Decabromodiphenyl ether in indoor dust from different microenvironments in a university in the Philippines

Chemosphere 90 (2013) 42–48

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Decabromodiphenyl ether in indoor dust from different microenvironments in a university in the Philippines Cressa Ria P. Fulong ⇑, Maria Pythias B. Espino Institute of Chemistry, College of Science, University of the Philippines, Diliman, Quezon City 1101, Philippines

h i g h l i g h t s " A method was developed to analyze BDE-209 in indoor dust from microenvironments in a university in the Philippines. " The method used ultrasonication extraction, SPE clean-up, and HPLC–UV determination. " BDE-209 was detected in all samples analyzed with some samples in levels below the quantification limits. " BDE-209 concentration is high in sites containing high number of electrical and electronic equipment.

a r t i c l e

i n f o

Article history: Received 19 December 2011 Received in revised form 4 May 2012 Accepted 30 June 2012 Available online 22 August 2012 Keywords: Decabromodiphenyl ether Indoor dust Ultrasonication HPLC–UV SPE

a b s t r a c t This study was conducted to develop a method for the determination of decabromodiphenyl ether (BDE209) in indoor dust from different microenvironments in a university in the Philippines. BDE-209 was extracted from dust samples by ultrasonication and determined by HPLC–UV. The determination was performed using external calibration and internal standard calibration. Internal standard calibration was shown to be more precise and sensitive than external calibration. The linearity for the concentration range of 0–300 lg L 1 BDE-209 was good (R2 = 0.993). The % absolute recovery and the % RSD for n = 8 spiked dust analysis based on a 0.2 g dust sample was 57% and 19%, respectively. The method detection limit was 285 ng g 1. All dust samples showed detectable levels of BDE-209 with some at levels below the quantification limits. The concentrations of BDE-209 in the quantified samples are within the range of 1103–4117 ng g 1 with an average concentration of 2172 ng g 1. The levels of BDE-209 found in the dust samples are comparable to those reported in house and workplace dusts from other Asian countries. Although not conclusive, it has been shown empirically that BDE-209 concentrations are higher in sampling sites containing more possible BDE-209 sources like electrical and electronic equipment. Ó 2012 Elsevier Ltd. All rights reserved.

1. Introduction Brominated flame retardants or BFRs are synthetic compounds used in modern products such as electrical and electronic appliances or equipment, construction materials, and textiles to reduce fire incidents that can cause major damages to people. They belong to a large group of compounds with high industrial demand due to their low production cost and high efficiency. The five major classes of BFRs are brominated bisphenols, cyclododecanes, phenols, phthalic acid derivatives, and diphenyl ethers (Birnbaum and Staskal, 2004). The brominated flame retardants like polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes, and polybrominated bisphenols are applied as additives to combustible materials in plastic components of consumer products such as couches, mattresses, carpet paddings, cushions, televisions, computers, car ⇑ Corresponding author. Tel./fax: +63 2 9818500x3654. E-mail address: [email protected] (C.R.P. Fulong). 0045-6535/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.chemosphere.2012.06.072

stereos, and navigation systems (Betts, 2008). They do not react with the polymer material. As such, they are easily leached off and can therefore contaminate the environment (de Wit et al., 2010). PBDEs are available as mixtures of congeners or similar compounds of the form C12H10 xBrxO (x = 1, 2 ,... ,10). There are 209 possible PBDE congeners that differ in number and position of bromination. However, there are only a few actual congeners in commercial mixtures due to the instability of most of the congeners. There are three commercially available PBDE products: decaBDE, octaBDE, and pentaBDE. Production and use of octaand pentaBDE are already banned by the European Union (EU) since 2004 (EU, 2003). DecaBDE or BDE-209 was originally exempted from the ban but in 2008, the exemption was officially annulled (EU, 2005, 2008). At present, its production and use in the United States are still being restricted until the expected phase out in 2013 (US EPA, 2009). Of the PBDEs, decaBDE comprises the major product in the market, accounting for approximately 80% of the total PBDE

