Characterization of Organic Particles from Incense Burning Using an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer

Incense burning is a common ritual in Asian communities both indoors in residential homes and outdoors in temple premises. Organic particles from burning of incense sticks, incense coils, and mosquito coils after extensive dilution (>1000×) were characterized by the Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The obtained mass spectra in general resemble those reported for biomass burning aerosols. Ion peaks with m/z values higher than 100 accounted for 15%–25% of the organic signals in the unit-mass-resolution (UMR) mass spectra. In the high-resolution (HR) mass spectra, the ion peaks at m/z 60 and 73 are found to be related to the sugar anhydrides as in particles from other biomass burning processes. In addition, the ion peaks at m/z 107, 121, 137, 151, 167, and 181, some of which (e.g., m/z 137 and 167) have been observed in particles from biomass burning but not yet assigned, were assigned to lignin-related components. Elemental analysis from the HR data reveals that a large portion of particulate organics from incense burning are oxygenated (O/C between 0.3 and 0.5) and unsaturated (and/or cyclic) in nature. Results from this study also highlight that mass spectra from HR-ToF-AMS measurements concerning primary emissions such as incense burning contain very useful information in the high m/z (>100) region about the chemical characteristics of those primary organic particles.

Copyright 2012 American Association for Aerosol Research     

Comparison of sulfoquinovosyl diacylglycerol from spinach and the purple bacteriumRhodobacter sphaeroides by fast atom bombardment tandem mass spectrometry

Isolated sulfoquinovosyl-diacylglycerol (SQD) from spinach and the purple bacteriumRhodobacter sphaeroides provide two sources of very different molecular species of SQD. We were able to demonstrate by fast atom bombardment-collisionally activated dissociation tandem mass spectrometry in the negative ion mode that the sulfoquinovosyl head group of the plant and bacterial lipids can be characterized by the common fragmentation pattern found in the spectra of both samples. Differences in the acyl functions from the two sources were also identified by this technique. SQD specific fragments are found atm/z 299, 283, 241, 225, 165 and 80 which indicate the presence of the sulfoquinovosyl moiety. The two predominant molecular species found in spinach contain palmitic and linolenic ([M−H]⁻ atm/z 815) or two linolenic acids ([M−H]⁻ atm/z 837) in thesn−1 andsn−2 positions, while the two major species of the bacterial lipid contain palmitic and 18∶1 (vaccenic) cids ([M−H]⁻ atm/z 819) or stearic and 18∶1 (vaccenic) acids, ([M−H]⁻ atm/z 847), respectively.     

Tandem mass spectrometry of negative ions from choline phospholipid molecular species related to platelet activating factor

Fast atom bombardment mass spectrometry of choline phospholipids produces negative ions characteristic of the intact molecule and tandem mass spectrometry of collision-induced decomposition of M-15 anions characterizes both the identity and substituent position of radyl groups. Certain choline phospholipid molecular species which may be of special interest in the generation of platelet activating factor contain a highly unsaturated fatty acyl substituent atsn-2 and an ether radyl group atsn-1; other choline phospholipid molecular species which contain esterified arachidonic acid are of interest as potential sources of arachidonate for eicosanoid biosynthesis. Collisional activated decomposition of 1-hexadecanoyl-2-arachidonoyl-sn-glycerophosphocholine produce abundant carboxylate anions atm/z 303 (arachidonate) andm/z 255 (hexadecanoate) in a ratio of 3∶1, diagnostic for thesn-2 arachidonoyl position. The ether analog, 1-O-hexadecyl-2-arachidonoyl glycerophosphocholine, produces only one collision-induced dissociation ion atm/z 303 and no product ions corresponding to the ether substituent atsn-1. Molecular weight information from the M-15 ion combined with the CID generated carboxylate anions completely characterize these important phospholipids. Precursor ion studies of M-15 anions from glycerophosphocholine lipids indicate that this ion is derived directly from a unique adduct ion formed by attachment of the molecular species to a matrix alkoxide ion, neutralizing the positive charge of the quaternary choline nitrogen. Decomposition of this adduct ion yields a methylated matrix molecule and the nominal M-15 ion. Based on a paper presented at the Third International Conference on Platelet-Activating Factor and Structurally Related Alkyl Ether Lipids, Tokyo, Japan, May 1989.     

