Guidelines for clinical trials of frontal fibrosing alopecia: consensus recommendations from the International FFA Cooperative Group (IFFACG).

BACKGROUND: Frontal fibrosing alopecia (FFA) has become one of the most common causes of cicatricial alopecia worldwide. However, there is a lack of clear aetiology and robust clinical trial evidence for the efficacy and safety of agents currently used for treatment. OBJECTIVES: To enable data to be collected worldwide on FFA using common criteria and assessment methods. METHODS: A multicentre, international group of experts in hair loss was convened by email to create consensus recommendations for clinical trials. Consensus was defined at > 90% agreement on each recommended part of these guidelines. RESULTS: Standardized diagnostic criteria, severity rating, staging, and investigator and patient assessment of scalp hair loss and other clinical features of FFA were created. CONCLUSIONS: These guidelines should allow the collection of reliable aggregate data on FFA and advance efforts in both clinical and basic research to close knowledge gaps in this condition.

Mesophilic microorganisms build terrestrial mats analogous to Precambrian microbial jungles.

Development of Archean paleosols and patterns of Precambrian rock weathering suggest colonization of continents by subaerial microbial mats long before evolution of land plants in the Phanerozoic Eon. Modern analogues for such mats, however, have not been reported, and possible biogeochemical roles of these mats in the past remain largely conceptual. We show that photosynthetic, subaerial microbial mats from Indonesia grow on mafic bedrocks at ambient temperatures and form distinct layers with features similar to Precambrian mats and paleosols. Such subaerial mats could have supported a substantial aerobic biosphere, including nitrification and methanotrophy, and promoted methane emissions and oxidative weathering under ostensibly anoxic Precambrian atmospheres. High C-turnover rates and cell abundances would have made these mats prime locations for early microbial diversification. Growth of landmass in the late Archean to early Proterozoic Eons could have reorganized biogeochemical cycles between land and sea impacting atmospheric chemistry and climate.

Bioturbation and directionality in Earth's carbon isotope record across the Neoproterozoic-Cambrian transition.

Mixing of sediments by moving animals becomes apparent in the trace fossil record from about 550 million years ago (Ma), loosely overlapping with the tail end of the extreme carbonate carbon isotope δ13 Ccarbonate fluctuations that qualitatively distinguish the Proterozoic geochemical record from that of the Phanerozoic. These Precambrian-scale fluctuations in δ13 Ccarbonate (PSF-δ13 Ccarbonate ) remain enigmatic, due to their high amplitude and inclusion of global-scale negative δ13 Ccarbonate values, below anything attributable to mantle input. Here, we note that different biogeochemical-model scenarios plausibly explaining globally synchronous PSF-δ13 Ccarbonate converge: via mechanistic requirements for extensive anoxia in marine sediments to support sedimentary build-up of 13 C-depleted carbon. We hypothesize that bioturbation qualitatively reduced marine sediment anoxia by exposing sediments to oxygenated overlying waters, which ultimately contributed to decreasing the carbon cycle's subsequent susceptibility to PSF- δ13 Ccarbonate . Bioturbation may also have reduced the quantity of (isotopically light) organic-derived carbon available to contribute to PSF- δ13 Ccarbonate via ocean crust carbonatization at depth. We conduct a comparative modelling exercise in which we introduce bioturbation to existing model scenarios for PSF- δ13 Ccarbonate : expressing both the anoxic proportion of marine sediments, and the global organic carbon burial efficiency, as a decreasing function of bioturbation. We find that bioturbation's oxygenating impact on sediments has the capacity to prevent PSF- δ13 Ccarbonate caused by authigenic carbonate precipitation or methanogenesis. Bioturbation's impact on the f-ratio via remineralization is partially offset by liberation of organic phosphate, some of which feeds back into new production. We emphasize that this study is semiquantitative, exploratory and intended merely to provide a qualitative theoretical framework within which bioturbation's impact on long-term, first-order δ13 Ccarbonate can be assessed (and it is hoped quantified in more detail by future work). With this proviso, we conclude that it is entirely plausible that bioturbation made a decisive contribution to the enigmatic directionality in the δ13 Ccarbonate record, from the Neoproterozoic-Cambrian boundary onwards.