C.R.P. Fulong, Maria Pythias B. Espino / Chemosphere 90 (2013) 42–48

production worldwide (Birnbaum and Staskal, 2004). Unlike the other commercial products, decaBDE is a relatively pure mixture composed of P97% decaBDE which is BDE-209, <3% nonaBDE, and small amounts of octaBDE (La Guardia et al., 2006). BDE-209 is used as an additive flame retardant primarily in electrical and electronic equipment. It is also used in textiles where it is applied as a polymer backcoat to the fabric. Like all the other PBDEs, the liphophilicity and limited biodegradability of BDE-209 make it highly accumulating in lipid-rich tissues. Frederiksen et al. (2009) summarized in a review article several studies that have shown the presence of BDE-209 not only in food, dust, air, and consumer products, but also in human tissues. BDE-209 (1400–6200 pg g 1 ww) was found in seafood like blue mussels (France), mackerel, eel, cod liver, and herring (Denmark), and bivalves (Korea). In a North American study, BDE-209 (10–288 pg g 1 ww) was found in egg, meat, and dairy products. BDE-209 was also found in indoor air in Sweden, Canada, and USA in the concentration range of 64–174 pg m 3. High levels of BDE-209 were found in indoor dust from Spain, Germany, Sweden, Denmark, Finland, UK, Canada, USA, Kuwait, and Singapore in the concentration range of 60–7100 ng g 1 dw, where the highest concentration was found in the UK. Several studies in Europe, USA, Australia, and Asia (Korea, Taiwan, China, and Indonesia only) have shown the presence of BDE-209 in human milk, serum, placenta, and adipose tissues. The presence of BDE-209 in the environment and in human tissues is still not well understood. But it is likely due to the migration of BDE-209 from flame retardant-treated products to the environment during the use, recycling, or disposal of these products. The route for human exposure to BDE-209 is possibly via inhalation, food ingestion, dust ingestion, or dermal absorption (US EPA, 2006). Dust ingestion is suspected to be the major pathway of human exposure due to the high levels of BDE209 found in indoor dust (Johnson-Restrepo and Kannan, 2009). Even though BDE-209 is relatively stable and has limited biodegradability, certain biotic or abiotic processes can occur to degrade BDE-209. UV or sunlight can photodegrade BDE-209 in organic or aqueous systems to form more persistent and toxic lower brominated compounds (Segev et al., 2009). Microorganisms can biodegrade BDE-209 into its debrominated forms. The reductive debromination of BDE-209 via aerobic biodebromination was shown to be a significant source of lower brominated diphenyl ethers in sediments (Deng et al., 2011). The effects of PBDEs in mammals include hepatic, immunological, endocrine disruption, reproductive effects, developmental and neurobehavioral alterations, and cancer (Costa and Giordano, 2011). Most of these effects are greater in lower BDEs than in BDE-209. Evidence of the carcinogenicity of BDE-209 in mice has made it become classified as a possible human carcinogen (US EPA, 2006). The prevalence and toxicity of BDE-209 have become a concern to the scientific community. Several analytical techniques are being employed for BDE-209 determination. Most analytical determinations include sample pre-treatment, extraction, and clean-up steps before the instrumental analysis. Extraction techniques are mainly solvent extraction as in Soxhlet extraction, ultrasonication, accelerated solvent extraction (ASE), or microwave-assisted extraction (MAE) (Dirtu, 2009). Although extraction recoveries are lower in ultrasonication, its advantages are lesser solvent use compared to Soxhlet extraction especially in microanalysis and lower cost over ASE and MAE. The clean-up step is important in the removal of sulfur by treatment with copper, gel-permeation chromatography, treatment with acid, silica-based solid phase extraction (SPE), or a combination of these techniques (Covaci et al., 2003). BDE-209 determination is mainly chromatographybased, usually GC–MS, GC–ECD, LC–MS, or HPLC–UV or by multiple-coupling of detectors like GC–MS/MS and LC–UV/MS

