新技术6:乙氧基黄叱精指示剂CIELAB色空间颜色特征
摘要:用CIE 1976(L*,a*,b*)色空间方法对乙氧基黄叱精在不同pH环境进行了测量,发现其变色点有8个,与文献记载有较大差异。用于指示的指标a*值、b*值、C*值、△E1、△E1-V可以作为变色的指标,发现在其在高pH环境有新的颜色变化,拟补了传统资料的不足。
关键词:乙氧基黄叱精,CIE,色度值,数字化图1. 乙氧基黄叱精的化学结构式
图1. 乙氧基黄叱精指示剂在pH环境的吸收曲线
图2显示,乙氧基黄叱精在不同pH值的溶液中的最大吸收峰是不同的。当pH值增加时,吸收峰向短波长方向移动。在pH1、pH2、pH3、pH4、pH5、pH6时,最大吸收峰的波长依次是480nm、480 nm、475 nm、465 nm、450 nm、445 nm。其中在pH3以后至pH6期间变化幅度较大,说明其变色阈值在该范围内激烈变化。pH6以后,即使pH增加,最大吸收峰也是445nm,最大吸收峰保持不变,说明分子结构在pH6以后已经保持稳定,不在变化。表1. 不同PH环境下乙氧基黄叱精指示剂最大吸收峰的变化
PH 波长 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
445 | 1.12468 | 1.43217 | 1.40751 | 1.37924 | 1.23078 | 0.97832 | 1.32918 | 0.93405 | 1.19237 | 1.24271 | 0.94790 | 1.01212 |
450 | 1.21149 | 1.54126 | 1.49826 | 1.43608 | 1.23844 | 0.96863 | 1.31602 | 0.92405 | 1.17872 | 1.22770 | 0.93672 | 0.99734 |
455 | 1.28742 | 1.63532 | 1.57194 | 1.47602 | 1.22794 | 0.94405 | 1.28232 | 0.89929 | 1.14608 | 1.19324 | 0.91068 | 0.96662 |
460 | 1.35021 | 1.71316 | 1.63171 | 1.49822 | 1.19944 | 0.90360 | 1.22672 | 0.86005 | 1.09437 | 1.13859 | 0.86924 | 0.91964 |
465 | 1.40037 | 1.77633 | 1.67313 | 1.50326 | 1.15367 | 0.84911 | 1.15278 | 0.80715 | 1.02535 | 1.06594 | 0.81449 | 0.85863 |
470 | 1.43642 | 1.81886 | 1.69673 | 1.49047 | 1.09180 | 0.78197 | 1.06144 | 0.74193 | 0.94079 | 0.97700 | 0.74723 | 0.78455 |
475 | 1.45564 | 1.84178 | 1.70080 | 1.46021 | 1.01758 | 0.70602 | 0.95705 | 0.66829 | 0.84553 | 0.87697 | 0.67100 | 0.70267 |
480 | 1.45811 | 1.84207 | 1.68544 | 1.41504 | 0.93498 | 0.62550 | 0.84801 | 0.59095 | 0.74455 | 0.77160 | 0.59140 | 0.61706 |
表2. 乙氧基黄叱精指示剂的色度值变化
PH | L* | a* | b* | 体积V |
0.0 | 99.69 | -0.049 | 0.193 | 99.6889 |
0.1 | 100.11 | 6.872 | 5.151 | 100.4787 |
0.2 | 89.24 | 15.975 | 13.688 | 91.6870 |
0.3 | 85.41 | 19.814 | 17.486 | 89.4094 |
0.4 | 78.14 | 23.107 | 20.514 | 84.0297 |
0.5 | 71.66 | 25.710 | 23.579 | 79.6994 |
0.6 | 70.50 | 26.820 | 25.011 | 79.4685 |
0.7 | 84.97 | 34.769 | 33.484 | 97.7211 |
0.8 | 84.58 | 35.572 | 34.636 | 98.0757 |
0.9 | 83.93 | 36.321 | 35.439 | 98.0762 |
1.0 | 83.19 | 37.680 | 37.273 | 98.6364 |
1.1 | 82.75 | 38.359 | 38.064 | 98.8353 |
1.2 | 82.42 | 38.907 | 38.796 | 99.0546 |
1.3 | 82.26 | 39.278 | 39.512 | 99.3499 |
1.4 | 81.67 | 39.497 | 39.691 | 99.0195 |