Evidence of oxygenic phototrophy in ancient phosphatic stromatolites from the Paleoproterozoic Vindhyan and Aravalli Supergroups, India.

Fossil microbiotas are rare in the early rock record, limiting the type of ecological information extractable from ancient microbialites. In the absence of body fossils, emphasis may instead be given to microbially derived features, such as microbialite growth patterns, microbial mat morphologies, and the presence of fossilized gas bubbles in lithified mats. The metabolic affinity of micro-organisms associated with phosphatization may reveal important clues to the nature and accretion of apatite-rich microbialites. Stromatolites from the 1.6 Ga Chitrakoot Formation (Semri Group, Vindhyan Supergroup) in central India contain abundant fossilized bubbles interspersed within fine-grained in situ-precipitated apatite mats with average δ13 Corg indicative of carbon fixation by the Calvin cycle. In addition, the mats hold a synsedimentary fossil biota characteristic of cyanobacterial and rhodophyte morphotypes. Phosphatic oncoid cone-like stromatolites from the Paleoproterozoic Aravalli Supergroup (Jhamarkotra Formation) comprise abundant mineralized bubbles enmeshed within tufted filamentous mat fabrics. Construction of these tufts is considered to be the result of filamentous bacteria gliding within microbial mats, and as fossilized bubbles within pristine mat laminae can be used as a proxy for oxygenic phototrophy, this provides a strong indication for cyanobacterial activity in the Aravalli mounds. We suggest that the activity of oxygenic phototrophs may have been significant for the formation of apatite in both Vindhyan and Aravalli stromatolites, mainly by concentrating phosphate and creating steep diurnal redox gradients within mat pore spaces, promoting apatite precipitation. The presence in the Indian stromatolites of alternating apatite-carbonate lamina may result from local variations in pH and oxygen levels caused by photosynthesis-respiration in the mats. Altogether, this study presents new insights into the ecology of ancient phosphatic stromatolites and warrants further exploration into the role of oxygen-producing biotas in the formation of Paleoproterozoic shallow-basin phosphorites.

Carbon isotope fractionation by anoxygenic phototrophic bacteria in euxinic Lake Cadagno.

Anoxygenic phototrophic bacteria utilize ancient metabolic pathways to link sulfur and iron metabolism to the reduction of CO2 . In meromictic Lake Cadagno, Switzerland, both purple sulfur (PSB) and green sulfur anoxygenic phototrophic bacteria (GSB) dominate the chemocline community and drive the sulfur cycle. PSB and GSB fix carbon utilizing different enzymatic pathways and these fractionate C-isotopes to different extents. Here, these differences in C-isotope fractionation are used to constrain the relative input of various anoxygenic phototrophs to the bulk community C-isotope signal in the chemocline. We sought to determine whether a distinct isotopic signature of GSB and PSB in the chemocline persists in the settling fraction and in the sediment. To answer these questions, we also sought investigated C-isotope fractionation in the water column, settling material, and sediment of Lake Cadagno, compared these values to C-isotope fractionation of isolated anoxygenic phototroph cultures, and took a mass balance approach to investigate relative contributions to the bulk fractionation signature. We found a large C-isotope fractionation between dissolved inorganic carbon (DIC) and particulate organic carbon (POC) in the Lake Cadagno chemocline. This large fractionation between the DIC and POC was also found in culture experiments carried out with anoxygenic phototrophic bacteria isolated from the lake. In the Lake Cadagno chemocline, anoxygenic phototrophic bacteria controlled the bulk C-isotope fractionation, but the influence of GSB and PSB differed with season. Furthermore, the contribution of PSB and GSB to bulk C-isotope fractionation in the chemocline could be traced in the settling fraction and in the sediment. Taken together with other studies, such as lipid biomarker analyzes and investigations of other stratified lakes, these results offer a firmer understanding of diagenetic influences on bacterial biomass.

