A Scoping Review on Fungus and Mycotoxin Studies in the Building's Environment: Mycotoxin Analysis by Mass Spectrometry

It has been well-established that mycotoxins are poisonous chemical metabolites secreted by certain molds. Some of them significantly affect the health of humans and livestock. Increasing attention is now being paid to uncovering and identifying mycotoxins' presence in the building's environment. However, the main challenge remains in suitable and reliable analytical methods for their identification and detection in infected structures. GC-MS and LC-MS/MS techniques have been used extensively for mycotoxin analysis, and advancement in these techniques enabled a more comprehensive range of mycotoxins to be detected. As such, this study aimed to address a brief overview of various phenomena of existing sample collection, preparation, and analysis to detect mycotoxins in the building's environment. This scoping review includes articles from 2010 to 2020 available from PubMed, Scopus, Cochrane, Wiley, Google Scholar, and ScienceDirect. Duplicate articles were removed, and exclusion criteria were applied to eliminate unrelated studies, resulting in 14 eligible articles. The present study provides an overview of mycotoxin analysis by GC-MS and LC-MS/MS in buildings. Many techniques are available for analyzing and detecting multiple mycotoxins using these methods. Future efforts would focus on rapid assays and tools enabling measuring a broader range of mycotoxins in a single matrix and lower detection limits. In addition, it would assist future findings on new techniques and mycotoxins that existed in the building's environment.


Introduction
Mycotoxins are secondary metabolites of fungi associated with various toxicities in humans and animals.Tey have long been studied because of their extensive exposure to food and feed commodities and their potential use as therapeutic drugs and biological warfare agents.Due to the prevalence of mycotoxin contamination in foods and feeds, many years of research have focused on ingesting these toxic compounds.Inhalation of mycotoxins has yet to attract much attention, and available reports point mainly to occupational and agricultural settings.In the 2000s, mycotoxins were hinted to be toxic agents adverse to human health through inhalation exposure in a nonagricultural indoor environment.Airborne mycotoxins have been reported in moldy buildings other than agricultural settings [1,2].Tey originate from the fungal pollution of the indoor environment, e.g., sterigmatocystin and afatoxins produced mainly by Aspergillus spp.which include A. versicolor and A. favus, and macrocyclic trichothecenes produced by Stachybotrys chartarum.A comprehensive review of fungal pollution in an indoor environment was documented by Khan and Karuppayil [3].Wood or wood-based products are susceptible to infestation by Cladosporium and Penicillium (Penicillium brevicompactum and Penicillium expansum), Trichoderma, and Aspergillus [4,5].Paecilomyces variotii, Trichoderma harzianum, and Penicillium species attack polyurethanes used in composites for insulation [6].Also, dust on the surfaces and inner wall materials used in buildings, such as prefabricated gypsum board, paper, and glue, represents an excellent substrate for fungal growth.According to D'Mello [7] and Ciegler and Bennett [8], one mold species can produce several mycotoxins, and vice versa, and diferent mold genera may produce the same mycotoxins.
Human health efects attributed to the inhalation of mycotoxins in workplaces include mucous membrane irritation, skin rash, nausea, immune system suppression, acute or chronic liver damage, acute or chronic central nervous system damage, endocrine efects, and cancer [9].Furthermore, some nonspecifc symptoms possibly related to mycotoxin production, such as cough, irritation of the eyes, skin, respiratory tract, joint aches, headache, and fatigue, have also been documented [10,11].Afatoxin, trichothecenes, and ochratoxins are the most well-known mycotoxins found in the indoor environment [12,13].To date, several hundred mycotoxins have been discovered.Various methods, including high-performance liquid chromatography techniques such as gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS), are widely used for identifying and detecting mycotoxins.Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) is vital and central for mycotoxin analysis.In contrast, the molecular polymerase chain reaction (PCR) approach and the enzyme-linked immunosorbent assay (ELISA) were commonly used in fungi identifcation [14].Te ability and sensitivity of multiple mycotoxin quantifcations in various matrices such as food, feed, and biological samples have expanded signifcantly since 2010, attributed to the progress in LC-MS and the combination of appropriate sample extraction and cleanup procedures [15][16][17].Tis approach is highly relevant as several mycotoxins tend to cooccur with others, regardless of the similarity in their chemical structure [18][19][20].Te most common mycotoxin extraction method applied for an indoor environment is liquid-liquid extraction (LLE) with a wide variety of solvents such as methanol [21][22][23][24], acetonitrile [25][26][27], and dichloromethane [28,29].In addition, the combination of the solvent mixture, e.g., methanol, dichloromethane, and ethyl acetate and chloroform and methanol, in diferent ratios has also been adopted [23,[30][31][32].
Tis selected study is a scoping review that aims to provide insight into the recent mycotoxin study and analysis in the building's environment using GC-MS and LC-MS/MS from the available literature.Tis review has also enabled us to identify the knowledge gaps and future potential research in this area.Validated and updated evidence from this review can assist professional bodies in the importance of this subject matter on human health and mitigation strategies.

