For those who have missed this achievement in any playthrough, I'd just like to point out that this achievement is cumulative over multiple playthroughs and saves. This means that we can manipulate the mechanics to be able to 'farm' the ADAM that you receive from a single little sister ADAM gathering.
If you have a save where there is a little sister to be rescued in the level, perfect - find the big daddy and little sister, take out the big daddy by your preferred methods, and then go to the first gathering, finally save when the little sister is done, but BEFORE you pick her up. This way you can load, pick up, load, pick up until you get the achievement.
If you do not have a save like the above, with prior knowledge of the campaign, you can get to the first ADAM gathering within 10-15 minutes of starting the game.
This can also be applied to the Trap Master and Look at You, Hacker achievements, too, as this is a great way to get a fair few splicers to one location. Simply save before you put the little sister down, and then you can either put traps down or hack bots to kill the splicers. Rinse and repeat.
Hope this helps!
(If you vote negatively, please let me know why so that I can improve the guide, thanks!)