Measuring acne using Coproporphyrin III, Protoporphyrin IX, and lesion-specific inflammation: an exploratory study.

Propionibacterium acnes: (P. acnes) produce Porphyrins; however, fluorescence measurement of Porphyrins from Ultraviolet-A (UVA) images has failed to establish a correlation. Acne clinical research and imaging has ignored the spectral excitation-emission characteristics and the exact pattern of the Porphyrins synthesized by P. acnes. In this exploratory study, for the first time, the possible relationships of Coproporphyrin III (CpIII) and Protoporphyrin IX (PpIX) fluorescence as well as acne lesion-specific inflammation measurements with clinical signs of acne are investigated. Furthermore, the sensitivity of these measurements in tracking and differentiating the known treatment effects of Benzoyl Peroxide (BPO) 5%, and combination of Clindamycin + BPO are also evaluated. Comedonal and papulopustular lesions identified by investigators during a live assessment of 24 mild-to-severe acne subjects were compared with fluorescence and inflammation measurements obtained from analysis of VISIA®-CR images. CpIII fluorescence spots showed a strong correlation (r = 0.69-0.83), while PpIX fluorescence spots showed a weak correlation (r = 0.19-0.27) with the investigators' comedonal lesion counts. A strong correlation was also observed between the investigators' papulopustular lesion counts and acne lesion-specific inflammation (r = 0.76). Our results suggest that CpIII fluorescence and acne lesion-specific-inflammation measurement can provide objective indication of comedonal and papulopustular acne severity, respectively. Furthermore, these measurements may be more sensitive and specific in evaluating treatment effects and early signs of acne lesion progression compared to investigators' lesion counts.

Evidence of molybdenum association with particulate organic matter under sulfidic conditions.

The geochemical behavior of molybdenum (Mo) in the oceans is closely linked to the presence of sulfide species in anoxic environments, where Fe availability may play a key role in the Mo scavenging. Here, we show that Mo(VI) is reduced in the presence of particulate organic matter (represented by sulfate-reducing bacteria). Molybdenum was immobilized at the surface of both living cells and dead/lysed cells, but not in cell-free control experiments. Experiments were carried out at four different Mo concentrations (0.1 to 2 mm) to yield cell-associated Mo precipitates with little or no Fe, consisting of mainly Mo(IV)-sulfide compounds with molecular structures similar to Mo enzymes and to those found in natural euxinic sediments. Therefore, we propose that Mo removal in natural sulfidic waters can proceed via a non-Fe-assisted pathway that requires particulate organic matter (dead or living sulfate-reducing bacteria). This pathway has implications for global marine Mo cycling and the current use of Mo-based proxies for paleo-environmental investigations.

A trophic framework for animal origins.

Metazoans emerged in a microbial world and play a unique role in the biosphere as the only complex multicellular eukaryotes capable of phagocytosis. While the bodyplan and feeding mode of the last common metazoan ancestor remain unresolved, the earliest multicellular stem-metazoans likely subsisted on picoplankton (planktonic microbes 0.2-2 µm in diameter) and dissolved organic matter (DOM), similarly to modern sponges. Once multicellular stem-metazoans emerged, they conceivably modulated both the local availability of picoplankton, which they preferentially removed from the water column for feeding, and detrital particles 2-100 µm in diameter, which they expelled and deposited into the benthos as waste products. By influencing the availability of these heterotrophic food sources, the earliest multicellular stem-metazoans would have acted as ecosystem engineers, helping create the ecological conditions under which other metazoans, namely detritivores and non-sponge suspension feeders incapable of subsisting on picoplankton and DOM, could emerge and diversify. This early style of metazoan feeding, specifically the phagocytosis of small eukaryotic prey, could have also encouraged the evolution of larger, even multicellular, eukaryotic forms less prone to metazoan consumption. Therefore, the first multicellular stem-metazoans, through their feeding, arguably helped bridge the strictly microbial food webs of the Proterozoic Eon (2.5-0.541 billion years ago) to the more macroscopic, metazoan-sustaining food webs of the Phanerozoic Eon (0.541-0 billion years ago).

