification, urine samples were extracted on-line using a Prospekt sample handler. The analytes retained on the C 2 SPE cartridge were eluted by the mobile phase directly on to the analytical high performance liquid chromatography column and analysed by positive ion atmospheric pressure chemical ionisation (LC/APCI+) MS in the multiple selective-ion recording mode. A major peak containing both ions ( m/ z) 280 and ( m/ z) 252 was observed. Full scan LC/APCI+/MS of the unknown indicated that the ion at ( m/ z) 280 was formed by the loss of an oxygen atom [ MH + → ( MH + − O)]. Samples were analysed by positive ion electrospray ionisation LC/MS on two different instruments and the unknown compound was identified as an N-oxide of the tert. nitrogen atom of the 2-(diethylamino)ethyl substituent on N 7 of the theophylline nucleus. This compound has not been reported previously either as an in vivo or in vitro metabolite of etamiphylline in any species. Thermal decomposition of the N-oxide could lead to an increase the detection period of the parent drug during routine GC/MS screening of post-competition greyhound urine samples.

Simultaneous determination of formate and acetate in whole blood and urine from humans using gas chromatography–mass spectrometry

We devised a sensitive and simple method for simultaneous determination of formate and acetate in whole blood and urine from humans using gas chromatography–mass spectrometry. Formate and acetate were alkylated with pentafluorobenzyl bromide in the mixture of acetone and phosphate buffer (pH 6.8). The derivatives obtained were analyzed using gas chromatography–mass spectrometry in positive-ion electron ionization (EI) mode. The lower limit of detection for both compounds was 0.02 mM. The calibration curves for formate and acetate were linear over the concentration range from 0.05 to 5.0 mM. Accuracy and precision of the method were evaluated and the coefficients of variation were within 10%. With use of this method, levels of formate and acetate in whole blood can be determined in forensic cases.

Detection of Eltenac in the Horse: Identification of Phase I Metabolites in Urine by Capillary Gas Chromatography-Mass Spectrometry and the Determination of Excretion Profile by Liquid Chromatography-Mass Spectrometry

Telzenac® (Eltenac; 0.5 mg kg−1) was administered intravenously to two thoroughbred horses. After initial alkaline saponification followed by enzymolysis of the urinary phase II conjugates, the combined unconjugated compounds and aglycones were isolated by mixed mode solid phase extraction (SPE). The acidic isolate was either methylated or silylated (trimethylsilyl ether, TMS) and analysed by positive ion electron ionisation gas chromatography-mass spectrometry (GC-EI+-MS). Eltenac and two isobaric metabolites, hydroxyeltenac (aromatic oxidation) and eltenac sulfoxide were tentatively identified. Base peaks in the EI+ spectra of underivatised, methylated and TMS derivatised eltenac are formed by an initial loss of H2O, CH3OH or (CH3)3-Si-OH respectively, followed by successive losses of a chlorine atom and a carbonyl group. Similar fragmentation patterns were observed for the methyl and TMS derivatives of the two metabolites. Triamcinolone acetonide was used as the internal marker for the semi-quantification of eltenac. Selected samples were base-hydrolysed and extracted on-line on a C2 SPE column using a Prospekt sample handler. The retained analytes were eluted directly on to an analytical LC column and analysed by high performance liquid chromatography positive ion atmospheric pressure chemical ionisation MS in the selective ion recording mode. Most of the drug was excreted in less than 24 h. However it could still be detected in urine by full-scan GC-EI+-MS for over 96 h.

Stereospecific fragmentations in the mass spectra of stereoisomeric isoindoloquinazolines

The mass spectrometric behavior of stereo- and regioisomeric, partially saturated isoindoloquinazolines was studied by positive-ion electron ionization (EI) and fast-atom bombardment (FAB/LSIMS) mass spectrometry combined with collision-induced dissociation (CID). A highly stereospecific retro-Diels-Alder process was observed in the cyclohexene-fused isomers under the EI conditions, and a corresponding (although less specific) fragmentation was observed in their FAB spectra. In the absence of RDA fragmentations, regio- and stereoisomers of the cyclohexane-fused heterocycles could be distinguished based on their FAB/CID spectra.

