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Siangproh W.,Srinakharinwirot University | Sonamit K.,Bureau of Quality and Safety of Food | Sonamit K.,Chulalongkorn University | Chaiyo S.,Srinakharinwirot University | Chailapakul O.,Chulalongkorn University
Analytical Letters | Year: 2013

A rapid, accurate and precise method for the determination of sudan I-IV in chili products using on-line solid phase extraction and LC-MS has been developed. Chili products were extracted with acetone and the analytes were cleaned up and enriched on an SPE column (C18, 15-40 μm) through on-line SPE. Chromatographic separation was performed on a C18 analytical column (2.1 × 150 mm, 3 μm) with gradient elution programming of 0.1% formic acid in water and 0.1% formic acid in acetonitrile. All four sudan dyes were separated in less than 8 min. Using in-house validation data, linearity coefficients of determination (R2) of more than 0.9997 were obtained. The limits of detection (LOD) and limits of quantitation (LOQ) for sudan I, II and IV were 0.03 and 0.05 mg kg-1, respectively, and 0.04 and 0.1 mg kg-1 for sudan III. The intra- and inter-day recoveries of the four sudan dyes in chili powder were between 90.1-101.6% and 90.2-102.0%, respectively, with relative standard deviation (RSD) between 0.014-0.164% and 0.011-0.202%, respectively. Therefore, this proposed method could be an alternative assay for the determination of sudan I-IV in chili products due to its rapidness, sensitivity, less sample and solvent consumption. © 2013 Copyright Taylor and Francis Group, LLC. Source


Payanan T.,Bureau of Quality and Safety of Food | Leepipatpiboon N.,Chulalongkorn University | Varanusupakul P.,Chulalongkorn University
Food Chemistry | Year: 2013

Lowerature cleanup, which is a simple and cost-efficient sample preparation technique that allows the convenient treatment of multiple samples simultaneously, was developed in conjunction with solidphase extraction (SPE) cleanup for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in refined and used edible oil samples by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Samples are extracted with a small amount of organic solvent and most of lipids in the extract were removed by lowerature cleanup. SPE cartridge was used to further cleanup prior to HPLC-FLD analysis. Optimum extraction of lowerature cleanup was achieved when using two extractions with a 4:1 (v/v) mixture of acetonitrile: acetone as the extraction solvent, freezing at between -18 °C and -25 °C for 24 h and then cleanup with an Alumina-N SPE cartridge. The PAH recoveries were 45.9-118.5%, with limit of detection (LOD) and limit of quantitation (LOQ) values of 0.13-3.13 μg/kg and 0.25-6.25 μg/kg across the 16 tested PAHs, respectively. The validated method was successfully applied for the determination of PAHs in reference materials of olive oil and real refined and used edible oil samples. © 2013 Elsevier Ltd. All rights reserved. Source


Thattiyaphong A.,National Institute of Health | Unahalekhaka J.,Regional Medical science Center 4 | Mekha N.,National Institute of Health | Nispa W.,National Institute of Health | And 2 more authors.
Journal of Immunoassay and Immunochemistry | Year: 2014

The selling and importing of puffer fish species and their products was banned in Thailand in 2002, because of possible neurotoxic effects. However, the sale of their flesh is still happening in Thai markets. Standard methods for toxin quantification (HPLC and LC-MS) have significant limitations, therefore a lateral flow, immuno-chromatographic test (TTX-IC) was developed as a tool for rapid detection of toxin. A total of 750 puffer fishes (387 Lagocephalus lunaris(LL), and 363 Lagocephalus spadiceus (LS)) and 100 edible fishes were caught in Thailand from June 2011-February 2012. Screening of TTX from their flesh by TTX-IC revealed that 69 samples (17.8%) of LL possessed TTX at dangerous levels but LS and edible fishes did not. A selected 339 samples were quantified by LC-MS/MS, showing 50 LL possessed TTX at dangerous levels. Comparison of results with LC-MS/MS showed the TTX-IC to have 94.0% sensitivity and 92.4% specificity. The TTX-IC will be a useful tool for TTX screening of a large number of samples, reducing the testing required by LC-MS/MS, thus reducing costs. All positive cases found should be confirmed by standard methods. © 2014 Copyright Taylor and Francis Group, LLC. Source


Yafa C.,National Institute of Metrology Thailand NIMT | Srithongtim S.,Environmental Research Training Center | Phukphatthanachai P.,National Institute of Metrology Thailand NIMT | Thiparuk A.,Environmental Research Training Center | And 21 more authors.
Accreditation and Quality Assurance | Year: 2010

Reference materials play an important role for evaluating the accuracy of analytical results, and are essential parts of good laboratory practice. They represent a key tool for quality control of chemical analyses. In Thailand, the demand of food and environmental reference materials is constantly increasing, and the National Institute of Metrology (NIMT, Thailand) is responding to the urgent needs for affordable materials, which require collaborative efforts at the national level. This paper describes the preparation of a new glutinous rice reference material, along with homogeneity and stability studies and the analytical work carried out for the certification of the contents of inorganic elements. The incurred material was collected from an actual rice paddy field. Material preparation along with homogeneity and stability testing were carried out at the Environmental Research Training Centre (ERTC). The homogeneity study was designed to have three experimental conditions; (A) 10 bottles of candidate materials being analyzed each with 2 replicates, (B) 20 bottles with 2 replicates, (C) 10 bottles with 7 replicates, in order to study the suitable treatments for homogeneity testing in the reference material production. It was shown that a minimum number of 10 bottles with duplicate analyses are enough to demonstrate the homogeneity of candidate reference material. Certification of a candidate reference material in a single laboratory using reference method was confirmed with an interlaboratory comparison participated by a certain number of well recognized testing laboratories in Thailand. Further elaborative results will be discussed. © Springer-Verlag 2009. Source


Lakshanasomya N.,Bureau of Quality and Safety of Food | Danudol A.,Bureau of Quality and Safety of Food | Ningnoi T.,Bureau of Quality and Safety of Food
Journal of Food Composition and Analysis | Year: 2011

Many analytical methods are available for total solids and total fat in various kinds of food. However, none is specific for coconut milk and products. The aim of this study was to establish methods and to conduct the method performance study on determination of total solids and total fat in coconut milk and products. In the single laboratory study, three methods for total solids determination were conducted: drying in hot air oven at 102 ± 2°C and at 130 ± 3°C and drying in vacuum oven at 70°C, 70. mmHg, as well as three methods for total fat determination: direct extraction method, acid hydrolysis method and alkaline hydrolysis method. Sixteen samples of aqueous coconut milk and coconut milk powder were selected as test materials. Total solids and total fat contents were analyzed in 10 individual samples of each test material (N=10). The statistical analysis (one-way ANOVA) showed no significant difference for total solids and no difference for total fat content by the used methods (p>0.05). Since the drying method by hot air oven at 102 ± 2°C is the most commonly used for total solids in food laboratories, it was selected for further inter-laboratory study. For total fat determination, the alkaline hydrolysis method (Roese-Gottlieb) was selected for further inter-laboratory study since it is less time-consuming and involves fewer steps than the acid hydrolysis method. Seventeen laboratories participated in the inter-laboratory study and seven representative test materials with varying levels of total solids and fat were used. The method performance characteristics are presented. These methods were proposed to CODEX and endorsed as the CODEX standard methods (type I) for aqueous coconut milk and coconut cream analyses. © 2010 Elsevier Inc. Source

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