Direct Analysis In Real Time Mass Spectrometry Research Articles

Assessing Antiparasitic Compounds Persistence in Cattle Hair by DART-MS.

This study introduces an alternative strategy for evaluating antiparasitic persistence compounds in cattle hair by Direct Analysis in Real Time Mass Spectrometry (DART-MS). The developed DART-MS method aimed to determine fenthion, chlorpyrifos, and cypermethrin in cattle hair samples. DART-MS analyses were performed in positive ion mode, and parameters related to the DART source were evaluated. The analytical performance demonstrated the efficiency of the optimized DART-MS method for fenthion, chlorpyrifos, and cypermethrin quantification in the evaluated samples, meeting criteria for precision, accuracy and limits of detection. Overall, the DART-MS method provided a fast and efficient analysis for determination of antiparasitic agents in cattle hair, which contributes to the evaluation of drug administration protocols and dosage intervals, and aids the safety and advancement of the livestock sector.

Rapid quantitative analysis of semi-volatile organic compounds in indoor surface film using direct analysis in real time mass spectrometry: a case study on phthalates

Abstract. Direct analysis in real time mass spectrometry (DART-MS) has recently emerged as a promising approach for measuring semi-volatile organic compounds (SVOCs) on indoor surface films. However, its broader application in indoor environments is limited by low measurement repeatability and no separation of isomers. Herein we developed a sampling suite of indoor surface films for DART-MS analysis, optimized settings of DART to obtain higher analytical performance, and demonstrated the possibility of separating isomeric compounds using tandem mass spectrometry (MS/MS). Two pairs of isomeric phthalate esters, including di(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP) and diisobutyl phthalate (DiBP) and di-n-butyl phthalate (DnBP), were used as examples for method optimization and validation. Under optimized conditions, the instrument responses for all four compounds exhibited good linearity (r>0.992) and acceptable repeatability (intraday relative standard deviation (RSD) < 11.0 %). The limits of quantification for the four phthalate esters ranged from 0.042 to 0.24 ng cm−2. The uncertainty in the separation of isomeric components using MS/MS was < 11.4 %, which is acceptable for real sample analysis. To further assess the developed method, we analyzed 10 film samples collected side by side in an occupied office. DnOP was not detected. The RSD among samples was 6.1 % for DEHP, 4.6 % for DnBP, and 10.4 % for DiBP, indicating the overall good repeatability of the collection and measurement method developed. With improved performance, the developed method increases the feasibility of the DART-MS technique for monitoring the dynamics of chemical composition of indoor surface films.

Recovery and detection of ignitable liquid residues from the substrates by solid phase microextraction – direct analysis in real time mass spectrometry

In this study, direct analysis in real time mass spectrometry (DART-MS) was coupled to the solid phase microextraction (SPME) to extract and analyze the ignitable liquid residues (ILR) present in the sample matrices. The SPME extraction parameters, such as extraction temperature and extraction time, were optimized using a two-factor central composite design. The SPME-DART-MS setup was utilized to analyze the substrates and fire debris matrices spiked with gasoline. The results indicate that the less volatile marker compounds from gasoline were recovered from the substrates and fire debris, and their profiles matched well with the gasoline liquid samples analyzed directly by DART-MS. As expected, the effective extraction of marker compounds in gasoline required a relatively high temperature, i.e., 150 ℃. In the presence of a matrix, a higher extraction temperature and longer extraction time could benefit the extraction efficiency. The desorption of ILR on SPME fiber was performed by inserting the fiber into the DART-MS helium gas stream at 300 ℃ for 1 min with no carry-over residues being observed between successive samples. The chemical information attained with this method is typically not observed in the current GC/MS-based practice. The SPME-DART-MS was also extended to reanalyze less volatile components of ILR on substrates after the ASTM E1412 activated charcoal method, which indicates its possible application subsequent to the traditional GC/MS ILR analysis. The SPME-DART-MS has shown promise in ILR detection as an important complementary tool.

Bioactive Compounds and Valorization of Coffee By-Products from the Origin: A Circular Economy Model from Local Practices in Zongolica, Mexico.