Detection and identification of carprofen and its in vivo metabolites in greyhound urine by capillary gas chromatography–mass spectrometry

Rimadyl ® (carprofen) was administered orally to the racing greyhound at a dose of 2.2 mg kg −1. Following both alkaline and enzymatic hydrolysis, postadministration urine samples were extracted by mixed mode solid-phase extraction (SPE) cartridges to identify target analyte(s) for forensic screening and confirmatory analysis methods. The acidic isolates were derivatised as trimethylsilyl ethers (TMS) and analysed by gas chromatography–mass spectrometry (GC–MS). Carprofen and five phase I metabolites were identified. Positive ion electron ionisation (EI +) mass spectra of the TMS derivatives of carprofen and its metabolites show a diagnostic base peak at M +⋅ −117 corresponding to the loss of COO–Si–(CH 3) 3 group as a radical. GC–MS with positive ion ammonia chemical ionisation (CI +) of the compounds provided both derivatised molecular mass and some structural information. Deutromethylation-TMS derivatisation was used to distinguish between aromatic and aliphatic oxidations of carprofen. The drug is rapidly absorbed, extensively metabolised and excreted as phase II conjugates in urine. Carprofen, three aromatic hydroxy and a minor N-hydroxy metabolite were detected for up to 48 h. For samples collected between 2 and 8 h after administration, the concentration of total carprofen ranged between 200 and 490 ng ml −1. The major metabolite, α-hydroxycarprofen was detected for over 72 h and therefore can also be used as a marker for the forensic screening of carprofen in greyhound urine.

In vivo biotransformation of 17 alpha-methyltestosterone in the horse revisited: identification of 17-hydroxymethyl metabolites in equine urine by capillary gas chromatography/mass spectrometry.

The in vivo phase I biotransformation of 17 alpha-methyltestosterone in the horse leads to the formation of a complex mixture of regio- and stereoisomeric C(20)O(2), C(20)O(3) and C(20)O(4) metabolites, excreted in urine as glucuronide and sulphate phase II conjugates. The major pathways of in vivo metabolism are the reduction of the A-ring (di- and tetrahydro), epimerisation at C-17 and oxidations mainly at C-6 and C-16. Some phase I metabolites have been identified previously by positive ion electron ionisation capillary gas chromatography/mass spectrometry (GC/EI + MS) mainly from the characteristic fragmentation patterns of their methyloxime-trimethylsilyl ether (MO-TMS), enol-TMS or TMS ether derivatives. Following oral administration of 17 alpha-methyltestosterone to two castrated thoroughbred male horses, the glucuronic acid conjugates excreted in post-administration urine samples were selectively hydrolysed by E. coli beta-glucuronidase enzymes. Unconjugated metabolites and the steroid aglycones obtained after enzymatic deconjugation were isolated from urine by solid-phase extraction, derivatised as MO-TMS ethers and analysed by GC/EI + MS. In addition to some of the known metabolites previously identified from the characteristic mass spectral fragmentation patterns of 17 alpha-methyl steroids, some isobaric compounds exhibiting a diagnostic loss of 103 mass units from the molecular ions with subsequent losses of trimethylsilanol or methoxy groups and an absence of the classical D-ring fragment ion were detected. From an interpretation of their mass spectra, these compounds were identified as 17-hydroxymethyl metabolites, formed in vivo in the horse by oxidation of the 17-methyl moiety of 17 alpha-methyltestosterone. This study reports on the GC/EI + MS identification of these novel 17-hydroxymethyl C(20)O(3) and C(20)O(4) metabolites of 17 alpha-methyltestosterone excreted in thoroughbred horse urine.

Detection of fenspiride and identification of in vivo metabolites in horse body fluids by capillary gas chromatography–mass spectrometry: administration, biotransformation and urinary excretion after a single oral dose

