A microfluidic testing cartridge for testing LAL-reactive substances in fluid samples is provided. The cartridge may include at least two (2) testing modules, wherein each testing module includes at least one inlet port for receiving one of the fluid samples, and at least four (4) testing channels in fluid communication with the inlet port. Each of the testing channels may include a metering portion for metering an aliquot of the fluid sample, an analyzing portion, and a mixing portion, wherein a valve is positioned between the metering portion and the analyzing portion to selectively fluidly separate the metering portion from the analyzing portion. The cartridge is insertable into an optical reader which performs optical measurements of the fluid sample within each testing channel during a testing process.