Polycyclic Aromatic Hydrocarbons (PAHs) Sample Preparation and Analysis in Beverages: A Review

The monitoring of food contaminants is of interests to both food regulatory bodies and the consumers. This literature review covers polycyclic aromatic hydrocarbons (PAHs) with regard to their background, sources of exposures, and occurrence in food and environment as well as health hazards. Furthermore, analytical methods focusing on the analysis of PAHs in tea, coffee, milk, and alcoholic samples for the last 16 years are presented. Numerous experimental methods have been developed aiming to obtain better limits of detections (LODs) and percent recoveries as well as to reduce solvent consumption and laborious work. These include information such as the selected PAHs analyzed, food matrix of PAHs, methods of extraction, cleanup procedure, LOD, limits of quantitation (LOQ), and percent recovery. For the analysis of tea, coffee, milk, and alcoholic samples, a majority of the research papers focused on the 16 US Environmental Protection Agency PAHs, while PAH4, PAH8, and methylated PAHs were also of interests. Extraction methods range from the classic Soxhlet extraction and liquid–liquid extraction to newer methods such as QuEChERS, dispersive solid-phase microextraction, and magnetic solid-phase extraction. The cleanup methods involved mainly the use of column chromatography and SPE filled with either silica or Florisil adsorbents. Gas chromatography and liquid chromatography coupled with mass spectrometry or fluorescence detectors are the main analytical instruments used. A majority of the selected combined methods used are able to achieve LODs and percent recoveries in the ranges of 0.01–5 ug/kg and 70–110%, respectively, for the analysis of tea, coffee, milk, and alcoholic samples.


Introduction
Food contaminants such as pesticide residues, mycotoxins, and environmental pollutants can be commonly found in raw materials for feed and food production processes due to non-identical worldwide weather, harvesting, and storage conditions (Nielen and Marvin 2008). In addition, food preparation steps such as cooking at a high temperature will potentially release food processing contaminants such as polycyclic aromatic hydrocarbons (PAHs), acrylamide, and heterocyclic amines into the food (Rey-Salgueiro et al. 2009). This has led to an increasing interest in the monitoring of these contaminants in food, which can be quite challenging due to the complexity of food matrixes in food products.
In this review, one of the food processing contaminants, namely PAHs, will be the main focus. The ever increasing in the number of articles regarding the presence of PAHs in foodstuffs has garnered attention worldwide due to its ubiquity, and the resulting health hazards that can arise through ingestion, inhalation, and dermal contact with PAHs. This review summarizes the studies carried out by researchers who utilized different extraction methods to determine the presence of PAHs in beverages. In addition, researchers are also focusing on developing simpler and alternative extraction, cleanup, and analytical methods, which yield good recoveries and limits of detection (LODs).

Background
PAHs are highly hydrophobic and organic lipophilic compounds with fused aromatic rings mainly composed of hydrogen and carbon atoms (Essumang et al. 2013). These compounds are semi-or non-volatile in nature, ubiquitous, and known for their carcinogenic and mutagenic potential (Ledesma et al. 2014). They range from two to up to ten fused aromatic rings (Huang and Penning 2014). Molecular sizes of PAHs determine their vapor pressures and therefore affecting their dispersal of in the environment. Heavy PAHs (four or more fused rings) have lower volatility and adsorb on combustion particles like soot whereas light PAHs (less than four fused rings) are extremely volatile compounds, existing mostly in their gaseous state and widely distributed (Lammel et al. 2010). Sander and Wise (2020) stated that 660 PAHs were revealed according to the NIST Special Publication 922 "Polycyclic Aromatic Hydrocarbon Structure Index." Nevertheless, 16 PAHs such as naphthalene (NPH), acenaphthylene (ACY), acenaphthene (ACP), f luorene (FLR), phenanthrene (PHE), anthracene (ANT), f luoranthene (FA), pyrene (PY), chrysene (CHR), benz(a)anthracene (BaA), benz(b)fluoranthene (BbFA), benzo(k)fluoranthene (BkFA), benz(a)pyrene (BaP), indeno(1,2,3-cd)pyrene (IP), benzo(g,h,i)perylene (BghiP), and dibenzo(a,h)anthracene (DBahA) were being chosen as priority pollutants by the United States Environmental Protection Agency (USEPA) (Tamakawa 2004). The 16 USEPA PAHs are mostly hydrophobic and non-polar solids with high melting and boiling points.

