Provided in certain embodiments are new methods for forming azido modified biomolecule conjugates of reporter molecules, carrier molecules or solid support. In other embodiments are provided methods for enzymatically labeling a biomolecules with an azide group.

A method and system for using spatially modulated excitation/emission and relative movement between a particle (cell, molecule, aerosol, . . . ) and an excitation/emission pattern are provided. In at least one form, an interference pattern of the excitation light with submicron periodicity perpendicular to the particle flow is used. As the particle moves along the pattern, emission is modulated according to the speed of the particle and the periodicity of the stripe pattern. A single detector, which records the emission over a couple of stripes, can be used. The signal is recorded with a fast detector read-out in order to capture the blinking of the particles while they are moving through the excitation pattern. This concept enables light detection with high signal-to-noise ratio and high spatial resolution without the need of expensive and bulky optics.

Provided are methods for determining the amount of tamoxifen and its metabolites in a sample by mass spectrometry. In some aspects, the methods provided herein determine the amount of N-Desmethyl Tamoxifen. In some aspects, the methods provided herein determine the amount of N-Desmethyl Tamoxifen and other tamoxifen metabolites. In some aspects, the methods provided herein determine the amount of tamoxifen, N-Desmethyl Tamoxifen, and other tamoxifen metabolites.

Provided are methods for determining the amount of tamoxifen and its metabolites in a sample by mass spectrometry. In some aspects, the methods provided herein determine the amount of norendoxifen. In some aspects, the methods provided herein determine the amount of norendoxifen and tamoxifen. In some aspects, the methods provided herein determine the amount of norendoxifen and other tamoxifen metabolites. In some aspects, the methods provided herein determine the amount of tamoxifen, norendoxifen, and other tamoxifen metabolites.

Provided are methods for determining the amount of tamoxifen and its metabolites in a sample by mass spectrometry. In some aspects, the methods provided herein determine the amount of N-Desmethyl Tamoxifen. In some aspects, the methods provided herein determine the amount of N-Desmethyl Tamoxifen and other tamoxifen metabolites. In some aspects, the methods provided herein determine the amount of tamoxifen, N-Desmethyl Tamoxifen, and other tamoxifen metabolites.