Methodology
Scoping reviews provide an excellent approach to analyzing research fndings on a particular topic.Scoping ofers an overview of the literature, narrowing down the related study to match our targeted case, and fnally summarising the main component, concepts, and the available data to give an insight into the gap that is available in the feld [33,34].Hence, a scoping review was chosen to review research articles on the available analytical techniques that allow the optimum discovery and quantifcation of targeted mycotoxins relying on the mass and ion charge methods.Te mass spectroscopy system ofers sensitivity and specifcity for challenging and matrix-complex samples.Te selected topic accommodated the proposed research study in the Institute for Medical Research (IMR), Malaysia (NMRR-18-962-41809).For the scoping approach, we adopted Arksey and O'Malley's [35] method consisting of six phases to guide the selection process of the suitable literature available for our review purposes.We also considered updated guidelines published by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) 2020 statement [36].

Phase 1:
Identifying the Research Question.Various methods have been adopted for determining mycotoxins, whether in the air, building materials, or dust, utilizing mass spectrometry or a more advanced tandem mass spectrometry method.As for our scope, we would like to answer "what are the recent methods of LC-MS/MS and GC-MS that are being used to determine the presence of mycotoxin in the targeted samples collected from indoor air in building environments?"2.2.Phase 2: Identifying the Relevant Studies.During the search, the following criteria were set as guidance: (1) Articles were written in English only (2) Articles published from 2010 to 2020 (3) Databases search from PubMed, Google Scholar, Cochrane, Scopus, Wiley, and ScienceDirect (4) Open-access research articles only, excluding review papers, book chapters, and conference papers (5) Keywords are indoor air, mycotoxin, LCMS/MS, and GCMS

Phase 3: Study Selection.
PRISMA guidelines were used in our study selection to assist as a guided protocol for the search.At the initial stage, all team members were assigned to a specifc database to conduct a web search based on the selected keywords.Te search was then transferred to the Microsoft Excel spreadsheet and assigned to team members to scrutinize the obtained papers based on our agreed inclusion criteria.Team members will review the journal papers' abstracts to determine their relevance to our review scope.Furthermore, the full articles will be retrieved, and the information will be transformed to highlight the fndings to decide whether a particular paper will be included or excluded for scoping review purposes.When members were unsure about the acceptability of a particular paper during abstracts or full-text screening, a discussion session was conducted to fnalize the decision.Te fow of the process is shown in Figure 1.  1 shows how the information was tabulated to meet the research questions and scoping review purposes.

Phase 5:
Collating, Summarising, and Reporting the Results.Te main aim of a scoping review is to collect the available data, results from fndings, and research output into more tangible information to be well-versed on the research that had taken place, the area that can be improvised, and fnally give an overview of the research gap that can be tackled for the future research direction (Figure 2).

