ChromaTwin Pro App – 1-Year Licence

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ChromaTwin Pro App – 1-year Licence

Same gradient table. Same column. Same mobile phase. Different chromatogram.

ACCESS ChromaTwin App™

1. Follow the link: https://chromatwin.vercel.app

2. Enter the access key provided with your purchase.

(This grants you a full 12 months of access to the application).

When a gradient method moves from one HPLC to another, the most common reason it fails is not the column or the chemistry. It is the volume of liquid between the point where the solvents mix and the head of the column - the dwell volume. An Agilent 1260 with a standard mixer holds about 0.6 mL. A Waters Alliance holdsabout 1.2 mL. At 1.0 mL/min the gradient reaches the column 0.6 minutes later on the Waters, every run. Retained peaks move, early peaks do not, the spacing between them changes, and a critical pair that passed in development fails system suitability with nothing else altered.

The usual fix is to shorten the initial hold a little at a time until the chromatogram looks right. That leaves a change in the record with no stated reason. ChromaTwin replaces it with arithmetic on two measured numbers and shows every step.

HOW IT WORKS

Enter the source and target instruments, each measured dwell volume, the method flow rate and the source gradient table. There is no calculate button; the result updates as you type.

- The adjusted gradient table for the receiving instrument, rounded to 0.01 min, the resolution the instruments themselves accept with each row labelled start, hold, ramp or step.

- A column-head chart: the source profile, the uncompensated target and the compensated target on one plot. The compensated trace should sit inside the source band for the whole run, that is the whole test.

- A hardware compensation matrix setting out the derivation line by line: both delay times, the volume difference, the time offset, the leading hold, the feasibility test, the compensation, the rounding cost and the verification.

- Copy table for the method editor, and Copy transfer record,both measured volumes, the derivation, the residual and the limits as plain text for the notebook or the transfer report.

THREE ROUTES, CHOSEN FOR YOU AND TESTED FIRST

- Shift the table: when the receiving instrument has the larger dwell volume and the method opens with a hold long enough to absorb the offset. This is the adaptation USP <621> places on the user.

- Delay the injection: when the hold is too short to cut. You can only cut a hold that is there, so ChromaTwin tests the hold against the offset on every transfer - the check most calculators skip.

- Insert a hold: when the receiving instrument has the smaller dwell volume and the gradient would arrive early.

A re-equilibration guard extends the final hold so the receiving instrument still sweeps the same volume before the next injection.

IT CHECKS ITS OWN ANSWER

The adjusted table - exactly as you would type it - is compared with the source profile at 1500 points across the run, and the largest difference is reported.

An amber warning stays on screen while either dwell volume is a library estimate rather than a measurement. Force a route past its feasibility test and a red warning, the real residual and DO NOT TRANSFER THIS TABLE follow the table into the copied transfer record.

ALSO INSIDE

- Measure Dwell Volume: the ramp-extrapolation protocol step by step, with a cross-check, plus typical values for eleven systems,for orientation only.

- Worked Reference: an Agilent 1260 to Waters Alliance transfer computed live by the same engine, source and adjusted tables side by side.

- Scope & Regulatory: what the method corrects, what it does not, and the USP <621> wording it rests on.

DETERMINISTIC BY DESIGN

Closed-form arithmetic - no model, no randomness. The same inputs always give the same table, and the engine is checked by twenty automated assertions on every build, including the worked example.

WHAT YOU GET

- ChromaTwin in your browser - nothing to install; Chrome, Edge, Firefox, Safari - A 1-year licence from the date of purchase

- A 20-page Professional User Guide: measuring dwell volume, every screen, the three routes, a worked transfer, diagnostics, scope, USP <621>, troubleshooting and a transfer checklist

- A Welcome & Access sheet with your app address and setup steps

WHO IT IS FOR

Analytical scientists transferring gradient HPLC methods between instruments, laboratories or sites - development to QC, sponsor to CRO, an old quaternary system to a new binary one - who want the change justified by arithmetic rather

than by trial and error.

WHO IT IS NOT FOR

If the column, detector or flow rate is changing too, dwell compensation alone will not solve it - see the scope below.

Licence terms

One licence activates on two devices, one at a time - a lab PC and a laptop, say. Licensed per user for 12 months from purchase. You can free a device yourself at any time from inside the app using "Use on another device".

Activating a new device is confirmed by a 6-digit code sent to the address that bought the licence.

Never write "hardware locked",a web page cannot read hardware.

Scope

ChromaTwin corrects one thing, exactly: the gradient delay caused by a difference in dwell volume. It does not correct a different column, detector, cell volume or data rate, another laboratory's water or buffer, gradient distortion from mixer geometry, extra-column dispersion, or a change of flow rate. The delayed-injection route is established practice but is not named in USP <621>; ChromaTwin says so rather than citing the chapter for it.

ChromaTwin is a calculation aid. It is not a validated computerised system and produces no controlled GxP record. Every transferred method must be confirmed on the receiving instrument and approved under your own quality system.

Calculations run in your browser; nothing you enter is uploaded, and there is no account to create.

Buying for your lab or company?

Pay by card or PayPal and download a PDF invoice with your company name and VAT/tax number from your receipt. Need an invoice before you pay, a purchase-order reference, or licences for 5 or 10 analysts? Email practicalpharma.science@yahoo.com with your company name, billing contact and number of users, and you'll receive a quote within one business day.

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