1.5 | 81.44 | 39.774 | 40.255 | 99.1708 |
1.6 | 81.35 | 40.009 | 40.501 | 99.2936 |
1.7 | 81.23 | 40.230 | 40.795 | 99.4020 |
1.8 | 81.11 | 40.379 | 41.054 | 99.4763 |
1.9 | 81.10 | 40.526 | 41.309 | 99.6326 |
2.0 | 81.01 | 40.602 | 41.622 | 99.7140 |
2.1 | 80.97 | 40.641 | 41.609 | 99.6936 |
2.2 | 80.88 | 40.698 | 41.693 | 99.6779 |
2.3 | 80.85 | 40.708 | 41.940 | 99.7650 |
2.4 | 80.85 | 40.741 | 41.879 | 99.7505 |
2.5 | 80.85 | 40.712 | 42.091 | 99.8320 |
2.6 | 80.86 | 40.683 | 42.107 | 99.8304 |
2.7 | 80.88 | 40.660 | 42.149 | 99.8532 |
2.8 | 80.88 | 40.555 | 42.261 | 99.8640 |
2.9 | 80.96 | 40.515 | 42.367 | 99.9514 |
3.0 | 81.00 | 40.385 | 42.409 | 99.9525 |
3.1 | 81.26 | 39.874 | 42.595 | 100.0403 |
3.2 | 81.22 | 39.991 | 42.577 | 100.0456 |
3.3 | 81.36 | 39.656 | 42.633 | 100.0511 |
3.4 | 81.42 | 39.533 | 42.704 | 100.0787 |
3.5 | 81.53 | 39.329 | 42.824 | 100.1379 |
3.4 | 81.59 | 39.208 | 42.878 | 100.1638 |
3.5 | 81.93 | 38.464 | 43.151 | 100.2673 |
3.7 | 81.93 | 38.440 | 43.067 | 100.2261 |
3.7 | 82.15 | 37.989 | 43.228 | 100.2986 |
3.8 | 82.85 | 36.356 | 43.882 | 100.5571 |
3.9 | 83.40 | 35.157 | 44.100 | 100.6777 |
4.1 | 84.20 | 33.320 | 44.636 | 100.9571 |
4.3 | 88.50 | 23.191 | 47.354 | 103.0190 |
4.5 | 91.69 | 15.594 | 49.187 | 105.2112 |
4.8 | 94.73 | 8.277 | 50.756 | 107.7905 |
5.0 | 96.42 | 4.150 | 51.546 | 109.4090 |
5.1 | 98.05 | 0.170 | 52.399 | 111.1734 |
5.3 | 98.98 | -2.090 | 52.788 | 112.2005 |
5.5 | 99.86 | -4.237 | 53.337 | 113.2886 |
5.7 | 100.26 | -5.226 | 53.495 | 113.7611 |
6.1 | 100.72 | -6.352 | 53.603 | 114.2710 |
6.9 | 100.90 | -6.775 | 53.706 | 114.5014 |
7.1 | 100.90 | -6.756 | 53.669 | 114.4810 |
7.3 | 100.97 | -6.915 | 53.680 | 114.5615 |
7.7 | 101.04 | -7.092 | 53.755 | 114.6655 |
7.9 | 101.07 | -7.118 | 53.816 | 114.7281 |
8.1 | 101.10 | -7.172 | 53.844 | 114.7660 |
8.4 | 101.12 | -7.182 | 53.778 | 114.7559 |
8.6 | 101.13 | -7.189 | 53.782 | 114.7662 |
8.9 | 101.08 | -7.053 | 53.732 | 114.6906 |
9.1 | 101.12 | -7.167 | 53.743 | 114.7365 |
9.4 | 101.14 | -7.204 | 53.749 | 114.7586 |
9.6 | 101.13 | -7.179 | 53.708 | 114.7346 |
9.7 | 101.15 | -7.208 | 53.723 | 114.7574 |
9.8 | 101.14 | -7.217 | 53.771 | 114.7759 |
10.0 | 101.15 | -7.229 | 53.692 | 114.7456 |