43

(Vonderheide, 2009). GC is the separation technique used in most of the PBDE analyses due to its high resolving power. However, it requires shorter columns in the analysis of less volatile and thermally-unstable congeners like BDE-209. The most popular detection technique is MS due to its sensitivity and selectivity. UV detection, on the other hand, is non-specific and less costly (Schlummer et al., 2005). The effective use of HPLC–UV was demonstrated in a study on BFRs (not including BDE-209) in soil (Yu and Hu, 2007). The diverse matrices where PBDEs are found and the different properties of the PBDE congeners hamper the development of a simple and general analytical determination for PBDEs. Global trends in PBDE exposure is hard to establish due to the different techniques being used. In addition to that, the environmental fate and exposure pathway to these compounds are still uncertain (Vonderheide et al., 2008). In Europe and America, the apparent increase of these compounds in the environment has been known in the last two decades but in Asia-Pacific, very little is known on PBDEs (Watanabe and Sakai, 2003). A study on the temporal trends of BFRs in Asian waters showed that the levels of PBDEs have risen significantly over the years (Tanabe et al., 2008). In the Philippines, limited information is currently available regarding PBDEs, especially BDE-209. One study was conducted wherein 12 PBDE congeners consisting of tri- to decaBDE were detected in human scalp hair from residents of Payatas and Malate in Metropolitan Manila (Malarvannan et al., 2010). The PBDE concentrations ranged from 21 to 646 ng g 1 in the hair samples, which were mainly attributed to BDE-209. An initial profiling of PBDEs in indoor dust in the Philippines using GC–MS was done in which BDE-47, BDE-99, BDE-100, and BDE-154 were found in the range 205–3758 ng g 1 (Espino and Leon, 2011). The study was limited to the lower brominated PBDEs. However, it is expected that BDE-209 is also present in indoor dust. In this study, an analytical determination method for BDE-209 in indoor dust by ultrasonication extraction and HPLC–UV determination was developed. The method was used to determine the occurrence of BDE-209 in indoor dust samples from inside offices, libraries, and other rooms located in the University of the Philippines Diliman Campus. BDE-209 was found to be prevalent in indoor dust in these microenvironments.

2. Materials and methods 2.1. Materials The decabromodiphenyl ether standard (98.3%, 50.22 ppm) was supplied by AccuStandard Inc. (New Haven, CT, USA). The internal standard solution pentabromophenol (PBP, 96%) was purchased from Sigma–Aldrich (St. Louis, MO, USA). A 1000 mg L 1 PBP stock solution was prepared by dissolving appropriate mass of PBP in methanol. This was used to prepare the 10 mg L 1 PBP solution spiked in all standard and extract solutions. Solvents such as water (HPLC-grade), acetonitrile (100%, HPLCgrade), and hexane (98.5%, AR) were purchased from JT Baker (Phillipsburg, NJ, USA). Nitric acid (69–70%, ACS) was supplied by JT Baker (Thailand) while sulfuric acid (98%, AR) and methanol (99.9%, HPLCgrade) were supplied by RCI Labscan Limited (Bangkok, Thailand). The HPLC mobile phase was 100% methanol. This was filtered through a nylon membrane filter (Whatman 47 mm, 0.45 lm pore size) and degassed by vacuum filtration before use. The silica gel (60–200 mesh) and anhydrous Na2SO4 (99.7%) were supplied by JT Baker (Phillipsburg, NJ, USA). The glass wool was supplied by Ajax Finechem Pty Ltd. (Auckland, New Zealand). The SPE tubes (6 mL, PE filtration tube with no frits) and tube adapters (for 6 mL sample reservoir) were purchased from Supelco (Bellefonte, PA, USA). The SPE tube was packed with 0.1 g glass

44

C.R.P. Fulong, Maria Pythias B. Espino / Chemosphere 90 (2013) 42–48

Table 1 Sampling site, site descriptions, and sampling date. Sample name

Sampling site (Name of UP office in Diliman, Quezon City)

Site descriptions

Offc1

CSRC office

Medium-sized office room with 1 photocopy machine, 3 PCs and 3 printers

Offc2

a

Sampling date

a

Offc3

College of Mass Communication, Film Building office ISSI office lounge

Small office room with 1 or more PCs , 1 photocopy machine, 1 microwave oven, 1 water dispenser, and 1 coffee maker Small room with 1 TV set and 1 stereo/speaker system

Offc4 Lib1

College of Education Dean’s office Third World Studies library

Medium-sized 2 office rooms with 1 desktop computer set and 1 telephone set Large library room with 7 industrial/wall fans, and 3 or more PCsa

Lib2

College of Law library

Very large library room with 4 or more PCsa and three photocopy machines

Clrm1

College of Law classroom

Large classroom with 2 TV sets and 4 small speakers

Cfrm1

Computer Centre computer room

Small office room with 4 PCs, 1 water dispenser, and 1 rice cooker

11/12/ 2010 11/23/ 2010 11/25/ 2010 12/9/2010 11/12/ 2010 11/25/ 2010 11/25/ 2010 11/18/ 2010

Accounts for presence of stored out-of-order PCs.