The Formation Mechanism of PAHs
PAHs are known to be formed by condensation processes of smaller organic compounds in absence of oxygen by either pyrolysis or pyrosynthesis (Ciemniak et al. 2019). Pyrolysis (pyro meaning "fire" and lysis for "separating") is the decomposition of organic material at elevated temperatures in an inert atmosphere and it involves irreversible change of chemical composition and physical phase (Viegas et al. 2019). At elevated temperatures above 200 °C, pyrolysis will occur and organic compounds will be fragmented, hence producing free radicals which unite to form stable polycyclic aromatic compounds (pyrosynthesis). The amount of PAHs formed is directly proportional with an increase in temperature, which affects both the structure and diversity of PAHs formation (Chen and Chen 2001).

Toxicological Aspects and Human Health Effects
The major health concern that arises from the ingestion of food contaminated with PAHs is the increased in risks of cancer (Huang and Penning 2014). Nevertheless, it was found that some PAHs are not carcinogenic on their own but may function as co-carcinogens (do not usually cause cancer on their own but promote the activity of other carcinogens in causing cancer). From the research experiments carried out on animals, the common areas of cancer formation after the consumption of PAHs are located within the digestive system (Huang and Penning 2014). However, PAHs tend to exist in complex mixtures of varying compositions, and hence the evaluation of their associated health risks can be challenging.
The Agency for Toxic Substances and Disease Registry (ATSDR 2009a) shared that besides contributing to the carcinogenicity and mutagenicity of the PAHs in experimented animals, certain PAHs can produce many other detrimental health effects, including reproductive, developmental, immunotoxic, and neurologic effects. However, the carcinogenic, mutagenic, and teratogenic effects of PAHs will only take place if a PAH-DNA adduct is formed (Höner 2001;Huang and Penning 2014). Developmental toxicity of PAHs occurs because PAHs have lipophilic characteristics enabling them to reach the embryo and fetus by passing through the placental barrier of a pregnant woman (Herbstman et al. 2012). In addition, immunotoxic effects from the PAHs are highly associated with immunosuppression where the exposed individual will have a higher susceptibility to infectious diseases and the formation of cancers (Huang and Penning 2014).
The International Agency of Research on Cancer (IARC) has categorized PAHs into five groups: Group 1 (carcinogenic to humans), Group 2A (probably carcinogenic to humans), Group 2B (possibly carcinogenic to humans), Group 3 (not classifiable regarding its carcinogenicity towards humans), and Group 4 (probably not carcinogenic to humans). BaP is one of the most carcinogenic compounds and has been regrouped from Group 2A to Group 1 and CHR has been reclassified from Group 3 to Group 2B, whereas BaA was reassigned from 2A to 2B (Ishizaki et al. 2010).

Sources and Occurrence of PAHs
PAHs are ubiquitous and diffusion into the environment can occur easily through both natural events and man-made processes. The World Health Organization (WHO 1998) stated that the primary anthropogenic products involved are from petroleum refineries, industrial machinery manufacturing, motor vehicle exhausts, coke production, barbeque smoke, tobacco smoke, and etc. Considerable amounts of PAHs are also found to be generated from natural sources, for instance, volcanic activity and forest fires. Furthermore, PAHs can be found in water (Rey-Salgueiro et al. 2009;Zhang et al. 2012), soil (Shang et al. 2014;Yu et al. 2019), air (Lammel et al. 2010, foods (García-Falcón et al. 2005a;Yebra-Pimentel et al. 2012), and street dust (Lorenzi et al. 2011;Gope et al. 2018). Consequently, the careful monitoring of PAHs is vital as certain PAHs have been found to be carcinogens in experimental animals, indicating the possible carcinogenic effects on humans (ATSDR 2009).