Evaluation of the new capture vaporizer for aerosol mass spectrometers: Characterization of organic aerosol mass spectra

The Aerosol Mass Spectrometer (AMS) and Aerosol Chemical Speciation Monitor (ACSM) are widely used for quantifying submicron aerosol mass concentration and composition, in particular for organic aerosols (OA). Using the standard vaporizer (SV) installed in almost all commercial instruments, a collection efficiency (CE) correction, varying with aerosol phase and chemical composition, is needed to account for particle bounce losses. Recently, a new “capture vaporizer” (CV) has been shown to achieve CE～1 for ambient aerosols, but its chemical detection properties show some differences from the SV due to the increased residence time of particles and vaporized molecules inside the CV. This study reports on the properties and changes of mass spectra of OA in CV-AMS using both AMS and ACSM for the first time. Compared with SV spectra, larger molecular-weight fragments tend to shift toward smaller ions in the CV due to additional thermal decomposition arising from increased residence time and hot surface collisions. Artifact CO⁺ ions (and to a lesser extent, H₂O⁺), when sampling long chain alkane/alkene-like OA (e.g., squalene) in the CV during the laboratory studies, are observed, probably caused by chemical reactions between sampled OA and molybdenum oxides on the vaporizer surfaces (with the carbon derived from the incident OA). No evidence for such CO⁺ enhancement is observed for ambient OA. Tracer ion marker fractions (f_m/z =, i.e., the ratio of the organic signal at a given m/z to the total OA signal), which are used to characterize the impact of different sources are still present and usable in the CV. A public, web-based spectral database for mass spectra from CV-AMS has been established.

Copyright © 2018 American Association for Aerosol Research     

Acid Precipitation versus Solvent Extraction: Two Techniques Leading to Different Lactone/Acidic Sophorolipid Ratios

Sophorolipids (SL) prepared from biotransformation of refined bleached deodorized (RBD) palm olein by Starmerella bombicola (ATCC 22214) occur as a mixture of homologs. Characterization of SL was performed using high-performance liquid chromatography with electrospray ionization mass spectrometry detection (HPLC-ESI-MS) under negative ion mode. Two different purification methods were compared: precipitation and solvent extraction. SL purified by precipitation and solvent extraction consisted of five major homologs with m/z values of 687, 645, 689, 705, and 661. The fractions of lactone and acidic SL via precipitation were 70.24 ± 1.4% and 29.76 ± 1.4%, respectively. SL isolated by solvent extraction contained 44.78 ± 1.9% lactone and 55.22 ± 1.9% acidic SL. Therefore, the purification method strongly impacted the composition of the SL products.     

Detection of oxysterols in oxidatively modified low density lipoprotein by MALDI‐TOF MS

A simple method for the detection of oxysterols in oxidatively modified LDL (Ox‐LDL) has been developed using MALDI‐TOF MS. To identify the ion peaks of oxysterols, seven major oxysterols in Ox‐LDL (7α‐hydroxycholesterol, 7β‐hydroxycholesterol, 7‐ketocholesterol, 5α,6α‐epoxycholesterol, 5β,6β‐epoxycholesterol, 25‐hydroxychokesterol, (25R)‐26‐hydroxycholesterol), and cholesta‐3,5‐dien‐7‐one were analyzed by MALDI‐TOF MS. Among these oxysterols, 7‐ketocholesterol, a very abundant oxysterol in Ox‐LDL, was found to show a characteristic peak of [M + H]⁺ at m/z 401. Cholesta‐3,5‐dien‐7‐one, which is known as a degradation product of 7‐ketocholesterol upon saponification of Ox‐LDL, gave a major peak of [M + H]⁺ at m/z 383. In contrast, other oxysterols showed similar peak patterns at m/z 367 and 385. These results were applied to the analysis of Ox‐LDL by MALDI‐TOF MS after saponification and hexane‐extraction, detecting ion peaks at m/z 367, 383, 385, and 401. This MALDI‐TOF MS method has a potential as a simple tool to show the presence of oxysterols in Ox‐LDL without derivatization and chromatographic separation.     

