CR Plus

Ultra-Low Bleed & Trace-Level Optimized

Overview

The CR Plus series represents the ultra-high-performance capillary columns tailored for trace-level and GC-MS applications. Building on the CR Standard phases, CR Plus columns are specially processed to further minimize bleed and maximize inertness, making them ideal for detecting analytes at extremely low concentrations (ppb to ppt levels). Chrom Science & Technology positions the CR Plus range as the solution for analysts who demand the cleanest baseline and highest sensitivity – for example, those running mass spectrometers, ECDs, or other detectors where background noise and active sites must be virtually eliminated. CR Plus columns are the premium offerings with Chrom Science & Technology’s quality standards, delivering on both precision and confidence.

Phase Chemistries (Complete List)

Phase Name	Stationary Phase	Polarity	USP Code(s)	Max Temp (°C)	Key Applications
CR-1 Plus	100% Dimethylpolysiloxane (Ultra-Inert)	Non-Polar	G1, G2	350	GC-MS of alkanes, gases; MS baseline reference
CR-5 Plus	5% Phenyl, 95% Methyl Polysiloxane (Ultra-Low Bleed)	Low-Polar	G27, G36	330	Pesticides, semivolatiles, PAHs via GC-MS
CR-35 Plus	35% Phenyl, 65% Methyl Polysiloxane	Mid-Polar	G28, G32	330	Confirmatory MS analysis of isomers
CR-1701 Plus	14% Cyanopropylphenyl, 86% Methyl Polysiloxane	Mid-Polar	G46	290	Residual solvents (USP ), volatile polar analysis
CR-624 Plus	6% Cyanopropylphenyl, 94% Methyl Polysiloxane	Low–Mid Polar	G43	270	VOCs via Purge & Trap GC-MS (EPA 524.3, 8260)
CR-Wax Plus	Polyethylene Glycol (PEG), High-Stability, Crosslinked	Polar	G16	270	Glycols, ethanolamines, polar volatiles via GC-MS
CR-5 MS Xil	5% Phenyl, MS-Selective (Xylene Isomers)	Low-Polar (Aromatic Selectivity)	G27+	320	o-, m-, p-Xylene separation in trace environmental samples
CR-5 MS Plus	5% Phenyl, Extended Inertness MS Grade	Low-Polar (Ultra-Inert for Trace MS)	G27++	330	Dioxins, PCBs, ultra-trace MS work requiring exceptional baseline and selectivity

CR-1 Plus – 100% Dimethylpolysiloxane, Ultra-Inert grade. This is the MS-optimized version of CR-1, ideal for GC-MS use when a non-polar low-bleed column is needed (e.g., for methane or butane analysis in MS or when a reference baseline is required). Provides the same apolar selectivity but with even lower bleed than standard CR-1.
CR-5 Plus – 5% Phenyl, 95% Methyl low-bleed phase. The go-to column for general GC-MS work (analogous to popular 5MS type columns). CR-5 Plus is processed to have ultra-low bleed even at high GC-MS interface temperatures (≥300 °C). It’s perfect for trace semivolatiles analysis (pesticides, PAHs) where column bleed can interfere with mass spectra.
CR-35 Plus – 35% Phenyl mid-polar MS column. This provides alternative selectivity in trace analysis, useful for certain confirmatory MS analyses (e.g., distinguishing isomers of semi-polar compounds). It is crossbonded and extremely inert, classified similarly to G28/G32 phases like its standard counterpart. T_max ~330 °C.
CR-1701 Plus – 14% Cyanopropylphenyl mid-polar, low-bleed. Developed for trace residual solvents and volatile polar compounds analysis by GC-MS. For example, in USP <467> residual solvent testing by GC-MS, an extremely clean baseline is critical – CR-1701 Plus offers that, with bleed well below USP limits for headspace GC-MS.
CR-624 Plus – 6% Cyanopropylphenyl phase optimized for volatiles by MS. Designed for purge-and-trap GC-MS (EPA 524.3, 8260) where even minor bleed could mask trace VOC peaks. CR-624 Plus has a higher max temp (~270 °C) than typical 624 columns due to improved stabilization, and demonstrates excellent signal-to-noise for late-eluting solvents.
CR-Wax Plus – Polyethylene glycol high-stability phase. A new generation PEG column with special inertness, rated to ~270 °C (higher than conventional wax). This phase is “mass spec friendly” – truly equivalent to Agilent Innowax® in stability – enabling polar compound GC-MS analyses (e.g. glycols, ethanolamines, flavor compounds) without the excessive bleed normally associated with wax columns. It is fully bonded (crosslinked) and water-resistant, so it endures repetitive solvent and steam injections better than standard wax columns.
CR-5 MS Xil – (Specialty Plus phase) 5% phenyl phase tweaked for xylene isomers and other specific aromatic separations in trace analysis. “Xil” indicates a unique selectivity ensuring baseline separation of difficult isomers (like o-, m-, p-xylene in environmental samples) while maintaining low bleed.
CR-5 MS Plus – (Special designation) This could refer to an even higher-grade 5% phenyl than CR-5 Plus, possibly with an “extended inertness” treatment. ; in CR terms, it means an ultra low-bleed 5% phenyl column for the most demanding MS work (e.g., dioxin or PCB congener analysis where even standard MS-grade might not suffice).

