Is the zakat nisab for gold to be extracted from pure gold (24 karat), or from adulterated gold if the gold content is predominant, knowing that it is possible to ascertain the percentage of pure gold nowadays?

There is no Zakat on adulterated gold and silver until their pure content reaches the nisab. This is the view of the majority of scholars, in contrast to Abu Hanifa, who holds that Zakat is obligatory if the adulterated metal reaches the nisab and the adulteration is less than half. The majority refutes Abu Hanifa's view by citing the Prophet's (peace be upon him) saying: "There is no sadaqa (Zakat) on less than five awāq of silver."