Arriving at a crossroads reached by many in the past and doubtless many in the future, Toni Ertl had a stark choice. Faced with unemployment when Oxford Bio-Innovation closed in 2008, he could look for a new job, or go it alone. He chose the latter.

As chief scientist with Bio-Innovation, Mr Ertl had been responsible for the development, manufacture and technical support of its clinical testing service.

Previous roles with Serotec, British Biotech and Wellcome Laboratories had given him unrivalled expertise in assay (analysis) techniques and quality control systems.

Determined to stick to his strengths, Mr Ertl founded The Assay and Control Company earlier this year.

The firm researches and produces controls for immunoassays and new kinds of immunoassays themselves.

An immunoassay is a biochemical test that measures the concentration of a substance in a biological liquid, typically serum or urine, using the reaction of an antibody, or antibodies, to its antigen.

An antigen is a substance that prompts the generation of antibodies and can cause an immune response.

Mr Ertl said: “Unlike many of the small biotechs, I’m not researching brand new technologies — I’m developing and perfecting existing ones.”

Assays can be done in a variety of ways, but are generally mechanised. The result is a figure within a range of probabilities, but knowing whether or not that figure is credible is key to the whole operation.

Each time an assay is run, there will be small variations in the figure, so it is not a case of looking for a number to repeat itself.

Mr Ertl is refining and making control serums identical to live tissue samples, that have been extensively checked to ensure their validity.

The serums have a defined range, so any results from an assay that fall within the range will usually be reliable.

Current efforts are concentrated on fertility tests. Such tests revolve around two hormones, inhibin-b and anti-Müllerian hormone or AMH, both of which affect fertility and pregnancy.

A woman is born with about one million eggs in her ovaries, a number that gradually declines until the menopause.

Some women lose eggs at a faster rate than others and will reach the menopause earlier.

So predicting the chances of pregnancy either by natural fertilisation or in-vitro fertilisation (IVF) is a vital and growing need.

Changes in lifestyle have further increased that demand. Career women who decide to marry later in life want to know if they should begin to try for children now, or whether they have time left before starting a family.

The assay to measure the number of eggs left is known as the Egg Timer test.

During testing before IVF, great care has to be taken. Part of the process calls for stimulation of natural hormones, as if the woman is going part-way through the pregnancy cycle.

Over stimulation can be harmful, so careful monitoring is required.

While the United States is a strong market for the natural and IVF assays, France is the biggest customer.

Mr Ertl said: “The French have taken to this in a big way, especially as they can obtain reimbursement from their medical insurance.”

The company is also researching kisspeptin or Kiss1, so named apparently by researchers at Hershey University after the Hershey’s Kisses chocolates.

Kiss1 affects the onset of puberty. While most children reach puberty within a normal timespan, a significant number do not.

Research is aimed at identifying the role of Kiss1 and how biochemical intervention can move puberty onset to within normal limits.

Mr Ertl founded the company with his own money in the Diagnox laboratories at Upper Heyford. With access to the laboratories and their equipment, he is saved the cost of establishing his own labs.

He said: “It’s a great place to start. I’m surrounded by like-minded people and we help one another and exchange ideas.”

By spring next year, Mr Ertl plans to have a modest turnover from sales of his controls to his target market, laboratories, hospitals, clinics and pharma companies conducting the tests.

Thanks to his career, he boasts an extensive network of researchers in the field.

By year two, the assay for Kiss1 is scheduled to be on the market.

Initial product sales will be in Europe, where regulation is comparatively light, later extending to the US.

The next phase will examine more fertility tests and research markers for ovarian cancer.

Known as the silent killer because it grows without showing symptoms, the disease needs better tests that can recognise the rogue cells that accompany it.

Within three to five years, Mr Ertl plans to have a team of up to eight staff, preferably funded by sales and some contract research rather than capital injection.

He added: “The company is about working with researchers and scientists, which is what I really enjoy.

“And quite a few of my network have expressed interest in providing funding, which augurs well, if I do need the money.”