Narin Boontanon

Determination of perfluorooctane sulfonate and perfluorooctanoic acid in food packaging using liquid chromatography coupled with tandem mass spectrometry

This research aimed to monitor the amounts of PFOS and PFOA in food packaging and study the migration of PFOS and PFOA from food packaging, using a saliva simulant and pressurized liquid extraction (PLE) technique. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was employed to determine residues of PFOS and PFOA by using a gradient reversed-phase method with ammonium acetate/acetonitrile buffer. A good linearity was established for PFOS and PFOA in a range of 0.05-10 μgL(-1), with R2 ≥ 0.9998. Of the samples extracted by methanol, the highest concentration of PFOS was found in fast-food container samples, at a level of 92.48 ng dm(-2). For PFOA, the highest concentration in samples extracted by methanol was found in ice cream cup samples, at a level of 16.91 ng dm(-2). The amounts of PFOS and PFOA that migrated from food packaging samples through contact with saliva simulant were 4.80 and 4.55 ng dm(-2), respectively. Saliva simulant could leach PFOS and PFOA from the group of the thickest paper samples (≤1 dm2 g(-1)) at levels of 7.01 and 6.41 ng dm(-2), respectively, indicating that paper with greater thickness and less area might release larger quantities of coated/added PFOS or PFOA.

Monitoring and determination of sulfonamide antibiotics (sulfamethoxydiazine, sulfamethazine, sulfamethoxazole and sulfadiazine) in imported Pangasius catfish products in Thailand using liquid chromatography coupled with tandem mass spectrometry

This research aimed to monitor the concentrations of sulfamethoxydiazine (SMD), sulfamethazine (SMT), sulfamethoxazole (SMX) and sulfadiazine (SDZ) in imported Pangasius catfish products in Thailand. The residues of the four sulfonamides (SAs) were analyzed by extraction process and liquid chromatography coupled with tandem mass spectrometry. The highest concentrations found were 10.97ng/g for SMD, 6.23ng/g for SMT, 11.13ng/g for SDZ and 245.91ng/g for SMX, which was higher than the European Union (EU) standard (100ng/g). Moreover, all samples contaminated with SMX also contained SMT, indicating that more than one antibiotic was used for production in the country of origin. Because Thai standards for antibiotics in food have not been completely set, all contaminated discovered would not be considered to be an illegal food, in which antibiotic residues may affect human health in the long term. Therefore, antibiotic residues in Pangasius catfish products should be continually regulated and monitored.

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) contamination from textiles.

ABSTRACT The goals of this study were to determine the concentrations of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in textiles and to determine PFOS and PFOA contamination in textile washing water. Quantification analysis was performed by high performance liquid chromatography coupled with tandem mass spectrometry. Analysis of 32 textile samples by methanol extraction revealed that the average concentrations of PFOS and PFOA were 0.18 µg m−2 (0.02 to 0.61 µg m−2) and 2.74 µg m−2 (0.31 to 14.14 µg m−2), respectively. Although the average concentration of PFOS found in textile samples was below European Union (EU) Commission regulations (<1 µg m−2), the average concentration of PFOA was 2.74 µg m−2, and 68.75% of textile samples had PFOA concentrations exceeding 1 µg m−2. Thus, based on these results, the concentration of PFOA in products should also be regulated. Experiments on PFOS and PFOA leaching into washing water were conducted. The maximum concentrations of PFOS and PFOA were measured after the first washing; the concentrations gradually decreased with each subsequent washing. PFOS and PFOA migrated from textiles and were released into the environment, with disappearance percentages of 29.8% for PFOS and 99% for PFOA. The data presented in this study showed that textiles could be a significant direct and indirect source of PFOS and PFOA exposure for both humans and the environment.

