Pengembangan Metode DGT (Diffusive Gradient in Thin Film) dengan Binding Agent MGO menggunakan Ekstrak Daun Dandang Gendis (Clinacanthus Nutans (Burm.f.) Lindau) untuk Pengukuran Fosfat di Lingkungan = Development of The DGT (Diffusive Gradient in Thin Film) Method with MGO Binding Agent using Dandang Gendis Leaf Extract (Clinacanthus Nutans (burm.f.) Lindau) for Phosphate Measurement in The Environment