Electrolytes like sodium, potassium, magnesium, calcium etc. are essential for maintaining the fluid balance and homeostasis in the human body. They are also useful biomarkers in understanding the pathophysiology of a host of diseases. The major aim of this study is to develop a strategy for fast, reliable and simultaneous assessment of sodium (Na+), lithium (Li+) and potassium (K+) in human samples. The device is developed utilizing the basic principle of optical emission spectroscopy (OES). The atomic emission spectra of the ions during their transition are acquired and analysed for the simultaneous detection of the specific electrolytes. Our self-developed software is used to acquire the optical signals and to calculate the electrolyte concentration. The device shows a satisfactory adjusted R2 value for the three electrolytes (0.954, 0.932 and 0.984 for Na+, Li+ and K+, respectively) with respect to the standard ISE method. The device utilizes a very small amount (∼100 μL) of serum and provides a good correlation with commercially available costly devices like blood gas analysers and ion selective electrodes for blood electrolyte analysis. Our self-developed low-cost device has the ability to offer a simultaneous assessment of the essential electrolytes. To our understanding, this device would be ideal for the point of care management of constantly recurring physiological disorders including Chronic Kidney Diseases (CKD) and bipolar disorder in economically challenged countries. © The Royal Society of Chemistry 2019.