I took a different approach, probably less elegant and certainly less flexible than others. But it does seems to work. As the choice of some variable names might indicate ( %HoA $aref ), I am relatively new to perlish ways and am just getting familiar with usage of the various data structures. 

use strict;
use warnings;

my %HoA;
while ( <DATA> ) {
    next if m/^\D/;   # ignore lines not beginning with a digit

    my ( $SampleID, $Time, $A_ObsConc, $C_ObsConc, $F_ObsConc )
        = unpack("A9 A8 A15 A9 A*", $_);

    push @{ $HoA{A} } ,   [ $SampleID, $Time, $A_ObsConc ];
    push @{ $HoA{C} } ,   [ $SampleID, $Time, $C_ObsConc ];
    push @{ $HoA{F} } ,   [ $SampleID, $Time, $F_ObsConc ];
}

for my $key ( sort keys %HoA ) {

    for  my $aref ( @{ $HoA{$key} } ) {
        printf("%s %6s %9s %9s\n", $key, @$aref );
    }
}

__DATA__
               A     C     F
SampleID        Time    ObsConc ObsConc ObsConc
5        24      2.27E+06        687.02  32521.94
5        168     1.92E+06        525.02  22198.44
5        12      2.94E+06        896.39  41331.61
5        -0.5    2.23E+06        942.34  40616.49
5        8       4.03E+06        1371.32 45863.69
6        24      1.02E+06        1057.89 46341.04
6        168     3.14E+06        4987.32 42166.08

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In reply to Re: format conversion, please help by farang
in thread format conversion, please help by david_lyon

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