Chemical profiling of Simiao pill and quantification of main effective constituents in it by ultra-high-performance liquid chromatography coupled with Q Exactive Orbitrap and triple quadrupole mass spectrometry

Simiao pill is one of the most commonly used prescriptions in traditional Chinese medicine for the treatment of hyperuricemia and gout. However, methods based on more accurate and comprehensive qualitative and quantitative analyses of the active ingredients are not yet perfect due to limited methodology. This not only hinders the elucidation of the pharmacological mechanism of Simiao pill, but also its comprehensive clinical development and utilization. In this study, we employed ultra-high-performance liquid chromatography-Q Exactive Orbitrap-mass spectrometry technology to perform rapid analysis and identification of the chemical constituents in Simiao pill. A total of 101 chemical components were identified, including 26 alkaloids, 15 terpenoids, 11 flavonoids, eight steroids, six fatty acids, five limonoids, four saponins, five phenylpropanoids, and 21 other compounds. In addition, we established a new method by high-throughput ultra-high-performance liquid chromatography-Q Exactive Orbitrap-mass spectrometry combined with ultra-high-performance liquid chromatography-triple quadrupole-tandem mass spectrometry technology for quantification of 14 main active ingredients, such as adenosine (1), phellodendrine (2), mangnoflorine (3), β-ecdysterone (4), 25R-inokosterone (5), 25S-inokosterone (6), jatrorrhizine (7), palmatine (8), chikusetsu saponin IVa (9), limonin (10), atractylenolide III (11), atractylenolide I (12), obacunone (13), and atractylenolide II (14) in Simiao pill. This work laid a foundation for further analysis and quality control of effective components in Simiao pill.

A dilute-and-inject low-pressure gas chromatography-tandem mass spectrometry method for phthalate determination in extra virgin olive oil

The goal of this study was to develop a method for the determination of nine phthalic acid esters in extra virgin olive oils using low-pressure gas chromatography-triple-quadrupole mass spectrometry. Sample preparation was simple, environmental friendly, and rapid inasmuch that it involved only dilution (< 1 mL of hexane). The low-pressure gas chromatography analyses were performed by using a 5 m wide-bore column. The limit of quantification for the phthalates ranged from 0.06 to 1.14 mg kg-1 . Both intra- and interday precisions were measured, with coefficient of variation values ranging from 0.2% to 11.7%. The trueness of the method was measured by evaluating accuracy at the initial stage of the work and after 2 months, with values ranging between -8.7% and 12.1%. Moreover, blind accuracy was comprised between -11.6% and 14.2%. The method involves the use of simplified instrumentation and reduced analysis times (nearly two times faster) compared to a previously published comprehensive two-dimensional gas chromatography-triple-quadrupole mass spectrometry method, leading to a reduction of energy and helium consumption. The approaches were compared in analytical terms and for the environmental impact. In total, 23 olive oil samples were analyzed, with at least one phthalate detected in all but one sample.

Measuring Marine Biotoxins in a Hypersaline Coastal Lagoon

Marine biotoxins have posed a persistent problem along various coasts for many years. Coastal lagoons are ecosystems prone to phytoplankton blooms when altered by eutrophication. The Mar Menor is the largest hypersaline coastal lagoon in Europe. Sixteen marine toxins, including lipophilic toxins, yessotoxins, and domoic acid (DA), in seawater samples from the Mar Menor coastal lagoon were measured in one year. Only DA was detected in the range of 44.9-173.8 ng L-1. Environmental stressors and mechanisms controlling the presence of DA in the lagoon are discussed. As an enrichment and clean-up method, we employed solid phase extraction to filter and acidify 75 mL of the sample, followed by pre-concentration through a C18 SPE cartridge. The analytes were recovered in aqueous solutions and directly injected into the liquid chromatography system (LC-MS), which was equipped with a C18 column. The system operated in gradient mode, and we used tandem mass spectrometry (MS/MS) with a triple quadrupole (QqQ) in the multiple reaction monitoring mode (MRM) for analysis. The absence of matrix effects was checked and the limits of detection for most toxins were low, ranging from 0.05 to 91.2 ng L-1, depending on the compound. To validate the measurements, we performed recovery studies, falling in the range of 74-122%, with an intraday precision below 14.9% RSD.

