Api qstar pulsar 1 mass spectrometer

Melting points were determined with an SGW X-4 micromeltingpoint apparatus (Shanghai Shenguang Instrument Co. Ltd, Shanghai, China). UV spectra were measured on a PuXi TU-1810 UV-visible spectrophotometer (Shanghai Lengguang Technology Co. Ltd., Shanghai, China). 1D and 2D NMR spectra were obtained at 500 and 125 MHz for ¹H and ¹³C, respectively, on a Bruker Avance 500 MHz spectrometer (Bruker Biospin Group, Karlsruhe, Germany) with tetramethyl silane (TMS) as an internal standard. Mass spectra were generated on a VG Autospec 3000 (VG Instruments, London, UK) or an API QSTAR Pulsar 1 mass spectrometer (Applied Biosystems, Foster, Waltham, MA, USA). Analytical and semipreparative HPLC were performed using a Dionex HPLC system equipped with a P680 pump, an ASI-100 automated sample injector, and a UVD340U multiple wavelength detector controlled by Chromeleon software (version 6.80) (Dionex, Sunnyvale, CA, USA). Commercially available Si gel (200–300 mesh, Qingdao Haiyang Chemical Co., Qingdao, China), Lobar LiChroprep RP-18 (40–63 μm, Merck, Darmstadt, Germany), and Sephadex LH-20 (Pharmacia, Pittsburgh, PA, USA) were used for open column chromatography. All solvents were distilled prior to use.

NMR spectra were acquired
on a Bruker AV750 MHz spectrometer using a 5 mm TCI Cryoprobe. Chemical
shifts (δ) were referenced to the MeOH-d₄ solvent to provide specific shifts. Oligopeptide AAKLVFF
(purity >98%) was purchased from CSBio (Shanghai) Ltd. The 3 mm
NMR
tubes and MeOH-d₄ (purity 99.8%) were
purchased from Deutero GmbH. Mass spectra were recorded on an API
QSTAR Pulsar 1 mass spectrometer (Applied Biosystems, Foster City,
CA). UV spectra were read from a PuXi TU-1810 UV–visible spectrophotometer
(Shanghai Lengguang Technology Co., Ltd., Shanghai, China). Column
chromatography (CC) was used with silica gel (200–300 mesh,
Qingdao Haiyang Chemical Factory, Qingdao, China), Lobar LiChroprep
RP-18 (40–60 μm, Merck, Darmstadt, Germany), and Sephadex
LH-20 (18–110 μm, Merck, Germany). Thin layer chromatography
(TLC) was performed with silica gel GF254 precoated plates (100 ×
200 mm, Qingdao Haiyang Chemical Group Corp., Qingdao, China). A separation
and purification experiment was carried out with distilled organic
solvents.