Effect of minoxidil topical foam on frontotemporal and vertex androgenetic alopecia in men: a 104-week open-label clinical trial.

BACKGROUND: Topical minoxidil formulations have been shown to be effective in treating androgenetic alopecia (AGA) for 12 months. Efficacy and safety in both frontotemporal and vertex regions over longer application periods have not been studied so far. OBJECTIVES: To evaluate the effect of 5% minoxidil topical foam (5% MTF) in the frontotemporal and vertex areas in patients with moderate AGA over 104 weeks. METHODS: An 80-week, open-label extension phase was performed, following a 24-week randomized, double-blind, placebo-controlled study in men with AGA grade IIIvertex to VI. Group 1 (n = 22) received ongoing 5% MTF for 104 weeks, Group 2 (n = 23) received placebo topical foam (plaTF) until week 24, followed by 5% MTF until week 104 during the extension phase. Frontotemporal and vertex target area non-vellus hair counts (f-TAHC, v-TAHC) and cumulative hair width (f-TAHW, v-TAHW) were assessed at baseline and at weeks 24, 52, 76 and 104. RESULTS: In Group 1, f-TAHW and f-TAHC showed a statistically significant increase from baseline to week 52 and week 76, respectively, returning to values comparable to baseline at week 104. No significant differences were found between baseline and week 104 in v-TAHC in Group 1 as well as f-TAHC, v-TAHC, f-TAHW and v-TAHW values in Group 2. CONCLUSIONS: 5% MTF is effective in stabilizing hair density, hair width and scalp coverage in both frontotemporal and vertex areas over an application period of 104 weeks, while showing a good safety and tolerability profile with a low rate of irritant contact dermatitis.

Quantifying dyspigmentation in facial skin ageing: an explorative study.

OBJECTIVE: The skin melanin system is affected by ageing, resulting in dyspigmentation with associated clinical and psychosocial consequences. In dark skinned phenotypes, broad evidence is available, whereas little is known about pigmentary changes in fair-skinned Caucasians. The objective of this study was to investigate age-related changes in facial pigmentation and dyspigmentation in subjects of skin phototypes II-III and to develop and test parameters for quantifying dyspigmentation. METHODS: Twenty-four skin healthy female subjects were recruited in three distinct age groups (30-40, 50-60, 70-80 years). Skin colour was measured by Mexameter and Chromameter. Skin dyspigmentation was measured by clinical evaluation and newly developed image-processing parameters on the cheeks and the forehead. The reliability of the clinical evaluation was investigated by intraclass correlation coefficients between three raters, and the validity of the dyspigmentation parameters was analysed by bivariate correlations with related measures. RESULTS: Skin lightness decreased with increasing age. Clinical dyspigmentation scores showed positive associations with chronological age ranging between 0.452 and 0.606. RBX(®) -Brown transformation-based hyperpigmentation and hypopigmentation indices increased with age, whereas the overall pigmentation intensity decreased with age at the cheeks. The image analysis-based parameters showed strong associations with the clinical scores and related measurements. CONCLUSION: We demonstrated age-related changes in the facial colour and dyspigmentation of fair-skinned Caucasian females. An increase in dyspigmentation was found by clinical scoring and the RBX(®) -Brown transformation-based pigmentation indices. The validity of hyper- and hypopigmentation indices and overall pigmentation intensity was supported. The RBX(®) transformation-based pigmentation indices might be applied in future studies to complement or substitute clinical evaluation.

Deep-water anoxygenic photosythesis in a ferruginous chemocline.

