The person tested may, at his own expense, have a physician, registered nurse, clinical laboratory technologist or clinical laboratory technician or any other qualified person of his choosing administer a test, approved by the Mississippi Forensics Laboratory created pursuant to Section 45-1-17, in addition to any other test, for the purpose of determining the amount of alcohol in his blood at the time alleged as shown by chemical analysis of his blood, breath or urine. The failure or inability to obtain an additional test by such arrested person shall not preclude the admissibility in evidence of the test taken at the direction of a law enforcement officer.