Qualitative and quantitative determination of chemical constituents in Jinbei oral liquid, a modern Chinese medicine for coronavirus disease 2019, by ultra-performance liquid chromatography coupled with mass spectrometry

Introduction: Traditional Chinese medicine (TCM) has the advantages of syndrome differentiation and rapid determination of etiology, and many TCM prescriptions have been applied to the clinical treatment of coronavirus disease 2019 (COVID-19). Among them, Jinbei Oral Liquid (Jb.L) has also shown an obvious curative effect in the clinic, but the related material basic research is relatively limited. Methods: Therefore, in this process, a systematic data acquisition and mining strategy was established using ultra-high- performance liquid chromatography coupled with quadruple time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Results and Discussion: With the optimized conditions, a total of 118 peaks were tentatively characterized, including 43 flavonoids, 26 phenylpropanoids, 14 glycosides, 9 phthalides, 8 alkaloids and others. To determine the content of relevant pharmacological ingredients, we firstly exploited the ultra-performance liquid chromatography method coupled with triple-quadrupole tandem mass spectrometry (UPLC-QqQ-MS/MS) method for simultaneous detection of 31 active ingredients within 17 min, and the validation of methodology showed that this method has good precision and accuracy. Moreover, analyzing the pharmacology of 31 individual of the medicinal material preliminarily confirmed the efficacy of Jb.L and laid a foundation for an in-depth study of network pharmacology.

Validation of a multiplexed and targeted lipidomics assay for accurate quantification of lipidomes

A major challenge of lipidomics is to determine and quantify the precise content of complex lipidomes to the exact lipid molecular species. Often, multiple methods are needed to achieve sufficient lipidomic coverage to make these determinations. Multiplexed targeted assays offer a practical alternative to enable quantitative lipidomics amenable to quality control standards within a scalable platform. Herein, we developed a multiplexed normal phase liquid chromatography-hydrophilic interaction chromatography multiple reaction monitoring method that quantifies lipid molecular species across over 20 lipid classes spanning wide polarities in a single 20-min run. Analytical challenges such as in-source fragmentation, isomer separations, and concentration dynamics were addressed to ensure confidence in selectivity, quantification, and reproducibility. Utilizing multiple MS/MS product ions per lipid species not only improved the confidence of lipid identification but also enabled the determination of relative abundances of positional isomers in samples. Lipid class-based calibration curves were applied to interpolate lipid concentrations and guide sample dilution. Analytical validation was performed following FDA Bioanalytical Method Validation Guidance for Industry. We report repeatable and robust quantitation of 900 lipid species measured in NIST-SRM-1950 plasma, with over 700 lipids achieving inter-assay variability below 25%. To demonstrate proof of concept for biomarker discovery, we analyzed plasma from mice treated with a glucosylceramide synthase inhibitor, benzoxazole 1. We observed expected reductions in glucosylceramide levels in treated animals but, more notably, identified novel lipid biomarker candidates from the plasma lipidome. These data highlight the utility of this qualified lipidomic platform for enabling biological discovery.

The Development of the Davis Food Glycopedia-A Glycan Encyclopedia of Food

The molecular complexity of the carbohydrates consumed by humans has been deceptively oversimplified due to a lack of analytical methods that possess the throughput, sensitivity, and resolution required to provide quantitative structural information. However, such information is becoming an integral part of understanding how specific glycan structures impact health through their interaction with the gut microbiome and host physiology. This work presents a detailed catalogue of the glycans present in complementary foods commonly consumed by toddlers during weaning and foods commonly consumed by American adults. The monosaccharide compositions of over 800 foods from diverse food groups including Fruits, Vegetables, Grain Products, Beans, Peas, Other Legumes, Nuts, Seeds; Sugars, Sweets and Beverages; Animal Products, and more were obtained and used to construct the “Davis Food Glycopedia” (DFG), an open-access database that provides quantitative structural information on the carbohydrates in food. While many foods within the same group possessed similar compositions, hierarchical clustering analysis revealed similarities between different groups as well. Such a Glycopedia can be used to formulate diets rich in specific monosaccharide residues to provide a more targeted modulation of the gut microbiome, thereby opening the door for a new class of prophylactic or therapeutic diets.