Occurrence of Perfluorooctane Sulfonate in the Water Environment of Bangkok, Thailand

Persistent organic pollutants (POPs) are organic substances that have characteristics of persistence in the environment; transboun- dary movement, or the ability to travel long distances through air and water; toxicity; and bioaccumulation in living things. Perfluorooctane sulfonate (PFOS), a toxic chemical that never breaks down, was added to the Stockholm Convention on POPs and was listed in the Annex B restrictions with many exemptions to continue using PFOS. This study focused on the occurrence of PFOS in the water system of Bangkok, Thailand,includingtheChaoPhraya andBangPakongRivers,tapwater in industrial zonesandresidential areas, drinkingwater,andindustrial wastewater.Seasonaleffect of PFOSbetweendryseason and wet season was also observedformore than 3years. Solid phase extraction (SPE) coupled with HPLC-ESI-MS/MS was used for the analysis of these compounds. PFOS was detected in most water samples. The average concentration of PFOS in the Chao Phraya River (urban area) was1.70 ng=L, whereas lower concentrations were detected in the Bang Pakong River (suburban area), residential tap water, and bottled drinking water, with averages of 0.7, 0.4, and 0.5 ng=L, respectively. Higher con- centrations(anaverageof25.1 ng=L)werefoundinindustrialtapwater,whosesourceswerefromsurfacewaterneartheindustrialzones.Much higherconcentrationsweredetectedinindustrialwastewater,withthemaximumof6;100.8 ng=L.Theseresultsindicatedthatindustrialwaste- water was one of the major sources of PFOS contamination in thewater system of the city of Bangkok. This study provided data on the spatial occurrence, its seasonal effect, and distribution of PFOS in the water environment of Bangkok and surrounding areas, which need continuous attention to this emerging contaminant. DOI: 10.1061/(ASCE)EE.1943-7870.0000603.

Evaluation of removal efficiency of human antibiotics in wastewater treatment plants in Bangkok, Thailand.

This study aimed to investigate the antibiotic concentration at each stage of treatment and to evaluate the removal efficiency of antibiotics in different types of secondary and advanced treatment, as well as the effects of the location of their discharge points on the occurrence of antibiotics in surface water. Eight target antibiotics and four hospital wastewater treatment plants in Bangkok with different conventional and advanced treatment options were investigated. Antibiotics were extracted by solid phase extraction and analysed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The antibiotic with the highest concentration at influent was cefazolin at 13,166 ng/L, while the antibiotic with the highest concentration at effluent was sulfamethoxazole at 1,499 ng/L. The removal efficiency of antibiotics from lowest to highest was sulfamethoxazole, piperacillin, clarithromycin, metronidazole, dicloxacillin, ciprofloxacin, cefazolin, and cefalexin. The adopted conventional treatment systems could not completely remove all antibiotics from wastewater. However, using advanced treatments or disinfection units such as chlorination and UV could increase the antibiotic removal efficiency. Chlorination was more effective than UV, ciprofloxacin and sulfamethoxazole concentration fluctuated during the treatment process, and sulfamethoxazole was the most difficult to remove. Both these antibiotics should be studied further regarding their contamination in sludge and suitable treatment options for their removal.

Extraction procedure optimization for perfluorooctane sulfonate and perfluorooctanoic acid in food packaging determination by LC-MS/MS

This research aimed to optimize the extraction method parameters for sample pretreatment and determine the levels of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) contamination in food packaging made of paper. Techniques used were pressurized liquid extraction (PLE) followed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Influence parameters of PLE were carefully evaluated for extracted concentration of samples in low level (ng g−1). The study found that the optimal conditions for PLE were 30 min static extraction time with a flush volume of 100% cell volume and one extraction cycle at 80°C and 1,000 psi. The extraction technique validated the absolute recovery from PFOS and PFOA fortified control samples at three different levels (5, 50, and 200 ng g−1), with seven repeats at each fortification level. The average recoveries were 79% or higher, with relative standard deviation (RSD) less than 11%. Optimization of the PLE method was established based on recovery data, accuracy, precision, and repeatability of the method. Using optimal PLE technique, PFOS and PFOA were extracted from 34 food-packaging samples collected in Thailand. PFOS and PFOA were detected in all kinds of collected samples, with average concentrations of 4.89 and 2.87 ng g−1, respectively. The concentrations of PFOS and PFOA were highest in fast-food container samples: 36.99 and 9.99 ng g−1, respectively.

