Development of a droplet cathode glow discharge excitation source for high throughput detection of Li, Ca and K in serum samples

Sensitive and high-throughput analysis of trace elements in biological samples with limited volume is of great significance for clinical studies. However, traditional analysis methods often require complex sampling systems, leading to large sample consumption and hindering the rapid detection of trace samples. In this study, we have developed a simple, sensitive and portable droplet cathode glow discharge (DCGD) array for the rapid analysis of micro-volume serum samples. It requires only 10 mu L of sample and utilizes a pipette gun for sample introduction, eliminating the need for pumps and valves in conventional solution discharge systems. The triggering and signal acquisition of each droplet sample can be completed within 300 ms, enabling the detection of approximately 240 samples per hour using the droplet array DCGD-OES. Under optimized conditions, the detection limits for Li, Ca and K were determined to be 0.002 mg L-1 (20 pg), 0.078 mg L-1 (780 pg), and 0.005 mg L-1 (50 pg), respectively. The accuracy of the proposed DCGD-OES method was verified through the analysis of two certified standard substances (Seronorm serum L-1 and L-2 RUO) and 20 real human serum samples, and the obtained relative standard deviation (RSD) is approximately 5% (n = 5). The results demonstrate that the low-cost, low-power DCGD-OES offers a promising and reliable approach for the rapid and high-throughput detection of Li, Ca, K and other important elements in volume-limited serum samples. Sensitive and high-throughput analysis of trace elements in biological samples with limited volume is of great significance for clinical studies.