javascript referencing extrenal database

I am having some difficulty with this script.
It was sent to me by a colleague to modify. There may be some redundant code there, as I only need a small part of what it originally did and have removed what I considered to be irrelevant.

I think I am close - but I keep getting a syntax error.

The DB is a Salesforce.com account.

Any help would be greatly appreciated!!!

{!REQUIRESCRIPT("/soap/ajax/9.0/connection.js")}

var records =
{!GETRECORDIDS($ObjectType.Participants__c)};

if (records[0] == null) {
alert("Please select at least one attendee to
email.");
}
else {
for ( var contactQR =
sforce.connection.query("SELECT Participant FROM Participant__c Where Id = '"
+ contactName+ "'");
var contactName =
contactQR.getArray('records')[0].Participant__c;

//Bind and send email
var singleEmailRequest = new
sforce.SingleEmailMessage();

singleEmailRequest.charset = "UTF8";
singleEmailRequest.subject = "";
singleEmailRequest.saveAsActivity = true;
singleEmailRequest.targetObjectId =
participant__c;

singleEmailRequest.htmlBody = "face=arial size=2>src='https://emea.salesforce.com/servlet/servlet.FileDownload?file=015200000008PB3'
border='0'>" +

//singleEmailRequest.plainTextBody = "Plain
text body";
sendEmailResults =
sforce.connection.sendEmail([singleEmailRequest]);
}

alert
("Your emails has been successfully
sent to selected attendees.");
}