N-Acetyl-L-Cysteine (NAC) is one of the most versatile amino-acid derivatives in the supplement industry, used in antioxidant, respiratory and liver-support formulas as the direct precursor to glutathione. Buyers mostly see a single number on quotations – a USP assay range of 98.5-101% – but handling, odor and grade selection decide whether production runs smoothly. This guide explains the specification, the formulation challenges and the quality checks that matter. Core Nutrix supplies N-acetyl-L-cysteine at 98.5-101% by USP assay (CAS 616-91-1), a white crystalline powder packed in 25 kg drums.
What the 98.5-101% Assay Means
- USP assay range: the pharmacopoeia defines NAC potency as 98.5-101% of the labeled content on the dried basis, measured by titration or HPLC – a far tighter window than typical botanical specs.
- Why a range, not a minimum: crystalline amino-acid derivatives are near-pure molecules, so the spec is a symmetric window around 100% rather than a “no less than” limit.
- Grade choices: USP grade suits supplements and functional foods; ask about pharmaceutical-grade documentation if the application requires it.
The Sulfur Odor Challenge
NAC is a sulfur-containing molecule, and its characteristic odor intensifies when the powder absorbs moisture or when blends sit in warm storage. The smell is normal chemistry, not contamination, but it shapes formulation choices:
- Capsules and tablets: the standard route; encapsulation masks most of the odor at the consumer level.
- Powders and drinks: use flavor systems built for sulfur notes – citrus and berry masks work better than vanilla.
- Storage: keep drums sealed, cool and dry; 24 months shelf life under these conditions, with the odor stable when the moisture barrier holds.
Applications Where NAC Earns Its Place
- Antioxidant formulas: as the glutathione precursor, NAC supports the body’s central intracellular antioxidant system; typical serving sizes run 600-1,200 mg.
- Respiratory products: NAC’s mucolytic heritage makes it a staple in seasonal respiratory and lung-support blends.
- Liver-support positioning: often combined with milk thistle in liver-support and liver formulas.
- Sports recovery: appearing in recovery stacks for oxidative-stress support after training.
Quality Checks Beyond the Assay
- Heavy metals and impurities: lead, arsenic, cadmium and mercury per batch, plus related-substance testing for pharmacopoeia compliance.
- Physical character: white crystalline powder with consistent particle size; spec the mesh if the line is compression-sensitive.
- Microbiology: standard TPC/yeast/mold panel on every COA.
- Third-party verification: SGS or Eurofins testing available on request.
NAC vs Glutathione: Why Not Just Sell Glutathione?
Glutathione itself is poorly absorbed intact through the gut, which is why the category standard is to supply its precursor instead. NAC is taken up, enters cells, and provides the cysteine that drives glutathione synthesis – a route the body uses constantly. This is why NAC remains the workhorse of antioxidant formulas even as liposomal and reduced glutathione products enter the market. For brands that want both stories, a combined NAC-plus-glutathione formula is a growing premium niche.
- Precursor logic: NAC supports the body’s own production, which is the more durable positioning.
- Cost advantage: NAC costs a fraction of finished glutathione per effective unit.
- Co-formulation: premium products often pair NAC with selenium or alpha-lipoic acid, which support the same antioxidant cycle.
Grades, Assay and Regulatory Notes
- USP assay 98.5-101%: the pharmacopoeia window, measured on the dried basis by titration or HPLC.
- White crystalline powder: color is a useful quick check – discoloration signals moisture or storage problems.
- Heavy metals: lead, arsenic, cadmium and mercury tested per batch, plus related substances for pharmacopoeia-grade material.
- Compliance: COA and MSDS ship with every batch, and compliance statements are available for import documentation.
Specify the mesh if your tableting line is compression-sensitive, and keep drums sealed between production draws.
Frequently Asked Questions (FAQ)
Is the sulfur smell a quality problem?
