我现在是做EDTA测定钙的滴定度 颜色老是判断失误 请各位大神指教纯蓝色究竟是啥色 
图片是先后顺序 最后一个和倒数第二个那个才是所谓的纯蓝色 都分辨不清了 有做过这方面实验的大神能指教一下么[img=,690,920]https://ng1.17img.cn/bbsfiles/images/2019/10/201910291119326081_5945_3490514_3.png[/img][img=,690,516]https://ng1.17img.cn/bbsfiles/images/2019/10/201910291119331312_1482_3490514_3.png[/img][img=,690,516]https://ng1.17img.cn/bbsfiles/images/2019/10/201910291119334483_7588_3490514_3.png[/img][img=,690,516]https://ng1.17img.cn/bbsfiles/images/2019/10/201910291119337546_9475_3490514_3.png[/img][img=,690,516]https://ng1.17img.cn/bbsfiles/images/2019/10/201910291119341144_3807_3490514_3.png[/img]