T-02
Chemical and compositional testing
Composition and condition measured to published methods, so you can show a product still matches the specification you sell it against.
- What it is
- Proximates, physical chemistry, stability indicators
- Who it is for
- Anyone selling against a written specification
- Turnaround
- 5–7 days
WHAT THIS IS
What this is, and why it matters
Chemical and compositional testing measures what a product is made of and what state it is in. Proximate analysis — moisture, ash, protein, fat, fibre, carbohydrate — establishes composition. Physical chemistry — pH, water activity, titratable acidity, salt — establishes the conditions that decide whether the product is stable and whether organisms can grow in it. Stability indicators such as peroxide value, free fatty acids and total volatile basic nitrogen establish whether it has begun to degrade.
These are the numbers underneath a specification. When a buyer rejects a delivery, when material from a new supplier behaves differently on the line, when a reformulation has to land on the same declared values, or when a complaint alleges the product was not what the label said, the answer is a measured value against a published method. Water activity and pH do double duty in particular: they are quality parameters, and they are the safety justification for how a product is stored and how long it keeps.
What this lane covers
- Proximate composition, physical chemistry, stability indicators
- Specification compliance, raw material verification, reformulation
TRIGGERS
When you need it
A specification has to be evidenced
Your own specification, a customer specification or an export requirement names values the product must meet. Composition measured to AOAC or ISO methods is what stands behind them when someone checks.
Incoming material needs verifying
Off-specification raw material is far cheaper to catch at goods-in than after it has been processed into finished product. A short proximate panel on each new supplier, and on each lot from a supplier still being approved, is the usual control.
You changed the recipe, or a complaint landed
A reformulation has to hit the same declared values, and a complaint alleging the product was wrong needs a measured answer rather than a position.
CATALOGUE
Chemistry — parameters
Moisture content
- Matrix
- Food
- Reference method
- ISO 662:2016 / AOAC 925.10
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Loss on drying
- Matrix
- Powders
- Reference method
- USP–NF <731>
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Total ash
- Matrix
- Food
- Reference method
- AOAC 942.05
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Acid-insoluble matter
- Matrix
- Food
- Reference method
- AOAC 941.12
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Sulphated ash
- Matrix
- Sugar and confectionery
- Reference method
- AOAC 945.63
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Conductivity ash
- Matrix
- Sugar
- Reference method
- ICUMSA GS1-13 (1994)
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Crude protein
- Matrix
- Food
- Reference method
- AOAC 954.01
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Crude fat
- Matrix
- Food
- Reference method
- AOAC 954.02
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Crude fibre
- Matrix
- Food
- Reference method
- AOAC 962.09
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Total sugar
- Matrix
- Food
- Reference method
- AOAC 923.09
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Total solids
- Matrix
- Juices
- Reference method
- AOAC 970.59
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Brix and total soluble solids
- Matrix
- Juices, jams, ketchup
- Reference method
- AOAC 970.59
- Run by
- Nexus bench
- Turnaround
- 5–7 days
pH
- Matrix
- Food
- Reference method
- AOAC 981.12
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Titratable acidity
- Matrix
- Food
- Reference method
- AOAC 942.15
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Free fatty acids and fat acidity
- Matrix
- Food, oils
- Reference method
- AOAC 940.28
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Peroxide value
- Matrix
- Oils, fats, fat-containing food
- Reference method
- Confirmed per request
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Water activity (aw)
- Matrix
- Food
- Reference method
- Confirmed per request
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Total volatile basic nitrogen
- Matrix
- Meat, fish
- Reference method
- Per partner laboratory method
- Run by
- Partner laboratory
- Turnaround
- Up to 14 days
Refractive index
- Matrix
- Oils
- Reference method
- AOAC 921.08
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Salt content
- Matrix
- Food
- Reference method
- USDA 1963 / AOAC
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Viscosity
- Matrix
- Liquid and semi-liquid samples
- Reference method
- USP
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Physical evaluation
- Matrix
- Rice, wheat, pulses, grains
- Reference method
- ISO 7303
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Test weight
- Matrix
- Rice, wheat, pulses, grains
- Reference method
- ISO 7303
- Run by
- Nexus bench
- Turnaround
- 5–7 days
Published from the laboratory’s own method list. Reference methods shown are the primary reference for each determination; the full reference set, sample requirement and confirmed turnaround are issued in writing before any sample is accepted.