The by-products of green coffee processing are rich in compounds that can be recycled for their possible use in the production of beverages, fertilizers and weed control in production areas. The objective of this work was to identify the organic and inorganic bioactive compounds of green coffee and the coffee by-products related to the production of origin, such as dried cascara (skin-pulp), parchment and silverskin (unroasted), in order to investigate the role their biomolecules may have in reuse through practices and local knowledge, not yet valued. The metabolomic profile by HPLC-ESI-HRMS of the aqueous extract of the dried cascara highlighted 93 non-volatile molecules, the highest number reported for dried cascara. They belong to groups of organic acids (12), alkaloids (5), sugars (5), fatty acids (2), diglycerides (1), amino acids (18), phospholipids (7), vitamins (5), phenolic acids (11), flavonoids (8), chlorogenic acids (17), flavones (1) and terpenes (1). For the first time, we report the use of direct analysis in real-time mass spectrometry (DART-MS) for the identification of metabolites in aqueous extracts of dried cascara, parchment, silverskin and green coffee. The DART analysis mainly showed the presence of caffeine and chlorogenic acids in all the extracts; additionally, sugar adducts and antioxidant compounds such as polyphenols were detected. The mineral content (K, Ca, P, S, Mg and Cl) by EDS spectrometry in the by-products and green coffee showed a relatively high content of K in the dried cascara and green coffee, while Ca was detected in double quantity in the silverskin. These metabolomic and mineral profile data allow enhancement of the link between the quality of green coffee and its by-products and the traditional local practices in the crop-growing area. This consolidates the community's experience in reusing by-products, thereby minimizing the impact on the environment and generating additional income for coffee growers' work, in accordance with the principles of circular economy and bioeconomy.

Two polymorph modifications of tris(hexafluoroacetylacetonato)iron(III) revealed: is that common for other trivalent metals?

A long-standing issue about the correct identification of an important starting reagent, iron(III) hexafluoroacetylacetonate, Fe(hfac)3 (1), has been resolved. The tris-chelated mononuclear complex was found to crystallize in two polymorph modifications which can be assigned as the low-temperature (1-L) monoclinic P21/n and the high-temperature (1-H) trigonal P-3. Low-temperature polymorph 1-L was found to transform to 1-H upon sublimation at 44 °C. Two modifications are clearly distinguished by powder X-ray diffraction (PXRD), single-crystal X-ray diffraction, differential scanning calorimetry (DSC), and melting-point measurements. On the other hand, the two forms share similar characteristics in direct analysis in real-time mass spectrometry (DART-MS), attenuated total reflection (ATR) spectroscopy, and some physical properties, such as color, volatility, sensitivity, and solubility. Analysis of the literature and some of our preliminary data strongly suggest that the appearance of two polymorph modifications for trivalent metal (both transition and main group) hexafluoroacetylacetonates is a common case for several largely used complexes not yet accounted for in the crystallographic databases.

An Agile and Accurate Approach for N-Nitrosamines Detection and Quantification in Medicines by DART-MS.

N-nitrosamines (NAs) are prevalent mutagenic impurities in various consumer products. Their discovery in valsartan-containing medicines in 2018 prompted global regulatory agencies to set guidelines on their presence and permissible levels in pharmaceuticals. In order to determine the NAs content in medicines, efficient and sensitive analytical methods have been developed based on mass spectrometry techniques. Direct analysis in real time-mass spectrometry (DART-MS) has emerged as a prominent ambient ionization technique for pharmaceutical analysis due to its high-throughput capability, simplicity, and minimal sample preparation requirements. Thus, in this study DART-MS was evaluated for the screening and quantification of NAs in medicines. DART-MS analyses were conducted in positive ion mode, for both direct tablet analysis and solution analysis. The analytical performance was evaluated regarding linearity, precision, accuracy, limits of detection, and quantification. The DART-MS proved to be suitable for the determination of NAs in medicines, whether through direct tablet analysis or solution analysis. The analytical performance demonstrated linearity in the range from 1.00 to 200.00 ng mL-1, limits of quantification about 1.00 ng mL-1, precision and accuracy lower than 15%, and no significant matrix effect for six drug-related NAs. In conclusion, the DART-MS technique demonstrated to be an alternative method to determine NAs in medicines, aligning with the principles of green chemistry.