Mycotoxins in Buildings
Tis review was started with a concurrent investigation on mycotoxins in Peninsular Malaysia's healthcare institutions initiated by researchers from the Institute for Medical Research (IMR), Malaysia.A scoping review was published covering topics on fungal identifcation in hospital settings, with participants from many nations and locations [38].Te review was generally on fungus profling in hospitals, with limited papers reviewed on mycotoxin distribution.Te fndings revealed that the most common fungal genera detected in such settings were Aspergillus sp., Cladosporium sp., Penicillium sp., and Fusarium sp. with the most identifed Aspergillus sp. in hospital wards being A. favus, A. fumigatus, and A. niger, when compared to several settings such as neonatal intensive care units (NICUs), labour rooms, laboratories, and others.Te fndings discovered that intensive care units (ICUs) and wards were home to various fungus species, primarily Aspergillus spp.(Sham et al., 2021).Additional information on analysis for secondary metabolites in indoor air in building environments reported in this current review believes that more studies in this area can be pursued to gain more knowledge and understanding to solve issues quickly and efectively.
In the past ten years (Jan 2010-Feb 2021), 14 published studies on analysis for secondary metabolites in indoor air in building environments were recorded.Five studies were published in 2016, followed by three earlier publications in 2011.Signifcant fndings from analysis of secondary metabolites in indoor air and studies on building environments based on 14 selected articles are listed in Table 2. Most studies on these areas were conducted in European countries, with four studies in France [21][22][23]32].One of each study was conducted in Italy [39], Croatia [30], Poland [27], Denmark [31], and Germany [25], respectively.Two studies were conducted in Finland [25], but another was in collaboration with researchers from the Netherlands and Spain [29].Tree studies were reported from outside Europe, one from the USA [24], and the other two were conducted in Malaysia.Both studies collaborated with a researcher from Sweden [28,40].
Indoor air samples and study locations were selected from water-damaged home buildings [21,24,25,27], schools and kindergartens [28,29,31,40], workplaces (farms and industries) [22,23,39], and few selected buildings and locations [30]  International Journal of Analytical Chemistry mention their location [32].Regarding study scope and objective, most studies provided qualitative and quantitative descriptions of the microbial toxins in indoor air and their metabolites found in samples.Lanier et al. [22] conducted an in vitro study on a specifc fungus to check on a specifc mycotoxin produced.Jeżak et al. [27] determined the toxicogenic potential of fungus isolates from moldy surfaces.
Tere are studies reported on mycobiota on building materials and bioaerosols collected from diferent selected locations [21,22,25,30].Pottier et al. [21] reported that nine out of twenty selected houses contained a fungus identifed as Serpula lacrymans.Also found in the selected houses were ligninolytic strains like Donkioporia expansa, Serpula himantioides, and Coniophora puteana.Lanier et al. [22] identifed 45 fungal species in the cattle shed where Stachybotrys chartarum was observed for the frst time.Among the common fungal species identifed were Aspergillus fumigatus, Cladosporium cladosporioides, Penicillium chrysogenum, Stachybotrys chartarum, Ulocladium chartarum, and Aspergillus glaucus.Stachybotrys chartarum was found to be the highest contribution of recurrent strain which was up to 41%.Fourteen fungus species (8 genera) and three yeast species (2 genera) were most frequently isolated on infected surfaces in residential rooms in Poland.Tey were identifed as Aspergillus versicolor, Cladosporium cladosporioides, Penicillium chrysogenum, Ulocladium chartarum, and Acremonium charticola.Four identifed genera were susceptible to humans (Aspergillus sp., Penicillium sp., Cladosporium sp., and Phoma sp.).Tese included two species capable of producing hazardous mycotoxins (Aspergillus versicolor and Penicillium chrysogenum) [27].
Aspergillus section Versicolores producing sterigmatocystin was found in an apartment's basements and grain mill, the frst study over a year in Croatia.Te dominant and highest sterigmatocystin-producing species identifed using the calmodulin sequence were A. jensenii (1.192-133.63μg/mL), A. creber, and A. griseoaurantiacus (208.29 μg/mL).Te study also showed that the Aspergillus extracts producing positivesterigmatocystin exert cytotoxicity towards A549 and THP-1 macrophage-like cells in low concentrations [30].A fungal toxicogenic evaluation was conducted from a mold-infected exterior found in a residential room in the urban agglomeration in Poland without the infuence of an environmental factor such as a food-afected building or area.Mycological analysis showed Aspergillus versicolor and Penicillium chrysogenum producing sterigmatocystin (Figure 3(a)) and roquefortine C at a range of 2.1-235.9μg/g and 12.9-27.6μg/g, respectively, and the detection from air dust and scrapped material was below the limit of detection [27].Indoor air quality greatly afects respiratory illnesses in which Norbäck et al. [40] found the prevalence of rhinitis and sick-building syndrome among students (n � 462; 14-16 years) from the tropical country of Malaysia.Total fungal DNA and Asp/Pen DNA were detected in all classrooms from Petri dishes and swab samples.In the Petri dish samples, 70% detection was obtained for A. versicolor DNA, 13% for S. chartarum, and 87% for Streptomyces DNA.Meanwhile, for swab samples, the detection was recorded at 56% for A. versicolor DNA, 3% for S. chartarum DNA, and 28% for Streptomyces DNA.
An interesting risk association existed between mycotoxin growing on wallpaper and the transfer to indoor air.A study by Aleksic et al. [32] showed mycotoxins growing on wallpaper followed by aerosolization from the infected surfaces produced  International Journal of Analytical Chemistry Te fnding of positive associations with specifc DNA from the fungal species A. versicolor and the bacteria Streptomyces spp., despite the lack of a link between total fungal DNA and respiratory health, highlights the importance of analyzing specifc microbes when studying respiratory health efects.Te use of qPCR to analyze fungal and bacterial DNA collected using the Petri dish sample method appears to be a promising tool for monitoring indoor mold exposure because it can detect both general and DNA sequences regardless of whether organisms are alive or dead [28] 6 International Journal of Analytical Chemistry Human lung A549 cells and THP-1 macrophage-like cells were cytotoxic to STC and most STC-producing aspergilli at relatively low concentrations, indicating that humans are at high risk during chronic exposure [30] International Journal of Analytical Chemistry  International Journal of Analytical Chemistry  [31] also reported that it was the frst time the same mycotoxins were found on the contaminated gypsum wallboard and settled dust.
Four mycotoxins were targeted at water recycling and recovery facilities in France.Ninety-four air samples revealed quantifable afatoxin B1 and sterigmatocystin, while gliotoxin and ochratoxin (Figure 3(b)) were not found in any samples.Mycotoxin exposure was reported to be insignifcant and did not give any concerning threat to the workers in a study conducted at waste management facilities [23].A comparative study using settled foor dust collected from waste management facilities in Germany and residential houses in Finland showed a wider range of metabolites in concentrations of 0.04-49, 1444.0 μg/kg (Vishwanath et al., 2011).

