这个有好几种不同的翻译吧,如果是上级给下级,可以说:I have asked Mr(or Mrs)XX to take charge of QC oeration,please contact him(or her) directy,thank you!
如果是平级,可以说：The QC job has been in the charge of Mr XX,not me any more ,pls contact him directly in future,thank you!