Studies related to the in vivo biotransformation and urinary excretion of fenspiride hydrochloride in the horse are described. After oral administration, the drug is metabolised by both phase I functionalisation and phase II conjugation pathways. Following enzymatic deconjugation, fenspiride and its phase I metabolites were isolated from post-administration biofluids using bonded co-polymeric mixed mode solid-phase extraction cartridges to isolate the basic compounds. Following trimethylsilylation (TMS), the parent drug and metabolites were identified by capillary gas chromatography–mass spectrometry (GC–MS). Fenspiride ( A) and seven metabolites ( B→ G) arising from oxidation on both the aromatic and heterocyclic substructures were detected in urine. The positive ion electron ionisation mass spectra of the TMS derivatives of fenspiride and its metabolites provided useful information on its metabolism. Positive ion methane chemical ionisation–GC–MS of the derivatives provided both derivatised molecular mass and structural information. Unchanged fenspiride can be detected in post-administration plasma and urine samples for up to 24 h. Maximum urinary levels of 100–200 ng ml −1 were observed between 3 and 5 h after administration. After enzymatic deconjugation, the major phenolic metabolite ( G) can be detected in urine for up to 72 h. This metabolite is the analyte of choice in the GC–MS screening of post-race equine urine samples for detection of fenspiride use. However, a distinct difference was observed in the urinary excretion of this metabolite between the thoroughbred horses used in UK study and the quarterbred and standardbred horses used for the USA administrations.

Biotransformation of cyclizine in greyhounds. 2: N 1 -dealkylation and identification of some neutral and phenolic metabolites in canine urine by gas chromatography-mass spectrometry

1. The in vivo enzymatic Phase I biotransformation of cyclizine (Marezine ®) in the racing greyhound has been shown to proceed via several different pathways. Aromatic and heterocyclic oxidation and the N 4 -demethylation of cyclizine lead to the formation of unconjugated and conjugated (Phase II) basic metabolites excreted in canine urine. 2. Enzymatic N 1 -dealkylation of cyclizine and its basic metabolites leads to the formation of the neutral and phenolic Phase I metabolites containing the diphenylmethane/methylene substructures. Further, Phase I metabolism of the neutral metabolites could also lead to the formation of several secondary phenolic products. These neutral and phenolic compounds are then excreted as unconjugated and Phase II conjugates in greyhound urine. 3. Following enzymatic deconjugation of selected post-Marezine administration urine samples from two greyhounds, the total aglycones were extracted and separated into neutral/acidic and basic fractions using copolymeric mixed-mode solid-phase extraction cartridges. 4. The neutral/acid isolates were further separated into neutral and phenolic fractions by column chromatography on a lipophilic strong anion-exchanger gel, triethylaminohydroxypropyl Sephadex LH-20 in OH - form. 5. The individual neutral and phenolic fractions obtained from the acid/neutral isolate were derivatized as trimethylsilyl ethers and analysed by positive-ion electron ionization gas chromatography-mass spectrometry (EI + -GC-MS). 6. Three compounds, diphenylmethane (M1), benzophenone (or diphenyl ketone, M2) and benzhydrol (M3), were identified in the neutral isolates by comparison of their EI + mass spectra with authentic standards. At least seven secondary compounds containing the functionalized diphenylmethylene substructure were detected in the phenolic isolates. As no authentic compounds are available, the structures of these putative metabolites (M4 → M10) were elucidated from an interpretation of the EI + -GC-mass spectra of their TMS derivatives.

Biotransformation of cyclizine in greyhounds. 1: identification and analysis of cyclizine and some basic metabolites in canine urine by gas chromatography-mass spectrometry

1. The partial in vivo biotransformation of Marezine ® [(cyclizine.HCl); 1-diphenylmethyl-4-methylpiperazine hydrochloride] in the racing greyhound and the excretion of the unconjugated and conjugated (Phase II) basic metabolites of cyclizine in canine urine are reported. 2. Using copolymeric bonded mixed-mode solid-phase extraction cartridges, the basic isolates from both unhydrolysed and enzyme hydrolysed urine samples were isolated, derivatized as trimethylsilyl ethers and analysed by positive-ion electron ionization gas chromatography-mass spectrometry (EI + -GC-MS). Selected samples were analysed by positive-ion methane chemical ionization (CI +) -GC-MS to aid structure elucidation of the putative metabolites. 3. Cyclizine was the major component excreted in post-administration urine. Five substrate-related basic compounds (M1 → M5) were tentatively identified by EI + - and CI + -GC-MS. The major Phase I metabolite was identified as norcyclizine [1-diphenylmethylpiperazine] (M1), the other metabolites (M2 → M5) were tentatively identified as monohydroxylated products based on MS data. 4. Cyclizine and the N 4 -desmethyl metabolite (M1) are excreted unconjugated; the other four hydroxylated metabolites are excreted as Phase II conjugates (glucuronides and/or sulphates). Structures of the putative basic metabolites are presented. At least four other basic metabolites were also detected in post-administration urine, but could not be characterized from GC-MS data. 5. All unhydrolysed post-administration urine samples were analysed by selected ion monitoring EI + -GC-MS to quantify cyclizine and norcyclizine (M1) using authentic cyclizine as the analyte and chlorcyclizine as the internal standard. The level of M1 is expressed as 'cyclizine equivalents'. The duration of urinary elimination of cyclizine and M1 was obtained from their excretion profiles. 6. From these studies, cyclizine and norcyclizine (M1) would be the target compounds of choice in the development of screening and confirmatory methods for the detection of cyclizine administration to racing greyhounds. Information on any of the other metabolites may also be of some value for confirmatory analysis.