10.2 | 101.16 | -7.220 | 53.727 | 114.7665 |
10.3 | 101.17 | -7.235 | 53.637 | 114.7333 |
10.4 | 101.17 | -7.208 | 53.631 | 114.7286 |
10.5 | 101.18 | -7.243 | 53.628 | 114.7385 |
10.7 | 101.19 | -7.273 | 53.584 | 114.7328 |
10.8 | 101.19 | -7.287 | 53.584 | 114.7359 |
10.9 | 101.20 | -7.286 | 53.540 | 114.7197 |
11.0 | 101.20 | -7.336 | 53.531 | 114.7164 |
11.1 | 101.21 | -7.311 | 53.420 | 114.6728 |
11.2 | 101.22 | -7.301 | 53.279 | 114.6188 |
11.3 | 101.18 | -7.334 | 53.214 | 114.5541 |
11.4 | 101.22 | -7.348 | 53.225 | 114.5995 |
11.5 | 101.24 | -7.360 | 53.063 | 114.5419 |
11.6 | 101.24 | -7.380 | 52.937 | 114.4839 |
11.7 | 101.26 | -7.373 | 52.914 | 114.4859 |
11.8 | 101.24 | -7.358 | 52.952 | 114.4887 |
11.9 | 101.24 | -7.430 | 53.068 | 114.5460 |
12.0 | 101.22 | -7.386 | 53.149 | 114.5676 |
12.1 | 101.00 | -7.339 | 53.267 | 114.4185 |
12.2 | 102.52 | -7.426 | 54.155 | 116.1813 |
12.3 | 102.48 | -7.391 | 54.337 | 116.2304 |
12.3 | 102.45 | -7.378 | 54.408 | 116.2382 |
12.4 | 101.37 | -7.420 | 53.900 | 115.0440 |
12.5 | 102.38 | -7.330 | 54.819 | 116.3660 |
图3. 乙氧基黄叱精指示剂在不同pH环境的CIE 1976(L*,a*,b*)参数(L*,a*,b*、C*,H*)—pH曲线
图4. 乙氧基黄叱精指示剂在不同pH环境的CIE 1976(△E1、△E1-V、△E2、△E2φ、△E2α、△E2-V、△E3、△E3-V)参数—pH曲线
图5. 乙氧基黄叱精指示剂在不同pH环境的CIE 1976(σE、σL*、σa*、σb*、σC*、σH*)参数—pH曲线
图3-1. 乙氧基黄叱精指示剂在不同pH环境的CIE 1976(L*)参数—pH曲线
图3-1的明度值L*在pH0.5处有比较激烈的下陷,pH4处有明显的上升至pH5.5后,趋于平缓。与资料的pH变色域pH3.5~ 5.5(红→黄)关系不大。只能说明在pH5.5之前,溶液的透明度变化比较大。图3-2. 乙氧基黄叱精指示剂在不同pH环境的CIE 1976(a*,b*)参数—pH曲线
图3-2中,pH的初始颜色从pH0到pH1的位置之间,呈明显的红黄色;pH1至pH3之间比较稳定;pH3开始至pH6之间,溶液变化比较激烈,依次为红黄色、黄色、黄色偏蓝;在pH6以后,黄色偏蓝的颜色保持稳定。图3-3. 乙氧基黄叱精指示剂在不同pH环境的CIE 1976(C*,H*)参数—pH曲线
从图3-3中看出,C*曲线变化不明显,不能作为颜色突变的指示性指标。图3-4. 乙氧基黄叱精指示剂在不同pH环境的CIE 1976(H*)参数—pH曲线
图4-1. 乙氧基黄叱精CIE 1976(L*,a*,b*)参数—pH曲线(△E1、△E1-V)
图4-2. 乙氧基黄叱精CIE 1976(L*,a*,b*)参数—pH曲线(△E2、△E2-V)
图4-3. 乙氧基黄叱精CIE 1976(L*,a*,b*)参数—pH曲线(△E2φ、△E2α)
图4-4. 乙氧基黄叱精CIE 1976(L*,a*,b*)参数—pH曲线(△E3、△E3-V)
图4-4中,△E3、△E3-V在pH4开始有变化,特别是△E3的变化较大,与图4-2中指标△E2、△E2-V在pH4.3处均有突出的峰相对应。图5-1. 乙氧基黄叱精指示剂在不同pH环境的CIE 1976(σE)参数—pH曲线
图5-2. 乙氧基黄叱精指示剂在不同pH环境的CIE 1976(σL*、σb*)参数—pH曲线
图5-3. 乙氧基黄叱精指示剂在不同pH环境的CIE 1976(σa*、σb*)参数—pH曲线
图5-4. 乙氧基黄叱精指示剂在不同pH环境的CIE 1976(σC*、σH*)参数—pH曲线
图5-5. 乙氧基黄叱精指示剂在不同pH环境的CIE 1976(σC*)参数—pH曲线