Sample Collection and Processing. Te sample collection
and extraction procedures for mycotoxin analysis are summarised in Table 3. Mold and mycotoxins were sampled using a variety of techniques.Building material and dust samples from damaged buildings were collected using a vacuum cleaner International Journal of Analytical Chemistry 12 International Journal of Analytical Chemistry International Journal of Analytical Chemistry  and Penicillium chrysogenum display this feature when cultivated on MEA medium in the laboratory.All the studies, including this study, used the HPLC approach; therefore, it is unclear why this study was not able to demonstrate the presence of mycotoxins in the air dust and scrape samples from fats [27] International Journal of Analytical Chemistry Tis study showed that three diferent toxinogenic species produce mycotoxins during their development on wallpaper.Tese toxins can subsequently be aerosolized, at least partly, from moldy material.Tis transfer to air requires air velocities that can be encountered under real-life conditions in buildings.Most of the aerosolized toxic load is found in particles whose size corresponds to spores or mycelium fragments.However, some toxins were also found on particles smaller than spores that are easily respirable and can deeply penetrate the human respiratory tract.All of these data are important for risk assessment related to fungal contamination of indoor environments [32] 16 International Journal of Analytical Chemistry 13 Germany Samples were collected using a vacuum cleaner from diferent waste management units and houses inhabited by less than 5 people Headspace volatile extraction procedure fully automated by an autosampler for microbial volatile organic compound using Agilent 6890 GC QTRAP 4000 LC-MS/MS with C18 column Method for LC-MS-MS was adopted from [26] Te use of LC-MS-MS and GC-MS provides many microbial metabolite and volatile anthropogenic chemical presence in indoor environments.Tis is the frst study to compare individual settled foor dust samples derived from relatively diferent indoor environments using both LC-MS/MS and GC-MS methods Vishwanath et al. 2011 [26] International Journal of Analytical Chemistry [25] to detect multiple microbial toxins from indoor samples and naturally infested materials.Two papers described airborne dust analysis by sampling samples using cotton swabs and Petri dishes.Tis is performed in a classroom where they are interested in the associations of respiratory symptoms with the levels of selected fungal DNA, furry pet allergens, and mycotoxins in schools [28,40].A vacuum cleaner was used to collect settled dust foored from houses inhabited by small groups of people, generally less than 5 (Vishwanath et al., 2011).
A foam swab wetted with methanol and swiped across the sampling area was performed for settled dust and moldy spot swab surfaces at diferent sites in school buildings [29].Scraping on moldy surfaces and airborne dust samples inside residential rooms were collected using the "aspirator and head with flter" sets.Te set consisted of a GilAir-5 (Sensidyne, USA) aspirator, an elastic hose, and an open-measuring head (Two-Met, Poland), with 37 mm diameter and 0.7 μm pore diameter of the GF/F glass fber flter (Whatman, UK) reported by [27].Pottier et al. used two methods to collect fungal aerosols in a damaged house: a sterile polytetrafuoroethylene (PTFE) flter with a 0.2 μm pore size attached to a calibrated vacuum pump and a sterile liquid with a cyclonic air sampler Coriolis ® (Bertin Technologies, France).PM4 and PM10 samplings were performed for indoor/outdoor environments [39].Another study on ambient air PM10 sampling was reported where bioaerosol from a cattle shed monitored revealed the presence of mycotoxins without concentration data due to below quantifcation unit.Airborne fungi were collected using a MAS-100 Eco air sampler (Merck, Darmstadt, Germany) with 400 holes (hole to agar impactor) and dichloran 18% glycerol agar (DG18) plates [30].Air sampling was carried out by collecting dust with a CIP 10 sampler.Te sampler uses the rotative cup technique with rotation, maintaining a fow rate of 10 L•min −1 .Te sampler cup had a porous polyurethane foam flter (PUF).After sampling, the rotating cup containing the PUF was removed from the sampler, closed by the cover, and stored at 4 ○ C before analysis [23].
Floor dust mycotoxins were reported by [24] where they used a vacuum attached to a polyethylene flter sock (Midwest Filtration Company, Fairfeld, OH, USA) and a precleaned crevice tool on a L'il Hummer ™ backpack vacuum sampler (100 ft3/min, 1.5 horsepower; ProTeam Inc., Boise, ID, USA).An Andersen multistage impactor (Tish 180 Environmental, OH, USA) was used for capturing particles according to 6 ranges of size and 181 aerodynamic characteristics.Each impactor stage had a fberglass disk to collect particles [32].Settled dust samples were collected from all available surfaces (shelves, tables, fridges, and tops of the hanging lamps) and other places (excluding the foor) that were regularly cleaned.Each sample was taken from an approximate surface area of 45 × 45 cm using a clean precision Kimwipes ® Lite wipe (Kimberly-Clark, GA, USA).Pure agar cultures were extracted using a microscale method modifed for Stachybotrys metabolites.Tree agar plugs (6 mm ID) were cut from a 15-day-old colony from each agar medium (potato dextrose agar (PDA) or malt-extract agar (MEA)) and placed in a 2 mL screw-top vial.Extracts from pure fungal cultures and cotton tip swabs from infected gypsum wallboards were further processed in laboratory before analysis for detection of mycotoxin metabolites by injection directly to an ultrahigh performance liquid chromatography diode array detector quadrapole time-of-fight mass spectrometry method (UHPLC-DAD_QTOF/MS) [31].
Depending on the type of samples collected for sampling, it is important to note that sampling techniques may difer depending on the specifc objectives, environment, and suspected mycotoxin contamination sources.Te vacuum cleaner can cover a large sampling area and larger sample material.At the same time, cotton swabs and Petri dishes allow for targeted sampling of specifc areas where mold growth is visible.Te GilAir-5 aspirator is a portable air sampling pump commonly used to collect and analyze various contaminants, including gases, vapors, and aerosols.