Food authentication goes green: Determination of the geographical origin of grain maize (Zea mays L.) using direct analysis in real time mass spectrometry (DART-MS)

Time savings, environmental friendliness and cost reduction are important criteria to determine the authenticity of feed and food in routine analysis. One analytical technique that is especially promising in terms of these criteria in metabolomics studies is Direct Analysis in Real Time Mass Spectrometry (DART-MS). In the present study, DART-MS is applied to 200 grain maize samples from seven geographical origins to develop a data processing workflow and an approach for origin analysis of grain maize. For the first time, such a large sample set was investigated using a DART-MS-based non-targeted lipidomics approach. Various open-source programs were used for pre-processing and random forest (RF) combined with repeated cross-validation was used for classification, resulting in an accuracy of 84.4%. Subsequently, the most important markers identified by RF, belonging to the classes of mono-, di- and triacylglycerols, were identified using DART-MS2. The chosen method significantly minimizes the time and solvent consumption compared to classic liquid chromatography electrospray ionization mass spectrometric (LC-ESI-MS) strategies and thus offers a more cost-effective and environmentally friendly alternative. Furthermore, the results show the high potential for determining the geographical origin of grain maize using DART-MS.

Development of a novel seized drug screening method utilizing DART-MS and used weigh paper

The conventional analytical scheme for seized drug analysis utilizes quick and cost-effective presumptive testing, such as color tests, followed by more discriminatory techniques, such as gas chromatography-mass spectrometry (GC–MS). Before the seized drug evidence is analyzed, the evidence is weighed using an appropriate weighing matrix and balance. Typically, the weighing matrix is discarded as chemical waste; however, the process of weighing the evidence leads to the deposition of drug residue onto the weighing matrix, which is then amenable to rapid analysis using ambient ionization approaches, such as direct analysis in real time mass spectrometry (DART-MS). This study demonstrates a DART-MS method for the rapid screening of seized drug evidence using filter paper and glassine paper weighing matrices commonly found in forensic laboratories. Validation experiments were performed using filter paper and glassine paper and compared to the results obtained using glass capillaries to assess the effectiveness of each weighing matrix. A total of 40 authentic samples, 20 filter papers and 20 glassine papers, were analyzed and the resulting spectra were searched using the National Institute of Standards and Technology (NIST) DART-MS Forensics Database and Data Interpretation Tool (DIT). When compared to the ground truth GC–MS results, the developed approach had a 90% correct identification rate, with all misidentifications being due to the presence of tablets rather than powder. The developed DART-MS screening method provides the seized drug community with a method to rapidly screen seized drug residue remaining from the weighing process and to improve the overall laboratory efficiency.

Rapid Determination of Flavorings in e-Cigarette Liquid by Direct Analysis in Real Time (DART) Mass Spectrometry (MS) in the Quick Strip Mode

Electronic cigarettes (E-cigarettes) have become popular around the world. An important reason is the variety of available flavors. However, many countries have imposed restrictions on flavor substances in E-cigarettes due to their potential health risks. Therefore, it is necessary to develop an effective way to identify flavorings in E-cigarette liquids. In this work, direct analysis in real time-mass spectrometry (DART-MS) in the quick strip (QS) mode was developed and applied to determine flavorings in the E-cigarettes. Vanillin, ethyl vanillin, maltol, and ethyl maltol were quantified. Meanwhile, the ionization efficiency of flavorings in the different solvents was compared in the QS mode, which revealed that the solvent boiling point was related to the analyte ionization efficiency. The effect of endogenous matrix (propylene glycol and glycerol) on flavoring ionization was also investigated. Calibration curves with satisfactory linearity (R 2 > 0.99) were established from 1 to 1000 μg L−1. Good sensitivity (limits of detection [LODs] < 0.3 μg L−1), recoveries (92.6% to 104.7%), and acceptable repeatability (relative standard deviations < 14.6%, n = 5) were obtained. The limits of quantification (LOQs; 10–50 μg g−1) for the E-cigarette liquid sample were much lower than the regulatory limits. The developed method provided a simple way for rapidly determining flavorings in E-cigarettes.