Mass spectrometric analysis of ceramide composition in mono-, di-, tri-, and tetraglycosylceramides from mouse kidney: an experimental model for uropathogenic Escherichia coli.

Many bacteria have been shown to bind to the carbohydrate part of glycosphingolipids, but also the lipid moieties of receptor-active glycolipids are of importance. To investigate the chemistry of the ceramides of kidney glycolipids to which the uropathogenic Escherichia coli bind, different mass spectrometric techniques were utilized. First, a mixture of glycolipids isolated from man and mice kidney was separated by thin-layer chromatography (TLC) and scanned by direct desorption from the plate by fast atom bombardment mass spectrometry (TLC/FAB-MS). Second, the glycolipids were purified by preparative TLC and analyzed by negative-ion FAB-MS. After methylation, further analyses were made with positive-ion FAB-MS, positive-ion electron ionization (EI)-MS, high-temperature capillary gas chromatography (GC/EI-MS) and positive-ion matrix-assisted laser desorption/ionization (MALDI)-MS. The ceramide compositions of the four glycolipids were determined using all these MS techniques and the reliability of the different methods for this type of analyses is discussed. Comparison of the mouse kidney glycolipids with the corresponding glycolipids from human kidney showed the same degree of hydroxylation of ceramides among mono- and disaccharide glycolipids, but a significantly higher degree of hydroxylation among mouse kidney glycolipids with three and four sugar residues. This result might be of relevance for the binding of P-fimbriated E. coli to the urinary tract tissues.

Tandem mass spectrometric study of the major fragmentation pathways of some non-ester pyrethroid insecticides having alkane, alkene and ether central linkages

The non-ester pyrethroid MTI-800 which has an alkane central linkage has been studied using a tandem quadrupole mass spectrometer incorporating a hexapole collision cell under positive-ion electron ionization conditions. Other structurally related insecticides, NRDC 199 and NRDC 200, which have alkene central linkages and Flufen-prox which has an ether central linkage, have also been studied. Conventional mass spectrometry using the first quadrupole analyser only and tandem mass spectrometry have been used in this study. The positive-ion electron ionization mass spectrum of MTI-800 is dominated by an intense even electron (EE+) 1-(4-ethoxyphenyl)-1-methylethylium ion fragment which subsequently loses ethylene from the ethoxy side chain. The influence of other isosteric or isoelectronic substitutions at the geminal dimethyl position of MTI-800 and variations at the alkane linkage is shown by additional fragmentation pathways. The relative intensities of their respective molecule ions vary from 0% to 7%. The expulsion of difluorocarbene (:CF2) as a neutral species from the 1-(4-hydroxyphenyl)-2,2,2-trifluoroethylium fragment ion of Flufenprox has also been rationalized. © 1997 John Wiley & Sons, Ltd.

In situ methylation of nucleic acids using pyrolysis/mass spectrometry.

Curie-point pyrolysis/triple quadrupole mass spectrometry (Py/MS/MS) has been used with tetramethylammonium hydroxide (TMAH) to conduct in situ methylation of nucleic acid bases. Nitrogen bases in free nucleotides, oligonucleotides, calf thymus DNA and whole bacterial cells reacted in situ during pyrolysis with TMAH to form the methylated bases. Derivatization increased the volatility of the nitrogen bases and the mass of the diagnostic base peaks, thereby removing them from the positions of lower-mass background peaks. The degree of methylation as a function of TMAH concentration for the oligonucleotide, calf thymus DNA, and the whole bacteria samples was determined and found to correlate with the nature of DNA. The methylated bases were identified by their positive-ion electron ionization fragmentation patterns and confirmed with tandem mass spectrometry. The detection of the methylated bases by Py/MS/MS facilitates the goal of identifying the nucleic acids in a complex mixture (i.e. whole bacterial cells) without extraction and prior derivatization.

