Improvement of a GC-MS analytical method for the simultaneous detection of 3-MCPD and 1,3-DCP in food.

Chloropropanols such as 3-monochloropropane-1,2-diol (3-MCPD) and 1,3-dichloropropan-2-ol (1,3-DCP) are produced by heat treatment in the presence of fat and hydrochloric acid during the manufacture of food stuffs such as hydrolyzed vegetable protein and soy sauce. 3-MCPD and 1,3-DCP have been detected in several foods. An efficient, highly selective GC-MS method was developed to determine the concentration of 3-MCPD and 1,3-DCP in food. Calibration curves for 3-MCPD and 1,3-DCP were constructed, and a correlation of determination (r2) ≥ 0.9990 was obtained. The limits of detection and quantitation for 3-MCPD in food were 0.6 and 2.0 µg/kg, respectively, and those for 1,3-DCP were 0.2 and 0.6 µg/kg, respectively. To the best of our knowledge, this GC-MS-based method is a newly improved analytical procedure for the simultaneous separation and determination of 3-MCPD and 1,3-DCP, at once and at low levels (µg/kg).

Isolation and structural characterization of a novel sibutramine analogue, chlorosipentramine, in a slimming dietary supplement, by using HPLC-PDA, LC-Q-TOF/MS, FT-IR, and NMR.

A novel sibutramine analogue was detected in a slimming formula by high performance liquid chromatography with a photo diode detector array (HPLC-PDA). The unknown compound exhibited an ultraviolet (UV) spectrum that was similar to that of chlorosibutramine, despite having a different HPLC retention time. Further analysis of the slimming formula by LC-quadrupole time-of-flight mass spectrometry (LC-Q-TOF/MS) showed that the unknown compound had the formula C18H27Cl2N. To elucidate the structure of this new sibutramine analogue, the target compound in the slimming formula was isolated on a preparative-LC system equipped with a PDA. After analysis by fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy, the unknown compound was identified as a sibutramine analogue in which the iso-butyl group on the side chain is replaced with an iso-pentyl group. This new sibutramine analogue was identified to be 1-(1-(3,4-dichlorophenyl)cyclobutyl)-N,N,4-trimethylpentan-1-amine and has been named as chlorosipentramine.

Heteroassembled gold nanoparticles with sandwich-immunoassay LSPR chip format for rapid and sensitive detection of hepatitis B virus surface antigen (HBsAg).

This study aimed to develop a more sensitive method for the detection of hepatitis B surface antigen (HBsAg) using heteroassembled gold nanoparticles (AuNPs). A single layered localized surface plasmon resonance (LSPR) chip format was developed with antigen-antibody reaction-based detection symmetry using AuNPs, which detected HBsAg at 10 pg/mL. To further improve the detection limit, a modified detection format was fabricated by fixing a secondary antibody (to form a heteroassembled sandwich format) to the AuNP monolayer, which enhanced the detection sensitivity by about 100 times. The developed heteroassembled AuNPs sandwich-immunoassay LSPR chip format was able to detect as little as 100 fg/mL of HBsAg within 10-15 min. In addition, the heteroassembled AuNPs sandwich-immunoassay LSPR chip format did not show any non-specific binding to other tested antigens, including alpha fetoprotein (AFP), C-reactive protein (CRP), and prostate-specific antigen (PSA). These findings confirm that the proposed detection strategy of heteroassembled AuNPs sandwich-immunoassay LSPR chip format may provide a new platform for early diagnosis of various human diseases.

Identification and structural elucidation of a new sildenafil analogue, dithiopropylcarbodenafil, from a premixed powder intended as a dietary supplement.

A new sildenafil analogue was detected during the monitoring of a premixed powder intended as a dietary supplement. The ultraviolet (UV) spectrum of the unknown compound was similar to that of dithiodesmethylcarbodenafil and dithiodesethylcarbodenafil, although their corresponding HPLC peaks were observed at different retention times. The chemical structure of the unknown compound was characterized by liquid chromatography-quadrupole-time-of-flight mass spectrometry (LC-Q-TOF/MS), followed by nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. The comparison of its structure with that of dithiodesmethylcarbodenafil, revealed that the N-methyl group on the piperazine ring is replaced by a propyl group. This new sildenafil analogue was identified as 5-(2-ethoxy-5-(4-propylpiperazine-1-carbonothioyl)phenyl)-1-methyl-3-propyl-1,6-dihydro-7H-pyrazolo[4,3-d]pyrimidine-7-thione and designated as a dithiopropylcarbodenafil. To the best of our knowledge, this is the first study reporting the identification and characterization of dithiopropylcarbodenafil.

Monitoring of the amphetamine-like substances in dietary supplements by LC-PDA and LC-MS/MS.