Te method of collection and the type of samples obtained are the main diferences between a sterile PTFE flter with a 0.2 m pore size attached to a calibrated vacuum pump and a sterile liquid with a cyclonic air sampler Coriolis ® .A sterile PTFE flter with a pore size of 0.2 m connected to a calibrated vacuum pump is commonly used to collect particulate matter such as dust, pollen, or other solid particles in the air.Te flter serves as a barrier, trapping particles while allowing air to pass through.Te flter can be removed and analyzed after sampling to determine the types and quantities of particles present.On the other hand, a sterile liquid with a cyclonic air sampler Coriolis ® collects microorganisms, such as bacteria and fungi, from the air.Te cyclonic action within the sampler separates and concentrates the airborne microorganisms onto a sterile liquid substrate.Tis liquid is then used for laboratory analysis to identify and quantify the microbial contamination present in the air.
Te main diference between PM10 and PM4 air flters lies in the size range of particles they are designed to capture.A PM10 air flter is specifcally engineered to capture particles 10 μm or smaller in diameter, including dust, pollen, mold spores, and larger airborne particles.By targeting this size range, the PM10 flter helps monitor and assess air quality, as these larger particles can potentially impact respiratory health and indoor or outdoor air pollution levels.On the other hand, a PM4 air flter is designed to capture particles that are 4 μm or smaller in diameter, including fner particles, such as combustion byproducts, soot, fne dust, and certain allergens.By focusing on this smaller particle size, the PM4 flter provides more detailed information about fne particulate matter, which is known to have potential health implications, especially when inhaled.
Te MAS-100 Eco air sampler is an advanced air quality monitoring and analysis device.It is specifcally designed to sample and measure microbial contamination in the air, including bacteria, fungi, and other microorganisms.Te MAS-100 Eco air sampler utilizes a high-performance fltration system to capture and collect these microorganisms, permitting further analysis and identifcation in laboratories.A CIP 10 sampler is an individual sampler that traps respirable particles.Te physical collection efciency of CIP 10 equipped with the inhalable fraction selector is estimated to be 50% for particles with an aerodynamic diameter of 1.8 mm and more than 95% for particles with an aerodynamic diameter greater than 2.8 mm.International Journal of Analytical Chemistry 3.2.Instrumentation Analysis.After sampling, mycotoxins require sample preparation using appropriate analytical instruments.Sample preparation demands using a suitable solvent to extract toxins from the matrix, a cleanup procedure to remove interferences from the matrix, and, if necessary, sample preconcentration before analysis.Selecting an appropriate solvent for mycotoxin extraction depends on the toxin's structure.Te most common method is liquid-liquid extraction (LLE), as shown in Table 3. Diferent types of solvent were used for the extraction of mycotoxins, such as methanol [21][22][23] and acetonitrile [25][26][27], and dichloromethane [28,29].Alternatively, a combination of a solvent mixture such as methanol, dichloromethane, and ethyl acetate [30,31] and chloroform and methanol (2 :1) [23,32] was performed to extract diferent metabolites from samples which are compatible with the solvent.One paper reported on the two-stage extraction (methanol followed by hexane) procedure [40].One paper conducted sampling on headspace-solid-phase microextraction (SPME), which employs a fber coated with an extracting phase, which can be a liquid (polymer) or a solid (sorbent), to extract various analytes (volatile and nonvolatile) from various media (Vishwanath et al., 2011).Another paper described an accelerated solvent extractor (ASE) step followed by solid-phase extraction (SPE), ultimately enhancing the purifcation of analytes, making it possible to eliminate, reduce, and suppress signals from interference [39].
Airborne and bioaerosol samples were analyzed for instrumentation analysis using two HPLC-MS/MS protocols to cover many mycotoxins.Positive and negative ion modes were chosen to obtain a good signal from mycotoxins [21,22].One study was reported on the ultraperformance liquid chromatography (UPLC) system connected to Xevo Triple Quadrupole to determine mycophenolic acid, sterigmatocystin, and macrocyclic trichothecenes [32], UPLC-Orbitrap [23], and UHPLC-QTOF [31].One paper reported mycotoxins in dust analyzed by gas chromatography-MS/MS [24], and one paper described mycotoxins indoor/outdoor airborne particulate matter using LC-MS/MS both in positive and negative ion modes to achieve efcient ionization for the known analytes [39].Combination analysis using GC-MS/MS and LC-MS/MS was competent to cover volatile and nonvolatile compounds.Tese instruments analyzed airborne dust, fungi, and moldy surface samples [25,28,29,40].Interestingly, one paper reported using headspace GC-MS, and detection and quantifcation were performed on QTRAP LC-MS/MS (Vishwanath et al., 2011).Two papers described the application of HPLC to detect mycotoxins.Concentrations were calculated based on peak areas of the analyte compared to calibrated standards [27,30].
Although some of the mycotoxins like sterigmatocystin are analyzed using detectors other than MS, e.g., UV-VIS [30], one of the advantages of MS over the other detectors is that it is easier to distinguish coeluting compounds using extracted ion chromatograms.LC-MS/MS ofers a sensitive, efcient, and multianalyte analysis which is of great importance, especially on mycotoxin determination in various matrices, including indoor environmental samples, for example, ambient air, settled dust, and moldy surface.Attempts to identify these toxins in dust particularly are challenging as it correlates to the amounts present in the sample.Many fungal metabolites possess the same elemental composition and coeluate at the same retention time.Tus, a specifc and sensitive instrument is required to distinguish similar compounds which are normally difcult to separate chromatographically.Indeed, several LC-MS/MS multimethods (≥2 mycotoxins) have already been developed for indoor environmental samples [28] ( Vishwanath et al., 2011).Developed methods were reported to produce good recovery ranging from 42 to 101.10% with CV around 10% and R 2 of 0.994-0.999(Table 4).