Occurrence of PAHs in Food
Natural sources and environmental pollution such as the deposition of airborne particulates to the soil and surface of plants can lead to the contamination of food with PAHs (Killian et al. 2000;Smith et al. 2001). Research has discovered that around 79-99% of mankind's susceptibility to PAHs were contributed by food consumption and it has been estimated that the possible total intake of PAHs through food is 2.5 µg/day (Menzie et al. 1992). Roasting, toasting, baking, smoking, frying, and baking are some of the food preparation techniques that can cause the formation of PAHs (Codex Alimentarius Commission 2005;European Commission 2002;Perelló et al. 2009). Moreover, PAHs have been found in food following preservation processes such as traditional drying and curing of food (de Vos et al. 1990). Various food samples, including roasted coffee (Houessou et al. 2006;Guatemala-Morales et al. 2016), tea (Lin et al. 2005;Wu et al. 2020), milk (Aguinaga et al. 2008;Sun et al. 2020), alcoholic beverages (Menezes et al. 2015;Singh et al. 2016), oils (Rodríguez-Acuña et al. 2008Yousefi et al. 2018), smoked meat Zachara et al. 2017), smoked cheese (Guillén and Sopelana 2005;Gul et al. 2015), smoked fish (Lund et al. 2009;Mahugija and Njale 2018), fruits (Jánská et al. 2006;Paris et al. 2018), and vegetables (Jánská et al. 2006;Jia et al. 2018) were found to contain PAHs at µg/kg concentrations.
The Scientific Opinion of the Panel on Contaminants in the Food Chain indicated that BaP alone was insufficient to gauge the amount of PAHs present in food (Alexander et al. 2008). Therefore, they suggested using PAH2, PAH4, and PAH8 to estimate the margins of exposure (MOE). PAH2 indicates BaP and CHR, whereas, PAH4 means BaP, BaA, Chry, and BbFA and PAH8 includes BaP, BaA, BkFA, CHR, BbFA, DBahA, BghiP, and IP (Alexander et al. 2008).

PAHs Found in Beverages
In the past 16 years, extensive research studies have been carried out by scientists to analyze the amount of PAHs in various beverages such as tea, coffee, milk, and alcoholic beverages as PAHs are formed during their production processes. The following sections provide a summary of the sources of PAHs in these beverages.

Tea
Tea is the second most consumed non-alcoholic beverage, the first being water (Benson et al. 2018). The Food and Agriculture Organization (FAO) of the United Nations (FAO 2012) stated that around 4 million tonnes of tea were consumed in 2010 and in the last 10 years; the quantity of tea produced has increased to an approximate of 5.35 million tonnes in 2013 (FAO 2015). Tea is known to be refreshing, medicinally beneficial, and an antioxidant, as well as having mild stimulant properties and pleasant aromas (Kuroda and Hara 1999;Pittler 2005). Agricultural products including raw ingredients of tea have a likelihood of being contaminated with contaminants such as PAHs. An example would be PAHs that are in the gaseous state or PAHs that are bounded to particulates in the air, which could be easily deposited on the leaves of tea and hence causing accumulation to occur (Jánská et al. 2006). Moreover, the accumulation of hydrophobic PAHs in fruit and herbal teas is possible due to the presence of lipophilic compounds, such as essential oils (Schlemitz and Pfannhauser 1997). PAHs are produced during the fresh leaf treatment process, such as the burning of oil, coal, and wood for drying or roasting of tea leaves (Lin et al. 2005). The analysis of PAHs in tea can be quite challenging as tea contains various co-extractives, for example, high levels of chlorophyll, polyphenols, organic acids, caffeine, sugars, and pigments. Nevertheless, the concentrations of co-extractives are highly dependable on the types of tea. Black teas are considered to have a complicated matrix as there is a high amount of interfering substances. The EU Commission (2011) has established regulated maximum levels of allowable PAHs on various food products, but none have been accepted and acknowledged for teas yet. Nevertheless, the maximum contaminant level (MCL) of PAHs in drinking water was set to be as follows: (1) 0.1 ppb for BaA, (2) 0.2 ppb for BaP, BbFA, BkFA, CHR, (3) 0.3 ppb for DBahA, and (4) 0.4 ppb for IP (ATSDR 2009b).

Coffee
Coffee is widely consumed around the world and chemical substances such as proteins, carbohydrates, fats, vitamins, water, minerals, flavoring substances, organic acids, and caffeine are present in coffee beans (Lee and Shin 2010). Roasting is an important step in order to bring out the flavor, aroma, and color of coffee and is normally carried out with temperatures of 120-230 °C (Tfouni et al. 2012). On the other hand, roasting can also prompt the production of unwanted and hazardous compounds such as PAHs, acrylamide, and furan (Tfouni et al. 2013). Additionally, coffee drinks that were brewed with PAH-contaminated green coffee beans might contain PAHs as well (Houessou et al. 2008). Nevertheless, for coffee and coffee substitutes, no maximum levels of PAHs have been established by the European Union (EU) Commission (Sadowska-Rociek et al. 2015).

