Jms 700 mstation

The perinatal dioxin exposure of children was estimated using the dioxin levels in their mothers’ breast milk collected one month after giving birth, since a previous study reported significant correlations between dioxin levels in breast milk and those in cord blood [23 (link)]. Seventeen 2,3,7,8-substituted congeners of polychlorodibenzodioxins (PCDDs) and polychlorodibenzofurans (PCDFs), including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), were measured using a gas chromatograph (HP-6980; Hewlett-Packard, Palo Alto, CA, USA) equipped with a high-resolution mass spectrometer (high-resolution-gas chromatography/mass spectrometry; MStation-JMS700, JEOL, Tokyo, Japan). More details of dioxin analysis were reported in our previous study [24 (link)]. The calculations of TEQ-PCDDs/PCDFs were referenced from the WHO 2005 toxic equivalent factor [25 (link)].
Increased risks (odds ratios) for high C-SARP aggression subscale scores associated with an increase in TCDD exposure were analyzed after adjusting for confounding factors, including the education of mothers, family income, area, sex, and the child’s age at the survey, using binary logistic regression analysis.

All commercially available materials from Sigma-Aldrich (Burlington, MA, USA), Daejung (Siheung, Korea), TCI (Tokyo, Japan), Chemieliva (Chongqing, China) and solvents were used without further purification. All small-scale screening reactions (≤10 mL of solvent) were performed in 50 mL round bottom flasks on a Radleys Carousel 6 Plus Reaction Station under an air atmosphere. HPLC was performed on a Hitachi LaChrom Elite HPLC system. ¹H NMR (400 MHz) and ¹³C NMR (100 MHz) were measured on a Bruker Avance 400 spectrometer system. ¹H NMR spectra chemical shifts were expressed in parts per million (ppm) downfield from tetramethylsilane, and coupling constants were reported in Hertz (Hz). Splitting patterns are indicated as follows: s, singlet; d, doublet; t, triplet; and q, quartet; m, multiplet. ¹³C NMR spectra were reported in ppm, referenced to deuterochloroform (77.16 ppm). Melting points were determined by DSC (Mettler Toledo). High resolution mass spectra (HRMS, JEOL MStation JMS-700) were obtained using an electron impact (EI) ionization technique (magnetic sector—electric sector double focusing mass analyzer) from the KBSI (Korea Basic Science Institute Daegu Center).

IR spectra were recorded on a JASCO FT-IR 410 infrared spectrophotometer (JASCO Inc.: Easton, MD, USA). The NMR experiments were performed on a Varian Unity 600 or 500 instrument (Varian Inc.: Palo Alto, CA, USA). Deuterated solvent was used as references for the ¹H and ¹³C NMR spectra. HREIMS and HRCIMS were performed on an MStation JMS-700 or a JMX-AX 500 spectrometer (JEOL Ltd.: Tokyo, Japan). TLC was carried out with silica gel 60 F254 and PR-18 F254 plates. HPLC was performed on a JASCO PU-1580 pump (JASCO Inc.: Easton, MD, USA) equipped with a JASCO UV-1575 detector (JASCO Inc.: Easton, MD, USA). All solvents used for extraction and isolation were of analytical grade.

Column chromatography was carried out using silica gel 60 (0.040–0.063 mm) (230–400 mesh ASTM). Thin-layer chromatography (TLC) was performed on precoated aluminum sheets coated with silica gel F250 (Merck, Germany). Nuclear magnetic resonance (NMR) experiments were carried out on a Bruker AVIII (500 MHz) spectrophotometer using CDCl₃ as the solvent and TMS as the internal standard. Mass spectral data were acquired on a JEOL MStation JMS-700 mass spectrometer.

Infrared absorbance spectra were collected with a Fourier transform infrared (FTIR) spectrometer (NICOLET 6700). Positive FAB-MS spectra were recorded on a JEOL MStation JMS700 mass spectrometer using m-nitrobenzyl alcohol as the matrix. 1H, gCOSY, and HSQC NMR experiments were performed with a Varian Mercury 400 MHz spectrometer. 13C experiments were performed with a Varian 400 MHz spectrometer equipped with a Varian OneNMR probe. Chemical shifts were referenced to the residual solvent peaks in CD3OD. Optical rotation was measured with a Jasco DIP 360 polarimeter fitted with a microcell (10 mm path length).

The synthesis of compounds 1–8 is detailed in Supplementary Methods (NMR spectra in Supplementary Figs. 11–18). All chemicals were purchased from Sigma Aldrich, Fluorochem, TCI organics or Cambridge Isotope Laboratories and used without further purification. Flash chromatography was carried out on a Reveleris X2 flash chromatography system. All NMR spectra were recorded at 25 ˚C. NMR spectra were measured on a Bruker Avance II 400 MHz, Avance III 400 MHz, Avance III 500 MHz or Avance III 600 MHz spectrometer. Chemical shifts are reported in ppm relative to the residual solvent peak. Chemical shifts (δ) are given in ppm and coupling constants (J) are quoted in hertz (Hz). Resonances are described as s (singlet), d (doublet), t (triplet), q (quartet) and m (multiplet). Electron impact mass spectrometry was carried out on a Jeol MStation JMS-700 high resolution mass spectrometer. Electrospray ionisation mass spectrometry was carried out on a Bruker microTOFq high resolution mass spectrometer (LTQ Orbitrap XL for compounds 7 and 8). Elemental analysis was measured with an Exeter CE-440 Elemental Analyser.

Optical rotation was measured using an auto digital polarimeter, and Fourier transform infrared (FT-IR) spectra were recorded using Nicolet 380 FT-IR spectrophotometer (Thermo Electron Corporation). Nuclear magnetic resonance (¹H NMR and ¹³C NMR) spectra were obtained using Varian Gemini 300 (300, 75 MHz) and Bruker Avance 500 (500, 125 MHz) using tetramethylsilane as internal standard. Low-resolution mass spectrometry profiles were obtained using a JEOL the MStation JMS-700. Chiral high-performance liquid chromatography (HPLC) analysis was performed using a Jasco LC-1500 Series HPLC system. Toluene (CaH₂), tetrahydrofuran (THF) (Na, benzophenone), and CH₂Cl₂ (CaH₂) reaction solvents were purified before use. The reagents used in this study were obtained from Aldrich, Acros, Alfa, Sigma, Merck, Fluka, TCI, and Lancaster, and purified or dried using a known method when necessary. Merck’s silica gel 60 (230–400 mesh) was used as the stationary phase in column chromatography.