Evaluation of the new capture vaporizer for aerosol mass spectrometers (AMS) through field studies of inorganic species

The aerosol mass spectrometer (AMS) and aerosol chemical speciation monitor (ACSM) are widely used for quantifying aerosol composition. The quantification uncertainty of these instruments is dominated by the collection efficiency (CE) due to particle bounce. A new “capture vaporizer” (CV) has been recently developed to achieve unit CE. In this study, we examine the performance of the CV while sampling ambient aerosols. AMS/ACSMs using the original standard vaporizer (SV) and CV were operated in parallel during three field studies. Concentrations measured with the CV (assuming CE = 1) and SV (using the composition-dependent CE of Middlebrook et al.), as well as SMPS and PILS-IC are compared. Agreement is good in all cases, verifying that CE ～ 1 in the CV when sampling ambient particles. Specific findings include: (a) The fragmentation pattern of ambient nitrate and sulfate species observed with the CV was shifted to smaller m/z, suggesting additional thermal decomposition. (b) The differences in fragmentation patterns of organic vs. inorganic nitrate and sulfur species are still distinguishable in the CV, however, with much lower signal-to-noise compared to the SV. (c) Size distribution broadening is significant, but its impact is limited in field studies since ambient distributions are typically quite broad. Consistent size distributions were measured with the SV and CV. (d) In biogenic areas, UMR nitrate is overestimated based on the default fragmentation table (～factor of 2–3 in SOAS) for both vaporizers, due to underestimation of the organic interferences. We also report a new type of small interference: artifact chloride signal can be observed in the AMS when high nitrate mass concentration is sampled with both the SV (～0.5% chloride/nitrate) or CV (～0.2% chloride/nitrate). Our results support the improved quantification with the CV AMS and characterize its chemical detection properties.

Copyright © 2017 American Association for Aerosol Research     

Mass Spectra of Unlabeled and Isotopically Labeled Hexamethylene Triperoxide Diamine (HMTD)

Electron impact (EI) mass spectra of unlabeled and ¹³C/¹⁵N labeled hexamethylene triperoxide diamine were obtained using a direct insertion probe. The most prominent peaks were the molecular ions (m/z 208 and m/z 216, respectively). An EI fragmentation pathway is proposed based on the mass spectral evidence.     

Characterization of primary fatty amides produced by lipase-catalyzed amidation of hydroxylated fatty acids

A novel hydroxylated primary fatty amide was produced from lesquerolic acid by direct amidation with ammonia catalyzed by immobilized Pseudozyma (Candida) antarctica lipase B (Novozym 435) in organic solvent. The amides of ricinoleic acid and oleic acid were also produced for comparison. The hydroxy FA were transformed at comparable rates to that of oleic acid. The rate of amide formation was greater for the longerchain lesquerolic acid than for ricinoleic acid. All products exhibited characteristic primary-amide mass spectrum peaks with a base peak at m/z 59 and a strong ion fragment at m/z 72. Other peaks present are consistent with cleavage on either side of the hydroxyl position. The mass spectra, together with ¹H and ¹³C NMR data, suggest that the products of lipase-catalyzed direct amidation of ricinoleic acid and lesquerolic acid are 12-hydroxy-9(Z)-octadecenamide and 14-hydroxy-11(Z)-eicosenamide, respectively.     

Characterization of epoxy carotenoids by fast atom bombardment collision-induced dissociation MS/MS

The characterization and structure of epoxy carotenoids possessing 5,6-epoxy, 5,8-epoxy and 3,6-epoxy end groups conjugated to the polyene chain were investigated using highenergy fast atom bombardment collision-induced dissociation MS/MS methods. In addition to [M-80]⁺, a characteristic fragment ion of an epoxy carotenoid, product ions resulting from the cleavage of C−C bonds in the polyene chain from the epoxy end group, such as m/z 181 (b ion) and 121 (c ion), were detected. On the other hand, diagnostic ions of m/z 286 (e-H ion) and 312 (f-H ion) were observed, not in the 5,6-epoxy or 5,8-epoxy carotenoid but in the 3,6-epoxy carotenoid. These fragmentation patterns can be used to distinguish 3,6-epoxy carotenoids from 5,6-epoxy or 5,8-epoxy carotenoids. The structure of an epoxy carotenoid, 3,6-epoxy-5,6-dihydro-7′,8′-didehydro-β,β-carotene-5,3′-diol (8), isolated from oyster, was characterized using FAB CID-MS/MS by comparing fragmentation patterns with those of related known compounds.     

