Validation of analytical methods for the determination of heavy metals in e-liquids from the Philippine market

Abstract Despite existing regulations on vaping, e-cigarette use continues to rise in the Philippines. Vaping has been linked to various health concerns – including nicotine addiction, respiratory and cardiovascular effects, cancer, and neurological or developmental impacts – due to exposure to harmful chemicals such as nicotine, formaldehyde, acrolein, and heavy metals. Heavy metals in vape may come from the device components or the e-liquid. This study validated methods for determining lead and cadmium using inductively coupled plasma optical emission spectrometer and mercury using a direct mercury analyzer to ensure the accuracy and reliability of heavy metals testing. Among the parameters assessed were linearity, detection limit, precision, and trueness by spike recovery. The methods were found to be suitable for detecting low levels of heavy metals in e-liquids, supporting regulatory compliance. A market survey was conducted to determine the contamination of heavy metals in different brands of e-liquids available in the Philippines. The concentrations of cadmium, lead, and mercury were found to be below the method detection limits of 0.029, 0.29, and 0.0014 mg/kg, respectively. This study strengthens the local testing capability and provides valuable data on the limited information on heavy metal contamination in e-liquids. The findings underscore the need for stricter regulations and continuous monitoring to safeguard public health.