Milk
Milk is an important essential dairy product required by humans and it contributes to the dietary intake of zinc, vitamin B12, magnesium, calcium, pantothenic acid, and selenium (Raza and Kim 2018). In dairy farming process, animal feed are at risk of contamination from water, soil, and air; organic contaminants such as PAHs can be transferred from the animals that have fed on contaminated feeds through different routes such as milk, urine, and feces (Grova et al. 2002). PAHs that are ubiquitous in the environment and are lipophilic have a huge tendency to be distributed in milk (Zhao et al. 2017(Zhao et al. , 2018. Hence, human diets will be contaminated with PAHs upon the ingestion of milk containing PAHs. Various milk samples undergo processes such as pasteurization and ultra-high-temperature processing (UHT). Results have shown that all the raw milk samples analyzed contained PAHs, but higher concentrations were observed in the UHT and pasteurized milk. This indicates that these heat treatment procedures have an effect on raising the levels of PAHs in milk (Naccari et al. 2011).

Alcoholic Beverages
Spirits are high-degree alcoholic beverages with an average alcohol content of 40% v/v and they are obtained from the distillation of low-degree alcoholic beverages (alcohol which are produced from the fermentation of sugar) (Cacho et al. 2016). Some examples of spirits are cachaça, gin, vodka, whisky, brandy, and rum. The WHO (2014) reported that around 9.2 L of pure alcohol is consumed per capita per year in the USA. However, researchers have discovered that PAHs can contaminate some of the spirits through various manufacturing processes. Cachaça is a Brazilian alcoholic distillate manufactured from fermented sugar cane juice and is ranked as the third largest distilled spirit consumed worldwide (Cardoso et al. 2004). Before the harvesting of the sugar canes take place, the sugar canes are being burnt to evaporate off the water in the stalk and to increase the sugar weight. This can contribute to the production of PAHs as the incomplete combustion of organic matters occur during this process and may be attached to the stalks of the sugar canes, hence contaminating the sugar cane juice during processing (Galinaro et al. 2007).
Rum is commonly produced from the distillation of fermented sugar cane molasses (by product of refining sugar cane) or sugar cane juice. Similar to the cachaça production process, the sugar cane is first burnt which creates the main source of contamination for PAHs (Riachi et al. 2014). In contrast, the flavor of whisky is developed during the aging process which involves smoking or charring oak wooden casks. This can lead to the migration of PAHs present in the woods to the whisky (Chinnici et al. 2007;Da Porto et al. 2006).
The production of cereal-based beverages such as beer, which is the most commonly consumed alcoholic beverage in the world, involves the roasting and toasting of barley, which are the main source of PAHs (Anderson et al. 2019;Rascón et al. 2019). Wine is commonly aged by being stored inside wood barrels or in steel tanks containing wood chips (Rascón et al. 2019). Chinnici et al. (2007) reported that the wood of the barrels and chips is naturally aged by the weather for 1-3 years, but are also toasted with open oak fires and other methods of toasting (electrical and convective heating), which will generate a significant amount of PAHs.

Analytical Methods for PAH Determination
Different methods have been validated for the extraction of PAHs in accordance with the matrixes of each food item since there is no existence of standardized methods for a particular matrix. Multiple extractions steps together with preconcentration procedures need to be carried out for PAHs that are in the ppb levels. In addition, there are challenges in obtaining repeatability for PAHs with two or three aromatic rings. Therefore, rapid, simple, and dependable analytical methods need to be developed so that precise deduction of contaminants in foods can be achieved. From this, the actual exposure of humans to PAHs in food can be evaluated.

Sample Preparation
Prior to the PAH analysis of samples, PAH samples must be protected against oxidation and photoirradiation processes as PAHs are sensitive towards light (Skláršová et al. 2012). Hence, minimum exposure of light towards the samples during matrix pretreatment is highly encouraged. Tamakawa et al. (1992) has found that during the sample preparation to extract PAHs, three or fewer aromatic rings of PAHs (ANT, FA and PY) were found to be sublimated easily during the concentration processes. Therefore, concentration to dryness should be monitored carefully to minimize any evaporation of PAHs and minimize losses of lower molecular weight PAHs. Internal standards or surrogates are being advised to be added to the samples before extraction to ensure precise and accurate quantification by analytical instruments (Guillen et al. 2000a(Guillen et al. , 2000b(Guillen et al. , 2000c.