No – NAC naturally carries a sulfur odor that strengthens with moisture and warmth. It does not indicate degradation, but it should shape your flavor and packaging choices.
What does USP grade mean?
The material meets the United States Pharmacopeia monograph, including the 98.5-101% assay range and impurity limits. The grade is stated on the COA.
Can NAC be used in effervescents or drinks?
Yes, with a flavor system built for sulfur notes and careful moisture control in packaging. Capsules remain the simplest route for odor-sensitive brands.
Is NAC vegan?
The standard material is produced by synthesis or fermentation from non-animal sources. Confirm the manufacturing route with the specification sheet for your label.
What documentation ships with each batch?
COA and MSDS with the USP assay, impurity and heavy-metal data. Compliance statements and third-party reports are available on request.
What is the MOQ?
Samples start at 0.5-1 kg depending on the item, and bulk ships in 25 kg drums (premium items from 5-10 kg). Contact us for a quote and a free sample.
Why is NAC popular in respiratory products?
NAC has a long clinical history as a mucolytic, and supplement formulas carry that heritage into seasonal respiratory-support blends at 600-1,200 mg servings.
What blend partners suit NAC?
Milk thistle for liver-support formulas, selenium for glutathione cycle support, and vitamin C for antioxidant synergy are the most common partners.
How should NAC be stored?
Sealed, cool and dry, away from moisture – the sulfur odor stays stable when the moisture barrier holds, and shelf life is 24 months.
What is the MOQ for NAC?
Samples start at 0.5-1 kg depending on the item, and bulk ships in 25 kg drums (premium items from 5-10 kg). Contact us for a current quote and a free sample.
Is NAC suitable for effervescent tablets?
Yes, with care – moisture control in packaging and sulfur-compatible flavors make effervescents workable, though capsules remain the simplest format for odor-sensitive lines.
Does NAC have any dietary restrictions?
The standard grade is synthetic or fermentation-derived and non-animal. Confirm the route on the specification sheet for vegetarian and vegan labels.
Can NAC be shipped with other powders in a blend?
Yes – premixed blends with milk thistle, selenium or vitamin C are common. Our OEM service handles blending with blend-uniformity documentation per batch.
How do I verify USP compliance?
The COA states the USP assay result and related substances. Independent labs such as SGS or Eurofins can re-verify on request.
What is the typical serving?
600-1,200 mg per day is the common antioxidant serving, split across one or two capsules depending on format.
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What you can expect from Core Nutrix
- Every batch released against the specification you approve, with a full COA (assay by HPLC/UV, heavy metals, microbiology, residual solvents, pesticide residue screened to EU MRLs).
- Free samples with COA and MSDS - freight collect, credited against your first bulk order.
- Third-party test reports, allergen and GMO statements, shelf-life and stability data supplied on request.
- Documentation support for your market entry: EU Regulation (EC) No 1924/2006 on nutrition and health claims, US 21 CFR 101.93 structure/function support, California Proposition 65 statements.
- One working day to a quotation, OEM/ODM projects from 100-500 kg, private label, custom specifications and packaging.
This is technical, business-to-business information for manufacturers and brand owners - not a consumer label and not medical advice. Where a claim is made about a finished consumer product, it must comply with the rules of the destination market; we supply the supporting technical documentation so your team can review it. Ask us for anything your market requires - we are glad to help.
Para amostras, o MOQ é de 1 kg, com envio em 1-3 dias. Para 5 kg, tratamos como pedido bulk, enviado em 7-15 dias. Enviamos para o Brasil via DHL, com frete por conta do comprador. – Core Nutrix Team
Varje batch skickas med COA och MSDS, inklusive HPLC/UV-resultat med spårbarhet. Kosher och Halal-certifikat finns tillgängliga på begäran. Vi kan också ordna tredjepartstestning vid behov. – Core Nutrix Team
El olor a azufre es real y me alegra que el artículo lo aborde con claridad. Hemos enmascarado con sabor a frutos rojos y funcionó bien, pero la humedad en el empaque es el factor crítico. Gracias por los detalles sobre el rango de 98.5-101%.