A Rapid Approach for the Detection of Dipicolinic Acid in Bacterial Spores Using Pyrolysis/Mass Spectrometry

Curie-point pyrolysis/triple quadrupole mass spectrometry and micro-tube furnace pyrolysis/quadrupole ion trap mass spectrometry have been used to detect dipicolinic acid (DPA) in sporulated whole bacteria. DPA in whole cells of sporulated Bacillus anthracis reacted in situ during pyrolysis with tetramethylammonium hydroxide to form the dimethyl ester derivative of DPA, dimethyl-2,6-dipicolinate (mDPA). The mDPA was identified by its positive-ion electron ionization fragmentation pattern and confirmed with tandem mass spectrometry. In an oxidative pyrolysis/quadrupole ion trap instrument, the mDPA mass spectrum showed characteristic positive-ion electron ionization fragmentation along with a significant [M+1]+ ion due to self-chemical ionization. The characteristic collision-induced dissociation fragments of mDPA were used to establish the presence of sporulation in B. anthracis whole cells at a concentration of 2.2×107 CFU (colony-forming units)/mL using the triple quadrupole instrument. The total time for analysis, including sample preparation, was less than 10 minutes for both instruments.

A rapid approach for the detection of dipicolinic acid in bacterial spores using pyrolysis/mass spectrometry.

Curie-point pyrolysis/triple quadrupole mass spectrometry and micro-tube furnace pyrolysis/quadrupole ion trap mass spectrometry have been used to detect dipicolinic acid (DPA) in sporulated whole bacteria. DPA in whole cells of sporulated Bacillus anthracis reacted in situ during pyrolysis with tetramethylammonium hydroxide to form the dimethyl ester derivative of DPA, dimethyl-2,6-dipicolinate (mDPA). The mDPA was identified by its positive-ion electron ionization fragmentation pattern and confirmed with tandem mass spectrometry. In an oxidative pyrolysis/quadrupole ion trap instrument, the mDPA mass spectrum showed characteristic positive-ion electron ionization fragmentation along with a significant [M+1]+ ion due to self-chemical ionization. The characteristic collision-induced dissociation fragments of mDPA were used to establish the presence of sporulation in B. anthracis whole cells at a concentration of 2.2 x 10(7) CFU (colony-forming units)/mL using the triple quadrupole instrument. The total time for analysis, including sample preparation, was less than 10 minutes for both instruments.

Positive ion EI mass spectra of 2,3,5-trisubstituted-1,5-benzothiazepines, diltiazem, clentiazem and their fat-soluble metabolites.

Diltiazem, clentiazem and their acidic and basic metabolites extractable with tert-butyl methyl ether, which are all 2,3,5-trisubstituted-1,5-benzothiazepines, were analysed by positive ion electron ionization (PIEI) mass spectrometry, and the structures of fragment ions and their fragmentation pathways were investigated. In all the mass spectra of these compounds, b1 ions ([R1 - CH = CH - OR2]+) or b2 ions ([R1 - CH = CH - OH]+, b1 - CH2CO; R2 = COCH3) were seen as the base peaks or one of the major peaks (R1 and OR2 are the substituents at position 2 and 3, respectively). These spectra varied greatly with the nature of the side-chain at position 5: in the spectra of compounds with a 5-(2-dimethylamino) ethyl group, the a1 ion, [CH2 = N(CH3)2]+, was the base peak ion; in those with a 5-(2-monomethyl-amino)ethyl group (trifluoroacetyl(TFA)-derivatives), no a1 ion peak was seen, but the a3 ion, [CH2CH2NCH3TFA]+, was one of the major peaks; in those of the derivatives bearing a 5-(2-amino) ethyl or -carboxymethyl group, no peaks indicating the structures of the side-chain group at position 5 could be seen. GC-mass chromatography using fragment ions such as the a1, a3, b1 and b2 ions enables detection of the unchanged drug and most of its metabolites obtained by extraction with organic solvents under acidic or basic conditions followed by derivatization.