Extraction
Various extraction methods have been proposed and validated by researchers globally; however, only successful and effective extraction procedures are integrated into the experiments to ensure that samples have minimum analytical interferences. Alkaline saponification/solvent extraction using ethanolic KOH, NaOH, and methanolic solution is the most common method used for the removal of fats, pigments, and other organic contaminants to avoid any interference during the analysis (Tatatsuki et al. 1985;Girelli et al. 2017). Certain PAHs can easily undergo chemical, physical, and biological change or breakdown when harsh saponification conditions are applied; therefore, for food samples that have low content of fat, liquid-liquid extraction (LLE) can be applied (Tatatsuki et al. 1985). Newer methods such as the QuEChERS method (abbreviated from quick, easy, cheap, effective, rugged, and safe) (Pincemaille et al. 2014) and dispersive liquid-liquid microextraction (dllMe) (Rivera-Vera et al. 2019) have been developed and diligently used by scientists for the determination of PAHs. In addition, the two newer methods mentioned above are more cost efficiency and safer as less solvent will be consumed during the process of extraction (Zelinkova and Wenzl 2015;Purcaro et al. 2013).
Other methods for PAH extraction in beverages are pressurized liquid extraction (PLE)   ). However, due to the challenging matrices present, inconsistent recoveries are often obtained and therefore causing an interference to the peaks in the chromatograms. The advantages and disadvantages of each method mentioned above are summarized in Table 1.
For tea samples, the commonly used method for extracting PAHs from the matrix is QuEChERS (Sadowska-Rociek et al. 2014;Tfouni et al. 2018). Recently, modern analytical chemistry strives to develop and integrate green chemistry into their research in which there is reduced usage of samples and solvents, which also employ easy procedures, simple analytical equipment, and reagents that are not harmful to individual health and the environment (Sadowska-Rociek et al. 2014). One of them is QuEChERS which was initially developed for the analysis of pesticide residues in food samples of plant origin (Anastassiades et al. 2003). On the other hand, coffee samples were conventionally extracted by saponification (Lee and Shin 2010). This is because coffee contains around 15% lipids which can cause interference during the analysis of PAHs (Houessou et al. 2006); hence, saponification using ethanolic KOH, NaOH, and methanolic solution is an effective method used for lipid removal. Alkaline saponification followed by LLE is also commonly done to remove fatty acids present in the matrix (Lee and Shin 2010). Chung et al. (2010) and Naccari et al. (2011) have applied saponification to extract PAHs from milk samples. This is due to the fact that PAHs are lipophilic and have a huge tendency to be distributed in milk (Zhao et al. 2017(Zhao et al. , 2018. According to literature, various methods ranging from LLE, SPE, SPME, QuEChERS, UAE, and DLLME were used to extract PAHs from alcoholic beverages . The LLE and SPE were the preferred methods many years ago, but in recent years, SPME, DLLME, and QuEChERS methods were used as analytical extraction methods for alcoholic beverages (Galinaro et al. 2007;Da Silva et al. 2019).

Cleanup
The cleanup of extracts is carried out to separate target PAHs from other compounds and to remove any interferences that can make the determination of PAHs challenging. Various cleanup methods such as column chromatography, SPE, gel permeation chromatography (GPC), and thin-layer chromatography (TLC) have been studied extensively (Tamakawa 2008). Normally, large volumes of hazardous solvents need to be used to purify the PAHs because they have lipophilic properties and their extraction is correlated with lipid constituents of food (Purcaro et al. 2013).

