离子对反相液相色谱-蒸发光散射检测法分析钻井液添加剂“小阳离子”的有效含量

建立了离子对反相液相色谱-蒸发光散射检测器测定钻井液添加剂“小阳离子”2,3-环氧丙基三甲基氯化铵(EPTMAC)和3-氯-2-羟丙基三甲基氯化铵(CHPTMAC)有效含量的方法。以Atlantis T3柱(150 mm×4.6 mm, 5 μm)为分析柱,流动相为甲醇-5 mmol/L七氟丁酸水溶液(10:90, v/v),流速为1 mL/min。蒸发光散射检测器漂移管的温度为50 ℃,气体压力为206.7 kPa(30 psi)。样品用超纯水稀释过滤后直接进样分析,10 min内EPTMAC和CHPTMAC获得分离和检测。采用二阶方程对标准曲线进行拟合,EPTMAC和CHPTMAC校正曲线的相关系数均为0.9995,检出限(S/N=3)分别为13 mg/L和18 mg/L,定量限(S/N=10)分别为45 mg/L和61 mg/L,平均回收率分别为91.2%～98.6%和93.2%～102.3%,相对标准偏差(n=5)分别为1.7%～2.5%和1.2%～1.8%。该方法快速准确,可用于油田钻井液添加剂“小阳离子”的质量控制。

Determination of the effective contents of small cation in drilling fluid additives using ion-pair reversed-phase liquid chromatography with evaporative light scattering detection

A method was developed for the determination the effective contents of “small cation”, 2,3-epoxypropyltrimethylammonium chloride (EPTMAC) and 3-chloro-2-hydroxypropyl-trimethylammonium chloride (CHPTMAC), in drilling fluid additives using ion-pair reversed-phase liquid chromatography with evaporative light scattering detection. The separation was performed on an Atlantis column (150 mm×4.6 mm, 5 μm) with the mobile phase of methanol-5 mmol/L heptafluorobutyric acid (10:90, v/v)at a flow rate of 1 mL/min. The drift tube temperature of the evaporative light scattering detector was set at 50 ℃ and the gas pressure was set at 206.7 kPa (30 psi). The sample was diluted by extra pure water and filtrated for analysis. The EPTMAC and CHPTMAC were completely separated and determined within 10 min. The calibration curves of them were fitted by quadratic equations. The correlation coefficients for both of them were 0.9995. The limits of detection were 13 mg/L and 18 mg/L, and the limits of quantifications were 45 mg/L and 61 mg/L for EPTMAC and CHPTMAC, respectively. Their average recoveries were 91.2%~98.6% and 93.2%~102.3% with the relative standard deviations (n=5) of 1.7%~2.5% and 1.2%~1.8%. These results demonstrate that the proposed method is simple and fast for the quality control of “small cation” in drilling fluid additives in oilfield.