Speciality - CromSil™ Acido - ChromScience & Technology

CromSil™ Acido

Organic Acids HPLC Column

A polymeric HPLC column optimized for organic acid analysis – separate and quantify organic acids (C1–C6) in complex samples with ease and high fidelity.

Overview

CromSil™ Acido is a specialty HPLC column developed to simplify the analysis of organic acids in various samples such as beverages, fermentation broths, and food products. Organic acids (like acetic, lactic, citric, malic acids, etc.) play crucial roles in flavor, fermentation, and metabolic processes, but their simultaneous separation can be challenging using standard columns or methods. This product is designed to solve that problem by employing a unique ion-exclusion mechanism that cleanly separates multiple organic acids in a single run, without requiring complex gradients or suppressors. In essence, CromSil™ Acido addresses the need for a straightforward yet powerful solution to organic acid profiling: it allows chemists and technicians to inject an acid-containing sample and get a clear chromatographic read-out of each acid’s concentration. The column’s purpose is to empower industries like food & beverage (e.g. wine and juice analysis), biotech (fermentation monitoring), and environmental testing to measure organic acid content with high accuracy and repeatability. By combining scientific precision (a proven sulfonated resin technology tailored for acids) with commercial practicality (robust, long-lasting performance and easy operation), CromSil™ Acido stands out as a reliable workhorse for any lab dealing with organic acid assays.

Technology Background

CromSil™ Acido is built polymeric resin technology, very similar to the CromSil™ Glyco carbohydrate column, but specifically tailored to the hydrogen ion form for organic acid separations. The column is packed with a sulfonated polystyrene-divinylbenzene resin where the active sites are sulfonic acid groups (–SO₃H) that are fully protonated (H⁺ form). This means the stationary phase is a strong cation exchanger loaded with H⁺ ions. The separation mechanism is predominantly ion-exclusion (ion exclusion chromatography): anions (deprotonated organic acids in solution) are repelled by the like-charged sulfonate sites and thus elute earlier, whereas the neutral (protonated) form of acids can penetrate the resin pores more and therefore elute later. In practice, by using a slightly acidic mobile phase (e.g. dilute sulfuric acid), most organic acids in the sample remain in their protonated form just enough to interact differentially with the resin. Stronger acids or more polar acids elute at characteristic times based on size exclusion and slight polarity differences.

This polymeric column operates without the need for chemical suppression or specialized detectors – for instance, organic acids can be detected by simple conductivity or UV at low wavelengths (210 nm) on this column. Chrom Science & Technology’s underlying technology has demonstrated that using a hydrogen-form sulfonated resin column allows efficient separation of mixtures of organic acids such as oxalic, malic, succinic, formic, lactic, acetic, etc.. CromSil™ Acido takes advantage of this by offering different column dimensions and resin cross-linking (e.g., 8% cross-linked polymer, known as BP-800-H in OEM terms) to handle a range of acid sizes and sample types. The resin’s polymer backbone permits operation over a wide range of concentrations and temperatures (often analyses are run at moderate temperature to improve resolution, e.g. 50–60°C, and with a dilute acid eluent). The technology is essentially an HPLC adaptation of ion-exclusion chromatography, providing a modern, fast, high-resolution alternative to traditional ion chromatography for organic acids – without requiring suppressors or carbonate eluents. In summary, CromSil™ Acido uses a protonated sulfonated polymer gel to exclude anionic species and separate organic acids in their undissociated form, leveraging a robust design to deliver consistent, high-quality results for organic acid analysis.

