You got to be joking right?? 4k for just diploma holder?? HR would rather hire a 1st class honors at a cheaper salary than to pay 4k to a diploma holder whose "experience" may not be exactly "professional" experience... most likely to be in an assistant kind of job position or some other menial supporting role...
My advise is to pursue a chemistry degree so that people will not use your diploma status against you when you are negotiating for better salary.. In Singapore, without the right papers to back you up.. You will always be at the disadvantage... This is more so in the chemical industry where you are from.. Knowledge certified by a degree is a must for better remunneration...