Vi att ni erbjuder tredjepartstestning. Kan vi få HPLC-resultat för varje batch och vilka certifikat ingår som standard? Vi behöver Kosher och Halal för vår EU-marknad.
Preciso de 5 kg de NAC grau USP para testes de formulação de um suplemento efervescente. Qual é o prazo de envio para o Brasil e o MOQ para amostras?
En tant que formulateur, je confirme que la gélule reste la voie la plus simple pour masquer l’odeur. Nous avons testé des comprimés effervescents et le contrôle de l’humidité est un vrai défi. L’article donne des conseils concrets et réalistes.
Good read. As an R&D manager, I’ve seen NAC suppliers come and go. The ones that understand the USP spec and can document it properly are rare. This article reflects real formulation experience.
Olá, vocês fazem envio para Portugal? Qual o prazo para uma encomenda de 25 kg? E temos que pagar alfândega?
Olá Fernanda, sim, enviamos para Portugal via DHL/FedEx. O prazo para 25 kg é de 7-15 dias. Para condições DDP, a alfândega é por nossa conta. Entre em contato para detalhes. – Core Nutrix Team
Precies wat ik zocht. De uitleg over de 98,5-101% assay range is duidelijk. We hebben deze specificatie nodig voor onze registratie in Europa. Bedankt voor het delen.
Tenemos stock para muestras y producción continua. Para 50 kg, el plazo de envío es de 7-15 días. Si necesita antes, consulte disponibilidad de stock inmediato. – Core Nutrix Team
The article is very informative. As a Japanese manufacturer, we appreciate the emphasis on moisture control. Our packaging team will definitely review our current approach based on these notes.
¿Tienen stock disponible en su almacén o trabajan bajo pedido? Necesito 50 kg de NAC para final de mes.
We distribute supplements across the Middle East. The humidity issue with NAC is critical in our region. This article confirms what we’ve learned through experience. Good to see suppliers addressing it.
Tak, próbka jest bezpłatna, pokrywasz koszt wysyłki. Do próbki dołączamy COA i MSDS. Wysyłka do Polski przez DHL/FedEx kosztuje około 30-50 USD. – Core Nutrix Team
Czy mogę dostać próbkę i pełną dokumentację do weryfikacji jakości przed zamówieniem? Jaki jest koszt wysyłki do Polski?
Ja, wir akzeptieren Letters of Credit für Großbestellungen. Für 1000 kg bieten wir Sonderkonditionen an. Bitte kontaktieren Sie uns für ein detailliertes Angebot. – Core Nutrix Team
Wie sieht es mit der Zahlungsabwicklung aus? Akzeptieren Sie Letters of Credit für größere Bestellungen? Wir würden gerne 1000 kg bestellen.
Excellent article sur le NAC. Le point sur le grade USP à 98,5-101% est très utile pour nos contrôles qualité. Nous utilisons ce produit dans nos formules antioxydantes depuis deux ans.
Vocês têm certificação Kosher? Precisamos para o mercado americano. E qual o prazo para envio de amostra para Nova York?
Olá Gustavo, sim, temos certificação Kosher e Halal disponíveis sob solicitação. Amostras para Nova York são enviadas em 1-3 dias via DHL/FedEx, chegando em cerca de 3-5 dias úteis. – Core Nutrix Team
Merhaba, evet örnek gönderiyoruz. Örnek ücretsizdir, kargo ücreti alıcıya aittir. Türkiye’ye DHL ile 3-5 iş günü içinde ulaşır. – Core Nutrix Team
Bardzo przydatny artykuł. Pracuję w firmie produkującej suplementy i zawsze mieliśmy pytania od klientów o zapach siarki. Teraz mogę odesłać ich do tego artykułu jako wiarygodnego źródła.