Investigating the combined capability of confocal Raman microscopy and direct analysis in real time-mass spectrometry (DART-MS) for the analysis of intact explosives

The identification of organic and inorganic components used to produce homemade explosives (HMEs) remains a challenge for forensic analysts due to their diverse physicochemical properties that require different instrumentation. This study aims to explore the combined use of direct analysis in real time-mass spectrometry (DART-MS) and Raman microscopy to provide a rapid and reliable analysis of a variety of intact explosives with minimal sample preparation, including 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), seven inorganic oxidizing salts, and five smokeless powder constituents. While both techniques were well-suited for the analysis of TNT and PETN, DART-MS had the advantage of being more sensitive compared to Raman spectroscopy for the identification of the organic components contained in smokeless powder. Even though the identification of ammonium-based salts using DART-MS could be achieved, the analysis of low-volatility compounds, such as the inorganic oxidizing salts, was more straightforward with Raman microscopy and did not require sample preparation. This study demonstrates the benefits and limitations of combining Raman microscopy and DART-MS for the analysis of intact explosives and precursors. Using this combined approach enabled the rapid identification of various organic and inorganic explosives and precursors with minimal sample preparation.

Understanding sensitivity and cross-reactivity of xylazine lateral flow immunoassay test strips for drug checking applications.

The continued prevalence of xylazine in the illicit drug market has necessitated development of quick and simple methods for identification, including lateral flow immunoassays (also known as "test strips"), like those frequently used to detect fentanyl. This study explored the drug checking applicability of the first publicly available xylazine test strips (XTS) using four sub-studies: reproducibility (i.e., consistency of positive results in a highly-concentrated xylazine solution); limit of detection on a calibration curve of xylazine concentrations; cross-reactivity against 77 commonly encountered drugs, cutting agents, and other structurally similar compounds; and applicability for analyzing community-acquired samples-where 100 drug residue samples were analyzed using XTS, direct analysis in real time mass spectrometry (DART-MS), and gas chromatography tandem mass spectrometry (GC-MS/MS). XTS consistently detected xylazine at concentrations ≥2.5μg/ml, and XTS results were reproducible. Sensitivity and specificity of XTS were calculated by comparing expected versus obtained results based on xylazine concentration of community-acquired samples measured by GC-MS/MS. XTS consistently detected xylazine in samples with concentration >2μg/ml and yielded a sensitivity of 0.974, specificity of 1.00, and overall accuracy of 0.986. Cross-reactivity with lidocaine, a common cutting agent, and lack of XTS reactivity with other α2 -agonists found in the illicit drug supply highlight the need to offer consumers comprehensive drug checking services that identify a range of substances and better inform them about drug contents.

Volatile fingerprints of beef cooking methods using sol–gel‐based solid‐phase microextraction (SPME) and direct analysis in real‐time mass spectrometry (DART‐MS)

RationaleThe aroma profile of food is a complex mixture of volatile compounds that constitutes a major component of the overall eating experience. The food service industry and chefs therefore constantly seek ways to investigate and thereby enhance the aroma profile. Oven cooking, sous vide and pan fry are three cooking methods of beef commonly practised by chefs. Near real‐time analysis of volatile compounds from these three cooking methods will provide insight into respective volatile fingerprints and help improve cooking techniques.MethodsVolatile compounds from three beef cooking methods were captured using an in‐house sol–gel based solid phase microextraction (SPME) method and analysed using direct analysis in real‐time mass spectrometry (DART‐MS). A volatile organic compound (VOC) standard was used to demonstrate successful implementation of the sol–gel coating technique. Volatile features discriminating the three cooking methods were shortlisted and statistically assessed by univariate and multivariate analyses.ResultsThe VOC standard was successfully adsorbed by the sol–gel method and detected by DART‐MS. Hierarchical cluster analysis clearly demarcated three beef cooking methods based on their volatile fingerprints. Out of 65 significant features differentiating the cooking methods, 50 were at highest concentrations from pan‐fry cooking only, followed by 14 with highest concentrations from oven cooking followed by pan frying. Sous vide followed by pan frying showed lowest concentrations of almost all volatile features.ConclusionsThe sol–gel‐based solid‐phase microextraction technique combined with DART‐MS was successful in differentiating beef cooking methods based on their volatile fingerprints. A workflow for rapid assessment of the volatile profile from beef cooking methods was established, providing a baseline to further explore volatile profiles from other key ingredients.

