Total Phosphorous and Mineral Content Determination in Rock Phosphates using ICP-MS

ABSTRACT

Phosphorous (P) is an essential element for plant growth and development, and its scarcity is a severe crop output constraint. Determination of total P in soil and fertilizers is very important in agriculture as the amount of P is related to crop production. Rock phosphate (RP) is an excellent natural source of P widely used for P fertilizer production. The objective of this study was to compare two different digestion methods, microwave digestion and hot plate digestion, and to evaluate the performance of two analytical techniques, inductively coupled plasma mass spectroscopy (ICP-MS) and colorimetry (UV-VIS), for measuring total P in imported RP samples. The validation of microwave digestion followed by analysis in ICP-MS was performed. Phosphorus has detection and quantification limits of 1 mg L⁻¹ and 5 mg L⁻¹ respectively through ICP-MS analysis. Average P recovery was found 92.12–96.53%. Precision in terms of intra-day (%RSD_R = 2.76–5.98 evaluated using ICP-MS) and inter-day (%RSD_r = 2.92–6.75) were found to be within the acceptable range (20%), indicating consistency of the proposed method to determine total-P over traditional UV-VIS method. The combination of microwave-assisted digestion and ICP-MS offers superior efficiency in determining both phosphorus (P) and heavy metals, including aluminum, iron, zinc, cadmium, strontium, manganese and chromium, in RP samples. Hence, this method is novel and rapid and is used for the quantification of total P in different RP samples for quality control.

KEYWORDS:

• ICP-MS
• microwave digestion
• rock phosphate
• total phosphorus
• UV-VIS
• validation

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work is supported by Institute of Pesticide Formulation Technology (IPFT), Department of Chemicals & Petrochemicals, Ministry of Chemicals & Fertilizers, GOI.