果汁中天然色素紫胶红的UPLC/TUV定量检测及UPLC - MS/MS结构确证

摘要

建立了天然色素紫胶红各组分的UPLC/TUV定量检测及UPLC - MS/MS结构确证方法,并将所建立的分析方法应用于果汁中紫胶红色素的定性定量检测.通过Oasis(R) HLB小柱固相萃取技术净化、提取果汁饮料样品中的紫胶红色素.使用Waters Acquity UPLC BEH Shield RP C18(1.7 μm,2.1 mm×100 mm)色谱柱,以乙腈和0.1％甲酸水溶液为流动相梯度洗脱,经UPLC分离,TUV检测器在286 nm波长下,串联质谱SIR模式检测,并通过MS/MS断裂机理分析对天然色素紫胶红中的各组分进行结构确证.采用面积归一化法确定紫胶红A、紫胶红B、紫胶红C与紫胶红E的相对含量分别为57.95％、31.33％、6.12％、2.96％.采用外标法定量,4种混合组分在0.029 ～11 mg/L范围内线性良好(r＞0.999),回收率为83％ ～ 111％,RSD为2.3％～9.2％,检出限为0.008 7 ～0.17 mg/kg,定量下限为0.029～0.58 mg/kg,可满足食品中天然色素含量的分析要求.%An ultra performance liquid chromatography - tandem mass spectrometric ( UPLC/TUV -MS/MS) method was developed for the determination and validation of laccaic acids in juice. The juice samples were cleaned by solid-phase extraction technique with Oasis HLB cartridge. The targeted compounds were separated on a Waters Acquity UPLC BEH Shield RP C18 column with aceton-trile -0. 1% formic acid as mobile phase by gradient elution, and detected with TUV detector at 286 nm. A quadrupole mass spectrometer with atmospheric electrospray ionization source was used for the identification under SIR mode and the collision induced dissociation analysis. The external standard method was used for quantitation analysis. It was found that the lac dye extract consisted of laccaic A, laccaic B, laccaic C and laccaic E, of which the relative contents were 57.95% , 31.33% , 6.12% and 2.96% , respectively, based on the area normalization method, and the calibration curves for four laccaic acids showed good linearities in the range of 0. 029 - 11 mg/L with correlation coefficients higher than 0. 999. The average recoveries of high, medium and low three spiked concentration levels were between 83% and 111% , with relative standard deviations( RSDs) of 2. 3% -9. 2% . The limits of detection (LOD) were in the range of 0. 008 7 -0. 17 mg/kg for the four components in juice matrix, and their limits of quantitation(LOQ) were 0. 029 -0. 58 mg/kg. The results demonstrated that the proposed method for laccaic acids determination in juice could meet the requirements for the natural color analysis in food safety.