Evaluation of a Method for Nitrotyrosine Site Identification and Relative Quantitation Using a Stable Isotope-Labeled Nitrated Spike-In Standard and High Resolution Fourier Transform MS and MS/MS Analysis

The overproduction of reactive oxygen and nitrogen species (ROS and RNS) can have deleterious effects in the cell, including structural and possible activity-altering modifications to proteins. Peroxynitrite is one such RNS that can result in a specific protein modification, nitration of tyrosine residues to form nitrotyrosine, and to date, the identification of nitrotyrosine sites in proteins continues to be a major analytical challenge. We have developed a method by which ¹⁵N-labeled nitrotyrosine groups are generated on peptide or protein standards using stable isotope-labeled peroxynitrite (O¹⁵NOO⁻), and the resulting standard is mixed with representative samples in which nitrotyrosine formation is to be measured by mass spectrometry (MS). Nitropeptide MS/MS spectra are filtered using high mass accuracy Fourier transform MS (FTMS) detection of the nitrotyrosine immonium ion. Given that the nitropeptide pair is co-isolated for MS/MS fragmentation, the nitrotyrosine immonium ions (at m/z = 181 or 182) can be used for relative quantitation with negligible isotopic interference at a mass resolution of greater than 50,000 (FWHM, full width at half-maximum). Furthermore, the standard potentially allows for the increased signal of nitrotyrosine-containing peptides, thus facilitating selection for MS/MS in a data-dependent mode of acquisition. We have evaluated the methodology in terms of nitrotyrosine site identification and relative quantitation using nitrated peptide and protein standards.     

Electrospray ionization MS of high M.W. TAG oligomers

Reported are the on-line LC/electrospray ionization MS of large, high M.W. oligomers formed from heated triolein, a TAG used as a model for dietary oils. Triolein, the major component of olive oil, canola oil, and other dietary oils, was heated at frying temperature, and the TAG oxidation products were separated using RP-HPLC coupled to an ion trap mass spectrometer via an electrospray ionization interface. Ammonium formate was added as a sheath liquid to promote ammonium adduct formation. Masses corresponding to ammonium adducts of intact carbon-linked dimers (m/z 1783–1787), trimers (m/z 2666–2672), and tetramers (m/z 3547–3557) of triolein, with and without additional sites of unsaturation, were observed. Also, dimers, trimers, and tetramers containing one, two, or three additional oxygens, also with and without additional sites of unsaturation, are reported. Based on the formation of some types of triolein dimers, we believe that tristearin might also form dimers, even though it has no readily oxidizable sites of unsaturation. Oxidized tristearin monomers, tristearin dimers, chainaddition products, and chain-shortened products are observed.     

Synthesis, mass spectrometry, and nuclear magnetic resonance characterization of Di-guerbet esters

Several Di-Guerbet esters (DGE) suitable for lubricant applications were synthesized from branched Guerbet alcohols and Guerbet acids. The mass spectra of DGE under electron-ionization and positive chemical-ionization (PCI) conditions were recorded. Gas chromatography-mass spectrometry, especially in PCI mode with methane as reagent gas, is an effective method for analyzing DGE. In methane positive chemical-ionization mass spectrometry, the DGE give molecular ion peaks. In both PCI and EI modes, some other characteristic ions including up to four McLafferty rearrangement products with high m/z are observed. Thus identification of both hydrocarbon moieties is possible. The DGE were also characterized by ¹H-and ¹³C nuclear magnetic resonance. Deceased.     

Analysis of saturated free fatty acids from pollen by HPLC with fluorescence detection

A sensitive method for the determination of free fatty acids using 2‐(2‐(anthracen‐10‐yl)‐1H‐naphtho[2,3‐d]imidazol‐1‐yl) ethyl‐p‐toluenesulfonate (ANITS) as tagging reagent with fluorescence detection has been developed. ANITS could easily and quickly label fatty acids in the presence of the K₂CO₃ catalyst at 90 °C for 40 min in N,N‐dimethylformamide solvent. From the extracts of rape bee pollen samples, 20 free fatty acids were sensitively determined. Fatty acid derivatives were separated on a reversed‐phase Eclipse XDB‐C₈ column by HPLC in conjunction with gradient elution. The corresponding derivatives were identified by post‐column APCI/MS in positive‐ion detection mode. ANITS‐fatty acid derivatives gave an intense molecular ion peak at m/z [M+H]⁺; with MS/MS analysis, the collision‐induced dissociation spectra of m/z [M+H]⁺ produced the specific fragment ions at m/z [M–345]⁺ and m/z 345.0 (here, m/z 345 is the core structural moiety of the ANITS molecule). The fluorescence excitation and emission wavelengths of the derivatives were λ_ex = 250 nm and λ_em = 512 nm, respectively. Linear correlation coefficients for all fatty acid derivatives are >0.9999. Detection limits, at a signal‐to‐noise ratio of 3 : 1, are 24.76–98.79 fmol for the labeled fatty acids.     

