Negative Chemical Ionization Mass Research Articles

Determination of perfluorocarboxylic acids in aqueous matrices by ion-pair solid-phase microextraction–in-port derivatization–gas chromatography–negative ion chemical ionization mass spectrometry

A rapid, selective and simple analytical procedure using tetrabutylammonium as ion pair in conjunction with solid-phase microextraction followed by in-port derivatization–GC–negative ion chemical ionization mass spectrometry was developed. The procedure allows an accurate determination of perfluoroalkylcarboxylic acids in aqueous samples at ng L −1 levels (i.e. method detection limit 20 ng L −1 for perfluorodecanoic acid) improving previous GC methods in terms of analysis time and sensitivity. Ammonia as reagent gas in the negative ion chemical ionization mass spectrometry increased the sensitivity at least 3-fold compared to methane for perfluorocarboxylic acid butyl esters. The developed procedure was successfully applied to effluents from wastewater treatment plants (i.e. 0.05–8.2 μg L −1) and harbor seawaters.

負イオン化学イオン化質量分析法による多環芳香族炭化水素の分析とコールタール分析への応用

負イオン化学イオン化質量分析法による多環芳香族炭化水素の分析とコールタール分析への応用

Quantification of F-ring isoprostane-like compounds (F 4-neuroprostanes) derived from docosahexaenoic acid in vivo in humans by a stable isotope dilution mass spectrometric assay

Lipid peroxidation has been implicated in the pathophysiological sequelae of human neurodegenerative disorders. It is recognized that quantification of lipid peroxidation is best assessed in vivo by measuring a series of prostaglandin (PG) F 2-like compounds termed F 2-isoprostanes (IsoPs) in tissues in which arachidonic acid is abundant. Unlike other organs, the major polyunsaturated fatty acid (PUFA) in the brain is docosahexaenoic acid (DHA, C22:6 ω-6), and this fatty acid is particularly enriched in neurons. We have previously reported that DHA undergoes oxidation in vitro and in vivo resulting in the formation of a series of F 2-IsoP-like compounds termed F 4-neuroprostanes (F 4-NPs). We recently chemically synthesized one F 4-NP, 17-F 4c-NP, converted it to an 18O-labeled derivative, and utilized it as an internal standard to develop an assay to quantify endogenous production of F 4-NPs by gas chromatography (GC)/negative ion chemical ionization (NICI) mass spectrometry (MS). The assay is highly precise and accurate. The lower limit of sensitivity is approximately 10 pg. Levels of F 4-NPs in brain tissue from rodents were 8.7±2.0 ng/g wet weight (mean±S.D.). Levels of the F 4-NPs in brains from normal humans were found to be 4.9±0.6 ng/g (mean±S.D.) and were 2.1-fold higher in affected regions of brains from humans with Alzheimer’s disease ( P=0.02). Thus, this assay provides a sensitive and accurate method to assess oxidation of DHA in animal and human tissues and will allow for the further elucidation of the role of oxidative injury to the central nervous system in association with human neurodegenerative disorders.

Pyrethroid soil extraction, properties of mixed solvents and time profiles using GC/MS-NICI analysis

Ultrasonic extraction was used to develop a suitable binary solvent system for the analysis of synthetic pyrethroid pesticides and mirex on soil. The analysis was carried out by gas chromatography with negative ion chemical ionization mass spectrometry (GC/MS-NICI). In the initial experiments, accurately weighed soil samples were spiked with a mixture of standard solution pyrethroids and mirex and shaken for 24 h to ensure homogeneity, then extracted with solvent. The extracts were evaporated to dryness before the volumetric internal standard was added. The binary solvents used in this study were various mixtures of hexane : acetone, hexane : dichloromethane (DCM), isooctane : acetone and isooctane : dichloromethane, representing different classes of polarity. The recoveries of all pyrethroids and mirex were satisfactory over three solvent systems: hexane : acetone, hexane : DCM and isooctane : acetone, but results of isooctane : DCM produced low recoveries. The average recovery increased with the extraction time, but the increase was not statistically significant. A 30-min optimum extraction was deemed sufficient for recovering pyrethroids from soil. After 30 min, extraction decreased owing to the re-distribution of the analyte on the soil matrix.