Determination of 18 Intact Glucosinolates in Brassicaceae Vegetables by UHPLC-MS/MS: Comparing Tissue Disruption Methods for Sample Preparation

Glucosinolates (GSLs) are important precursor compounds with anticancer activities in Brassicaceae vegetables and are readily hydrolyzed by myrosinase. Given the diversity of these species, establishing an accurate and universal method to quantify intact GSLs in different plant tissues is necessary. Here, we compared and optimized three tissue disruption methods for sample preparation. After microwave treatment for 90 s, 13 GSLs in homogenized Chinese cabbage samples were recovered at 73–124%. However, a limitation of this method was that different tissues could not be processed under the same microwave conditions. Regarding universality, GSLs in Brassicaceae vegetables could be extracted from freeze-dried sample powder with 70% methanol (v/v) or frozen-fresh sample powder with 80% methanol (v/v). Moreover, heating extraction is necessary for GSLs extracted from frozen-fresh sample powder. Average recoveries of the two optimized methods were 74–119% with relative standard deviations ≤ 15%, with the limits of quantification 5.72–17.40 nmol/g dry weight and 0.80–1.43 nmol/g fresh weight, respectively. Notably, the method for analyzing intact GSLs was more efficient than that for desulfo-GSLs regarding operational complexity, detection speed and quantification accuracy. The developed method was applied to identify the characteristic GSLs in 15 Brassicaceae vegetables, providing a foundation for further research on GSLs.

A Workflow to Perform Targeted Metabolomics at the Untargeted Scale on a Triple Quadrupole Mass Spectrometer

The thousands of features commonly observed when performing untargeted metabolomics with quadrupole time-of-flight (QTOF) and Orbitrap mass spectrometers often correspond to only a few hundred unique metabolites of biological origin, which is in the range of what can be assayed in a single targeted metabolomics experiment by using a triple quadrupole (QqQ) mass spectrometer. A major benefit of performing targeted metabolomics with QqQ mass spectrometry is the affordability of the instruments relative to high-resolution QTOF and Orbitrap platforms. Optimizing targeted methods to profile hundreds of metabolites on a QqQ mass spectrometer, however, has historically been limited by the availability of authentic standards, particularly for "unknowns" that have yet to be structurally identified. Here, we report a strategy to develop multiple reaction monitoring (MRM) methods for QqQ instruments on the basis of high-resolution spectra, thereby enabling us to use data from untargeted metabolomics to design targeted experiments without the need for authentic standards. We demonstrate that using high-resolution fragmentation data alone to design MRM methods results in the same quantitative performance as when methods are optimized by measuring authentic standards on QqQ instruments, as is conventionally done. The approach was validated by showing that Orbitrap ID-X data can be used to establish MRM methods on a Thermo TSQ Altis and two Agilent QqQs for hundreds of metabolites, including unknowns, without a dependence on standards. Finally, we highlight an application where metabolite profiling was performed on an ID-X and a QqQ by using the strategy introduced here, with both data sets yielding the same result. The described approach therefore allows us to use QqQ instruments, which are often associated with targeted metabolomics, to profile knowns and unknowns at a comprehensive scale that is typical of untargeted metabolomics.

A Multidimensional Mass Spectrometry-Based Workflow for De Novo Structural Elucidation of Oligosaccharides from Polysaccharides

Carbohydrates play essential roles in a variety of biological processes that are dictated by their structures. However, characterization of carbohydrate structures remains extremely difficult and generally unsolved. In this work, a de novo mass spectrometry-based workflow was developed to isolate and structurally elucidate oligosaccharides to provide sequence, monosaccharide compositions, and glycosidic linkage positions. The approach employs liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based methods in a 3-dimensional concept: one high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-QTOF MS) analysis for oligosaccharide sequencing and two ultra high performance liquid chromatography-triple quadrupole mass spectrometry (UHPLC-QqQ MS) analyses on fractionated oligosaccharides to determine their monosaccharides and linkages compositions. The workflow was validated by applying the procedure to maltooligosaccharide standards. The approach was then used to determine the structures of oligosaccharides derived from polysaccharide standards and whole food products. The integrated LC-MS workflow will reveal the in-depth structures of oligosaccharides.