(Note: All CR Plus phases maintain the same selectivity as their Standard equivalents; the “Plus” simply denotes their enhanced performance for trace/critical work.)

Technical Specifications

Feature	Specification & Notes
Column Type	Fused silica capillary with polyimide outer coating
Stationary Phase Bonding	Fully bonded (crosslinked) phase for solvent resistance and temperature stability
Surface Deactivation	Proprietary ultra-inert deactivation for trace analysis (equivalent to leading “UI” or “Plus” column brands)
Film Thickness Range	0.10 μm to 5.00 μm
Internal Diameter (ID)	0.10 mm to 0.53 mm
Available Lengths	10 m, 15 m, 30 m (standard), 60 m
Temperature Limits	Phase-dependent, up to 330–350 °C
Column Bleed (CR-5 Plus)	< 3 pA on FID at 320 °C (30 m × 0.25 mm × 0.25 µm) – suitable for GC-MS SIM or high-sensitivity detectors
Detector Compatibility	Optimized for GC-MS, ECD, FID, TCD
Inertness Validation	Tested with probe compounds (e.g. amines, acids, sulfurs, organophosphates) – ensures symmetrical peaks, no tailing
Regulatory Compliance	Meets or exceeds USP, Ph.Eur, EPA method criteria for GC columns
Packaging & QC	Individually tested and QC certified; includes bleed profile, efficiency (plates/m), and selectivity check

CR Plus columns share the physical construction of the Standard series (fused silica tubing, polyimide outer coating, fully bonded stationary phase) but undergo additional proprietary deactivation and conditioning steps. This results in exceptionally low column bleed even at the upper ends of their temperature limits. For example, a CR-5 Plus 30 m × 0.25 mm × 0.25 µm column might show bleed well below 3 pA on an FID at 320 °C, making it suitable for GC-MS SIM mode even in late elution. All CR Plus columns are tested with sensitive detectors (MS or ECD) to ensure no ghost peaks or active site tailing for a panel of probe compounds (acids, bases, sulfurs). Inertness is such that even tricky analytes like organophosphates, mercaptans, or amines elute as symmetric peaks (these columns often use ultra-inert surface deactivation comparable to competitor “UI” or “Plus” brands).