Sorption–desorption studies of six pyrethroids and mirex on soils using GC/MS-NICI

Sorption–desorption equilibria of six pyrethroids (permethrin, cyfluthrin, cypermethrin, λ-cyhalothrin, deltamethrin and fenvalerate) and mirex were determined in soils possessing a range of organic content (1.15–2.46%). Solutions (in deionized water, pH 6.5–7.4) of the samples were shaken using a mechanical shaker for 24 h. The suspensions were centrifuged and aliquots of clear supernatant were passed through a C-18 column (SPE extraction). The eluates were concentrated to dryness before a volumetric standard was added. The analytes were determined by gas chromatography with negative ion chemical ionization mass spectrometry (GC/MS-NICI) either in SIR or SCN mode. Sorption isotherm parameters (n and k) were calculated according to the Freundlich equation. The values of n are around unity. Permethrin and cyfluthrin were the least sorbed pyrethroids, k<2, mirex and fenvalerate the most. The effect of the pH on sorption was examined also (at pH values 2, 4, 6 and 9). Sorption behaviour on different soils and silica was also examined. Desorption studies were conducted on the same pyrethroid solutions. After sorption, the supernatant was replaced with a similar volume of deionized water. Desorption was achieved by removing all the supernatant from the centrifuged samples and then replacing it with deionized water. This equilibration process was repeated five times. Each time the suspension was centrifuged, concentrated and analyzed using GC/MS analysis. The residual amount of pyrethroid on the soil was calculated as the difference between the initial amount and the desorbed amount (mass balance).

Identification of Trimer and Dimer of 4-hydroxy-3-methoxy benzaldehyde in crystal structure of Vanillin

The effect of intermolecular hydrogen bonding on the molecular structure of vanillin has been studied using negative ion chemical ionization (NICl) mass spectrometry methods. The [Trimer-H2O] and [Dimer-H2O] were observed at m/z 438 and 286 respectively in NICl (CH4) mass spectrum of vanillin. The NICl (Cl) mass spectrum of vanillin differs where deprotonated molecular ion peak, [monomer-H] at m/z,151 was the second most abundant ion peak. The base ion peak was observed at m/z,187 due to the presence of monomer+35Cl. The [Trimer-H2O] and [Dimer - H2O] were not detected due to the presence of chloride ion. The results obtained support that the crystal of vanillin consists of trimer and dimer of 4-hydroxy-3-methoxy benzaldehyde. Keywords 4-hydroxy-3-methoxy benzaldehyde, vanillin, intermolecular hydrogen bonding. (Global Journal of Pure and Applied Sciences: 2002 9(1): 101-104)

APPLICATIONS OF NEGATIVE ION CHEMICAL IONIZATION MASS SPECTROMETRY TECHNIQUE IN ENVIRONMENTAL ANALYSIS

With the availability of Negative Ion Chemical Ionization (NCI) mode of ionization on most bench top Mass Spectrometry (MS), many analytical problems involving the analysis of electron capturing organic compounds can be easily resolved. The Negative Ion Chemical Ionization Mass Spectrometry (NCI/MS) technique has been utilized for many types of analysis at the Environmental Protection Laboratory on a regular basis for routine analysis and resolving sensitivity, matrix and interference problems. NCI/MS is shown to provide inroads in the identification and lowering of detection limits for halogenated pesticides, polychlorinated biphenyls (PCBs), dioxins and furans. NCI/MS specificity and selectivity are shown to eliminate interferences caused by substances such as plasticizers and other nonhalogenated compounds including petroleum products when analyzing contaminated sample extracts.