Rapid authentication of red wine by MALDI-MS combined with DART-MS

A simple, rapid and high-throughput approach was developed for authentication of red wine for the first time, by combining spectral results from matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and direct analysis in real time mass spectrometry (DART-MS). By coupling with orthogonal partial least squares discrimination analysis (OPLS-DA), this approach enabled successful classification of 535 wines from 8 countries, with the correct classification rates of 100% on the calibration set and over 90% on the validation set for almost all countries, and 26 potential characteristic markers selected. Compared to one single technique, this approach allowed detection of more compound ions, and with better fitting and predictive performances. The satisfactory differentiation results of vintages and grape varieties further verified the robustness of the approach. This study demonstrated the feasibility of combining multiple mass spectrometric techniques for wine analysis, which can be extended to other fields or to combinations of other analytical techniques.

Rapid headspace solid-phase microextraction sheets with direct analysis in real time mass spectrometry (SPMESH-DART-MS) of derivatized volatile phenols in grape juices and wines

Volatile phenols possess “smoky, spicy” aromas and are routinely measured in grapes, wines and other foodstuffs for quality control. Routine analyses of volatile phenols rely on gas chromatography – mass spectrometry (GC-MS), but slow throughput of GC-MS can cause challenges during times of surge demand, i.e. following ‘smoke taint’ events involving forest fires near vineyards. Parallel extraction of headspace volatiles onto sorbent sheets (HS-SPMESH) followed by direct analysis in real time mass spectrometry (DART-MS) is a rapid alternative to conventional GC-MS approaches. However, HS-SPMESH extraction is poorly suited for lower volatility odorants, including volatile phenols. This work reports development and validation of an HS-SPMESH-DART-MS approach for five volatile phenols (4-ethylphenol, 4-ethylguiacol, guaiacol, 4-methylguaiacol, and cresols). Prior to HS-SPMESH extraction, volatile phenols were acetylated to facilitate their extraction. A unique feature of this work was the use of d6-Ac2O as a derivatizing agent to overcome issues with isobaric interferences inherent to chromatography-free MS techniques. The use of alkaline conditions during derivatization resulted in cumulative measurement of both free and bound forms of volatile phenols. The validated HS-SPMESH-DART-MS method achieved a throughput of 24 samples in ∼60 min (including derivatization and extraction time) with low limits of detection (<1 μg L−1) and good repeatability (3–6% RSD) in grape and wine matrices. Validation experiments with smoke-tainted grape samples indicated good correlation between total (free + bound) volatile phenols measured by HS-SPMESH-DART-MS and a gold standard GC-MS method.

Rapid Characterization of Hops (Humulus lupulus) Using DART-MS and Chemometrics

Hops represent a key ingredient in beer and are often utilized to impart specific flavors. The popularity of hoppy beers (e.g., India Pale Ales) is raising expectations for stability, quality, and unique organoleptic properties of hops. Evaluation of hops is typically performed by sensory evaluation, requiring a trained human panel, and often yielding subjective results with limited throughput. Here, we present the use of ambient mass spectrometry (AMS) as an alternative approach to enable objective and rapid chemical fingerprinting of hops for quality screening reflective of sensory. Twelve hop samples were sourced from three different suppliers across four different farms located in Washington and Oregon (U.S.A.) over two growing seasons. The samples included three commercial cultivars, Cascade, Centennial, and Strata. The hop samples were extracted using an 80% ethanol solution and chemical fingerprints were acquired by Direct Analysis in Real Time Mass Spectrometry (DART-MS). The resulting data were used to train and validate predictive multivariate statistical models. Additionally, authentic standards of important hop compounds (hop α-acids, terpenes) were used to putatively annotate DART-MS signals and traditional sensory analysis was performed to support that the DART-MS data is reflective of sensory attributes. The results demonstrate the potential of this approach for rapid evaluation of hops quality. Ultimately, implementation of this tool could have applications for quality assurance programs and rapid phenotyping of hops by producers.

