Final answer:
In the United States, the amount of pseudoephedrine one can purchase in one day is regulated by federal law to prevent misuse in the production of methamphetamine. The current maximum purchase limit is 3.6 grams per day, not exceeding 9 grams in a 30-day period.
Step-by-step explanation:
In the United States, the amount of pseudoephedrine that someone can purchase in one day is regulated by the federal government. Due to its potential misuse in the illegal production of methamphetamine, there are restrictions on the quantity of pseudoephedrine that an individual can purchase.
The current federal law allows a maximum purchase limit of 3.6 grams of pseudoephedrine per day, and no more than 9 grams in a 30-day period. These limits are in place to prevent excessive buying and to track the sales of pseudoephedrine.
It's important to note that these limits may vary by state, as some states have implemented stricter regulations on the sale and purchase of pseudoephedrine.