We’ve been sourcing NAC for our nutraceutical line in India. The shelf life note of 24 months is accurate based on our experience. Good to see a supplier that states it clearly upfront.
Türkiye’ye örnek gönderimi yapıyor musunuz? Örnek için kargo ücreti ne kadar ve ne kadar sürede ulaşır?
Здравствуйте, условия оплаты обсуждаются индивидуально. Для объёмов от 500 кг действуют специальные цены. Свяжитесь с нами для коммерческого предложения. – Core Nutrix Team
Ciao Gabriele, il campione parte in 1-3 giorni lavorativi. Il MOQ per ordini commerciali è 25 kg (un fusto). Spediamo in Italia con DHL/FedEx espresso. – Core Nutrix Team
Здравствуйте, какие условия оплаты вы предлагаете для постоянных клиентов? И предоставляете ли скидки при объёме от 500 кг?
Great article. As an importer in Ireland, I always check the assay range on the COA. The 98.5-101% spec is what separates quality suppliers from the rest. Bookmarked for reference.
Qual è il tempo di consegna per un campione in Italia? E il MOQ per un ordine commerciale?
The article’s point about the sulfur smell not indicating degradation is important. We had a customer complaint once and had to explain this at length. Good to have a reference from a supplier that knows their product.
هل يمكن تخصيص حجم الجزيئات ليتناسب مع تركيبة أقراص فوارة؟ وهل توفرون خدمة التغليف الخاص؟
نعم، نخصص حجم الجزيئات حسب المواصفات المطلوبة. نوفر خدمة التغليف الخاص OEM/ODM. يرجى التواصل معنا لمناقشة التفاصيل. – Core Nutrix Team
Artigo muito útil. Uso NAC em cápsulas para minha marca no Brasil e o odor é sempre um desafio. A dica sobre controle de umidade na embalagem já vou aplicar na próxima produção.
Tak, próbki są bezpłatne, pokrywasz tylko koszt wysyłki. Wysyłka próbki 1-3 dni. Zamówienie 100 kg realizujemy w 7-15 dni i wysyłamy do Polski kurierem lub drogą lotniczą. – Core Nutrix Team
Czy mogę otrzymać próbkę przed zamówieniem komercyjnym? Jaki jest czas realizacji zamówienia na 100 kg do Polski?
Kunnen jullie een monster sturen naar Nederland? En wat zijn de kosten voor verzending? We willen graag de geur testen in onze formule.
Buen dato sobre el rango de 98.5-101%. Muchos proveedores no cumplen con esa especificación. Llevamos dos años comprando NAC a China y siempre pedimos el COA antes de pagar. Buen artículo para compartir con nuestro equipo de calidad.
Hallo, ja we sturen gratis monsters; de verzendkosten zijn voor de koper. Verzending naar Nederland via DHL/FedEx duurt 3-5 werkdagen. U ontvangt het COA bij het monster. – Core Nutrix Team
As a quality manager, I appreciate the article mentioning impurity limits in the USP monograph. We verify every COA against the pharmacopeia. This supplier seems transparent about their testing methods. Will request a sample.
Chào chị, đơn 100kg sản xuất trong 7-15 ngày. Chúng tôi có vận chuyển đường biển và đường hàng không đến Việt Nam. Điều kiện giao hàng EXW, FOB, CIF, DDP/DDU. – Core Nutrix Team
Cho tôi hỏi, nếu đặt hàng 100kg NAC thì thời gian giao hàng về Việt Nam là bao lâu? Có hỗ trợ vận chuyển đường biển không?
We import supplements to Lagos and the humidity is our biggest enemy with NAC. The article’s advice on moisture control in packaging is crucial. Glad to see a supplier that understands real-world conditions.
Articolo molto chiaro. Il punto sull’odore di zolfo che si intensifica con l’umidità è importante. Nei nostri stabilimenti in Italia controlliamo l’umidità relativa sotto il 30% durante il confezionamento e funziona bene.