Recently, amphetamine-like substances derived from the ß-phenylethylamine core structure have been detected in dietary supplements. Especially, ß-methylphenylethylamine (BMPEA), an amphetamine isomer, has been found in dietary supplements labeled as containing Acacia rigidula. The U. S. Food and Drug Administration determined that BMPEA is not naturally present in food and does not meet the statutory definition of a dietary ingredient. In addition, BMPEA has been classified as a psychotropic drug in South Korea and a doping substance by the World Anti-Doping Agency. The aim of this study was to determine whether dietary supplements contained amphetamine and amphetamine-like substance, including ß-phenylethylamine (ß-PEA) and BMPEA using LC-PDA and LC-MS/MS. In 10 of 110 samples, illegally added compounds were detected in the following ranges; ß-PEA 1.4-122.0 mg/g and BMPEA 4.7-37.6 mg/g. This study will contribute to enhancement of food safety in the South Korea.

Identification and quantification of adulteration in Garcinia cambogia commercial products by chromatographic and spectrometric methods.

Species of genus Garcinia are rich sources of bioactive constituents with antimicrobial, anticancer, anti-inflammatory, hepatoprotective and anti-HIV activities. Commercial products of Garcinia cambogia are used as anti-obesity drugs with increasing market demand. Because of the high price of its products, it can be adulterated with similar lower-priced species. This study was designed to develop and validate an accurate and efficient method for the detection of any adulteration (G. indica) in G. cambogia products. For this purpose, high performance liquid chromatography (HPLC) was used to analyse the ethanolic fruit rind extracts of G. cambogia and G. indica, their formulations of 0.5, 1, 2, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 95% G. indica with G. cambogia, and 11 G. cambogia commercial products. The analytical methods were validated by quality assurance parameters of linearity, sensitivity, precision and accuracy. Two marker peaks were detected in G. indica fruit extract, whereas G. cambogia did not show these peaks. The detected peaks were identified as anthocyanins; cyanidin-3-O-sambubioside and cyanidin-3-O-glucoside. In the study to determine the effect of pH and temperature on the stability of its anthocyanin content, HPLC analysis of G. indica extract showed the highest content at pH 1 and 50°C. Using two different mobile phases, the limits of detection (LOD) for cyanidin-3-O-sambubioside and cyanidin-3-O-glucoside were 0.036 and 0.059, and 0.022 and 0.033 mg kg-1, respectively. Furthermore, the inter-day precision (< 3.2%) confirmed that the applied analytical method fulfils the required criteria of Association of Official Analytical Chemists (AOAC). From this study, it was found that the HPLC method used for the detection of adulteration in G. cambogia products is rapid and accurate.

Specific PCR assays to determine bovine, porcine, fish and plant origin of gelatin capsules of dietary supplements.

Gelatin, a purified protein derived mostly from pig skin and bovine tissue, is used widely in both food and pharmaceutical industries. Here, to determine the species of origin of capsule gelatin, we developed a sensitive and reliable test using the polymerase chain reaction (PCR) method, which included 1) species-specific or universal primer sets, designed to detect short 16S ribosomal RNA (rRNA) gene sequences from cow, pig, and fish (tilapia) as well as genes encoding the large subunit of plant ribulose-1,5-bisphosphate carboxylase oxygenase and 2) species-specific PCR coupled with whole-genome amplification. This method was used to verify manufacturing label claims of 28 gelatin capsule samples sold as dietary supplements. The results from 27 samples were consistent with gelatin-related information on the manufacturer label, while one sample that mentioned tilapia gelatin was found to contain only bovine DNA. This rapid method can therefore be used to verify the authenticity of gelatin capsules.

Gas chromatograph-mass spectrometric method for the determination of carvedilol and its metabolites in human urine.

A sensitive and efficient method was developed for the determination of carvedilol and its metabolites in human urine by gas chromatography-mass spectrometry (GC-MS). Urine samples were hydrolyzed with beta-glucuronidase/arylsulfatase (from Helix pomatia) and the target compounds were extracted with liquid-liquid extraction. The extracts were completely derivatized with MSTFA and MBTFA and analyzed by GC-MS using an Ultra-2 column. The linearity of the assay ranges were 0.75-75 ngmL(-1) for carvedilol and o-desmethyl carvedilol (o-DMC), and 3.0-75 ngmL(-1) for 4-hydroxyphenyl carvedilol (4-HPC) and 5-hydroxyphenyl carvedilol (5-HPC). The absolute recovery of carvedilol and its metabolites added to a blank urine sample was 80.1-97.8%. The limits of detection (LOD) and quantitation (LOQ) of carvedilol and o-DMC were 0.30 and 0.75 ngmL(-1), and its of 4-HPC and 5-HPC were 0.75 and 3.0 ngmL(-1), respectively. The reproducibilities were 1.86-11.5% for the intra-day assay, and 0.70-1.71% for the inter-day assay precision and the degree of inaccuracy was -3.0 to 3.9% at the concentration of 75 ngmL(-1). The proposed GC-MS method was effective for the determination of carvedilol and its three metabolites in human urine.