Ferruginous Lake Matano, Indonesia hosts one of the deepest anoxygenic photosynthetic communities on Earth. This community is dominated by low-light adapted, BChl e-synthesizing green sulfur bacteria (GSB), which comprise ~25% of the microbial community immediately below the oxic-anoxic boundary (OAB; 115-120 m in 2010). The size of this community is dependent on the mixing regime within the lake and the depth of the OAB-at ~117 m, the GSB live near their low-light limit. Slow growth and C-fixation rates suggest that the Lake Matano GSB can be supported by sulfide even though it only accumulates to scarcely detectable (low µm to nm) concentrations. A model laboratory strain (Chlorobaculum tepidum) is indeed able to access HS- for oxidation at nm concentrations. Furthermore, the GSB in Lake Matano possess a full complement of S-oxidizing genes. Together, this physiological and genetic information suggests that deep-water GSB can be supported by a S-cycle, even under ferruginous conditions. The constraints we place on the metabolic capacity and physiology of GSB have important geobiological implications. Biomarkers diagnostic of GSB would be a good proxy for anoxic conditions but could not discriminate between euxinic and ferruginous states, and though GSB biomarkers could indicate a substantial GSB community, such a community may exist with very little metabolic activity. The light requirements of GSB indicate that at light levels comparable to those in the OAB of Lake Matano or the Black Sea, GSB would have contributed little to global ocean primary production, nutrient cycling, and banded iron formation (BIF) deposition in the Precambrian. Before the proliferation of oxygenic photosynthesis, shallower OABs and lower light absorption in the ocean's surface waters would have permitted greater light availability to GSB, potentially leading to a greater role for GSB in global biogeochemical cycles.

Alcohol Limits and Public Safety.

On May 14, 2013, the National Transportation Safety Board (NTSB) recommended lowering the legal blood-alcohol limit to 0.05 g/dL for motor vehicle operators in the United States, in an effort to reduce the risk of injuries and deaths caused by a driver's alcohol impairment (NTSB/SR-13/01). This recommendation has prompted other organizations and agencies, including the National Safety Council, to evaluate and consider supporting this action. In order to determine the scientific and legal feasibility and advisability of lowering or establishing 0.05 per se laws, we examined 554 alcohol-related publications. Risk factors, instrument reliability, law enforcement, and adjudication issues were considered in this overview of the literature. The extensive scientific literature reviewed provides ample support for lowering the operation of motor vehicle alcohol limits to 0.05, and for supporting the NTSB recommendations. Research clearly demonstrates that impairment begins at very low concentrations, well below the recommended NTSB limit, and increases with concentration. Lowering the limit to 0.05 will save many lives and prevent injuries. Breath, blood, and saliva samples have proved to be accurate and reliable specimens for legal acceptability in a court of law.

Nitrogen cycle feedbacks as a control on euxinia in the mid-Proterozoic ocean.

Geochemical evidence invokes anoxic deep oceans until the terminal Neoproterozoic ~0.55 Ma, despite oxygenation of Earth's atmosphere nearly 2 Gyr earlier. Marine sediments from the intervening period suggest predominantly ferruginous (anoxic Fe(II)-rich) waters, interspersed with euxinia (anoxic H(2)S-rich conditions) along productive continental margins. Today, sustained biotic H(2)S production requires NO(3)(-) depletion because denitrifiers outcompete sulphate reducers. Thus, euxinia is rare, only occurring concurrently with (steady state) organic carbon availability when N(2)-fixers dominate the production in the photic zone. Here we use a simple box model of a generic Proterozoic coastal upwelling zone to show how these feedbacks caused the mid-Proterozoic ocean to exhibit a spatial/temporal separation between two states: photic zone NO(3)(-) with denitrification in lower anoxic waters, and N(2)-fixation-driven production overlying euxinia. Interchange between these states likely explains the varying H(2)S concentration implied by existing data, which persisted until the Neoproterozoic oxygenation event gave rise to modern marine biogeochemistry.

Towards a consistent classification scheme for geochemical environments, or, why we wish the term 'suboxic' would go away.

