Source: https://guthlabs.ai/docs/instruments/percent-solution-concentration-unit-converter-865c2ba7/implementation/

instrument implementation / implementation-contract

# Percent Solution / Concentration Unit Converter implementation

A source-bound implementation contract for Percent Solution / Concentration Unit Converter; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t5-202

**Effect**: Computation or source lookup only

## Input and validation requirements

A zero density creates a genuine division-by-zero case that must be rejected. The ppm test also exposes a convention hazard: aqueous ppm and mass-based ppm produce different results when density is not 1.0.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "value": 1,
    "source_unit": "%w/v",
    "target_unit": "mg/mL"
  },
  "expected_outputs": {
    "value": 10,
    "unit": "mg/mL"
  },
  "working": "1% w/v = 1 g per 100 mL. 1 g = 1000 mg, so 1 g/100 mL = 1000 mg/100 mL = 10 mg/mL."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/percent-solution-concentration-unit-converter-865c2ba7/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/percent-solution-concentration-unit-converter-865c2ba7/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/percent-solution-concentration-unit-converter-865c2ba7/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche5/tranche5-results.json`