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# UnitConcentrationMass

A unit of measure for concentration of mass.

```
class UnitConcentrationMass
```

## Overview

You typically use instances of [`UnitConcentrationMass`](/documentation/Foundation/UnitConcentrationMass) to represent specific quantities of concentration using the [`NSMeasurement`](/documentation/Foundation/NSMeasurement) class.

### Concentration of Mass

Concentration is the abundance of a constituent within a volume. Concentration can be expressed by SI derived units in terms of kilograms per cubic meter (kg/m3).

The [`UnitConcentrationMass`](/documentation/Foundation/UnitConcentrationMass) class defines its [`baseUnit()`](/documentation/Foundation/Dimension/baseUnit()) as [`gramsPerLiter`](/documentation/Foundation/UnitConcentrationMass/gramsPerLiter), and provides the following units, which are initialized using [`UnitConverterLinear`](/documentation/Foundation/UnitConverterLinear) converters with the specified coefficients:

|Name                    |Method                                                                                                             |Symbol|Coefficient        |
|------------------------|-------------------------------------------------------------------------------------------------------------------|------|-------------------|
|Grams Per Liter         |``doc://com.apple.foundation/documentation/Foundation/UnitConcentrationMass/gramsPerLiter``                        |g/L   |`1`                |
|Milligrams Per Deciliter|``doc://com.apple.foundation/documentation/Foundation/UnitConcentrationMass/milligramsPerDeciliter``               |mg/dL |`0.01`             |
|Millimoles Per Liter    |``doc://com.apple.foundation/documentation/Foundation/UnitConcentrationMass/millimolesPerLiter(withGramsPerMole:)``|mmol/L|`18 * gramsPerMole`|

## Topics

### Accessing the Base Unit

[`baseUnit()`](/documentation/Foundation/Dimension/baseUnit())

Returns the base unit.

### Accessing Predefined Units

[`gramsPerLiter`](/documentation/Foundation/UnitConcentrationMass/gramsPerLiter)

The grams per liter unit of concentration.

[`milligramsPerDeciliter`](/documentation/Foundation/UnitConcentrationMass/milligramsPerDeciliter)

The milligrams per deciliter unit of concentration.

[`millimolesPerLiter(withGramsPerMole:)`](/documentation/Foundation/UnitConcentrationMass/millimolesPerLiter(withGramsPerMole:))

Returns the millimoles per liter unit with the specified number of grams per mole.


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