Byrdwell William Craig
Food Composition and Methods Development Lab, Beltsville Human Nutrition Research Center, USDA, ARS, 10300 Baltimore Ave., Building 161, Beltsville, MD, 20705, USA.
BMC Res Notes. 2019 Aug 1;12(1):477. doi: 10.1186/s13104-019-4506-7.
Short-chain triacylglycerols (TAGs) in lipid extracts of biological samples are not sufficiently resolved using conventional reversed-phase separation on two C18 columns in series, or using a two-dimensional chromatographic separation with a silver ion column as the second dimension (D). An additional dimension of separation was required.
The hardware and software components to allow a second second-dimension (D) separation and three total separation dimensions were developed. Two contact closure (CC) activated 4-port, 2-position valves (4P2PVs) for ultra-high performance liquid chromatography (UHPLC) were joined together and used for one of two second dimensions in comprehensive two-dimensional liquid chromatography (2D-LC) coupled to four mass spectrometers simultaneously in parallel in an LC1MS2 × (LC1MS1 + LC1MS1) = LC3MS4 configuration. A timed contact closure circuit (TCCC) controlled the two UHPLC valves, operated by repetitive CCs for the 4P2PVs. The TCCC-controlled 4P2PVs were used to direct a portion of the D eluent to one of the two D's for separation by a quaternary UHPLC system that was not allowed by the commercial 2D-LC system. The D separation was a non-aqueous reversed-phase HPLC instrument used for separation of TAGs; the commercial 2D-LC D binary UHPLC was used for silver-ion chromatography of unsaturated TAGs; and the CC-controlled second D was used for separation of short-chain (SC) saturated TAGs.
使用串联的两根C18柱进行常规反相分离，或使用以银离子柱为第二维的二维色谱分离（D）时，生物样品脂质提取物中的短链三酰甘油（TAGs）无法得到充分分离。需要额外的分离维度。
开发了允许进行第二次第二维（D）分离和三个总分离维度的硬件和软件组件。将两个用于超高效液相色谱（UHPLC）的接触闭合（CC）激活的4端口、2位置阀（4P2PVs）连接在一起，并用于全二维液相色谱（2D-LC）的两个第二维之一，该2D-LC同时与四台质谱仪并行联用，采用LC1MS2 × (LC1MS1 + LC1MS1) = LC3MS4配置。一个定时接触闭合电路（TCCC）控制这两个UHPLC阀，通过对4P2PVs的重复CC操作来运行。由TCCC控制的4P2PVs用于将一部分D洗脱液导向两个D之一，以便通过四元UHPLC系统进行分离，而商用2D-LC系统不允许这样做。D分离是使用非水反相HPLC仪器分离TAGs；商用2D-LC D二元UHPLC用于不饱和TAGs的银离子色谱分析；由CC控制的第二个D用于分离短链（SC）饱和TAGs。
