Development of matrix reference material for reliable phenthoate determination in mango by gas chromatography-nitrogen phosphorus detector (GC-NPD) and gas chromatography tandem mass spectrometry (GC-MS/MS)

Organophosphate pesticides, like phenthoate, are essential for agricultural production and pest control, but excessive levels can be harmful. Pesticide residue analysis in food requires matrix reference materials (RMs), which are scarce for all pesticide-matrix combinations. This study developed an RM for detecting phenthoate residues in mangoes. The material was lyophilized, fortified with phenthoate, homogenized, and characterized. Homogeneity and stability were assessed using Gas Chromatography with Nitrogen-Phosphorus Detector (GC-NPD) following ISO Guide 35:2017. Linear regression and Cochran's Test found no significant trends or outliers. ANOVA confirmed the homogeneity of the prepared RM, with a standard uncertainty ( u bb ) of 3.24 %. The RM remained stable at 4 °C for three weeks and at −20 °C for six months, with a standard uncertainty ( u lts ) of 7.09 %. GC-MS/MS quantified the reference value as 15.69 ± 4.0 μg/kg (n = 6) at a 95 % confidence level (k = 2). This RM aids in quality control and method validation for phenthoate detection in mangoes.