Ag/AgCI, double junction reference
PCA200
Overview
Entry level automation for pKa, logP/D, Solubility and Dissolution measurement
- pH-metric pKa, logP and logD
- Optional Solubility module
- Optional Dissolution module
- pH range of 1.8 - 12.2 (for standard titrations)
- Measurements down to 0.5mM
- Built-in traceability and reminders
- Supports D-PAS for spectrophotometric pKa
- Temperature controlled sample position
PCA200 is a semi-automated instrument for high-quality measurement. It is ideal for laboratories with a low sample throughput, or for academic research applications.
In pH-metric methods, pKa is measured by titrating a solution of the sample in water or solvent with acid and base, and calculating the pKa from the shape of the titration curve. In principle they will always find the pKas of a sample, provided the concentration is adequate (e.g. >0.0005M). In practice it may be necessary to work at a lower concentration using a pH/UV method and the D-PAS accessory. LogP is also measured by a pH-metric method, based on a two-phase acid- base titration in a mixture of water and octanol. It works well for poorly water-soluble samples, because they tend to dissolve in the octanol phase.
PCA200 can be used with D-PAS for spectrophotometric pKa measurement. Results are calculated by RefinementPro 2 software. PCA200 can also be upgraded to perform Solubility measurements. Since its introduction in 2000, PCA200 has become the instrument of choice for measurements of ionisable compounds in low-throughput environments such as formulation and regulatory support departments in pharmaceutical research and in universities.
specification
pH electrodes
Stirrer
Overhead, variable speed
Temperature probe
PT100, allows automatic temperature compensation
Precision dispensers
Acid and Base, minimum of 0.4µL with 5mL syringe
DualTip dispenser
Two quartz dispenser tubes
Probe movement
Fully automated X-Y axis
Washes
Two water washes and one special wash station provided
Electrode storage/calibration
Two pH7 buffer positions, one storage and one calibration
Single sample holder
Glass temperature control vessel (external circulating bath required)
Purge gas
Nitrogen or argon required
Partition solvents
Supports 7 including Octanol and a generic solvent
CoSolvents
Supports 10 including MeOH and DMSO
Keypad
Liquid-crystal 16-line display for text and graphics, 22-buttons for numeric data entry
System standardisation
Sirius Four-Plus(TM) procedure
Sample concentration
>0.5 mM (depending on the pH range)
pH-range
1.8 - 12.2
Assay volume
Minimum 5mL, maximum 20mL
Spectroscopy
Supports D-PAS
Services required
One mains power inlet (110 or 240 V)
Connection to the PC
Cable from PCA200 to PC serial comm port
Computer
Windows 2000 or XP
Software
PCA200 Firmware Version 2.107. RefinementPro Version 2.0.1.1
Reagent requirements
See 'pH-metric reagents' sheet
Dimension
600 x 440 x 520mm (WxDxH)
Weight of unit
25kg
Dimensions of packaging
900 x 800 x 750mm (WxDxH)
Weight of packed unit
Services required
You will need a computer, which is required to run the software that accompanies the instrumentation. The minimum specification as shown below.
PC specification
Pentium processor Minimum 128 MB RAM Hard disk, CD ROM, floppy drive
1024 x 768 screen display One free PCI expansion slot for data collection card (for D-PAS if required later) of size 175 x 110 x 15mm (LxWxH). Graphics card that supports OpenGL One free serial port
PCA200 connection to the PC
Cable to serial port (no limit to length)
Software required
Windows 2000 or Windows XP operating system PCA200 firmware revision 2.107 RefinementPro version 2.0.1.1
Sirius will supply all the necessary cables between the instrumentation and the PC. You will also require access to a colour printer, either local or networked.
Services required D-PAS
You will need a computer, which is required to run the software that accompanies the instrumentation. The minimum specification as shown below.
PC specification
Pentium processor Minimum 128 MB RAM Hard disk, CD ROM, floppy drive
1024 x 768 screen display One free PCI expansion slot for data collection card (for D-PAS if required later) of size 175 x 110 x 15mm (LxWxH). Graphics card that supports OpenGL One free serial port
D-PAS connection to the PC
Cable to serial port (800mm maximum length) Note: hence the PC must be next to the D-PAS
GLpKa connection to the PC
Cable to serial port (no limit to length)
D-PAS connection to the PCA200
Attaches to the left side of the PCA200 and via-dip pro
Software required
Windows 2000 or Windows XP operating system PCA200 firmware revision 2.107 RefinementPro version 2.0.1.1
Sirius will supply all the necessary cables between the instrumentation and the PC. You will also require access to a colour printer, either local or networked.