Electrochemistry-electrospray ionization FT ICR mass spectrometry (EC ESI MS) of guanine–tyrosine and guanine–glutathione crosslinks formed on-line

Crosslinking of guanine with tyrosine and glutathione is studied by on-line electrochemistry electrospray ionization mass spectrometry (EC ESI MS) in the positive ion mode with a high resolution FT ICR mass spectrometer without the use of an external oxidizer in the sample. Dimeric adducts of guanine with tyrosine (m/z 331) and (m/z 333) and a dimer of guanine with glutathione (m/z 459) are detected in the mass spectra of guanine–tyrosine and guanine–glutathione mixtures in addition to dimers of guanine (m/z 303) and tyrosine (m/z 361) and (m/z 363) and glutathione dimers (m/z 613) and (m/z 615). Guanine tetramers (m/z 627) and tetramers of guanine with 1 or 2 tyrosines, but not with three tyrosines, were also identified in the mass spectra of guanine–tyrosine mixtures. Formation of radicals and other oxidation products during positive ion mode ESI can drive the formation of covalent dimer adducts of guanine with tyrosine and glutathione. When low EC cell voltage is applied in on-line EC ESI MS, changes in ion intensities reflect changes in the oxidation conditions and are more apparent for 2e, 2H⁺ than for the 1e, 1H⁺ oxidation processes. Efficient oxidation during ESI is indicated for analytes with low redox potentials.     

A Screening Method to Evaluate Soybean Oil‐Based Biodiesel Oxidative Quality During Its Shelf Life

Biodiesel quality is negatively affected by oxidation, which occurs primarily during the storage and distribution steps. Therefore, the use of suitable analytical methods to assess the oxidation of this biofuel is a fundamental requirement. A direct ambient ionization mass spectrometric technique (EASI‐MS) was tested as a screening method to evaluate the oxidative quality of biodiesel during its shelf life. Using EASI‐MS, the relative abundance of the hydroperoxide ion of m/z 349 was monitored during the induction period (IP) in soybean and a blend of soybean/beef‐tallow (70/30) biodiesel samples. The peroxide value obtained by AOCS Cd 8b‐90 was used as a standard method to evaluate the EASI‐MS data by comparison. The results showed that the peroxide value and EASI‐MS data were highly correlated during the IP for both samples (r > 0.98). Relative abundances of the ion of m/z 349 below 72 % was also found to characterize biodiesel in an initial oxidation stage, whereas abundances exceeding 72 % indicated biodiesel samples nearing the end of their stability. EASI‐MS was therefore found to provide a simple and effective analytical protocol to evaluate the oxidative quality of biodiesel during the IP.     

Contribution of Selected Dicarboxylic and ω-Oxocarboxylic Acids in Ambient Aerosol to the m/z 44 Signal of an Aerodyne Aerosol Mass Spectrometer

The Aerodyne aerosol mass spectrometer (AMS) employs flash vaporization (600°C) followed by 70-eV electron impact ionization (EI) to detect organic and inorganic aerosols. The signal at mass-to-charge ratio (m/z) 44 (mainly CO ₂ ⁺ ) is considered the most reliable marker of oxygenated organic aerosol. This study is the first to evaluate the contribution of selected low molecular weight dicarboxylic acids (diacids) and ω-oxocarboxylic acids (ω-oxoacids) to the particle-phase m/z 44 signal of the AMS mass spectrum. Ambient measurements were conducted at a surface site in Tokyo (35°39 ′ N, 139°40 ′ E) during August 3–8, 2003. Diacids and ω-oxoacids were measured using a filter sampling followed by extraction, derivation, and gas chromatograph-flame ionization detector (GC-FID) analysis. The mass concentrations of diacids and ω-oxoacids show tight correlation with the m/z 44 signal (r ² = 0.85–0.94) during the measurement period. Laboratory experiments were also performed to determine the fragment patterns of selected diacids (C₂–C₆ diacids and phthalic acids) and ω-oxoacid (glyoxylic acid) in ambient aerosols. Here, we report for the first time that the selected organic acids could account for 14 ± 5% of the observed m/z 44 signal on average during the measurement period. Oxalic acid (C₂) is the largest contributor, accounting for 10 ± 4% of the observed m/z 44 signal. These results would be useful for interpreting the m/z 44 signals obtained from ambient measurements in various locations.     

