Natrium benzoat dan kalium sorbat merupakan bahan tambahan pangan yang secara luas digunakan pada bahan makanan ataupun minuman guna mencegah atau menghambat kerusakan bahan pangan yang dapat disebabkan oleh jamur, bakteri ataupun mikroba pembusuk. Penentuan kadar natrium benzoat dan kalium sorbat dalam bahan makanan seperti kecap dan saus tomat dilakukan dengan teknik HPLC fasa terbalik dengan kolom C18 dan menggunakan fasa gerak berupa campuran metanol dan buffer fosfat. Kondisi optimum pemisahan kedua bahan pengawet diperoleh pada komposisi fasa gerak metanol : buffer fosfat (15:85) dengan pH buffer 6,8 serta laju alir eluen 1,0 mL/min. Kondisi optimum pemisahan kedua bahan pengawet tersebut memenuhi parameter validasi dengan persen perolehan kembali > 90% dan %RSD < 2% untuk uji presisi. Batas deteksi (LoD) untuk natrium benzoat dan kalium sorbat berturut- turut 2,305 mg/L dan 0,390 mg/L sementara limit kuantisasi (LOQ) natrium benzoat dan kalium sorbat masing-masing sebesar 7,685 mg/L dan 1,300 mg/L.

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Sodium benzoate and potassium sorbate are food additives which widely used in foods or beverages to prevent or to delay the decay of foodstuffs that can be caused by fungi, bacteria, or microbe. Determination of the amount of sodium benzoate and potassium sorbate in foods namely soy sauce and tomato sauce was done by HPLC technique in reverse phase with C18 column and the blend of methanol and phosphate buffer as mobile phase. The optimum separation condition for both preservatives was achieved at methanol and phosphate buffer blending ratio of 15 : 85 in which the buffer's pH was 6,8 and the flow rate was 1,0 mL/min. The optimum separation condition for both preservatives agreed to the validation parameters with the percent recovery higher than 90% and %RSD smaller than 2% for the presicion. The limit of detection for sodium benzoate and potassium sorbate were 2,305 mg/L and 0,390 mg/L respectively, while the limit of quantization for sodium benzoate and potassium sorbate were 7,685 mg/L and 1,300 mg/L respectively.