wool, 1 g activated acidic silica gel, and 1 g anhydrous Na2SO4. The activated acidic silica gel was prepared using a method given elsewhere (US EPA, 2007). The packed SPE column was first conditioned five times with 1 mL hexane before use. Blank dusts were prepared by a threefold ultrasonic aided solvent extraction with hexane. Hexane was then decanted and the dust was oven dried at 70 °C for 30 min. 2.2. Methods 2.2.1. Sampling The dust samples were collected from the filters of air conditioners in four offices, two libraries, a classroom, and a computing facility in the campus of the University of the Philippines in Diliman, Quezon City, Philippines. The sampling location conditions are varied in many aspects like room size, age, ventilation, furnishing, and air conditioner type. The sampling period was from November to December 2010. Detailed descriptions of the sampling locations are provided in Table 1. Composite dust samples were collected from any visible deposits in the intake air filters. A disposable steel brush (Home Solutions wire brush, Positive Principles Enterprise, Manila, Philippines) was used to collect dust samples in a foodgrade aluminum foil. The dust samples were then transferred into 20-mL glass vials. These were stored at 0 °C until analysis. 2.2.2. Extraction The dust samples collected were homogenized by passing through a stainless-steel sieve (500 lm sieve opening size)

Fig. 1. Chromatograms of (A) 100 lg L is at 8.56 min.

1

purchased from W.S. Tyler (Mentor, OH, USA). These were then dried for 1 h at room temperature inside desiccators with self-indicating, coarse silica gel desiccant supplied by TechnoPharmchem (Haryana, India). A 0.2 g dried and homogenized dust sample was weighed in a 20-mL glass scintillation vial with cover. The dust sample was left to stand with 3 mL hexane for 30 min to allow complete soaking. Then it was sonicated for 15 min using a Power Sonic 401 ultrasonicator (Hwashin Technology, Geonggi-do, Korea). After sonication, the dust sample with extract was left to cool and settle for 60 min at 0 °C before the extract was drawn out of the vial using a Pasteur pipette into another 20-mL glass scintillation vial. Another 3 mL hexane was added to the dust sample and the entire extraction procedure was repeated with the second extract collected into the same 20-mL glass scintillation vial. 2.2.3. Clean-up A 2 mL concentrated nitric acid was added to 1 mL extract (dust sample, blank dust, and spiked dust) in a 20-mL glass scintillation vial. This was manually shaken for 30 min then left to stand for 5 min before drawing out the hexane extract into a 4-mL glass vial using a Pasteur pipette. The hexane extract was then further cleaned by SPE. One milliliter portion of the extract was passed through a previously prepared SPE column via positive pressure from a 10-mL glass syringe. The eluate was collected in a 4-mL glass vial (eluate 1). Then, two 1-mL portions of hexane were consecutively passed through the SPE column and collected in separate 4-mL glass vials (eluates 2 and 3). These eluates were solvent-exchanged into methanol by evaporation in a water bath

PBP internal standard in methanol, where PBP is at 2.10 min and (B) 100 lg L

1

both BDE-209 and PBP in methanol, where BDE-209

45

C.R.P. Fulong, Maria Pythias B. Espino / Chemosphere 90 (2013) 42–48 Table 2 Mean and % RSD of BDE-209 and PBP standard peaks. Standard, n = 7

BDE-209 (30 lg L PBP (100 lg L 1)

Peak RT

1

)

Peak area

Area ratio

Mean (min)

% RSD

Mean

% RSD

Mean

% RSD

8.49 2.14

0.27 0.49

489 13 421

24 5

0.04

26

Table 3 Linearity, IDLs, MDLs, LOQs, and % absolute recoveries of the optimized method. Quality control parameters

IDL, n = 7 (30 lg L 1 spike) BDE-209 concentration (lg L IDL (lg L 1) MDL, n = 8 Absolute recovery (%) MDL (ng g 1) LOQ (ng g 1) Linearity, n = 4 Calibration range (lg L Calibration equation R2

1

)

Mean (% RSD)

1

)

External calibration

Internal standard calibration

33 (17) 18

34 (16) 16

64 (10) 495 855

57 (19) 285 780

0–300 y = 16.53x 0.997

at 70 °C and addition of 500 lL methanol. The eluates in methanol were then spiked with 5 lL of the 10 mg L 1 PBP solution. 2.3. Instrumental analysis The analysis was carried out using a Shimadzu LC 10AS liquid chromatograph equipped with CBM 102 Communication Bus, isocratic pump, column oven, and SPD UV–Vis Detector. A ThermoHypersil HyPURITY C18, 250 mm  4.6 mm  5 lm column (Bellefonte, PA, USA) and a 4  3 mm HPLC guard cartridge column (Phenomenex, USA) were used. The following are the HPLC conditions: 225 nm UV detector wavelength, 30 °C column oven temperature, 100% methanol eluent, 1 mL min 1 flow rate, and 20 lL injection volume. 2.4. Method validation The identification of BDE-209 and PBP was based on the retention times. The BDE-209 in the sample was quantified by external