Bench space (min)
Width 780mm
Depth 440mm
Height 660mm
This excludes the space required for the PC and printer
Argon
Supply of argon ready to be connected to the right-hand side of PCA200. Your supply must be fitted with a pressure reducer that gives 0-5 bar. The standard working pressure required for PCA200 is 0.5 bar
Temp. circulator
PCA200 has only two dispensers so the ISA water, partition solvents, and co-solvents must be added manually. The volumes added have to be accurate so it is recommended to use positive displacement pipettes, e.g. Eppendorf, which have disposable tips. To cover the range of volumes required, use two variable volume pipettes, i/ 20µL-200µL and ii/500-5000µL
Set-up a constant temperature circulator that will supply temperature controlled water to the PCA200 temperature control unit. Sirius will supply two connectors that fit tubing with an internal diameter of 5mm. The customer is required to supply suitable tubing to fit between these connectors and the water circulator. Ensure that the circulator is below the height of the bench on which the PCA200 will be sited.
A suitable specfication is:
5-80°C
+/-0.1°C
2 psi free flow pressure
Maximum pressure when outlet is blocked 10 psi
4L capacity
Cooling rate of 1 degree per 2-3 minutes
The customer is required to make up the following reagents:
Distilled/de-ionised water
This water is used for making up reagents and for rinsing. It should be freshly distilled or de-ionised, or purchased (e.g. HPLC-grade). The resistivity of the water should be more than 10MW cm.
ISA water (Ionic strength adjusted water): 0.15M Potassium Chloride
Volume required: 4L
This solution is distilled or deionised water with its ionic strength adjusted by
the addition of inert "background electrolyte" salt. This ISA water is used as the
matrix for all the titrations.
Acid titrant: 0.5M Hydrochloric acid
Volume required: 1L
We suggest that customers purchase this ready-made as a volumetric
standard. Check that the solution does not contain mercury salts or other
additives. Sirius recommend Aldrich 31,895-7 05027N HCI solution.
Base: 0.5M Potassium Hydroxide
Volume required: 1L
Must be made from CO2 -free ampoules of KOH solution.
Do not use flakes or pellets of KOH, or ready-made volumetric standards, as
these forms of KOH usually contain significant amounts of CO2-. The Sirius
applications laboratory uses ampoules containing concentrated KOH solution.
Suitable ampoules are supplied by Fisher and Merck.
The KOH solution should not be stored in a glass container after preparation
because KOH slowly dissolves silica from the glass, which interferes with
pKa determinations.
Partition solvent
olume required: 1L
The partition solvent most commonly used is octan-1-ol (C8H17OH) which is the
default partition solvent when GLpKa is installed. The octanol should be
"water-saturated" (this can be done at the time of installation). We recommend
"partition-grade" octanol.
CoSolvent solutions
Up to four CoSolvents can be connected to the 4-way valve. The customer should supply 1L of 80% methanol at the time of installation. Additional solutions can be made up during or after installation. To make up 80% methanol, weigh 11.18g of KCI, dissolve in 200mL of water and add methanol to make volume up to 1L in a volumetric flask.
Surfactant wash solution
Volume required: 1L
This is a 0.5% solution of Triton X-100 in water. Dissolve 5mL of Triton X-100
in 1L of water. (Triton X-100 is a Registered Trademark of Rohm and Haas)
Potassium Hydrogen Phtalate (KHP)
Weight required: 100g
High purity crystalline solid used for standardising base titrant.
Soda lime, self-indicating
Used to recharge the CO2 absorption tube which is fitted to the KOH reagent bottle.
Mid-range Phosphate buffer for D-PAS
Potassium dihydrogen orthophosphate, AR grade (Fisher p/no P/4800/60) 0.40g in 200mL ISA water
Latest product news
PCI card
PCI card A PCI card must be installed in the PC to receive the spectral data from D-PAS. The cases
of some modern computers are so small that there is no room inside them to accommodate the PCI
card, even though the PCI slot is available. We therefore recommend that the PC chosen to use with
D-PAS has one free full height PCI expansion slot for D-PAS data collection size 175 x 110 x 15 mm.
A low profile 2.2 standard slot is unsuitable.
Added: 2006
Literature
Electronic copies of our PCA200 brochure and technical specifications are available for download:
> PCA200 Brochure> PCA200 Techinical Specifications
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AAPS Annual Meeting
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