What to do if I had gas sprayed all over me at a gas station nd my hand was burning for about an hour and I missed a potential job interview?

You would not have a case, unfortunately.

1) First, bear in mind that you'd have to prove that the person (presumably a gas station attendent) was negligent, or unreasonably careless, in spraying you and that your own carelessness did not contribute. This may have been the case, but the important thing to remember is that it must be proven to win.

2) You can only sue for medical costs if you incur them, or pain and suffering for significant, long lasting pain or disability that affects your life in a material way. Or rather: you can sue for any injury, but the amount of money you could recover is limited to the severity and medical costs of the injury. A hand experiencing burning sensations for an hour would result in getting maybe a few dollars--far less than the cost of the lawsuit.

3) The missed job interview is not something you can recover for because--

a) You'd have to prove that there was no way you could have gone after having been sprayed with gas--i.e. you couldn't go anyway and deal with the discomfort; couldn't call and reschedule; etc.

b) More importantly, since you can't prove that you would have been hired had you gone to the interview, even if you can show that the spraying stopped you from going, you can't prove that actually cost you a job...and if you can't prove that, you can't recover any money.