Analysis
To determine the quantity of PAHs in beverages, chromatographic analysis methods using analytical instruments are most commonly employed, such as liquid chromatography (LC) coupled with a fluorescence detector (FLD) (Kayali-Sayadi et al. 2000) and gas chromatography coupled with mass spectrometry (GC-MS) (Purcaro et al. 2007;Schulz et al. 2014;Zhou et al. 2018;Sun et al. 2020). High-performance liquid chromatography with fluorescence detection (HPLC-FLD) is a highly recommended method for the routine screening purpose of PAHS due to its selectivity and sensitivity. HPLC is also preferable for the quantification of PAH isomers. For instance, the isomers chrysene/triphenylene, the first is a target PAH but the second may interfere with chrysene quantification by gas chromatography (GC) (Zelinkova and Wenzl 2015). Therefore, HPLC should be selected for this analysis as GC is unable to resolve some pairs of peaks.
GC-MS is a widely acclaimed analytical instrument for the analysis of PAHs in food samples, and researchers have been extensively employing GC-MS in their studies. This is because GC has a better resolution efficiency compared to HPLC (Tamakawa 2008) and MS provides high selectivity and sensitivity as well as structural information of PAHs (Plaza-bolaños et al. 2010). GC-MS allows the resolution of PAHs with poor fluorescence, such as NPH, ACY, ACP, and FLR or non-fluorescence PAHs, such as cyclopenta(c,d)pyrene (CPcdP) (Cai et al. 2009). Furthermore, gas chromatography-tandem mass spectrometry (GC-MS/MS) detection is a widely popular method which presents high sensitivity and resolution (Plaza-bolaños et al. 2010).
Based on literature reviews, PAHs in beverages were most frequently analyzed by GC-MS in selected ion monitoring (SIM) mode, where only masses of PAHs of interested are monitored. The limits of detections (LODs), limits of quantifications (LOQs), and percent recoveries for the analysis of beverages using GC-MS and HPLC gathered from different literatures are summarized as shown in Table 2 and Table 3, respectively. For the separation of compounds in complex food samples including beverages, two types of columns that are commonly used in GC analysis are DB-5MS column coated with 5%-phenyl-Arylene-95%-dimethylpolysiloxane (Sadowska-Rociek et al. 2015;Roudbari et al. 2020) and HP-5MS column coated with 5%-phenyl-95%-dimethylpolysiloxane Zhou et al. 2018). Whereas for the HPLC analysis, the C18 column or its equivalence, running in isocratic or gradient elution, is favorable for the analysis of PAHs in most of the reported publications as summarized in Table 3 (Garcia Londoño et al. 2015;Shi et al. 2016;Tfouni et al. 2018;Mañana-López et al. 2021). There are also an increasing number of columns which are specifically developed for the analysis PAHs using HPLC  N/A not available such as Eclipse PAH column, Supelcosil™ LC PAH column, Hypersil Green PAH column, Envirosep-PP, Pinnacle II PAH, Vydac™ and LiChrospher PAH column to name a few (Shi et al. 2016;Thea et al. 2016;Kayali-Sayadi et al. 1999;Santonicola et al. 2017;Adisa et al. 2015;Zuin et al. 2005;Viñas et al. 2007). This indicates the growing importance of the analysis of PAHs. According to Table 2 and Table 3, it was observed that different results of LODs, LOQs, and recoveries were obtained when different sample extraction methods, cleanup, and instrumental analysis were employed. The lowest LODs obtained using GC-MS for the analysis of tea, tea infusions, ground coffee, coffee brew, milk, and alcoholic beverages were 0.01-0.02 µg/kg, 0.1-0.28 ng/L, 0.03-0.18 µg/kg, 0.67-18 ng/L, 3-1500 ng/L, and 0.02-0.6 ng/L respectively. For HPLC, the lowest LODs reported for tea, tea infusions, ground coffee, coffee brew, milk, and alcoholic beverages were 0.32-4.63 ng/L, 0.2-2.1 ng/L, 0.01-0.21 µg/ kg, 0.1-10 ng/L, 0.0004-4.9 µg/kg, and 0.1-2.0 ng/L respectively. Lower LODs in beverages were observed with the usage of HPLC compared to GC. In addition, percentage recoveries were mostly within the range of 70-110% for beverages analyzed using GC and HPLC.

Conclusion
Global concerns have been raised due to the discovery of increasing amounts of PAHs found in beverages, prompting researches to develop sample extraction and analytical methods for the determination of PAHs in the past 16 years. Extraction methods with the usage of green extractants to minimize hazardous organic solvents wastage to the environment are being developed as well as integrated into existing research, and have been used extensively due to their simplicity. Analytical instruments, in particular GC and HPLC with detectors such as MS, MS/MS, FID and FLD are generally favored for the analysis of PAHs; LOD as low as 0.02 ppt level can be accomplished. It was found that QuECh-ERS is a popular method for the extraction of PAHs from tea, whereas saponification is more commonly used for the extraction of PAHs from both coffee and milk. For alcoholic beverages, LLE, SPE and microextraction techniques are commonly used.