A myo-inositol derivative: R1, R2, R3 and R4 are identical, being selected from PO3H2, PO3Na2, PO3K2, PO3Li2, PO3Ca, PO3Mg, PO3(NH4), PO3(RNH3)2, PO3(R2NH2)2, PO3(R4N)2, PO(OR)2, H, COZ and BHPP, where R is benzyl or alkyl of 1 to 6 carbon atoms and Z is an alkyl or arylalky group providing a cleavable protecting group; R5 of H, benzyl, 4-methoxybenzyl, COZ, PO3H2, PO3Na2, PO3K2, PO3Li2, PO3Ca, PO3Mg, PO3(NH4)2, PO3(RNH3)2, PO3(R2NH2)2, PO3(R4N)2, PO(OR)2, and BHPP, where R is benzyl or alkyl of 1 to 6 carbon atoms and Z is an alkyl or arylalky group providing a cleavable protecting group; X is one of CH2, CH2CH2O, and CH2CH2CH2O; n is an integer from 1 to 8; L1 is a single bond or CH2; L2 is one of a single bond, CONH, CH2CONH, CH2CH2CONH, CH2CH2NHCO, CH2CH2NHCONH, CH2CH2NHCSNH, CH2CH2NHSO2, CH2CH2CH2NHCO, CH2CH2CH2NHCONH, CH2CH2CH2NHCSNH, CH2CH2CH2NHSO2, NHCO, NHCONH, NHCSNH, OCONH, CH2, CH2CH2, CH2CH2O, CH2CH2S, CH2CH2NH, CH2CH2CH2, CH2CH2CH2O, CH2CH2CH2S, CH2CH2CH2NH, and NH—SO2; and R6 is a UV-visible chromophore, a UV-chromophore, a fluorescent moiety, or a radiolabeled moiety.