Dimensions available are the same as standard columns, but optimized dimensions are highlighted for trace work: e.g., 0.25 mm ID with 0.25–0.50 µm film for optimum MS sensitivity, or 0.32 mm ID × 0.25 µm for ECD methods. Thicker films (1–5 µm) in the Plus series are used when high sample loading and low-bleed are both required (for instance, a 1.0 µm CR-1 Plus for solvent screening by headspace GC-MS). Temperature limits remain similar or slightly improved, thanks to the improved phase stability: CR-1 Plus and CR-5 Plus can be used to ~340 °C, and CR-Wax Plus up to 270 °C (which is notably higher for a wax phase).

Importantly, bleed profiles of CR Plus columns are not only low, but also reach stabilization faster – meaning a shorter conditioning time is needed before the column is ready for trace analysis. They also exhibit less noise drift in MSD total ion chromatograms, which translates into lower detection limits. The phase chemistry and USP classifications remain the same (e.g., CR-5 Plus is still USP G27/G36 like CR-5), so all method compliance is retained while gaining performance.

Typical & Advanced Applications

CR Plus columns are recommended wherever trace analyte detection or extremely clean baselines are required. Key application areas include:

Environmental Trace Analysis (EPA & EU methods)

When measuring pollutants at ppb levels in complex matrices, CR Plus excels.
For example, in EPA 8270 (semivolatile organics by GC-MS), a CR-5 Plus ensures that the late-eluting PAHs or phthalates are not obscured by column bleed ions.
In volatile analyses like EPA 524.3/624 (drinking water VOCs), a CR-624 Plus provides a noise-free baseline for detecting chlorinated VOCs down to part-per-trillion.
Pesticide multi-residue analysis by GC-MS/MS (used in food safety) benefits from CR Plus columns (e.g., CR-5 Plus or CR-35 Plus) by minimizing background and preventing active pesticide degradation on the column.

Forensic & Toxicology (Ultra-trace)

In forensic toxicology labs, identifying drugs or toxins at low levels via GC-MS demands the highest inertness.
CR Plus columns (CR-1 Plus or CR-5 Plus) are ideal for GC-MS of drugs of abuse, explosives residues, and firearm discharge residues, where they contribute no interfering background.
For headspace GC-MS of blood alcohols or solvent vapors, CR-624 Plus or CR-Wax Plus provide clear separation of volatiles with no bleed up to the final bake-out – critical for legal defensibility of results.

Clinical & Metabolomics

Trace analysis of biomarkers, volatiles, or steroid hormones by GC-MS/SIM often uses derivatization followed by GC. CR Plus columns (like CR-1701 Plus or CR-Wax Plus, depending on polarity needed) give exceptionally sharp peaks for derivatized acids and sugars, with minimal background.
This can improve the detection of compounds like aldehydes in breath (using CR-Wax Plus for maximum polar sensitivity) or steroid metabolites in serum (using CR-1701 Plus for moderate polarity and low bleed).

Industrial Hygiene & Air Monitoring

Monitoring ppb-level hazardous air pollutants (e.g., benzene, 1,3-butadiene, vinyl chloride) via GC-MS requires low background.
CR Plus columns (non-polar or mid-polar depending on target) ensure that clean canister or thermal desorption analyses can be done.
The inertness of CR Plus also prevents adsorption of active analytes like acrolein or formaldehyde (when derivatized), improving accuracy for OSHA/EPA air toxics methods.

High-Sensitivity R&D

In research settings, whenever GC-MS is pushed to its limits – e.g., detecting trace pheromones in environmental samples, or analyzing outgassing compounds from materials – CR Plus columns provide the needed performance headroom.
They are suitable for column bleed-sensitive techniques like GC-TOF-MS and GC×GC-MS (especially in the primary column position, to avoid overwhelming the detector in comprehensive 2D GC).

