Development of Analytical and Preparatory Techniques - Chlorophyll Biosynthesis and Technological Applications - page 81

units, are also reported in Table 3.2 (column 7). The percent error between the
actual and calculated Soret excitation amplitudes for Chl a in the mixtures were
calculated and reported in column 8 of Table 3.2 . The mean per cent error (i.e. X 1 )
and the standard deviation of the mean per cent error (i.e.Sx 1 ) were then calculated
and reported in column 9 of Table 3.2 . The same procedure was applied for
mixtures of tetrapyrroles containing only 10 and 6 % of Chl a , respectively, and
equal amounts of the other three tetrapyrroles. The X 1 and Sx 1 values were
calculated and also reported in column 9 of Table 3.2 . Also reported in Table 3.2
(Mixture 1) is the data on the reliability of determining the Soret excitation
amplitude of pure solutions of Chl a in HEA, in the absence of other added
tetrapyrroles.
Altogether the data reported in Table 3.2 indicated that both the mean per cent
error (X 1 ) between the amount of pigment added and the amount determined by
calculation and the standard deviation of these determinations (Sx,) increased as the
proportion of Chl a in the mixture was decreased. The systematic variation in the
mean per cent error was corrected for in Eq. ( 3.33 ) by the [(A 1 )(X ] )/100factor. It is
obvious that

this correction becomes negligible for pure solutions of Chl

a (X 1 ¼ 0.7 %) and for mixtures in which the Chl a relative concentration

amounted to 27 % or more of the total tetrapyrrole content (X 1 ¼ 2.2 %). The

correction becomes significant, however, for mixtures containing between 10 and
6 % of Chl(ide) a (Table 3.2 ). In all cases the standard deviation (Sx 1 ) of the mean
per cent error was reasonable and ranged from

0.6 % to 11.5 % of the

A 1 calculated values (Table 3.2 ).
It is therefore recommended that for precise calculations with Eq. ( 3.1 ), the
proper values for X 1 , and Sx 1 , should be calculated by interpolation from Table 3.2 .
For less rigorous calculations an overall average value of +10 % for Xx and 5%

for Sx, may be used.

3.4.2 Calculation of Pheo(phorbide) a

3.4.2.1 Calculation of Pheophytin and Pheophorbide a [Pheo
(Phorbide)] a in Various Pigment Mixtures

The equation for calculating pheo(phorbide) a (F674 E4121] was derived from the
following simultaneous equations:

ð F674 E412 Þ¼ Chl ð ide Þ a ð F674 E412 Þþ Pheo ð bide Þ a ð F674 E412 Þ

þ Chl ð ide Þ b ð F674 E412 Þþ Pheo ð bide Þ b ð F674 E4l2 Þ

ð F674 E433 Þ¼þ k 13 Chl ð ide Þ a ð F674 E4l2 Þþ k 14 Pheo ð bide Þ a ð F674 E412 Þ

þ k 15 Chl ð ide Þ b ð F674 E412 Þþ k 16 Pheo ð bide Þ b ð F674 E4l2 Þ