The pharmacokinetics of the prostaglandin E1 analogue misoprostol in plasma and colostrum after postpartum oral administration

Objective: To study pharmacokinetics of prostaglandin E1 analogue, misoprostol in plasma and colostrum after postpartum oral administration. Study design: Twenty women received 600 μg doses of misoprostol orally after delivery. Plasma levels of the principal metabolite, misoprostol acid, were measured at 2, 10, 20, 30, 40, 50, 60, 90, 120, 180, 240 and 300 min (48 samples). Colostrum was expressed from the breasts to measure misoprostol acid at 60, 120, 180, 240, and 300 min (24 samples). Assay was done using isotope dilution gas chromatography (GC)/negative ion chemical ionisation mass spectrometry (MS). Results: The plasma concentration of misoprostol acid rose quickly. Two minutes after oral administration its mean level was 91.5 pg/ml, peaked at 20 min (344 pg/ml), then fell steeply by 120 min (27.8 pg/ml) and remained low for the duration of the study. Misoprostol acid in colostrum reached maximum concentration of 20.9 pg/m within 1 h after oral administration. It then declined gradually to 17.8 pg/ml at 2 h, 2.8 pg/ml at 4 h and to <1 pg/ml at 5 h. Areas under misoprostol concentration versus time curves up to 5 h were 290.1 pg h/ml in the plasma and 51.4 pg h/ml in colostrum, respectively. Conclusion: Misoprostol acid is secreted in colostrum within 1 h of oral administration of 600 μg of misoprostol; the pharmacokinetics of misoprostol after oral administration during postpartum is similar to that of other pregnancy periods.

Improved sample preparation for the quantitative analysis of paroxetine in human plasma by stable isotope dilution negative ion chemical ionisation gas chromatography–mass spectrometry

An improved sample work-up and derivatisation procedure for the quantitative determination of paroxetine in human plasma by gas chromatography–negative ion chemical ionisation mass spectrometry is presented. Solvent extraction from plasma samples at alkaline pH was combined with derivatisation to the pentafluorobenzyl carbamate derivative in one step and subsequently analysed without any further purification. Thus, lengthy and time-consuming solvent evaporation steps are avoided to assure high-throughput analysis. Complete validation data are presented. The method is rugged, rapid and robust and has been applied to the batch analysis of paroxetine during pharmacokinetic profiling of the drug.

Enantiomer ratios, patterns and levels of toxaphene congeners in human milk from Germany

High resolution gas chromatography (HRGC) coupled to quadrupole negative ion chemical ionization (NICI) mass spectrometry (MS) was used to investigate congener patterns, levels and enantiomer distribution of selected toxaphene congeners (#26, #41, #44, #50, #63, B7-1453) in human milk from Germany. #50 and #26 were the most abundant congeners. Furthermore, the identification of B7-1453, B8-1412, #41, #42, #44 and #63 was possible. Levels for the sum of #26, #41, #44 and #50 ranged from 7 to 24 microg kg(-1) milk fat and contributed between 2 and 9% to the total burden of investigated organochlorines such as selected compounds of the chlordane group, HCH, DDT and polychlorinated biphenyls (PCB). Capillaries coated with heptakis-(2,3,6-O-tert-butyldimethylsilyl)-beta-cyclodextrin (TBDMS-CD) or octakis-(2,3,6-tri-O-ethyl)-gamma-cyclodextrin (TEG-CD) were used for the enantioselective separations. Enantiomer ratios (ER) and enantiomer fractions (EF) of the abundant toxaphene congeners #26 and #50 as well as of B7-1453, #41 and #63 were determined. Greatest deviations from a racemic composition in individual human milk samples were found for #41 (1.54-2.37), #50 (1.37-1.72) and #63 (0.53-0.71) whereas ERs for #26 were close to 1. Compared to wildlife biota such as fish and raptors ER changes were more pronounced in human milk but comparable to human adipose tissue.