Performance Benefits

Benefit	Detail
Ultra-Low Bleed	Up to 50% lower bleed at 300 °C compared to standard-grade columns – enabling cleaner mass spectra and better S/N ratio in GC-MS, especially in SIM mode.
Enhanced Sensitivity	Allows detection of femtogram-level analytes like dioxins or trace VOCs, often missed with conventional columns. Ideal for ultra-trace regulatory testing.
Superior Inertness	Proprietary surface deactivation ensures peak symmetry for active compounds like amines, organophosphates, phenols, and sulfur compounds.
Ghost Peak Elimination	Avoid false positives and baseline artifacts – no ghost peaks, no tailing, even for sticky analytes.
First-Injection Success	Higher precision means more successful runs on the first injection, saving analyst time and avoiding costly re-runs.
Longer Column Lifetime	Robust bonded phase and inert surface reduce contamination buildup, resulting in fewer replacements and maintenance cycles.
Reduced Instrument Maintenance	Lower bleed and surface cleanliness reduce detector fouling, meaning fewer bake-outs, less downtime, and extended detector life.
Regulatory Ready	Validated performance meets or exceeds USP, Ph.Eur, EPA, and ISO standards – trusted in pharma, food safety, and environmental testing.
Cost-Efficient Premium	Though a high-performance product, CR Plus offers long-term savings via improved durability, productivity, and fewer consumable replacements.
Confidence in Data Integrity	Analysts can trust every peak – essential for complex or high-stakes testing (e.g., environmental forensics, compliance testing, R&D profiling).

The CR Plus line’s tagline is “When every ion counts.” The scientific advantage is clear: these columns dramatically reduce column-originating noise, thereby improving the signal-to-noise ratio for trace analytes – a direct boost to detection limits. For example, using a CR Plus column can lower the MS baseline enough to detect an extra femtogram of a dioxin or an extra ng/L of a pesticide that might have been lost in background otherwise. The extra deactivation also means sticky compounds (like phenols, amines, organometallics) elute cleanly, enhancing quantitation accuracy. This provides a persuasive benefit to labs: more successful analyses on the first injection, less time spent troubleshooting ghost peaks or tailing.

From a commercial perspective, while CR Plus columns represent a premium product, they offer cost savings in the long run: their extended lifetime (due to robust inertness and lower contamination buildup) means fewer replacements. They also save analyst time (and instrument wear) by reducing the need for frequent maintenance or bake-outs. A hybrid tone example: Scientific data demonstrates CR Plus columns have up to 50% lower bleed at 300 °C than standard columns, translating into real-world advantages like clearer mass spectra and longer maintenance intervals – productivity that any lab manager can appreciate.

In marketing terms, CR Plus columns let users push the boundaries of their GC systems. Whether it’s achieving regulatory compliance for ultra-trace monitoring or simply gaining confidence that an analyte peak is real and not an artifact, these columns provide that higher level of trust. Ultimately, CR Plus delivers “MS-grade performance redefined” – giving chromatographers both the hard data quality and the peace of mind that come from using the best technology available.

Industry Compliance & Standards

CR Plus columns meet all the same formal standards as their Standard counterparts (USP, EPA, etc.), and in many cases exceed the requirements for bleed and inertness specified by these agencies. For instance, some EPA methods for semivolatiles provide a maximum allowable column bleed at a certain temperature – CR Plus columns typically come in well below those limits, providing extra assurance. In the pharmaceutical arena, while USP methods might not explicitly require “MS-grade” columns, the use of CR Plus can be a regulatory advantage: it ensures that system suitability tests (like signal-to-noise for a sensitivity solution) easily pass, and that no unknown peaks (ghost peaks) appear in blank runs.

Additionally, CR Plus columns are fully compatible with sensitive methods like US EPA Method 524.3, which demands very low background for detecting VOCs – our CR-624 Plus’s inertness and low bleed align perfectly with such method’s QC criteria. For laboratories following EUROPA (EN) standards or ISO methods for environmental analysis, CR Plus columns help meet stringent detection limits and identification criteria (e.g., for Persistent Organic Pollutants). In summary, any method that calls for a “low-bleed” or “MS” column (such as “5MS” or “Wax MS” etc.) can be directly fulfilled by a CR Plus column of matching chemistry, with full confidence in meeting method performance requirements.