A method for determining the purity or authenticity of a substance being transported in a container through a supply chain comprising: a. a step of providing an entry transmitter (310, 410) for generating a first multi-frequency coded ultrasonic signal, wherein said entry transmitter (310, 410) is a piezoceramic transmitter, and wherein the frequencies of said first multi-frequency coded ultrasonic signal comprises a primary frequency and higher harmonics of said primary frequency, and an entry receiver (320, 420) for receiving said first multi-frequency coded ultrasonic signal after it has passed through the container and through the substance, wherein said entry receiver (320, 420) is a piezoceramic receiver, wherein the phase of each frequency of said first multi-frequency coded ultrasonic signal is determined and wherein the travel times of the frequencies of said first multi-frequency coded ultrasonic signal are determined after it has passed through the container and through the substance; b. a step of generating an entry identifier of the substance in the container based on the phase of each frequency and the travel times of the frequencies of said first multi-frequency coded ultrasonic signal; c. a step of recording said entry identifier at an entry point of said supply chain; d. a step of transporting the substance in the container to a destination; e. a step of providing an exit transmitter for generating a second multi-frequency coded ultrasonic signal, wherein said exit transmitter is a piezoceramic transmitter and wherein the frequencies of said second multi-frequency coded ultrasonic signal comprises a primary frequency and higher harmonics of said primary frequency and an exit receiver for receiving said second multi-frequency coded ultrasonic signal after it has passed through the substance and the container, wherein said entry receiver (320, 420) is a piezoceramic receiver, wherein the phase of each frequency of said first multi-frequency coded ultrasonic signal is determined, and wherein the travel times of the frequencies of said second multi-frequency coded ultrasonic signal are deteminded after it has passed through the substance and the container; f. a step of generating an exit identifier of the substance in the container based on the phase of each frequency and the travel times of the frequencies of said second multi-frequency coded ultrasonic signal; and, g. a step of comparing said entry identifier and said exit identifier to determine whether the substance in the container has been altered during travel through the supply chain. a. a step of providing an entry transmitter (310, 410) for generating a first multi-frequency coded ultrasonic signal, wherein said entry transmitter (310, 410) is a piezoceramic transmitter, and wherein the frequencies of said first multi-frequency coded ultrasonic signal comprises a primary frequency and higher harmonics of said primary frequency, and an entry receiver (320, 420) for receiving said first multi-frequency coded ultrasonic signal after it has passed through the container and through the substance, wherein said entry receiver (320, 420) is a piezoceramic receiver, wherein the phase of each frequency of said first multi-frequency coded ultrasonic signal is determined and wherein the travel times of the frequencies of said first multi-frequency coded ultrasonic signal are determined after it has passed through the container and through the substance; b. a step of generating an entry identifier of the substance in the container based on the phase of each frequency and the travel times of the frequencies of said first multi-frequency coded ultrasonic signal; c. a step of recording said entry identifier at an entry point of said supply chain; d. a step of transporting the substance in the container to a destination; e. a step of providing an exit transmitter for generating a second multi-frequency coded ultrasonic signal, wherein said exit transmitter is a piezoceramic transmitter and wherein the frequencies of said second multi-frequency coded ultrasonic signal comprises a primary frequency and higher harmonics of said primary frequency and an exit receiver for receiving said second multi-frequency coded ultrasonic signal after it has passed through the substance and the container, wherein said entry receiver (320, 420) is a piezoceramic receiver, wherein the phase of each frequency of said first multi-frequency coded ultrasonic signal is determined, and wherein the travel times of the frequencies of said second multi-frequency coded ultrasonic signal are deteminded after it has passed through the substance and the container; f. a step of generating an exit identifier of the substance in the container based on the phase of each frequency and the travel times of the frequencies of said second multi-frequency coded ultrasonic signal; and, g. a step of comparing said entry identifier and said exit identifier to determine whether the substance in the container has been altered during travel through the supply chain.