Liquid chromatography - high resolution mass spectrometry (LC-HRMS) developed to screen some residues in rice. Pesticides, aflatoxin B1, aflatoxin B2, aflatoxin G1, aflatoxin G2 and quaternary ammonium surfactants were detected by the optimized method. Rice samples were extracted and cleaned by QuEChERS then analyzed by QExactive system with HESI ionization source for both negative and positive modes. The C18 reversed phase column was used and the mobile phase consists of water and Methanol containing 0.1% formic acid and 10 mM ammonium formate. The method was applied successfully to analyze 60 rice samples collected in Hanoi city. The results showed that 5 pesticides in 30 rice samples from 10.3 to 160 µg/kg.  

Introduction: Non-syndromic hearing loss (NSHL) in children, which has numerous causes, can impede or even postpone the acquisition of spoken language. In Vietnam, screening programs and genetic testing for NSHL are rarely applied. In this study, 31 pediatric patients had their medical histories collected alongside sequencing results for the GJB2 and TECTA genes to determine the prevalence of these mutations in the community and their associations with potential risk factors. Methods: Information and blood samples were collected from 31 severe-to-profound pediatric NSHL patients. DNA was extracted, amplified by polymerase chain reaction (PCR), and directly sequenced for the detection of GJB2 (connexin 26) and TECTA mutations. Results: No TECTA gene mutations were detected. GJB2 mutations were identified in eight patients (25.8%), with three (9.7%) cases of heterozygous c.109G>A (V37I), four (12.9%) cases of homozygous c.109G>A (V37I), and one (3.2%) case of heterozygous c.299-300delAT. There were no significant associations between having mutated GJB2 genes and living in urban areas, having a family history of prelingual deafness, or having an abnormal obstetric history (p > 0.05, Fisher's exact tests). Conclusion: Our study addresses the high prevalence of GJB2 mutations as causative factors in hearing loss in diagnosed patients at the Otorhino-laryngology Hospital in Ho Chi Minh City, Viet Nam. Further studies are required to obtain a better understanding of the genetic spectrum of NSHL and to articulate its relationship with various risk factors.

In this study, a method for simultaneous determination of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in paper-based food packaging was validated. The paper samples were extracted with ethanol/water (1 : 1, v/v) mixture at 70°C for 2 h by using an incubator shaker. The extracts were passed through 0.2 μm filters before LC-MS/MS analysis. The method detection limit and method quantification limit of both PFOA and PFOS were 0.1 and 0.3 ng/g, respectively. Correlation coefficients > 0.99 were obtained over concentration ranges from 0.3 to 10 ng/mL. The method recovery ranged from 100 - 106% with good repeatability (RSD < 5%). The method was applied to analyze 23 paper samples, however, PFOA and PFOS were not detected in any of these samples.

A sensitive method has been developed and validated for simultaneous determination of some steroid hormones (trenbolone, 17β-estradiol, progesterone, testosterone, estrone, melengestrol acetate and zeranol). Samples were hydrolyzed to release analytes, and analytes were then extracted from sample matrix using QuEChERS technique, detected and quantified by using reversed phase liquid chromatography coupled with tandem mass spectrometry. The tandem mass spectrometric detection was done by using ESI ion source working in positive mode and multiple reaction monitoring (MRM) quantitation. Validation results show that the method is sensitive and selective for analyzing seven steroid hormones on milk and dairy products. The quantitation limit of the method for these analytes ranged from 0.1 to 2.0 µg/kg. Method recovery was from 70.4 to 110.0 %. Relative coefficient of variation varied from 2.7 to 12%. The method was applied to determine steroid hormones in 40 milk and dairy product samples collected from different markets and commercial centers in Hanoi.