Identification of toxaphene congeners in bird eggs by combining quadrupole NICI-mS and ion trap EI-MS/MS

Quadrupole negative ion chemical ionisation (NICI) mass spectrometry (MS) and ion trap electron ionisation (EI) tandem mass spectrometry (MS/MS) were applied to the identification of toxaphene congeners in eggs from different species of Norwegian predatory birds. Identification criteria were retention time, degree of chlorination (NICI), and the abundance ratio between two daughter ions (m/z 269 and m/z 233) selected from the full scan daughter ion spectrum after collision induced dissociation of m/z 305 (EI-MS/MS). In this way the following congeners could be unequivocally detected: Parlar #26, #32, #38, #40, #41, #42, #44, #50, #51, #58, and #63 as well as the recently described toxaphenes B7-1453 and B8-1412. Furthermore, a number of hitherto unreported toxaphenes were found. Compared to NICI-MS, ion trap EI-MS/MS suppressed interferences from sample matrix and other polychlorinated compounds more efficiently. The advantages of the proposed approach were demonstrated by analysing the congener pattern present in seven eggs from Norwegian birds of prey. Levels of toxaphenes (80–740 ng/g wet weight) were two to twenty times lower than for chlordanes (170–1 600 ng/g wet weight) and polychlorinated biphenyls (2900–8000 ng/g wet weight). Parlar #26, B8-1412, #40, #41, #50 contributed about 80–90% to the quantified toxaphene burden.

Study of the enantioselective elimination of four toxaphene congeners in rat after intravenous administration by high resolution gas chromatography negative ion mass spectrometry

This study was performed to investigate the possible enantioselective metabolism of the four chlorinated bornanes: #26, #32, #50 and #62 (according to the Parlar nomenclature) by rats. Rats were exposed to a mixture of these toxaphenes by a single intravenous injection. Enantiomer ratios (ER) as well as the enantiomer fractions (EF) were determined in brain, adipose tissue and liver samples at six time intervals by high resolution gas chromatography (HRGC) coupled to negative ion chemical ionization (NICI) mass spectrometry (MS). Capillaries coated with heptakis-(2,3,6- O-tert-butyldimethylsilyl)-β-cyclodextrin (TBDMS-CD) or octakis-(2,3,6-tri- O-ethyl)-γ-cyclodextrin (TEG-CD) were used for the enantioselective separations. Significant time-dependent changes of ER and EF were found in all the three tissues for #26, #50 and #62. Greatest deviations from racemic composition were found in the liver, which is known to be the major metabolizing organ for toxaphenes. #32 was metabolized the fastest, but showed no changes in ER. Brief information is also included about the possible reasons for the different behaviors of the four congeners in the studied tissues.

Molecular weight distribution and regioisomeric structure of triacylglycerols in some common human milk substitutes

AbstractTriacylglycerol (TAG) molecular weight distribution and regioisomeric structure of selected molecular weight species in human milk and in 32 human milk substitutes was determined. Negative ion chemical ionization mass spectrometry was used to determine the molecular weight distribution and collisionally induced dissociation tandem mass spectrometry applied to identify the sn‐2 and sn‐1/3 positions of fatty acids in TAG. The main molecular weight species of human milk TAG in decreasing order of abundance were 52∶2, 52∶3, 52∶1, 54∶3, 50∶2, 50∶1, 54∶4, 48∶1, 54∶2, 48∶2, 46∶1, 52∶4, and 50∶3 (acyl carbon number/number of double bonds), constituting 83 mol% of total TAG molecular species. In human milk substitutes, the proportion of the corresponding molecular weight species varied from 33 to 87 mol%. The main TAG regioisomers within the molecular weight species 52∶2, 52∶3, and 50∶1 in human milk were 18∶1‐16∶0‐18∶1 (83 mol%), 18∶1‐16∶0‐18∶2 (83 mol%), and 18∶1‐16∶0‐16∶0 (80 mol%), respectively. In human milk substitutes, the corresponding proportions varied in a wide range of 0–82 mol%, 0–100 mol%, and 0–73 mol%, respectively. Although TAG structures in some human milk substitutes closely resembled those in human milk, the great variation among samples leads to the conclusion that it is still possible to improve the TAG composition in human milk substitutes by applying novel methods to synthesize structured TAG.