119.6

0–300 y = 0.001x 0.993

0.011

calibration and internal standard calibration. The linear calibration solutions were 0, 30, 50, 70, 100, 200, and 300 lg L 1 BDE-209 standard solutions spiked with 100 lg L 1 PBP internal standard (R2 P 0.999). The repeatability of the determination method was measured by the percent relative standard deviation (% RSD) of the retention times, peak areas, and calculated BDE-209 concentrations of seven measurements of a 30 lg L 1 BDE-209 standard solution. The instrument detection limit, IDL, was determined from the standard deviation of seven replicate measurements of 30 lg L 1 BDE-209 standard solution and using the equation IDL = (tn 1,1 l =0.99)(s), where t(n 1,l 1=0.99) is the students’ t value of n = 7 for 99% confidence level and standard deviation estimate with n 1 degrees of freedom and s is the standard deviation of the replicate analyses. The limit of quantitation or LOQ is ten times this s. The method detection limit, MDL, was calculated from the standard deviation of eight replicate analyses of 1500 ng g 1 BDE-209 spiked in a blank dust sample and analyzed using the optimized method. This was calculated based on the equation: MDL = (t(n 1,1 l =0.99))(s),

Fig. 2. Chromatogram of an indoor dust extract (Lib 1 sample) with detectable BDE-209.

46

C.R.P. Fulong, Maria Pythias B. Espino / Chemosphere 90 (2013) 42–48

where t(n 1,l 1=0.99) is the students’ t value of n = 8 for 99% confidence level and standard deviation estimate with n 1 degrees of freedom and s is the standard deviation of the replicate analyses. The % absolute recovery was determined using standard additions of 1500 ng g 1 BDE-209 spike on blank dusts. This was calculated as the percent ratio of the measured concentration and the spiked concentration of BDE-209. 2.5. Quality control Solvent and procedural blanks were analyzed with every batch of three to five samples to check for interferences and contamination from solvent and glassware. The % absolute recovery of the spiked blank dust samples ranged from 44% to 81%. The repeatability of the method as assessed from the % RSD of the absolute recoveries of eight replications of spiked blank dust samples was 19%. The MDLs based on 0.2 g sample were 495 and 285 ng g 1 for the external calibration and internal standard calibration, respectively. The LOQs of the optimized method were 855 ng g 1 for the external calibration and 780 ng g 1 for the internal standard calibration based on 0.2 g sample. BDE-209 concentrations in dust samples which are lower than the LOQ are reported as ‘‘below LOQ’’. 3. Results and discussion 3.1. Extraction The basis for using hexane as the extraction solvent was a previous study by Espino and Leon (2011) which demonstrated the use of hexane as the extraction solvent for other PBDEs. BDE-209 in the indoor dust samples was thus extracted in hexane by ultrasonication. Different volumes of hexane were tested in extracting 300 ng BDE-209 spiked in a 0.2 g blank dust. The highest average % absolute recovery of 57% was obtained in two extractions with 3 mL hexane each time. Therefore, this was the optimum extraction volume of hexane used to extract BDE-209 in dust samples. Abb et al. (2011) also used utrasonication to extract BDE-209 in dust samples. Similar to this study, they also extracted BDE-209 in two extractions but using acetone and toluene as the extracting solvents. 3.2. Clean-up A chromatogram of a BDE-209 spiked blank dust extract without clean-up is provided as Supplementary data (Fig. S-1). Due to the presence of several interfering peaks which hinders the quantitation of BDE-209, a clean-up procedure was necessary. These interfering peaks were removed with the use of nitric acid and acidified activated silica gel packed SPE. After elution of the extract through the SPE, 192 ng BDE-209 or 64% absolute recovery (based on external calibration) and 171 ng BDE-209 or 57% absolute recovery (based on internal standard calibration) could be recovered up to the second elution with 1 mL hexane. 3.3. Quantitation and recovery Chromatograms of PBP and BDE-209 are shown in Fig. 1. Hexane was not the preferred solvent for BDE-209 determination using HPLC–UV due to the presence of solvent peaks at the retention times (RTs) of both BDE-209 and PBP. Methanol was then used as the solvent for all standards, spiked dusts, and dust samples. PBP and BDE-209 appeared at RTs 2.14 min and 8.49 min, respectively. The BDE-209 peak is completely resolved from other neighboring peaks while the PBP peak is not. The % RSDs of PBP peaks’ RT and peak area were 0.49% and 5%, respectively (Table 2). The