GC/MS and DART-MS as complementary methods for investigating the effects of weathering on chemical profiles of ignitable liquids: A case study for paint thinner

In this study, gas chromatography/mass spectrometry (GC/MS) and direct analysis in real time mass spectrometry (DART-MS) were used to analyze paint thinner samples weathered under different conditions. As GC/MS total ion chromatograms (TIC) of weathered paint thinner samples varied significantly due to the disparate evaporation rates of organic compounds in the mixture, DART-MS spectra have shown more consistent profiles among different samples. The distinctive ion clusters identified in the DART-MS spectra were attributed to the less volatile glycol ethers and polymeric compounds with alkyl chains in the paint thinner samples. Analysis of variance-principal component analysis (ANOVA-PCA) was applied to study the contributions of weathering degree and temperature factors to the total variance of GC/MS TIC and DART-MS spectral datasets and found that both factors played significant roles in the weathering process (p < 0.05), though weathering degree contributed to considerably more total variance to GC/MS TIC profiles (i.e., 93.4%). The paint thinner GC/MS and DART-MS profiles were compared with those from other common ignitable liquids, such as gasoline, torch fuel, lighter fluid, and Japan drier. The partial least squares discriminant analysis (PLS-DA) models were constructed to classify the ignitable liquids with the classification rates of 99.97 ± 0.02% and 99.80 ± 0.08% for models based on GC/MS and DART-MS data, respectively. Our study has shown that DART-MS can provide discriminative information for distinguishing ignitable liquid samples and complement the existing GC/MS method by the detection of less volatile compounds.

An analytical platform for near real-time drug landscape monitoring using paraphernalia residues

Deaths attributed to drug overdoses are constantly on the rise, but drug trends are frequently changing and often differ across geographical regions. Current analytical techniques are limited in their abilities to rapidly identify drugs that would inform both public health and law enforcement officials about the evolving drug landscape. The work presented here outlines an analytical platform that utilizes ambient ionization mass spectrometry and additional techniques (e.g., tandem mass spectrometry) to qualitatively analyze trace residues from drug paraphernalia to quickly detect both drugs and cutting agents. To demonstrate proof-of-concept, samples collected from syringe service programs throughout the state of Maryland were analyzed by direct analysis in real time – mass spectrometry (DART-MS) to provide rapid, near complete chemical profiles (drugs, cutting agents, and other compounds of interest). To obtain a more complete chemical profile, it was found that a small subset of samples (7.5 %) benefited from additional analysis by either direct analysis in real time – tandem mass spectrometry (DART-MS/MS) or liquid chromatography – tandem mass spectrometry (LC-MS/MS). This additional analysis enabled confirmation of the presence or absence of questioned compounds, assisted in identification of new compounds, and provided isomer differentiation without hindering the rapid reporting of results. This analytical platform utilizing DART-MS and, where necessary, tandem mass spectrometry techniques, was found to detect a wide range of drugs and cutting agents in a manner that can better inform public health and public safety personnel about the drug landscape in “near real-time”.

Mapping hyperspectral NIR images using supervised self-organizing maps: Discrimination of weedy rice seeds