Improved assay for the quantification of the major urinary metabolite of the isoprostane 15-F 2t-Isoprostane (8-iso-PGF 2α) by a stable isotope dilution mass spectrometric assay

Background: The F 2-isoprostanes (IsoPs) are a series of novel prostaglandin (PG)-like compounds generated from the free radical catalyzed peroxidation of arachidonic acid. One IsoP, 15-F 2t-IsoP (8-iso-PGF 2α), has been shown to be formed in abundance in vivo and to exert potent biological activity. Methods: As a means to assess the endogenous production of this compound, we previously developed a method to quantify the major urinary metabolite of 15-F 2t-IsoP, 2,3-dinor-5,6-dihydro-15-F 2t-IsoP (2,3-dinor-5,6-dihydro-8-iso-PGF 2α, 15-F 2t-IsoP-M ), by gas chromotography (GC)/negative ion chemical ionization mass spectrometry (MS) employing stable isotope dilution methodology. While useful, we found that the assay occasionally suffered from the presence of impurities that co-elute on GC with 15-F 2t-IsoP-M, making the measurement of this compound difficult. We now report a modified assay for the quantification of 15-F 2t-IsoP-M employing GC/MS that alleviates this problem. Results: Precision of the assay is ±7% and the accuracy is 96%. The lower limit of sensitivity is approximately 8 pg. Normal concentrations of this metabolite in urine were found to be 0.46±0.09 ng/mg creatinine (mean±1 S.D.) Urinary excretion of 15-F 2t-IsoP-M is markedly altered in situations associated with increased or decreased oxidant stress in vivo. Conclusions: This assay provided a sensitive and accurate method to assess endogenous IsoP generation and can be used to further explore the role of oxidant injury in human disease.

Simultaneous determination of delta9-tetrahydrocannabinol and 11-nor-9-carboxy-delta9-tetrahydrocannabinol in human plasma by solid-phase extraction and gas chromatography-negative ion chemical ionization-mass spectrometry.

Delta9-tetrahydrocannabinol (THC) and 11-nor-9-carboxy-delta9-tetrahydrocannabinol (THCA) in human plasma can be simultaneously detected using solid-phase extraction with gas chromatography and negative ion chemical ionization mass spectrometry. THC-d3 and THCA-d3 are added as internal standards; protein is precipitated with acetonitrile and the resulting supernatants diluted with 0.1 M sodium acetate (pH 7.0) prior to application to the solid-phase extraction columns. THC and THCA were eluted separately and then pooled, dried under air, and derivatized with trifluoroacetic anhydride and hexafluoroisopropanol. The derivatized THC-d0 gives abundant molecular anions (m/z 410), and the derivatized THCA-d0 gives abundant fragment ions (m/z 422) formed by loss of (CF3)2CHOH from its molecular anion. The recoveries of THC and THCA were 74% and 17%, respectively. The lower and upper limits of quantitation were 0.5 and 100 ng/mL for THC and 2.5 ng/mL and 100 ng/mL for THCA. The within-run accuracy and precision for THC (measured at 0.5, 1, 10 and 75 ng/mL) ranged from 98 to 106% (% target) and 4.1 to 9.5 (%CV), respectively. For THCA, the within-run accuracy and precision (measured at 2.5, 5, 10, and 75 ng/mL) ranged from 89 to 101% and 4.3 to 7.5%, respectively. The between-run accuracy and precision for THC ranged from 92 to 110% and 0.4 to 12.4%, respectively. The between-run accuracy and precision for THCA ranged from 97 to 103% and 6.5 to 12.3%, respectively. In processed samples stored in reconstituted form at -20 degrees C, THC and THCA were stable for at least three days. THC and THCA stored in plasma were stable following three freeze/thaw cycles. THC and THCA in whole blood at room temperature for 6 h, or in plasma stored at room temperature for 24 h, did not show significant change. Storage in polypropylene containers for 7 days at -20 degrees C and the presence of 1% sodium fluoride or the cannabinoid receptor antagonist, SR141716, at 1 microg/mL did not interfere with the quantitation of THC and THCA. In three individuals who smoked marijuana under controlled dosing conditions, peak THC concentrations of 151, 266, and 99 ng/mL were seen in the first plasma samples drawn immediately after the end of smoking, and corresponding peak THCA concentrations of 41, 52, and 17 ng/mL occurred at 0.33 to 1 h after cessation of smoking.