Technical Specifications

Stationary Phase: Sulfonated Polystyrene–Divinylbenzene strong cation-exchange resin in H⁺ form (equivalent to USP L17 packing). This is a macroporous polymer that provides ion-exclusion separation specifically for organic acids. The resin is low cross-link (~8% DVB) to allow adequate pore accessibility for small organic molecules, and the sulfonic acid sites are fully protonated.
Column Format: Standard analytical column 300 mm × 7.8 mm ID, 9 µm particle size. This long format maximizes resolution between multiple organic acids. Shorter columns (100 mm) and smaller inner diameters (4.6 mm) are optionally available for faster analysis or compatibility with HPLC systems requiring lower flow, as are guard columns (50 mm × 4.6 mm) to protect against sample particulates or strongly retained contaminants.
Optimal Mobile Phase: Typically 0.002–0.01 N H₂SO₄ (sulfuric acid) in water is used as the mobile phase. This acidic eluent keeps acids mostly protonated and also provides the conductivity necessary for detection if using a conductivity detector. It’s essentially an isocratic method – one simple mobile phase throughout the run, which the column is designed for. The use of mineral acid ensures no organic contaminants or baseline drift.
Detection Compatibility: The column works well with Differential Refractive Index (RI) detection for a universal approach, or UV at 210 nm for those acids that have some UV absorbance (many organic acids absorb strongly in deep UV). It is also fully compatible with conductivity detection without the need for suppressors, because the eluent (dilute H₂SO₄) produces a baseline conductivity that is steady and the organic acids (particularly ionic form as they elute) produce peaks on that baseline. Users can choose the detection method based on sensitivity needs – RI offers simplicity, while conductivity offers greater sensitivity for strong acids, and UV is useful for certain compounds.
Temperature Range: Recommended operating temperature is ambient up to ~60–65°C. Running at elevated temperature (50–60°C) often improves resolution and reduces analysis time by lowering viscosity and sharpening peaks. The column hardware and resin are stable in this range (polymeric columns often benefit from warmth to enhance mass transfer).
pH Range: Operational pH is typically 1.5 to 3.0 (due to the acidic mobile phase). The packing itself can tolerate up to pH 14 in cleaning conditions, but using basic conditions will convert the H⁺ form to another form, so in practice the column is always used and stored in an acidic state. For cleaning, flushing with slightly higher acid normality or water is common rather than any basic solutions, to maintain performance.
Capacity & Linear Range: The 7.8 mm ID column has a good sample capacity; it can handle injection volumes in the 20–50 µL range for typical concentrations (up to tens of mmol/L of each acid) without overloading. This is sufficient for most applications like fruit juice analysis, where acids are in the 0.1–1% range. The linear range of detection spans from low ppm up to percent levels of acids, depending on detector (with conductivity, one can detect low ppm easily, whereas RI might be higher).
Plate Count: A 300 mm polymeric column provides plate counts on the order of ~5,000–7,000 for small organic acids, which is ample for separating mixtures of five or more acids. Resolution (Rs) between critical pairs (e.g., malic vs maleic acid, or acetic vs propionic if present) is typically >2 under standard conditions, based on OEM performance data.
Hardware: PEEK (polyether ether ketone) tubing and end-fittings to avoid any metal interaction or corrosion from the acidic eluent. This also ensures compatibility with sensitive samples (no metal leaching). The column can withstand pressures up to ~2500 psi, which covers the pressure of water at 0.5 mL/min in a 300 mm × 7.8 mm column comfortably.