Decreased Serum Levels of Sphingomyelins and Ceramides in Sickle Cell Disease Patients

Limited data are available on the serum levels of different sphingomyelin (CerPCho) and ceramide (CER) species in sickle‐cell disease (SCD). This study was aimed at identifying the levels of C16–C24 CerPCho and C16–C24 CER in serum obtained from SCD patients and controls. Circulating levels of neutral sphingomyelinase (N‐SMase) activity, ceramide‐1‐phosphate (C1P), and sphingosine‐1‐phosphate (S1P) were also determined. Blood was collected from 35 hemoglobin (Hb)A volunteers and 45 homozygous HbSS patients. Serum levels of C16–C24 CerPCho and C16–C24 CER were determined by an optimized multiple reaction monitoring (MRM) method using ultrafast liquid chromatography (UFLC) coupled with tandem mass spectrometry (MS/MS). Serum activity of N‐SMase was assayed by standard kit methods, and C1P and S1P levels were determined by enzyme‐linked immunosorbent assay. A significant decrease was observed in the serum levels of C18–C24 CerPCho in patients with SCD compared to controls. No significant difference was found in C16 CerPCho levels between the two groups. Very‐long‐chain C22–C24 CER were significantly decreased in SCD, while long‐chain C16–C20 CER levels showed no significant difference between SCD patients and controls. Significant positive correlation was found between the serum total cholesterol levels and C18–C24 CerPCho and C22–C24 CER in SCD patients. Patients with SCD had significantly elevated serum activity of N‐SMase as well as increased circulating levels of C1P and S1P compared to controls. The decrease in serum levels of C18–C24 CerPCho in patients with SCD was accompanied by decreased levels of C22–C24 CER. Future studies are needed to understand the role of decreased CerPCho and CER in the pathophysiology of SCD.     

Determination of Tertiary-butylhydroquinone and Its Metabolites in Rat Serum by Liquid Chromatography–Ion Trap Mass Spectrometry

A new method applying sensitive and selective liquid chromatography coupled with mass spectrometry (LC/MS/MS) for analyzing tertiary-butylhydroquinone (TBHQ) and its metabolites in rat serum was validated. Using an extracted ion chromatogram (EIC) of m/z 149, free TBHQ was observed in rat serum after dosing TBHQ at 350 mg/kg to male and female Sprague–Dawley (SD) rats. Four major metabolites of TBHQ were identified—a TBHQ-sulfate, two TBHQ-sulfate-derived substances and a TBHQ-glucuronide through MSⁿ spectra. Besides its simplicity, the sample treatment allows one to obtain a very good recovery of analysts, namely around 95%. This result suggests that the method described here is useful for the analysis of TBHQ and its metabolites in rat serum. Moreover, the metabolism of TBHQ was investigated using the method. After oral administration, TBHQ appear to be more completely absorbed and bio-transformed by males than females, which may result in higher acute oral toxicity of TBHQ for males than females.     

The Origin and Ecological Function of an Ion Inducing Anti-Predator Behavior in <Emphasis Type="Italic">Lithobates</Emphasis> Tadpoles

In aquatic environments, chemical cues are believed to be associated with prey response to predation risk, yet few basic cue compositions are known despite the pronounced ecological and evolutionary significance of such cues. Previous work indicated that negatively-charged ions of m/z 501 are possibly a kairomone that induces anti-predator responses in amphibian tadpoles. However, work described here confirms that this specific ion species m/z 501.2886 is produced by injured tadpoles, exhibits increased spectral intensity with higher tadpole biomass, and is not produced by starved predators. These results indicate the anion is an alarm cue released from tadpoles. High resolution mass spectrometry (HR-MS) revealed a unique elemental composition for [M-H]^?, m/z 501.2886, of C₂₆H₄₅O₇S^? which could not be determined in previous studies using low resolution instruments. Collision induced dissociation of m/z 501 ions formed product ions of m/z 97 and m/z 80, HSO₄^? and SO₃^?, respectively, showing the presence of sulfate. Green frog tadpoles, Lithobates clamitans, exposed to the m/z 501 anion or sodium dodecyl sulfate exhibited similar anti-predator responses, suggesting organic sulfate is a tadpole behavior modifier.