How to match throughput to a real test menu, what open and closed reagent systems commit you to, why water and power decide reliability, and how to price the consumables that outlive the instrument.
The specification sheet a supplier hands over leads with tests per hour. It is the number that gets compared across bids, and it is close to the least useful number in the decision. An analyser rated at several hundred photometric tests an hour will spend most of its life in a district hospital running fewer than twenty samples a day, and what decides whether it is still working in year four is not its rated speed. It is water, power, reagent supply and whether an engineer can reach it.
Write down the tests you actually report, and the number of samples per working day at the busiest hour rather than the daily average. A laboratory receiving outpatient samples between eight and eleven in the morning has a peak load several times its hourly average, and that peak is what the analyser has to clear before the reporting deadline.
Then split the menu into three groups, because they carry different consequences.
The ion selective electrode module deserves separate thought. It is the part that fails most often, its electrodes are consumable items with a defined life, and on many platforms it is the module that stops the whole analyser when it goes down. If electrolytes are a large share of your workload, ask what the laboratory does on the day that module is out of service, and whether a small standalone electrolyte analyser as a backup costs less than an emergency service call from Dhaka.
This is the decision with the longest tail. A closed system reads a barcode on the manufacturer's own reagent pack and will not run anything else. An open system lets you program parameters and use third party reagents. Suppliers describe the choice in terms of flexibility. In practice it is a choice about who carries the risk of supply.
| Closed system | Open system | |
|---|---|---|
| Reagent source | Manufacturer only | Manufacturer or third party |
| Method parameters | Locked, validated by the manufacturer | Programmed and verified by your laboratory |
| Effect of a supply interruption | Analyser stops until stock arrives | A substitute reagent can be verified in |
| Who owns method performance | The manufacturer, with documented support | Your laboratory, which must hold the evidence |
| Where cost is controlled | At tender, then largely fixed for the instrument life | At every reagent purchase, if you have staff to verify |
For a laboratory working toward ISO 15189 assessment through the Bangladesh Accreditation Board, the closed system is easier to defend, because the method validation dossier comes with the reagent. For a laboratory with an experienced chief technologist and a habit of documenting verification, the open system is real money saved every month. Choosing an open system and then buying whichever reagent is cheapest without verifying it is the worst of both, and it is common.
Ask one question of any closed system bidder and get the answer in writing: what is the reagent price today, and what mechanism sets the price in year three? An attractive instrument price attached to an uncapped reagent commitment is not a saving, it is a deferred cost with no ceiling.
Build the running cost before comparing capital prices. The line items get forgotten in a predictable order.
Multiply by your real annual sample count, not the analyser's capacity, and compare the total across five years. That comparison frequently reverses the ranking that capital price alone produced.
Chemistry analysers need purified water of a defined grade, continuously, at a defined flow and pressure. This is not something to sort out after delivery. Reverse osmosis followed by deionisation, with a storage vessel and a recirculation loop, is the usual arrangement, and every part of it needs somewhere to sit and a drain to discharge to.
Two local conditions make this harder than the manual suggests. Feed water in much of Dhaka and the district towns carries a hardness and particulate load that shortens membrane life, so a pretreatment stage and a realistic membrane replacement budget belong in the plan from day one. And through the monsoon, a storage vessel that sits warm and stagnant over a weekend grows bacteria, which shows up as drifting blanks on Monday morning long before anybody suspects the water. Size the storage for a day's use rather than a week's, keep the loop recirculating, and put the sanitisation interval in the maintenance schedule where it will be signed for.
Where the analyser is going into an existing room, confirm the drain. A benchtop analyser producing liquid waste needs a waste route that is not a bucket somebody empties, and a bucket is what you will find if nobody specified otherwise.
An analyser interrupted in the middle of a run does not simply resume. Depending on the platform it may abort the run, discard the reaction contents, require a wash cycle and a recalibration, and consume reagent doing it. That is the real cost of a power event, and it recurs.
Room conditions matter for the same reason. Manufacturers state an operating temperature and humidity range, and an analyser in a room whose air conditioning is sized for the people rather than the heat load will drift out of that range every afternoon. Size the cooling for the instrument heat output plus the room, and specify two smaller units rather than one large one, so that a compressor failure does not stop the laboratory.
Instrument reliability in Bangladesh is decided less by the badge than by whether a trained engineer can be on site quickly with the part in hand. Before the contract, get three specific answers rather than a general assurance: where the nearest trained engineer is based, which spare parts are held in country as opposed to ordered on demand, and what the escalation route is when a part is not in that stock.
Then write the answers into the contract as response times with a defined start point. A guaranteed attendance measured from the moment a fault is logged means something. A guaranteed attendance measured from when the supplier acknowledges the log does not.
The first is quality control treated as an expense to be minimised. A laboratory running one level of control once a week cannot say what its results were doing between Monday and Friday, and no amount of instrument quality substitutes for that. Budget the control material with the reagent, as one line, so it cannot be cut separately.
The second is documentation that exists only in the supplier's file. Installation records, the room temperature and humidity log, calibration certificates, the water quality record and the service visit reports belong in your laboratory, in your custody, from the day of installation. Reconstructing them two years later, when an assessor asks, is not possible.