Method Validation.
GC-MS and LC-MS/MS are widely used techniques for mycotoxin analysis in various environmental samples, including building materials, due to their high sensitivity, selectivity, and ability to analyze complex matrices.Tese techniques have successfully identifed and quantifed a broad range of mycotoxins, even at low levels, and can diferentiate between mycotoxin isomers and closely related compounds.However, the reliability and accuracy of these techniques depend on proper method development, validation, and quality control measures.Te lack of such data in studies signifcantly impacts the interpretation and outcomes.Without proper validation and quality control, fndings may be infuenced by matrix interferences, extraction efciency, instrument variability, and method biases.Torough evaluation and reporting of method performance parameters, such as limit of detection (LOD), limit of quantitation (LOQ), linearity, accuracy, precision, and selectivity, are essential.Quality control measures, including calibration standards, matrix-matched standards, and internal standards, are crucial to ensure accuracy and reliability.In addition, using appropriate quality control samples, such as certifed reference materials, helps assess measurement uncertainty and ensures comparability across studies.
In mycotoxin analysis, it is crucial to mitigate matrix efects to ensure accurate and reliable results.Matrix efects occur when the sample matrix interferes with the ionization and detection of analytes, resulting in signal suppression or enhancement.To ensure optimal performance, assessing the practices employed to mitigate matrix efects (e.g., matrixmatched calibration, internal standards, and diferent sample preparation techniques) is essential.Te recovery value was 53 ± 6% with 11.2% CV [28,[42][43] International Journal of Analytical Chemistry  To obtain an accurate measurement, matrix-matched standards to reduce matrix efects [24], stable isotopelabelled internal standards such as the 13C standard [21], and efcient sample cleanup [39] are normally performed.Te detection and quantifcation of an analyte are signifcantly infuenced by matrix efects associated with heterogeneous components in environmental samples [44].Coextracted matrix components may cause interference with active sites in the GC inlet liner and the column and produce diferential analyte signals between the matrix-containing sample extract and the matrix-free standard extract [45][46][47].Efcient sample preparation, for example, solid-phase extraction (SPE) or LLE, is essential and has been found to reduce matrix efects potentially [48].Te efectiveness of these techniques in reducing matrix efects can vary depending on the sample matrix and mycotoxin of interest.Tis step is crucial, and optimization is needed to minimize sample loss.An internal standard (IS) is frequently used to improve the precision of quantitative analysis in which it compensates for matrix efects or sample loss during preparative procedures.In other words, it monitors and corrects any variations during sample preparation, extraction efciency, and instrument response.Terefore, the selected IS should be similar to the target analytes regarding ionization properties or chemical structures to ensure it always reacts the same way as the analytes of interest, especially with a matrix [49].An IS labelled with (13C) or (15N) was commonly employed for each group of mycotoxins, for instance, Fumonisin B1-13C34 and Deoxynivalenol-13C15 [21,22,39].However, a nonlabelled IS, such as reserpine, has also been used as an internal standard [40].According to Saito et al. [24], the accuracy of the results is largely dependent on the matrix efects, the appropriateness of IS, or the combination of them.On the other hand, only fve publications reported analyses have been performed using GC-MS with the negative chemical ionization (CI) mode.Trichodermol and verrucarol, which are in the group of trichothecenes, are the most common mycotoxins tested by GC-MS [24,28,29,40] (Vishwanath et al., 2011).