Key Features & Benefits

One-Run Separation of Multiple Organic Acids: CromSil™ Acido can simultaneously separate a broad panel of organic acids – from small, highly polar acids like oxalic (C₂) to larger acids like citric – in a single isocratic run. For example, in a fermentation sample it can distinctly elute lactic, acetic, succinic, formic, and others with clear resolution. This all-in-one capability increases throughput (no need for multiple methods for different acids) and gives a complete acid profile at a glance, which is invaluable for monitoring processes like fermentation or food ripening where multiple acids change over time.
No Ion Suppression Needed: Unlike ion chromatography systems that require suppressors or specialized conditions, this column uses a simple acidic eluent and relies on the intrinsic ion-exclusion mechanism. No suppressor unit is required for conductivity detection – the result is a simpler setup and lower maintenance. This makes the technique more accessible; any standard HPLC with an RI or UV detector (or a conductivity detector) can perform high-quality organic acid analysis with CromSil™ Acido.
Excellent Organic Acid Selectivity: The H⁺ form resin preferentially excludes anionic species, meaning that organic acids (which partially dissociate) elute primarily based on their pKa and size. Stronger acids or multi-acid molecules (e.g., citric being triprotic) interact differently than weaker acids, yielding a unique selectivity not attainable on C18 or other columns. For instance, this column can resolve malic acid from lactic acid, or gluconic acid from acetic acid, where other columns might co-elute them. The selectivity is tailored to carboxylic acids, giving clear advantages in resolution.
Robust and Reusable: As a polymeric column, CromSil™ Acido shows exceptional chemical and thermal robustness. The packing does not degrade in low pH, and it can be flushed with strong acids for regeneration if contaminated. Its longevity is a major advantage in high-throughput environments – you can run hundreds of injections (of filtered samples) without significant change in retention or resolution. This durability means cost savings, as the column does not need frequent replacement and can handle “dirtier” samples (such as fermenter broths after minimal prep) better than more delicate columns.
Versatile Detection Options: The column’s output can be monitored by multiple common detectors depending on the user’s needs – RI for universal detection, UV for certain acids, or conductivity for high sensitivity. This flexibility is a benefit because different labs have different detector availability and target acids. For example, a winery lab might use UV 210 nm to monitor malic and tartaric acids, whereas a bioprocess lab might use conductivity to quantify acetic and butyric acids at low levels. CromSil™ Acido works with all these approaches, providing consistent retention times across detector types.
Application in Mixed Analyte Systems: The column isn’t limited to strictly organic acids – it can separate some sugar/alcohol components in the same run if present. For instance, a sample that contains both residual sugars and organic acids (common in fermentation) can be analyzed with this one column: sugars elute separately (through a different mechanism) and acids through ion-exclusion, often allowing a combined profile of sugars and acids. While its primary design is for acids, this “two-in-one” capability in certain cases adds value, letting analysts see the full metabolic picture (e.g., glucose consumed and lactic acid produced) without column switching.

Application Segments

CromSil™ Acido is broadly applicable anywhere organic acid quantification is needed, boosting efficiency in:

Food & Beverage Analysis: Widely used in beverage QC and development – for example, in wine analysis, it separates malic, lactic, tartaric, citric, acetic acids to monitor malolactic fermentation and overall wine acidity profile. In fruit juice and soft drink analysis, it measures preservative acids (benzoic, sorbic) along with natural acids (ascorbic, citric) for regulatory compliance and flavor balance. Dairy products (yogurt, kefir) labs also use it to check lactic and acetic acid levels that indicate fermentation status. The column’s ability to handle high-acid matrices and provide clear results helps ensure products taste right and meet labeling requirements.
Fermentation & Biotech: In biofuel and biochemical production, CromSil™ Acido is a go-to tool for fermentation monitoring. It can track acids like lactic, acetic, succinic, formic which are often by-products or indicators of process health. For instance, in an ethanol fermenter, rising acetic acid might signal contamination – this column allows early detection. In antibiotic or amino acid fermentations, it quantifies metabolic acids that affect yields. Biotech researchers also use it for metabolic profiling in engineered microbes, as it provides quick feedback on how modifications change the organic acid secretion/consumption.
Environmental Samples: Environmental testing labs use the column to measure organic acids in water or soil extracts, as indicators of pollution or biodegradation. For example, short-chain fatty acids in landfill leachate, or acetic and formic acid in atmospheric aerosol samples (after sample prep), can be analyzed. While ion chromatography is common in environmental analysis, CromSil™ Acido provides an alternative when only organic acids (and not inorganic anions) are of interest, with simpler operation.
Clinical/Biomedical Research: The column finds use in niche clinical chemistry applications, such as analyzing organic acidurias in urine (with appropriate sample prep). For instance, a researcher might use it to separate and measure lactic, pyruvic, and other acids in biological fluids to study metabolic disorders. Its gentle conditions (just water + slight acid) are compatible with biological samples and it can complement more expensive techniques like GC-MS for organic acid analysis in a medical research context.
Chemical Manufacturing QA: Producers of organic acids or acid-containing products (such as a manufacturer of acetic or citric acid in bulk, or companies making acidulant blends for food) employ CromSil™ Acido to check purity and content. If you produce formic acid, this column can confirm there are no higher acids contaminating the batch. If you blend a vinegar product, the column quantifies acetic acid content accurately. Its precision and ease-of-use support quality assurance in production settings where acid concentration is a critical spec.

Final Call to Action

Control Your Separations Like Never Before.