repeatability and feasibility of the use of PBP as the internal standard could be supported by these % RSDs. In addition, interfering peaks were absent at the RT of PBP in the solvent blank and blank dust extracts. BDE-209 analysis using external calibration and internal standard calibration were compared in this study. The correlation coefficients of 0–300 lg L 1 BDE-209 standards for external calibration and internal standard calibration were 0.997 and 0.993, respectively (Table 3). The IDLs were 18 and 16 lg L 1 and the LOQs were 855 and 780 ng g 1 for external calibration and internal standard calibration, respectively. Based on the IDLs and the LOQs, internal standard calibration using PBP as the internal standard is slightly better than external calibration. As a quality control, solvent blank and blank dust extracts were analyzed prior to each sample analysis. Solvent blank and blank dust extracts were shown to have no interfering peaks at the RTs of BDE-209 and PBP. Because a certified reference material for dust with BDE-209 was not available in this study, recovery of spiked BDE-209 in blank dust was measured. Chromatograms of solvent blank, blank dust extract, and spiked blank dust extract are provided as Supplementary data (Figs. S-2–S-4). The optimized method provided a reasonable mean absolute recovery of 57%. The % RSD of the recoveries (n = 8) was 19%. The % absolute recoveries are provided as Supplementary data (Table S-1). Considering all of the results described above, the optimized method for extraction, clean-up, and determination of BDE-209 from dust samples was shown to be repeatable and precise with acceptable accuracy. Abb et al. (2011) were able to quantify BDE-209 using HPLC/UV using the following conditions: C18 column, 100% methanol as the mobile phase, 0.5 mL min 1 flow rate, 20 °C column temperature, and 250 nm UV detection wavelength. They demonstrated that a simple external calibration method is as good as the more tedious standard addition method in quantifying BDE-209. In this study, similar mobile phase and type of column were used to quantify BDE-209 but the other parameters were different: 1 mL min 1 flow rate, 30 °C column temperature, and 225 nm UV detection wavelength. The faster flow rate provided a shorter analysis time. 3.4. BDE-209 in indoor dust samples A university environment was the chosen sampling area because of the large number of people staying in this place throughout the day. Some empirical data regarding the sampling sites, like room size, number of electronic equipment, and air conditioner type, were also noted in Table 1. Eight rooms were sampled for dust deposited in filters of air conditioners. The air conditioner’s mechanism of filtering the air for dust is similar to that of a vacuum cleaner. It was assumed that the dusts in these filters represent all the dust found inside the room. BDE-209 was detected in all dust samples collected. Fig. 2 shows a typical chromatogram of a sample (Lib1) that was analyzed. The chromatogram is from the third eluate of the extract

Table 4 BDE-209 concentrations (in ng g Sample

Offc1 Offc2 Offc3 Offc4 Lib1 Lib2 Clrm1 Cfrm1

1

, n = 3) in the indoor dust samples.

Mean BDE-209 concentration in ng g

1

(% RSD, n = 3)

Internal standard calibration

External calibration

3442 (17) 1399 (26) 1103 (25) Below LOQ 2473 (29) Below LOQ 1829 (19) 4117 (27)

2490 (25) 1352 (22) 930 (25) Below LOQ 1900 (30) Below LOQ 1664 (23) 3363 (35)

47

C.R.P. Fulong, Maria Pythias B. Espino / Chemosphere 90 (2013) 42–48 Table 5 Concentrations of BDE-209 in indoor dust samples from different countries. Dust type

Mean BDE-209 (ng g a

1

)

Method

Country

Reference

Philippines China China Belgium USA Hongkong Hongkong/ China China Japan Germany/USA

This study Zeng et al. (2011) Chen et al. (2010a) D’Hollander et al. (2010) Batterman et al. (2010) Wong et al. (2011) Wong et al. (2011)