The determination of 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in hair using negative ion gas chromatography-mass spectrometry and high-volume injection.

The determination of 11-nor-delta9-THC-9-carboxylic acid (THC-COOH) in hair specimens at the sensitivity required to detect marijuana users is a difficult analytical problem. A sensitive and specific method has been developed for the quantitative assay of THC-COOH in hair. Hair specimens were washed, incubated in sodium hydroxide, subjected to solid-phase extraction, and analyzed using high-volume injection coupled with negative chemical ionization (NCI) mass spectrometry. A common disadvantage of chemical ionization, the production of a single mass-to-charge ratio ion, was also addressed. By specific selection of the derivatizing agent, three ions were monitored, allowing the calculation of two ion ratios, as in electron impact mode. The method was applied to several hair specimens taken from known marijuana users and workplace specimens. This is the first publication describing the use of high-volume injection and NCI mass spectrometry for the determination of THC-COOH in hair.

Quantitation of acyl migration during lipase‐catalyzed acidolysis, and of the regioisomers of structured triacylglycerols formed

AbstractVarious MLM‐type (M, medium‐chain fatty acids; L, long‐chain fatty acids) structured triacylglycerols were produced in pilot‐ or small‐scale packed‐bed reactors by lipasecatalyzed acidolysis. The incorporation and acyl migration of octanoic acid were measured by gas chromatography and Grignard degradation, and ranged from 39.0 to 48.7% and 0.6 to 9.3%, respectively. Quantitation of triacylglycerol molecular species was performed by ammonia negative ion chemical ionization (NICI) mass spectrometry (MS). The proportion of ACN (acyl carbon number) 34 species that contained one C18 fatty acid and two C8∶0′ in samples analyzed, varied from 12.5 to 23.2%. The selected regioisomers MLM and MML within the ACN 34 species group were quantified by NICI tandem MS (MS/MS) and were in the range of 97.1 to 98.4% and 1.6 to 2.9%, respectively. There was no correlation between the level of acyl migration during lipase‐catalyzed esterification and the level of regioisomers of the selected MLM‐type triacylglycerols in the structured lipid samples.

Validation of a method for the detection and confirmation of nitroimidazoles and corresponding hydroxy metabolites in turkey and swine muscle by means of gas chromatography–negative ion chemical ionization mass spectrometry