It is our opinion that the nomenclature used to define geochemical environments is inconsistent and confusing, and in particular the use and meaning of the term 'suboxic', which is widely applied in the geochemical and ecological literature. Our purpose here is to review the redox zonation of natural systems and the nomenclature used to designate this. Finally, we will outline what we feel is a straightforward and non-contradictory scheme for classifying metabolic zones and geochemical environments.

Mass Spectra and Cross-Contribution of Ion Intensity Between Drug Analytes and Their Isotopically Labelled Analogs - Benzodiazepines and Their Derivatives.

With GC-MS as the preferred method and isotopically labeled analogs (ILAs) of the analytes as the internal standards (ISs) of choice for quantitative determination of drugs/metabolites in biological specimens, one important aspect associated with chemical derivatization (CD) is that the CD products derived from the analyte and the selected IS must generate ions suitable for designating the analyte and the IS. These ions must not have significant cross-contribution (CC), i.e., ISs' contribution to the intensities of the ions designating the analytes, and vice versa. With this in mind, the authors have reviewed literature and information provided by manufacturers, searching for suitable CD reagents, CD methods, and ILAs of the analytes related to the following 18 benzodiazepines: oxazepam, diazepam, nordiazepam, nitrazepam, temazepam, clonazepam, 7-aminoclonazepam, prazepam, lorazepam, flunitrazepam, 7-aminoflunitrazepam, N-desalkylflurazepam, N-desmethylflunitrazepam, 2-hydroxyethylflurazepam, estazolam, alprazolam, α-hydroxyalprazolam, and α-hydroxytriazolam. These analytes and ILAs were derivatized with various derivatization groups, followed by GC-MS analysis. The resulting mass spectrometric data are systematically presented in two forms: (a) full-scan mass spectra; and (b) CC data of ion-pairs with potential for designating the analytes and their respective ILAs (candidates of ISs in quantitative analytical protocols). Many of these full-scan mass spectra are not yet available in the literature and should be of reference value to laboratories engaged in the analysis of these drugs/metabolites. Full-scan MS data were further used to select ion-pairs with potential for designating the analytes and ISs in quantitative analysis protocols. The CC data of these ion-pairs were evaluated using data collected in selected ion monitoring mode and systematically tabulated, making the data readily available for analysts searching for this important analytical parameter.

Sulphur isotopes and the search for life: strategies for identifying sulphur metabolisms in the rock record and beyond.

The search for life can only be as successful as our understanding of the tools we use to search for it. Here we present new sulphur isotope data (32S, 33S, 34S, 36S) from a variety of modern marine environments and use these observations, along with previously published work, to contribute to this search. Specifically, we use these new data to gain a sense of life's influences on the sulphur isotope record and to distinguish these biologically influenced signatures from their non-biological counterparts. This treatment extends sulphur isotope analyses beyond traditional (34S/32S) measures and employs trace isotope relationships (33S/32S, 36S/32S), as the inclusion of these isotopes provides unique information about biology and its role in the sulphur cycle through time. In the current study we compare and contrast isotope effects produced by sulphur-utilizing microorganisms (experimental), modern and ancient sedimentary records (observational) and non-biological reactions (theoretical). With our collective search for life now extending to neighbouring planets, we present this study as a first step towards more fully understanding the capability of the sulphur isotope system as a viable tool for life detection, both on Earth and beyond.

Mass Spectra and Cross-Contribution of Ion Intensity Between Drug Analytes and Their Isotopically Labelled Analogs - Common Opioids and Their Derivatives.