Levels of perfluorinated compounds (PFCs) in groundwater around improper municipal and industrial waste disposal sites in Thailand and health risk assessment

The aims of this study were to examine the levels of perfluorinated compounds (PFCs) in groundwater around improperly developed municipal and industrial waste disposal sites, including estimating non-cancer risk and cancer risk from ingestion of the groundwater. A total of 27 groundwater samples were collected from two cities in Thailand, Ayutthaya and Chonburi. Seven target compounds were extracted by solid phase extraction (SPE) and analyzed by high-performance liquid chromatography-tandem mass spectrometer (HPLC-MS/MS). The results showed that the total PFCs in groundwater around municipal waste disposal sites (MWDSs) varied from 1.68 to 7.75 ng/L. In groundwater around the industrial waste disposal site (IWDS), total PFCs varied from 2.64 to 42.01 ng/L, which were significantly different from those found in groundwater around the MWDSs at p < 0.01. PFOS and PFOA were ubiquitous in both areas, while perfluorohexane sulfonate (PFHxS) was frequently found in the samples around IWDS. The findings possibly suggest that PFHxS has been introduced for use as an alternative substance for most current C8 and higher due to it having shorter chain length and shorter half-lives. The results for both non-cancer risk and cancer risk in all samples were acceptable.

Study of hybrid membrane filtration and photocatalysis for removal of perfluorooctanoic acid (PFOA) in groundwater

Groundwater contamination in Thailand from leaking of leachate due to improper solid waste disposal can cause contamination by PFOA (one of the perfluorinated compounds). This study proposed a new idea for the removal of PFOA from groundwater using a combination of membrane filtration and photocatalysis. Spiked groundwater samples were treated by nanofiltration and the rejected part was sent to a UV contact tank for photocatalysis. All samples were analyzed by high-performance liquid chromatography-tandem mass spectrometer (HPLC-MS/MS). The results showed that the removal efficiency of nanofiltration was 99.62%, and the rejected part was degraded by photocatalysis at an efficiency of 59.64%. Thus, the contaminants released to the environment were only 34.23%, which is around three times lower than nanofiltration alone. The results of this technical feasibility study proved that hybrid membrane filtration and photocatalysis are able to remove and degrade the contaminants in the rejected part significantly before being released to the environment, which has been the biggest gap in the processing of membrane filtration, and should be studied further in other aspects, such as fouling effects, energy consumption, and operating costs in a long-term pilot run.

Determination and health risk assessment of enrofloxacin, flumequine and sulfamethoxazole in imported Pangasius catfish products in Thailand

ABSTRACT The goals of this study were to determine the levels of three antibiotics – enrofloxacin, flumequine and sulfamethoxazole – in Pangasius catfish products imported into Thailand and to assess the health risks from consumption. To extract these antibiotic residues, acetonitrile, methanol and a small amount of formic acid were used as solvents. Determination of the antibiotics after extraction steps was carried out by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) technique. The results showed that 14 and 3 samples of Pangasius catfish products were contaminated with enrofloxacin and sulfamethoxazole, respectively. No flumequine residue was found. While the concentration levels of these antibiotics in most contaminated samples were lower than the European Union (EU) standard, one sample was found to contain sulfamethoxazole at 245.91 µg kg−1, which was higher than the EU standard (100 µg kg−1), indicating the likelihood that some contaminated freshwater fish products are widely distributed in Thai markets. Notably, the concentration levels of enrofloxacin in samples of Pangasius catfish with skin were higher than in non-skin products, suggesting that products with skin might retain more antibiotic residues than non-skin products. Although the hazard quotient showed that consuming imported Pangasius catfish products, based on the current consumption rate, will not adversely affect consumer health, antibiotic residues in Pangasius catfish products imported into Thailand should be continually monitored.

Estimation of pathways of the production of greenhouse gases in the tropical swamp forest in Thailand by stable isotope investigation

Dynamics of greenhouse gases (N2O and CH4) with the dry–wet cycle along with the variation of oxidation–reduction boundaries were investigated in the tropical wetland in monsoon Asia. It was clarified that the production of N2O and CH4 was closely related to the development of a redox boundary in the Bang Nara River systems. An intermittent increase in N2O was observed at the beginning of the rainy season, when a large amount of easily decomposable organic matter was introduced into the river. After 10 days, when dissolved oxygen was consumed completely at the middle reaches, the emission of CH4 became maximal due to the possible occurrence of denitrification. The distribution of stable isotope ratios in N2O clearly demonstrated that nitrification is the major process for its production. Furthermore, the production of N2O in this study area was found to vary in time and space with changes in the redox boundary along the water flow.