Mastitis merupakan penyakityang merugikan peternak sapiperah karena dapat menurunkan produksi susu. Untukpengobatan mastitis biasanya digunakan antibiotika. Halmi menyebabkan adanya residu dalam susu. TUJUanpenelitian mi adalah untuk mengetahui tenggang wakturesidu kloksasilin dalam susu yang berasal dari ambingyang menderita mastitis. Lima ekor sapi Frisian hoistainpenderita mastitis diberi 200 mg/kuartir/hari kloksasilinselama 3 hari berturut-turut. Residu dalam susu diamatiselama 10 hari dengan alat KCKT. Ekstraksi diawali denganpenambahan asetonitril untuk mengendapkan protein danlemak, kemudian penyar-ian dengan CH2C1 2 dalam suasanabufer fosfat •pH 2,2. Petroleum eter (30°-60°C) ditambahkanpada ekstrak CH2C12 untuk mempermudah ekstraksiselanjutnya menggunakan bufer fosfat pH 7. Filtrat yang• diperoleh ditambahkan ammonium sulfat Jenuh sebelum disaridengan asetonitril. Pada alat KCKT .digunakan kolompBondapak t19 RP (300 mm x 3,9 mm. 10 Mm) dengan fasegerak KH2PO4 0,01 M : CH7CN : CHOH (50 :30 : 20)dengan kecepatan aliran 1 mi/menit dan dideteksi pada220 nm. Hasil analisis menunjukkan bahwa residukloksasilin tidak terdeteksi lagi pada han ke-8 dihitungsejak hari pengobatan terakhir.

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Mastitis in dairy cow has caused a significant losses to

the farmers due to reduced in milk production. Intensive

used of antibiotics in the treatment of mastitis have

caused antibiotic residue in milk. A study was carried out

to determine withdrawal time of cloxacillin in milk

produced by mastitis dairy cow. Five Frisian ha1tain

suffering from mastitis were treated intramammarily with

200 mg/quarter/day of cloxacillin for 3 successive days.

The residue was observed for 10 days using HPLC method.

Extraction was performed with the addition of CH 3CN to

precipitate proteins and lipids, followed by CH.C1,, in

phosphate buffer at pH 22. Petroleum ether (30°-60°C) was

added to the CH2C1 2 extract to facilitate further

extraction in phosphate buffer at pH 7. Saturated ammonium

sulfate was added to the filtrate before extracting with

CHCN. HPLC analysis was carried out using /.iBondapak C18

Reversed-Phase column (300 mm x 3.9 mm, 10 m) and

KH2PO4 0.01 M : CH3CN : CH3OH (50 : 30 : 20) as mobile

phase with a flow rate of 1 ml/minute and detected at

220 nm. The results showed that cloxacillin residue was

not detected anymore in milk after 8 days since the last

day of treatment.