She is most known for revolutionizing many in vitro self-testing systems for diabetes and other diseases while working at Miles Laboratories.

In December 1941 when Pearl Harbor was bombed, many young men either enlisted or were drafted into the army.

During her final year at Wooster, she took interest in the Koppers Chemical Company in Orrville, Ohio.

However, she was put down after hearing that her job would be testing the creosote that fence posts were dipped in before they were sold to local farms.

[4] Upon graduating from Wooster, Free immediately began working as a quality control chemist for Miles Laboratories (known as the creators of Alka-Seltzer), which involved testing the quality of ingredients in the company's line of vitamins[3] An offer from the Mellon Institute eventually came after a few weeks she accepted the offer from Miles, but she was unfortunately locked into her position by then.

[7] Eventually, they were able to create Multistix, which enabled a urine analysis that combined multiple tests into one strip.

[7] Several other testing strips were developed and added to the market, including Uristix, Ketostix, Dextrostix, Labstix, and the still-current product, Multistix.

[5][1] Free moved into the Growth and Development Department in 1969, and she eventually became the director of Specialty Test Systems seven years later.

She was Director of Marketing Services for the Research Products Division when Bayer Diagnostics acquired Miles in 1978.

In that year, she and her husband co-authored their second book, Urinalysis in Laboratory Practice, which is still a standard work in the field.

She has devoted special attention to educating both female and underprivileged students, through programs such as "Kids & Chemistry" and "Expanding Your Horizons.

[12] As president, she considered her top priority to be to raise public awareness of the positive role chemistry has played in our lives.