Lines marked “partner laboratory” are managed and reported by Nexus Labs and run on a partner laboratory’s bench. Which laboratory, and its accreditation position, is named on request before the work is commissioned.
PROCESS
How it works
Send the brief before the sample
Product type, the determinations you need, and what the result has to be compared against — your specification, a customer specification, or an export requirement. That comparison changes how the report is written, so it is worth stating up front.
Sample requirements confirmed in writing
Quantity, packaging and whether the sample needs to arrive chilled depend on which determinations are running. They are confirmed in writing before dispatch, along with anything that has to be sampled in duplicate.
On the bench, to a published method
Every determination runs to the ISO, AOAC or APHA method named in the catalogue above, and that reference travels onto the report line rather than sitting in a footnote. Turnaround runs from acceptance at the laboratory, not from the day the sample left you.
Reported so the result can be acted on
Results are reported per determination with the method reference and the unit. Where you named a specification, the report sets each result beside its specification value so the comparison is done on the page rather than in a spreadsheet afterwards.
What you get back
A report giving each determination, the method used, the measured value with its unit, and — where you supplied one — the specification value beside it. Enough to attach to a delivery, a customer response or a technical file without rewriting it first.
Service facts
| Parameter | Value | Note |
|---|---|---|
| Accreditation position | Not on the accredited scope. The laboratory’s accredited testing certificate covers food and agricultural microbiology only. Chemical and compositional work runs in house to published AOAC, ISO and USP methods, and the report names the method against every result. | Stated per discipline, never implied by a badge. |
| Sample requirements | Confirmed to you in writing before dispatch. Container, quantity, temperature and hold time change with the parameter and the matrix, so they are issued per request rather than published as one list. | Per-parameter detail publishes with the confirmed method list. |
Q+A
Common questions
Chemistry
Can you run the full proximate panel on one sample?
Yes — moisture, protein, fat, ash, fibre and carbohydrate are run as one panel. The laboratory confirms in writing the sample quantity it needs before you send anything.
Is carbohydrate measured or calculated?
Usually calculated by difference from the measured proximates, which is standard practice. The certificate states how every reported value was obtained, so there is no ambiguity when a customer or auditor asks.
My in-house moisture reading disagrees with your result — whose is right?
Possibly both — different methods give different numbers, and moisture is the clearest example of it. The report states the method used, so compare like with like before concluding either instrument is wrong. If your customer’s specification names a method, tell the laboratory and it confirms in writing whether it runs that method.
Is stability testing the same as a shelf-life study?
No. Physical and chemical stability work tells you how a parameter behaves over time or under a condition — a shelf-life study is a designed programme behind a printed date, and it has its own page. If you are not sure which you need, describe the decision you are trying to make and the laboratory will say which service answers it.
My customer’s specification names parameters I don’t recognise — can you help?
Send the specification as it stands. The laboratory confirms in writing which parameters it covers, and names any it does not, rather than substituting a near-equivalent silently.
Send the sample question or the instrument list. It is read by a bench professional, not routed through a ticket queue. Call +966 59 637 8052 or write to lab-mgr@qsinexus.com.
CONTINUE
Where to next
Sending a sample
Packing, labelling, temperature and what has to travel with the sample so it arrives usable.
ReadThe GSO standards that actually bite
Labelling, nutrition, packaging and microbiological criteria, with the current edition for each.
ReadForms and documents
Submission form, chain of custody and the calibration request, ready to fill in first.
Read