Reliable identification and quantification of anabolic androgenic steroids in dietary supplements by using gas chromatography coupled to triple quadrupole mass spectrometry

The aim of the present research was the identification and quantification of specific anabolic androgenic steroids (AASs) and other sterane structured compounds in dietary supplements (DSs). The adulteration of DSs by these compounds is of a particular concern in athletes, because it might lead to a positive doping result. The research was focused on the optimization of a highly sensitive and selective GC-based analytical strategy using triple quadrupole MS as detector. Chromatographic method and multiple reaction monitoring (MRM) transitions of 28 target compounds were optimized. Sample clean-up was carried out by using a solid phase extraction (SPE) procedure, while the derivatization of AASs was performed by using N-methyl-N-(trimethylsilyl)-trifluoroacetamide (MSTFA). The method was validated, and the following parameters were investigated: linearity range, limit of detection, accuracy, and precision expressed in terms of intra-day precision. The calibration curves were evaluated by using regression model and resulting in a good determination coefficients (R² ≥ 0.9912). The residuals were scattered randomly around zero. The limits of detection (LODs) were lower than 7.0 ng g^-1 or ng ml^-1 . The accuracy assessment was evaluated in different forms of DSs characterized by high sample-to-sample variability (liquid, powder, tablet, capsule, protein, and herbal-based). Intra-day assay precision was in all cases lower than 20%. The developed analytical method was successfully applied to the analysis of 67 commercially available dietary supplements. In five cases, one or more steroid-type compounds were found in the concentration of 5 ng g^-1 -100 μg g^-1 , which might result adverse analytical findings in athletes.

Determination of 14 heterocyclic aromatic amines in meat products using solid-phase extraction and supercritical fluid chromatography coupled to triple quadrupole mass spectrometry

A novel, simple, and sensitive method has been developed for simultaneous determination of 14 heterocyclic aromatic amines in meat product using solid-phase extraction combined with ultrahigh-performance supercritical fluid chromatography coupled to tandem quadrupole mass spectrometry. The analytes could be separated within 7 min and identified using their retention times and mass. The developed method was validated based on the linearity, limits of quantification, precision, and accuracy. The recovery ranged from 52.3 to 97.5% with an acceptable standard deviation, which is not higher than 6%. The limits of quantitation ranged from 0.03 to 0.17 µg/kg. The selectivity and sensitivity were satisfactory in multiple reaction monitoring mode. The method was applied to commercial meat products, and the results demonstrated that the novel method has potential for the analysis of the targets in food matrices. This is the first work reporting the simultaneous quantification of 14 heterocyclic aromatic amines by means of ultrahigh-performance supercritical fluid chromatography coupled to tandem quadrupole mass spectrometry.

[Determination of nicotine in wild edible fungi by QuEChERS-ultra performance liquid chromatography-triple quadrupole mass spectrometry]

Yunnan Province has many wild edible fungi resources, and of these, endogenous nicotine has received extensive attention in recent years. In this study, wild edible fungus was used as the research object, and the QuEChERS method was improved, including optimization of solvent extraction and purification conditions and optimization of the chromatographic behavior of nicotine under different mobile phase conditions for ultra performance liquid chromatography (UPLC). Combined with triple quadrupole mass spectrometry, a high-efficiency, rapid, and sensitive method for the determination of nicotine in wild edible fungi was established. The results showed that an ammonia:acetonitrile (6:94, v/v) mixed solution can completely extract nicotine from wild edible fungi, and the extraction solution was purified by graphitized carbon black (GCB) and N-propylethylenediamine (PSA) mixed filler. Then, a 0.1% (volume percentage) ammonia solution and acetonitrile were used as the mobile phases. The nicotine peak obtained in the positive ion multiple reaction monitoring (MRM) mode had a better peak shape and better response. The linear relationship of nicotine mass concentration with peak area in the range of 0.05-50.0 μg/L was good. The correlation coefficient (r²) was 0.9999. The limit of quantification was 0.2 μg/kg, and the limit of detection was 0.05 μg/kg. The average recovery rates at three spiked concentrations were in the range of 86.34%-96.4%, and the relative standard deviations varied from 4.44% to 6.3%. The sensitivity and recovery of this method are consistent with the rapid determination of nicotine in the edible fungus industry.

