1️⃣/🅱️

#parts per billion #ratio #billionth

🤏/🌍

#parts per billion #trace amount #tiny fraction #ratio #billionth

🔬/🅱️

#parts per billion #microscopic #trace analysis #billionth

💧/🅱️

#parts per billion #dilution #water quality #billionth

🧪🔬🅱️

#parts per billion #lab analysis #trace analysis #billionth