---
title: "ASTM D1091"
url: "https://mat-cs.com/astm-d1091"
description: "These test methods cover the determination of phosphorus in unused lubricating oils and lubricating oil additives and their concentrates."
---

ASTM Standard Withdrawn 2021

# ASTM D1091

Standard Test Methods for Phosphorus in Lubricating Oils and Additives

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## Significance and Use

4.1 Knowledge of the phosphorus content, and thus the phosphorus-containing additives, in a lubricating oil or additive can be used to predict performance characteristics. This test method is suitable for most applications requiring the determination of phosphorus.

## Scope

1.1 These test methods cover the determination of phosphorus in unused lubricating oils and lubricating oil additives and their concentrates. The test methods are not restricted with respect to the type of phosphorus compounds that may be present—for example, trivalent or pentavalent phosphorus compounds, phosphines, phosphates, phosphonates, phosphorus sulfides, and so forth—since all are quantitatively converted to an aqueous solution of orthophosphate ion by oxidation of the sample during the course of analysis.

1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.