Determination of 18 phenolic acids in tobacco and rhizosphere soil by ultra high performance liquid chromatography combined with triple quadrupole mass spectrometry

An ultra high performance liquid chromatography with triple quadrupole mass spectrometry method for the determination of free and bound phenolic acids in tobacco plant and soil was developed. A simple solid-phase extraction, which used Polar Enhanced Polymer column as stationary phase and methanol as mobile phase, was used for the clean-up of bound phenolic acids, and a liquid-phase extraction using chloroform as solvent was used to purify free phenolic acids. With our method, 18 phenolic acids in rhizosphere soil of continuous cropping flue-cured cultivar k326 were separated and determined within 6 min with recoveries of 82-107% and relative standard deviations (n = 5) of 1.1-4.8%. Results showed that free phenolic acids accounted for 0-9, 92-100, and 69-100% of total phenolic acids in rhizosphere soil, cultivar k326 roots and leaves, respectively. Results also revealed that p-hydroxybenzoic acid, p-coumaric acid, vanillic acid, ferulic acid, and syringic acid were the predominant phenolic acids in rhizosphere soil of cultivar k326, and continuous cropping of cultivar k326 in the same farmland could lead to the accumulation of these phenolic acids in soil except syringic acid. The determination of phenolic acids provided detailed information for evaluating their source and characteristics in continuous cropping tobacco plant and soil.

[Determination of 14 sweeteners in liquid foods by hydrophilic interaction liquid chromatography-tandem mass spectrometry]

A method for the simultaneous determination of six artificial sweeteners and eight steviol glycosides in liquid food samples by hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) was developed.The sweeteners in the samples were separated by a Waters Xbridge Amide column (150 mm×5.0 mm, 3.5 μm) at 35℃, and eluted with acetonitrile-10 mmol/L ammonium formate (65:35, v/v) at a flow rate of 0.4 mL/min.Then, the analytes were detected using an electrospray ion source in negative mode (ESI^-) under multiple reaction monitoring (MRM) mode.Good linear relationships were obtained, and the correlation coefficients (r²) of the 14 sweeteners were greater than 0.995.The limits of detection (LODs, S/N=3) and the limits of quantification (LOQs, S/N=10) ranged from 0.03 to 0.7 mg/kg and 0.1 to 2.2 mg/kg, respectively.The average recoveries varied from 80.8% to 108.7% at spiked levels of 2, 5 and 20 mg/kg, and the relative standard deviations (RSDs) ranged from 1.5% to 7.7%(n=6).The proposed method is simple, accurate and sensitive for the simultaneous determination of the 14 sweeteners in liquid food samples.

Qualitative and Quantitative Analysis of Phenolic Acids, Flavonoids and Iridoid Glycosides in Yinhua Kanggan Tablet by UPLC-QqQ-MS/MS

A simple, rapid and specific ultra-performance liquid chromatography-triple quadrupole mass spectrometry method was developed for the analysis of 29 bioactive components (10 phenolic acids, 16 flavonoids, and three iridoid glycosides) in Yinhua Kanggan tablet (YHKGT), a herbal prescription used for treating upper respiratory infections, fevers, coughs and pharyngalgia. The separation was successfully achieved using a Waters Cortecs UPLC C18 column (50 × 2.1 mm, 1.6 μm) and gradient elution with water-0.1% formic acid and acetonitrile. Polarity switching mode was used in the optimization of multiple reaction monitoring conditions. The analytical method was validated for linearity, precision and accuracy. Calibration curves for the 29 marker compounds showed good linear regression (r > 0.9982). The limits of detection (LOD) and limits of quantification (LOQ) for the 29 analytes were in the range of 0.03–4.99 ng/mL and 0.16–14.87 ng/mL, respectively. The relative standard deviation (RSD) values of intra-day precision, inter-day precision, repeatability, and stability were less than 2.79%, 4.87%, 4.18% and 4.71%, respectively. The recoveries of the 29 marker compounds were in the range of 94.67%–104.78% (RSD ≤ 4.72%). These results have shown that this developed method was efficient for the quality evaluation of YHKGT.

