Development of Analytical and Preparatory Techniques - Chlorophyll Biosynthesis and Technological Applications - page 94

and K 2 in Eqs. ( 3.41 ) and ( 3.42 ) and by further reduction of the substituted
equations, the latter assume the following form:

DV MPE ð E424 F591 Þ¼ 1 : 014 ð E424 F591 Þ 0 : 106 ð E417 F587 Þ (3.44)

and

MV MPE ð E417 F587 Þ¼ 1 : 013 ð E417 F587 Þ 0 : 131 ð E424 F591 Þ (3.45)

3.5.2.3 Calculation of Small Proportions of MV Mg-Protoporphyrins
in the Presence of Much Larger Proportions of DV
Mg-Protoporphyrins and in the Absence of Interference
by Other Tetrapyrroles

To detect very small proportions of MV Mg-Protos ( < 5 %) in the presence of much

larger proportions of DV Mg-Protos ( 95 %), the shortwavelength excitation

spectrum of the X + Y mixture is best recorded at an emission wavelength of
584 nm instead of at 587 nm. In this case the (E417 F587) Soret excitation
amplitudes in Eqs. ( 3.41 ), ( 3.42 ), ( 3.43 ), ( 3.44 ) and ( 3.45 ) are replaced by (E417F
584) Soret excitation amplitudes. The latter further optimize the detection of very
small proportions of MV Mg- Protos. As a consequence Eqs. ( 3.41 ) and ( 3.42 ) are
transformed to:

>

DV MPE ð E424 F591 Þ¼ 1 : 010 ð E424 F591 Þ 0 : 439 ð E417 F584 Þ (3.46)

and

MV MPE ð E417 F584 Þ¼ 1 : 010 ð E417 F584 Þ 0 : 023 ð E424 F591 Þ (3.47)

3.5.2.4 Conversion of the MV and DV Mg Protoporphyrins Soret
Excitation Ratios to MV and DV Mg-Protoporphyrins
Concentrations

As was just pointed out, Eqs. ( 3.44 ) and ( 3.45 )or ( 3.46 ) and ( 3.47 ) allow the
calculation of the net Soret excitation amplitudes of the MV and DV Mg-Protos
components in mixtures of these two tetrapyrroles. Although the absolute values of
the two Soret excitation magnitudes depend on the condition of the frozen sample
(vide supra), the relative amplitudes of the MV and DV Mg-Proto signals, for any
one sample, are independent of the frozen condition of that sample. This is because
the excitation spectra which are needed for solving Eqs. ( 3.44 )( 3.45 ), ( 3.46 ), ( 3.47 )
and ( 3.47 ) are recorded on the same frozen sample. As a consequence the ratio of