Okay. I'll try to help you and get the data without any surrounding whitespace.

Here's your example once again in a monospace font:

  Acq On    : 18 Feb 2007  22:39                       Operator: FJN
  Sample    : Jones 1925 10                            Inst    : GC_MS

     1) 5aAndrostan-3a,17a-diol     11.24  241   186712   2500.00         0.02
    27) Stigmasterol                26.97  394     9158   2500.00 ng      0.02
    30) Cholesteryl Butyrate        30.59  368    23219   2500.00         0.02

First of all, a pattern to get the text from the labels:

Acq On    : (\d{1,2}\s\w+\s\d{4}\s+\d+:\d+)\s+Operator: (\S*)\s+Sample    : (.*?)(?=  )\s+Inst    : (\S*)

Then a pattern for  the xx) ... lines.

^ *(\d+)\) (.*?)(?=  | \d) +(\d+\.\d+) +(\d+) +(\d+) +(\d+\.\d+) +([a-z]*) +(\d+\.\d+)

using the multiline (m) modifier

I'm assuming you are using spaces not tabs in the text. I didn't know that else might show in the ng (nanogram?) column so I just allowed a string of lowercase latin characters. If there's no weight column the result in the respective match will simply be NULL.

Oh, and my best wishes to Mr or Mrs Jones: get well soon (I guess?)!