Conclusions
In conclusion, various techniques are available for analyzing and detecting multiple mycotoxins using LC-MS/MS and GC-MS methods.Mold and mycotoxin analysis has evolved in sampling techniques, processing, preconcentration, and instrumentation over the past years.Technological advances are beginning to overcome many challenges posed by the complexity of detecting multiple mycotoxins.Mass spectrometry advancements such as ionization modes, sensitivity, and acquisition speed have increased throughput, the number of mycotoxins that can be simultaneously screened, and the discovery of novel compounds of mycotoxins.Modern technologies, such as hyphenated liquid or gas mass spectrometry, have enabled these analytical methods to be developed and validated for mycotoxin analysis.However, due to the variety of chemical structures, using a single method for mycotoxin analysis is impossible.Routine analysis faces signifcant challenges due to the demand for rapid, simultaneous, and accurate determination of multiple mycotoxins.Future eforts would concentrate on rapid assays and tools that measure a broader range of mycotoxins in a single matrix and lower detection limits.Highly sophisticated multianalyte methods based on liquid chromatography coupled with multiple-stage mass spectrometry have been developed to identify and determine multiple mycotoxins.Tis new era of various screening mycotoxin and detection technologies will beneft future research.

Future Perspectives
It is anticipated analytical techniques and technologies for mycotoxin detection are likely to advance.Tis could include creating more sensitive and specifc methods, such as advanced chromatographic techniques or rapid screening methods based on biosensors or nanomaterials.Tese advances will allow for faster and more accurate detection of mycotoxins in a variety of samples.
Moreover, there will be a greater emphasis on developing portable and feld-deployable mycotoxin analysis devices.Tis will enable on-site testing and real-time monitoring, which is especially important in monitoring building environments where rapid decisions are required to prevent mycotoxin contamination.