Belgium Canada UK USA Portugal China

D’Hollander et al. (2010) Harrad et al. (2008) Harrad et al. (2008) Harrad et al. (2008) Cunha et al. (2010) Chen et al. (2010b)

GC–ECNI/MS

Thailand

Harrad et al. (2010)

GC–MS LC–APPI–MS/MS

Portugal UK

Cunha et al. (2010) Harrad and Abdallah (2011)

University (n = 8) Office (n = 56) Office (n = 12) Office (n = 10) Office (n = 10) Workplace (n = 55) House (n = 23)

2172 618 3148 1513 6930 4506 2458

HPLC/UV GC–MS GC–ECNI/MS GC–ECNI/MS GC–MS GC–MS GC–MS

House (n = 76) House (n = 2) House (n = 26)

2598 390 3177

House House House House House House

590 670 45 000 1600 751 5762 (n = 39, near e-waste area); 6298 (n = 27, near urban area) 33 000

GC–ECNI/MS GC–HRMS LC–UV–ESI–MS/ MS GC–ECNI/MS GC–ECNI/MS GC–ECNI/MS GC–ECNI/MS GC–MS GC–ECNI/MS

(n = 43) (n = 7) (n = 16) (n = 17) (n = 11)

E-waste storage facility (n = 25) Car (n = 9) Car

2819 190 000b

Chen et al. (2010a) Takigami et al. (2009) Abb et al. (2011)

(n = 14, cabin); 2700b (n = 14, trunk) a b

Four offices, two libraries, one classroom, and one computing facility. Median value.

from Lib1, wherein BDE-209 is clearly present. The complete chromatograms of eluates 1–3 for this sample are provided as Supplementary data (Fig. S-5). The ranges of BDE-209 concentration found in the sampling sites (excluding those at levels below the LOQs) were 930–3363 ng g 1 using external calibration and 1103–4117 ng g 1 using internal standard calibration. The calculated BDE-209 concentrations had % RSDs of 27% and 24% using external calibration and internal standard calibration, respectively. The concentrations of BDE-209 in the dust samples are summarized in Table 4. The highest BDE-209 concentration was found in a small computer center room (Cfrm1), while the lowest was found in an office lounge (Offc3). These results demonstrated the assumption that BDE-209 would be present in high concentration in indoor environments with many possible sources such as electrical and electronic equipment. The highest concentration of BDE-209 was found in Cfrm1 where four old and new computers were present. In contrast, the lowest concentration of BDE-209 was found in Offc3 where only one TV set was present. In addition, below LOQ levels of BDE-209 were found in the College of Law library (Lib2) and the College of Education Dean’s office (Offc4). Minimal amount of BDE-209 was expected in Offc4 because there was only one personal computer present in this office. Although Lib2 was equipped with a number of computers and photocopy machines, the large room size could have helped disperse BDE209 and minimized its concentration in dust. This study showed the occurrence of BDE-209 in indoor dust from a computing facility, a classroom, four offices, and two libraries of a university in the Philippines. The determination of BDE-209 in indoor dust was done with several variabilities, such as the function and size of the sampling site, and the period of dust deposition. The comparability of the concentrations of BDE-209 in these sites may thus be limited. Nonetheless, these findings present the first report on BDE-209 contamination in indoor environments in the Philippines. In particular, the data presented here provide initial estimates of the exposure levels of university students and personnel to BDE-209 in indoor dust in this university environment.

3.5. Comparison to other studies A major challenge in BDE-209 determination in any matrix is the thermal-instability and photodegradation of BDE-209. Unlike most PBDEs which are commonly analyzed by GC–MS using regular columns, BDE-209 which is unstable at high temperatures requires a shorter column and short period of analysis. This is probably one good explanation why recent studies on BDE-209 in indoor dust relied on LC-based determination like the studies of Abb et al. (2011) and Harrad and Abdallah (2011). Summarized in Table 5 are several recent studies on BDE-209 in dust from different countries. In these studies, dusts were taken from cars, houses, offices, e-waste storage facilities, and workplaces, locations which are frequented by people. In the case of e-waste storage sites, these areas contain large volumes of waste electrical and electronic equipment which are major sources of BDE-209. As expected, the highest concentrations of BDE-209 were found in or near these sites. High concentrations of BDE-209 were also found in car dust. House, office, and workplace dusts contain varying amounts of BDE-209. To date, the available measurements on BDE-209 in Asian countries show higher concentration of BDE-209 in offices and workplace dusts than in house dusts. This study is the first account on BDE-209 contamination in dust samples from a university environment in the Philippines. The data reported here could serve as an initial exposure level to BDE-209 from indoor dust in a university environment in the country. In indoor dust from various countries (Table 5), BDE-209 was in the range of 390–45 000 ng g 1 for house, office, and workplace dusts. Within this range is the average BDE-209 concentration reported in this study, which is 2172 ng g 1. At present, there is still no standard exposure limit to BDE-209. Studies on BDE-209 levels in different environmental matrices would therefore be useful in order to gauge the level of BDE-209 contamination in environmental samples like indoor dust.