Guten Tag, haben Sie Erfahrung mit magensaftresistenten Kapseln für NAC? Können Sie das Produkt direkt in Kapseln abfüllen oder liefern Sie nur das Pulver?
Guten Tag, wir liefern das Pulver in verschiedenen Spezifikationen. Die Kapselabfüllung kann über unseren OEM-Service arrangiert werden. Bitte kontaktieren Sie uns für Details zu Ihrem Projekt. – Core Nutrix Team
サンプルは1〜3日で発送し、DHLエクスプレスで日本まで約3〜5日です。支払い条件はご相談に応じます。バルク注文のリードタイムは7〜15日です。 – Core Nutrix Team
サンプルの発送は日本まで何日くらいかかりますか？また、支払い条件はどのようになっていますか？
Formulator here from the US. The flavor system note for effervescents is spot on. We tried masking sulfur notes with citrus but it wasn’t enough. Capsules are definitely the simplest route for odor-sensitive brands, as the article says.
Здравствуйте, интересует срок хранения NAC в порошке при соблюдении условий. И какие методы тестирования вы используете — HPLC или UV?
The 98.5-101% assay range is exactly what our QC team looks for. We’ve had issues with cheaper suppliers selling degraded product. Good to know you include COA with every batch. We’ll be ordering a sample this week.
Здравствуйте, срок хранения 24 месяца в запечатанной упаковке в прохладном сухом месте. Используем HPLC и UV с полной прослеживаемостью каждой партии. – Core Nutrix Team
نعم، نوفر شهادات حلال وكوشير عند الطلب. الحد الأدنى للكميات الكبيرة هو 25 كجم (برميل واحد). الشحن متاح عبر الجو أو البحر مع شروط EXW أو FOB أو CIF. – Core Nutrix Team
هل يمكنكم توفير شهادة الحلال مع الشحنة؟ وما هو الحد الأدنى لطلب الكميات الكبيرة؟
Dobrze napisany artykuł. U nas w Polsce często klienci pytają o zapach siarki i myślą, że produkt jest zły. Teraz będę mógł im pokazać ten artykuł jako potwierdzenie, że to naturalna cecha NAC.
Hej Viktor, vi kan anpassa partikelstorleken enligt era specifikationer. Vi skickar med DHL/FedEx till Sverige, både express och flyg. Prover skickas inom 1-3 dagar. – Core Nutrix Team
Hej! Vi funderar på att testa ert NAC i en dryck. Har ni möjlighet att anpassa partikelstorleken för bättre löslighet? Och hur fungerar frakten till Sverige?
As a brand owner in the UAE, I appreciate the note about moisture control in packaging. We’ve had returns due to clumping in summer months. The sulfur odor is definitely something to design around, especially in a hot climate. Good article.
Me gustó la explicación sobre el rango de 98.5-101% para grado USP. Es un detalle que muchos proveedores no saben explicar. Nosotros usamos NAC en cápsulas y el tema del olor es real, pero manejable con buena tecnología de encapsulado.
Bonjour Christophe, oui nous proposons l’OEM/ODM avec spécifications personnalisées. Pour 500 kg vers la France, comptez 7 à 15 jours de production selon la personnalisation, plus le transport aérien ou maritime selon votre choix. – Core Nutrix Team
Bonjour, travaillez-vous avec des conditionnements personnalisés pour des gélules végétales ? Quel est le délai pour une commande OEM de 500 kg vers la France ?
Olá Helena, sim, todas as amostras grátis saem com COA e MSDS do lote correspondente. O frete da amostra fica por conta do comprador. Para bulk, o prazo é de 7 a 15 dias. – Core Nutrix Team
Preciso do certificado de análise do lote antes de fechar o pedido. Vocês enviam o COA junto com a amostra grátis ou só no pedido em bulk?