[ska0007]

Having trouble with this question:

A 2.5g sample of milk powder was dissolved in 50mL of distilled water. A very small volume of that solution was analysed [for lead content, using atomic absorption spectroscopy] and gave an absorption reading of 0.130.

The zero standard, distilled water, gave an absorbance reading that was not zero. Suggest a reason for this.

[Arkcon]

Can you begin to figure this one out for yourself?  Do you have any guesses?  The Forum Rules, posted in red, at the top of each page say you should make an attempt.  Can you think about how the instrument works, to come up with an answer?

[ska0007]

At the time I wrote the post I had no ideas at all. The only one I can think of now is that some light was absorbed by the equipment used, e.g. the glass beaker holding the water or the monochromator?

[Arkcon]

That's a pretty good first guess.  One question: what do you mean by beaker holding the water -- is it really in the light path of an AAS?  If so, is it really a beaker, or something else?