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4. Conclusions A simple analytical determination method for BDE-209 contamination in indoor dust by ultrasonication extraction and HPLC–UV determination was optimized and validated in this study. The optimized method was validated using both external calibration and internal standard calibration with the latter as the more sensitive and repeatable technique. This optimized method was used to determine contamination of BDE-209 in indoor dust from a university environment in the Philippines. High concentrations of BDE209 in dust were found in sites with large number of possible sources of BDE-209 such as electrical and electronic equipment. BDE-209 was detected in all sampling sites with an average concentration of 2172 ng g 1 excluding those at below LOQ. The present contamination of BDE-209 in indoor dust in microenvironments within a university in the Philippines was demonstrated in this study. As the first account of BDE-209 contamination in indoor dust in a university environment in the country, this will be a good initial estimate of the exposure level of university students and personnel to BDE-209. The optimized method would be a good tool in further studies of BDE-209 contamination in other environmental matrices such as soil, sediment, or sludge in the Philippines. Acknowledgements C.R. Fulong is grateful to the Philippine Commission on Higher Education (CHED) for her MS thesis grant. M.P. Espino acknowledges the University of the Philippines Natural Science Research Institute for the funding support of this study (Project No. CHE-10-2-03). Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.chemosphere. 2012.06.072. References Abb, M., Stahl, B., Lorenz, W., 2011. Analysis of brominated flame retardants in house dust. Chemosphere 85, 1657–1663. Batterman, S., Godwin, C., Chernyak, S., Jia, C., Charles, S., 2010. Brominated flame retardants in offices in Michigan, USA. Environ. Int. 36, 548–556. Betts, K.S., 2008. Unwelcome guest: PBDEs in indoor dust. Environ. Health Persp. 116, 202–208. Birnbaum, L.S., Staskal, D.F., 2004. Brominated flame retardants: cause for concern. Environ. Health Persp. 112, 9–17. Chen, L., Huang, Y., Peng, X., Xu, Z., Ye, Z., 2010a. PBDEs in indoor dust in SouthCentral China: characteristics and implications. Chemosphere 78, 169–174. Chen, S., Wang, J., Ma, Y., Tian, M., Luo, X., Mai, B., 2010b. Brominated flame retardants in house dust from e-waste recycling and urban areas in South China: implications on human exposure. Environ. Int. 36, 535–541. Costa, L.C., Giordano, G., 2011. Is decabromodiphenyl ether (BDE-209) a developmental neurotoxicant? Neurotoxicology 32, 9–24. Covaci, A., Voorspoels, S., de Boer, J., 2003. Determination of brominated flame retardants, with emphasis on polybrominated diphenyl ethers (PBDEs) in environmental and human samples – a review. Environ. Int. 29, 735–756. Cunha, S.C., Kalachova, K., Pulkrabova, J., Fernandes, J.O., Oliveira, M.B.P.P., Alves, A., Hajslova, J., 2010. Polybrominated diphenyl ethers (PBDEs) contents in house and car dust of Portugal by pressurized liquid extraction (PLE) and gas chromatography–mass spectrometry (GC–MS). Chemosphere 78, 1263–1271. de Wit, C.A., Herzke, D., Vorkamp, K., 2010. Brominated flame retardants in the Arctic environment – trends and new candidates. Sci. Total Environ. 408, 2885– 2918. Deng, D., Guo, J., Sun, J., Chen, X., Qiu, M., Xu, M., 2011. Aerobic debromination of deca-BDE: isolation and characterization of an indigenous isolate from a PBDE contaminated sediment. Int. Biodeter. Biodegr. 65, 465–469. D’Hollander, W., Roosens, L., Covaci, A., Cornelis, C., Reynders, H., Van Campenhout, K., de Voogt, P., Bervoets, L., 2010. Brominated flame retardants and

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