For the quantitation of most drugs and their metabolites, GC-MS is currently the preferred method and isotopically labeled analogs of the analytes are the internal standards (ISs) of choice. Under this analytical setting, chemical derivatization (CD) plays a critical role in the sample preparation process. In addition to meeting the conventional objectives of CD, products derived from the selected CD method must generate ions suitable for designating the analyte and the IS; these ions cannot have significant cross-contribution (CC), i.e., contribution to the intensity of the ions designating the analyte by the IS, and vice versa. With this in mind, the authors have reviewed literature and information provided by manufacturers, searching for suitable CD reagents, CD methods, and isotopically labeled analogs of the analytes related to the following 11 opioids: heroin, 6-acetylmorphine, morphine, hydromorphone, oxymorphone, 6-acetylcodeine, codeine, hydrocodone, dihydrocodeine, oxycodone, and noroxycodone. These analytes and ISs were derivatized with various derivatization groups, followed by GCMS analysis. The resulting MS data are systematically presented in two forms: (a) full-scan mass spectra; and (b) CC data of ion-pairs with potential for designating the analytes and their respective ISs. Many (if not most) of these full-scan mass spectra are not yet available in the literature and should be of reference value to laboratories engaged in the analysis of these drugs/metabolites. Full-scan MS data were further used to select ion-pairs with potential for designating the analytes and ISs in quantitative analysis protocols. The CC data of these ion-pairs were evaluated using data collected in selected ion monitoring mode and systematically tabulated, readily available for analysts searching for this important analytical parameter.

Mass spectrometric data characteristics of commonly abused amphetamines with sequential derivatization at two active sites.

There have been reports on improved chromatographic parameters derived from the incorporation of sequential derivatization in preparing biological specimens for the analysis of opiates. This current study was designed to characterize the mass spectrometric data resulting from sequential derivatizations of commonly abused amphetamines (along with all commercially available deuterated analogs) containing two active sites, i.e., amphetamine, methylenedioxyamphetamine, phenylpropanolamine. The first derivatization groups included in this study were trifluoroacetyl, pentafluoropropionyl, and heptafluorobutyryl, while t-butyldimethylsilyl was used as the second derivatization group. Products resulting from the first step and the two-step derivatization processes were analyzed by GC-MS. Full-scan mass spectrometric data were used to select ions with potential for designating the analytes and their respective isotopically labeled analogs in quantitative analysis protocols. Selected ion monitoring data were then collected and assessed to determine the quality of these ions when one or two different derivatization groups were incorporated in the sample preparation processes. A total of 77 full-scan mass spectra and 8 ion intensity cross-contribution tables, representing various forms of derivatization and isotopic analogs of the three amphetamines, are systematically presented for reference. Evaluations of these data concluded that many, but not all, products derived from "double derivatization" (sequential derivatization with two derivatization groups), generate ions of higher quality than those derived from "single derivatization".

Mass Spectrometric Data of Commonly Abused Amphetamines and Their Derivatives - Cross Contribution of Ion Intensity between the Analytes and Their Isotopically Labeled Analogs.

With GC-MS as the preferred method and isotopically labeled analogs of the analytes as the internal standards (ISs) of choice for the analysis of drugs/metabolites in biological specimens, one important aspect associated with chemical derivatization (CD) is that the CD products derived from the analyte and the selected IS must generate ions suitable for designating the analyte and the IS; these ions cannot have significant crosscontribution (CC), i.e., contribution to the intensity of the ion designated for the analyte by the IS, and vice versa. With this in mind, the authors have reviewed literature and commercial information on common CD reagents and methods and conducted a thorough search of isotopically labeled analogs of commonly abused amphetamine-type drugs/metabolites that are commercially available. These ISs and analytes were then derivatized with various derivatization groups. These CD products were then analyzed by GC-MS and the resulting MS data are presented here in two forms: (a) systematic presentation of full-scan spectra; and (b) tabulation of CC data for ions with potential for designating the ISs and analytes. Many (if not most) of these full-scan spectra are not yet available in the literature and should be of daily reference value to forensic and clinical laboratories that are engaged in the analysis of these drugs/metabolites. Full-scan MS data were further used to select ion-pairs with potential for designating the analytes and ISs in quantitative analysis protocols. The CC data of these ion-pairs were evaluated using data collected under the SIM mode and summarized in table format. These data should save enormous amounts of time and efforts for practicing laboratories in their search for this analytical parameter.