Simplify the following text for a Grade 13 native English-speaking person.
Original: In analytical chemistry , a trace element is an element in a sample that has an average concentration of less than 100 parts per million ( ppm ) measured in atomic count , or less than 100 micrograms per gram .
Simplified: In analytical chemistry , a trace element is an element in a sample that has an average concentration of less than 100 parts per million measured in atomic count , or less than 100 micrograms per gram .