Collision induced dissociations of non-derivatized and trimethylsilyl-derivatized estradiols: similarities in fragmentation patterns

Fragmentation mechanisms of estradiol and trimethylsilyl (TMS)-derivatized estradiol were studied by triple quadrupole tandem mass spectrometry (MSMS) and density functional theory (DFT) at B3LYP/6-311G(d,p) level. Collision induced dissociations (CID) of estradiol give product ions that are associated with the cleavage of B, C and D rings. Characteristic fragments from the cleavage of the aromatic ring A were not identified, and this was confirmed with both labeled estradiol and trimethylsilyl (TMS)-derivatized estradiol. The mechanisms are based on charge-site directed, radical-directed and charge remote fragmentations that are consistent with previous studies of steroids. CID spectra show ion pairs at m/z: 145/146, 157/158, 185/186, 211/213 and 225/226 with significant intensities, suggesting that these pairs are not from isotopic contributions. The mechanisms show similarities with some minor differences in the fragmentation patterns between the non-derivatized and the TMS-derivatized estradiol.

Molar-based targeted metabolic profiling of cyanobacterial strains with potential for biological production

Recently, cyanobacteria have become one of the most attractive hosts for biochemical production due to its high proliferative ability and ease of genetic manipulation. Several researches aimed at biological production using modified cyanobacteria have been reported previously. However, to improve the yield of bioproducts, a thorough understanding of the intercellular metabolism of cyanobacteria is necessary. Metabolic profiling techniques have proven to be powerful tools for monitoring cellular metabolism of various organisms and can be applied to elucidate the details of cyanobacterial metabolism. In this study, we constructed a metabolic profiling method for cyanobacteria using 13C-labeled cell extracts as internal standards. Using this method, absolute concentrations of 84 metabolites were successfully determined in three cyanobacterial strains which are commonly used as background strains for metabolic engineering. By comparing the differences in basic metabolic potentials of the three cyanobacterial strains, we found a well-correlated relationship between intracellular energy state and growth in cyanobacteria. By integrating our results with the previously reported biological production pathways in cyanobacteria, we found putative limiting step of carbon flux. The information obtained from this study will not only help gain insights in cyanobacterial physiology but also serve as a foundation for future metabolic engineering studies using cyanobacteria.

Investigating the presence of omeprazole in waters by liquid chromatography coupled to low and high resolution mass spectrometry: degradation experiments

Omeprazole is one of the most consumed pharmaceuticals around the world. However, this compound is scarcely detected in urban wastewater and surface water. The absence of this pharmaceutical in the aquatic ecosystem might be due to its degradation in wastewater treatment plants, as well as in receiving water. In this work, different laboratory-controlled degradation experiments have been carried out on surface water in order to elucidate generated omeprazole transformation products (TPs). Surface water spiked with omeprazole was subjected to hydrolysis, photo-degradation under both sunlight and ultraviolet radiation and chlorination. Analyses by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-QTOF MS) permitted identification of up to 17 omeprazole TPs. In a subsequent step, the TPs identified were sought in surface water and urban wastewater by LC-QTOF MS and by LC coupled to tandem mass spectrometry with triple quadrupole. The parent omeprazole was not detected in any of the samples, but four TPs were found in several water samples. The most frequently detected compound was OTP 5 (omeprazole sulfide), which might be a reasonable candidate to be included in monitoring programs rather than the parent omeprazole.

Formation and speciation of nine haloacetamides, an emerging class of nitrogenous DBPs, during chlorination or chloramination

Haloacetamides (HAcAms) are an emerging class of nitrogenous disinfection by-products (N-DBPs) of health concern. However, there are very limited data on the formation and speciation of the nine bromine- and chlorine-containing haloacetamides (HAcAm9). In the study, their formation and speciation during chlor(am)ination were investigated for a group of waters with a range of specific ultraviolet absorbance at 254 nm (SUVA₂₅₄), dissolved organic nitrogen (DON), and bromide levels. The waters that were the least impacted by anthropogenic pollution had the lowest DON levels, the highest ratios of dissolved organic carbon (DOC) to DON, and exhibited the least HAcAm9 formation. DON/DOC may act as an indicator of HAcAm yields during chlorination. HAcAm9 exhibited more formation during chloramination in the low-SUVA waters with no bromide, relative to high-SUVA waters with bromide. The selected waters all formed primarily dihalogenated (di-) HAcAms, followed by trihalogenated (tri-) species and, to a much lesser extent, monohalogenated (mono-) HAcAms. Di-HAcAm formation had similar trends as that of HAcAm9; whereas chloramination formed more mono- and less tri-HAcAms than chlorination. Bromine utilization factors and bromine incorporation factor increased with decreasing and increasing bromide during either chlorination or chloramination, and bromine was easier to incorporate into tri-HAcAms during chloramination than chlorination.