The results of a validation study of a GC–NCI–MS method for the quantitative determination of 5-nitroimidazoles {1,2-Dimethyl-5-nitroimidazole (dimetridazole, DMZ), 1-methyl-2-[(carbamoyloxy)methyl]-5-nitroimidazole (ronidazole, RNZ), 1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole (metronidazole, MNZ) and 2-isopropyl-1-methyl-5-nitroimidazole (ipronidazole, IPZ)} including the hydroxy metabolites of these agents {2-hydroxymethyl-1-methyl-5-nitroimidazole (HMMNI), 1-(2-hydroxyethyl)-2-hydroxymethyl-5-nitroimidazole (MNZOH), and 1-methyl-2-(2′-hydroxyisopropyl)-5-nitroimidazole (IPZOH)} in turkey and swine muscle are presented. The validation was carried out according to the requirements of the draft for the revision of Commission Decision 93/256/EC, which is expected to be adopted by the European Commission in due course. The determination of the method’s performance parameters revealed decision limits (CC α ) between 0.65 and 2.8 μg/kg for DMZ, RNZ/HMMNI, MNZ and MNZOH. Confirmatory analyses according to the requirements of the forthcoming EC decision are possible for all analytes except for IPZ and IPZOH where already the decision limits (CC α ) were higher (5.2 μg/kg) than for the above-mentioned nitroimidazoles. The within-laboratory reproducibility and the mean recovery were in an acceptable range for all analytes.

A new peroxycarboxylic nitric anhydride identified in the atmosphere: CH2=CHC(O)OONO2 (APAN)

We detected a peroxyacyl nitrate (PAN)‐type compound, peroxyacryloyl nitrate (CH2=CHC(O)OONO2, APAN) which has not previously been reported in the atmosphere. Identification of APAN was made from negative ion chemical ionization (NICI) mass spectra of a cryogenically concentrated ambient air sample by comparison with a synthesized standard. The thermally fragile nature of the compound, and the retention time of the synthesized standard provide additional evidence for the existence of APAN in ambient air. Observations made at a suburban site in Tokyo, and at Rishiri Island, a remote site in northern Japan, suggest the ubiquitous presence of APAN in the global atmosphere. While its mixing ratio was usually low (&lt;1% of PAN), high‐APAN episodes (∼4% of PAN) were observed at Rishiri Island. APAN can be formed from acrolein, which is directly emitted from vehicle exhaust, and may be produced by oxidation of 1,3‐butadiene and aromatics. Further measurements of APAN along with acrolein and other NMHCs are required to understand its distribution, behavior, and sources in the atmosphere.

Software (MSPECTRA) for automatic interpretation of triacylglycerol molecular mass distribution spectra and collision induced dissociation product ion spectra obtained by ammonia negative ion chemical ionization mass spectrometry.

Rapid analysis of molecular mass distributions of triacylglycerol (TAG) mixtures and regioisomeric structures of selected molecular mass species is possible using ammonia negative ion chemical ionization mass spectrometry utilizing sample introduction by direct exposure probe. However, interpretation of spectra and calculation of results is time consuming, thus lengthening the total analysis time. To facilitate result calculation a software package (MSPECTRA 1.3) was developed and applied to automatic processing of triacylglycerol molecular mass distribution spectra and collision induced dissociation (CID) product ion spectra. The program is capable of identifying triacylglycerol molecular mass species possessing different ACN:DB (acyl carbon number:number of double bonds) ratios on the basis of m/z values of [M - H](-) ions. In addition to such identification the program also corrects spectra for abundances of naturally occurring (13)C isotopes and calculates relative proportions of triacylglycerol molecular species in the analyzed samples. If several replicate spectra are processed simultaneously the program automatically calculates an average and standard deviation of relative proportions of molecular species. In the case of CID spectra the program identifies fatty acid fragment ions [RCO(2)](-) and the corresponding [M - H - RCO(2)H - 100](-) ions, and calculates the relative proportions of ions in both groups. These proportions are then used automatically to calculate the fatty acid combinations comprising the parent triacylglycerol molecule and the regiospecific positions of fatty acids. Processing of several replicate product ion spectra simultaneously produces averaged proportions of regioisomers comprising the parent triacylglycerol molecular species and the standard deviation of the analysis. The performance of the program was tested by analyzing triacylglycerol samples of human milk, human milk substitutes, human chylomicron and cocoa butter, and by comparing results obtained by automated processing of the data with manually calculated results.