Figure 2 :
Figure 2: Accepted articles published according to year.

Figure 3 :
Figure 3: (a, b) Examples of some of the mycotoxin structures mentioned in text.

the capillary voltage was 40
V, the needle voltage was 5,000 V, and the electron multiplier voltage was 2,000 V. Te MS spectra were collected as centroid data from m/z 100 to 800, with a scan time of 0.5 s and a scan width of 0.7 s GC-MS-MS (CP-3800): the derivatives were analyzed by using MS-MS in negative ion chemical ionization mode, at an energy of 70 eV and an ion source temperature of 150 °C,

Table 1 :
[37]chart of literature search strategy.PRISMA fowchart on literature selection based on inclusion/exclusion criteria to identify the occurrence of AR in the environment of dairy farms[37].Search strategy for identifcation of studies.

Table 2 :
Highlights on fndings of analysis for secondary metabolites in indoor air and studies of building environments based on 14 selected articles.

Table 2 :
Continued.Lower species diversity was obtained in the GM with relatively high STC levels (0.06-2.35 μg/g) in 52% samples.STC cannot be fully attributed to Aspergilli (Versicolores).
462 students from four classes of grade two were selected to participate in the questionnaire survey To see if there was a link between rhinitis and other types of weekly SBS symptoms among junior high school students in Johor Bahru, Malaysia, and levels of cat allergen (Fel d 1), two mycotoxins (verrucarol and sterigmatocystin), and fve fungal DNA sequences in the
biomarkers were identifed in pure fungal cultures and cottontipped swab extracts collected from kindergarten in Greater Copenhagen.Te identifcation revealed 12 Stachybotrys metabolites with atranones and macrocyclic trichothecenes (Figure 3(b)) on the gypsum wallboard.Došen et al.

Table 3 :
Various procedures for mycotoxin studies in indoor air.