Determination of Platinum in Human Plasma by Microchip-based Nanoflow Injection and Inductively Coupled Plasma Mass Spectrometry

Abstract A microfluidic chip-based nanoflow injection system was set up for inductively coupled plasma mass spectrometry (ICP-MS). The sample plug loaded into the sampling channel of the microchip was driven into ICP-MS, as soon as the multi-functional valve was changed from the load position to the inject position. The sample plug shape depends on the sampling channel. 40–200 nL sample was introduced into ICP-MS with 5–25 mm sampling channel. The proposed microchip-based nanoflow injection sampling system offers many advantages such as low sample consumption, satisfactory precisions (less than 3.0%), low sampling dead volume (nearly zero) and easy fabrication etc. With 200-nL sampling volume and a flow rate of 20 μL min −1 for the carrier, a peak profile with the highest peak height within the shortest time was obtained. The absolute detection limit of the chip-based nanoflow injection sampling system for 195 Pt was 2.54 fg under the optimized conditions, which was improved by a factor of 3200 in comparison with the conventional sampling system. A sample throughput of 48 h −1 was obtained with the nanoflow injection sampling system. Relative standard deviations of peak heights of 10 replicate trials of 10 μg L −1 standard solution and the human plasma sample S1 were 1.71% and 2.65%, respectively. The contents of platinum in six human plasma samples detected by the proposed method agreed well with those by the conventional sampling system, and the recoveries of six plasma samples ranged from 94.3% to 103.0%. These results indicate the good accuracy of the present method.