Weedy rice is one of the most problematic weeds in rice-growing regions, particularly in Southeast Asia. Unlike other types of weeds, it is extremely difficult to distinguish weedy rice from cultivated rice directly from paddy seeds as they exhibit common morphological features. As such weed management can be a difficult, time-consuming, and inaccurate process that is often carried out manually. This study offers a novel classification approach based on an artificial neural network (ANN), utilizing self-organizing maps (SOMs), to directly discriminate weedy rice using the near-infrared (NIR) hyperspectral imaging (HSI) technique. The physical attributes, thermal behavior, and chemical profiles of the weedy and cultivated rice were thoroughly investigated by a range of analytical techniques, including optical microscopy, scanning electron microscopy, thermogravimetric analysis, and direct analysis in real-time mass spectrometry (DART-MS). For direct sample analysis by HSI, a global self-organizing map was generated with optimized parameters (scaling value and map size). The color indices (Red, Green, Blue values) of the sample image were defined to obtain a color ratio that can be used to classify unknown samples. The optimal threshold for classification was carefully determined using a receiver operating characteristic (ROC) curve. Performance metrics (sensitivity, specificity, precision, accuracy, and misclassification error) were used to evaluate the performance of the model. Classification accuracies of 98% (Weedy vs PL2) and 88% (Weedy vs RD49) were obtained with balanced sensitivity and specificity. The classification was assessed from the whole sample image, which was completely independent of the selected region of interest. As far as we know, this is the first instance where SOMs have been utilized to appraise seed quality by means of authentic HSI images.

Ancient Chromophores and Auxiliaries: Phrygian Colorants from Tumulus MM at Gordion, Turkey, ca 740 BCE

This paper discusses colorants found in Tumulus MM, the tomb of King Midas or his father, at Gordion, the capital of the Phrygian kingdom. Chromophores, colorants, and auxiliaries are preserved largely independent of the textiles they once colored. The Tumulus MM textiles are now fragmentary due to the degradation processes that occurred inside the tomb chamber. For DHA 26 (Vienna, Austria, 2007), we discussed a group of golden-yellow fragments from Tumulus MM that appeared to be tabby cloth but were skeletal lattices of goethite, αFeOOH (yellow ochre), as identified by FTIR, with SEM/EDS, XRD with molybdenum Kα radiation, NIR, and Raman spectroscopy. The “dyeing” has been replicated using a patented method; originally it may have involved a controlled redox reaction, based on our preliminary experiments. Amidst the goethite lattices, some skeletal fragments were green, with near-black lines within the yarn spiral, identified as indigo by FTIR at the time. Other masses with colorations of red, orange/brown, and purple with deep red veins did not yield identifiable inorganic coloration profiles with SEM/EDS. A purple fragment (2003-Tx-6 Front) was assayed by ICP-MS for mordants and for bromine, but neither could be found. Recently, direct analysis in real time mass spectrometry (DART-MS) enabled us to successfully detect organic colorants. For one fragment, indoxyl, isatin, indigo, and leuco-indigo were identified. One striated red-to-brown mass (2003-Tx-3) contained alizarin, purpurin, xanthopurpurin, lucidin, and other madder substituents; it also contained indigo/isatin but neither indoxyl nor leuco-indigo. Other beige-brown masses like 2003-Tx-5 sometimes contained alizarin, xanthopurpurin, rubiadin, and lucidin but rarely purpurin or indigo-related compounds. The purple (2003-Tx-6) shared the madder analogues with browner hues. The versatility appears related to that found in Anatolian pile carpets and flat weaves. Our new analyses confirm that the Phrygian textile colorists were indeed superb, versatile dyers.

Influence of host-guest interactions on analytical performance of direct analysis in real-time mass spectrometry.

To systematically study the influence of host-guest interactions on the analytical performance of direct analysis in real time mass spectrometry (DART-MS), the interactions between cyclodextrins (CDs) and different Sudan dyes were investigated. The results showed that the host-guest interaction between CDs and Sudan dyes did not affect qualitative analysis of the target compounds, but led to a lower signal intensity for Sudan dyes, thus affecting quantitative analysis of the target compounds. The stronger the host-guest interaction, the weaker the signal intensity of target compound on DART-MS. The results also show that both in solution and in solid-phase microextraction (SPME), the addition of organic solvents can weaken the host-guest interaction between CDs and Sudan dyes, thus improving the signal intensity in DART-MS. In SPME, adding organic solvents has a certain practical value and can improve the efficiency of Sudan dye analysis. This study suggests that appropriate sample pretreatment is needed to weaken noncovalent interactions prior to DART-MS analysis to obtain more accurate quantitative results. The data provide some insight into the effects of other noncovalent interactions on the efficiency of DART-MSas an analytical tool, as well as the potential to study intermolecular interactions with DART-MS.